Scaling behavior in exclusive meson photoproduction from Jefferson Lab at large momentum transfers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dey, Biplab

2014-07-01

With the availability of new high-statistics and wide-angle measurements for several exclusive non-πN meson photoproduction channels from Jefferson Lab, we examine the fundamental scaling law of 90° scattering in QCD that was originally derived in the high-energy perturbative limit. The data show scaling to be prominently visible even in the medium-energy domain of 2.5 GeV ≲√s≲2.84 GeV, where √s is the center-of-mass energy. While constituent quark exchange suffices for pseudoscalar mesons, additional gluon exchanges from higher Fock states of the hadronic wave functions appear be needed for vector-meson production. Finally, the case of the Φ(1020), where two-gluon exchanges are knownmore » to dominate, is especially illuminating.« less

First measurement of the Sivers asymmetry for gluons using SIDIS data

NASA Astrophysics Data System (ADS)

Adolph, C.; Aghasyan, M.; Akhunzyanov, R.; Alexeev, M. G.; Alexeev, G. D.; Amoroso, A.; Andrieux, V.; Anfimov, N. V.; Anosov, V.; Antoshkin, A.; Augsten, K.; Augustyniak, W.; Austregesilo, A.; Azevedo, C. D. R.; Badełek, B.; Balestra, F.; Ball, M.; Barth, J.; Beck, R.; Bedfer, Y.; Bernhard, J.; Bicker, K.; Bielert, E. R.; Birsa, R.; Bodlak, M.; Bordalo, P.; Bradamante, F.; Braun, C.; Bressan, A.; Büchele, M.; Chang, W.-C.; Chatterjee, C.; Chiosso, M.; Choi, I.; Chung, S.-U.; Cicuttin, A.; Crespo, M. L.; Curiel, Q.; Dalla Torre, S.; Dasgupta, S. S.; Dasgupta, S.; Denisov, O. Yu.; Dhara, L.; Donskov, S. V.; Doshita, N.; Dreisbach, Ch.; Duic, V.; Dünnweber, W.; Dziewiecki, M.; Efremov, A.; Eversheim, P. D.; Eyrich, W.; Faessler, M.; Ferrero, A.; Finger, M.; Finger, M.; Fischer, H.; Franco, C.; Du Fresne von Hohenesche, N.; Friedrich, J. M.; Frolov, V.; Fuchey, E.; Gautheron, F.; Gavrichtchouk, O. P.; Gerassimov, S.; Giarra, J.; Giordano, F.; Gnesi, I.; Gorzellik, M.; Grabmüller, S.; Grasso, A.; Grosse Perdekamp, M.; Grube, B.; Grussenmeyer, T.; Guskov, A.; Haas, F.; Hahne, D.; Hamar, G.; von Harrach, D.; Heinsius, F. H.; Heitz, R.; Herrmann, F.; Horikawa, N.; D'Hose, N.; Hsieh, C.-Y.; Huber, S.; Ishimoto, S.; Ivanov, A.; Ivanshin, Yu.; Iwata, T.; Jary, V.; Joosten, R.; Jörg, P.; Kabuß, E.; Kerbizi, A.; Ketzer, B.; Khaustov, G. V.; Khokhlov, Yu. A.; Kisselev, Yu.; Klein, F.; Klimaszewski, K.; Koivuniemi, J. H.; Kolosov, V. N.; Kondo, K.; Königsmann, K.; Konorov, I.; Konstantinov, V. F.; Kotzinian, A. M.; Kouznetsov, O. M.; Krämer, M.; Kremser, P.; Krinner, F.; Kroumchtein, Z. V.; Kulinich, Y.; Kunne, F.; Kurek, K.; Kurjata, R. P.; Lednev, A. A.; Lehmann, A.; Levillain, M.; Levorato, S.; Lian, Y.-S.; Lichtenstadt, J.; Longo, R.; Maggiora, A.; Magnon, A.; Makins, N.; Makke, N.; Mallot, G. K.; Marianski, B.; Martin, A.; Marzec, J.; Matoušek, J.; Matsuda, H.; Matsuda, T.; Meshcheryakov, G. V.; Meyer, M.; Meyer, W.; Mikhailov, Yu. V.; Mikhasenko, M.; Mitrofanov, E.; Mitrofanov, N.; Miyachi, Y.; Nagaytsev, A.; Nerling, F.; Neyret, D.; Nový, J.; Nowak, W.-D.; Nukazuka, G.; Nunes, A. S.; Olshevsky, A. G.; Orlov, I.; Ostrick, M.; Panzieri, D.; Parsamyan, B.; Paul, S.; Peng, J.-C.; Pereira, F.; Pešek, M.; Peshekhonov, D. V.; Pierre, N.; Platchkov, S.; Pochodzalla, J.; Polyakov, V. A.; Pretz, J.; Quaresma, M.; Quintans, C.; Ramos, S.; Regali, C.; Reicherz, G.; Riedl, C.; Roskot, M.; Rogacheva, N. S.; Ryabchikov, D. I.; Rybnikov, A.; Rychter, A.; Salac, R.; Samoylenko, V. D.; Sandacz, A.; Santos, C.; Sarkar, S.; Savin, I. A.; Sawada, T.; Sbrizzai, G.; Schiavon, P.; Schmidt, K.; Schmieden, H.; Schönning, K.; Seder, E.; Selyunin, A.; Silva, L.; Sinha, L.; Sirtl, S.; Slunecka, M.; Smolik, J.; Srnka, A.; Steffen, D.; Stolarski, M.; Subrt, O.; Sulc, M.; Suzuki, H.; Szabelski, A.; Szameitat, T.; Sznajder, P.; Takekawa, S.; Tasevsky, M.; Tessaro, S.; Tessarotto, F.; Thibaud, F.; Thiel, A.; Tosello, F.; Tskhay, V.; Uhl, S.; Vauth, A.; Veloso, J.; Virius, M.; Vondra, J.; Wallner, S.; Weisrock, T.; Wilfert, M.; Ter Wolbeek, J.; Zaremba, K.; Zavada, P.; Zavertyaev, M.; Zemlyanichkina, E.; Zhuravlev, N.; Ziembicki, M.; Zink, A.; Compass Collaboration

2017-09-01

The Sivers function describes the correlation between the transverse spin of a nucleon and the transverse motion of its partons. For quarks, it was studied in previous measurements of the azimuthal asymmetry of hadrons produced in semi-inclusive deep inelastic scattering of leptons off transversely polarised nucleon targets, and it was found to be non-zero. In this letter the evaluation of the Sivers asymmetry for gluons is presented. The contribution of the photon-gluon fusion subprocess is enhanced by requiring two high transverse-momentum hadrons. The analysis method is based on a Monte Carlo simulation that includes three hard processes: photon-gluon fusion, QCD Compton scattering and the leading-order virtual-photon absorption process. The Sivers asymmetries of the three processes are simultaneously extracted using the LEPTO event generator and a neural network approach. The method is applied to samples of events containing at least two hadrons with large transverse momentum from the COMPASS data taken with a 160 GeV/c muon beam scattered off transversely polarised deuterons and protons. With a significance of about two standard deviations, a negative value is obtained for the gluon Sivers asymmetry. The result of a similar analysis for a Collins-like asymmetry for gluons is consistent with zero.

Resonance--Continuum Interference in Light Higgs Boson Production at a Photon Collider

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dixon, Lance J.; Sofianatos, Yorgos; /SLAC /Stanford U., Phys. Dept.

2009-01-06

We study the effect of interference between the Standard Model Higgs boson resonance and the continuum background in the process {gamma}{gamma} {yields} H {yields} b{bar b} at a photon collider. Taking into account virtual gluon exchange between the final-state quarks, we calculate the leading corrections to the height of the resonance for the case of a light (m{sub H} < 160 GeV) Higgs boson. We find that the interference is destructive and around 0.1-0.2% of the peak height, depending on the mass of the Higgs and the scattering angle. This suppression is smaller by an order of magnitude than themore » anticipated experimental accuracy at a photon collider. However, the fractional suppression can be significantly larger if the Higgs coupling to b quarks is increased by physics beyond the Standard Model.« less

Mixing of the lowest-lying qqq configurations with JP =1/2- in different hyperfine interaction models

NASA Astrophysics Data System (ADS)

Chen, Jia; An, Chunsheng; Chen, Hong

2018-02-01

We investigate mixing of the lowest-lying qqq configurations with JP = 1/2- caused by the hyperfine interactions between quarks mediated by Goldstone Boson Exchange, One Gluon Exchange, and both Goldstone Boson and One Gluon exchange, respectively. The first orbitally excited nucleon, Σ, Λ and Ξ states are considered. Contributions of both the contact term and tensor term are taken into account. Our numerical results show that mixing of the studied configurations in the two employed hyperfine interaction models are very different. Therefore, the present results, which should affect the strong and electromagnetic decays of baryon resonances, may be used to examine the present employed hyperfine interaction models. Supported by National Natural Science Foundation of China (11675131,11645002), Chongqing Natural Science Foundation (cstc2015jcyjA00032) and Fundamental Research Funds for the Central Universities (SWU115020)

Photon induced {lambda}(1520) production and the role of the K* exchange

DOE Office of Scientific and Technical Information (OSTI.GOV)

Toki, Hiroshi; Research Center for Nuclear Physics; Garcia-Recio, Carmen

2008-02-01

We study the photon induced {lambda}(1520) production in the effective Lagrangian method near threshold, E{sub {gamma}}{sup LAB}{<=}2 GeV, and in the quark-gluon string model at higher energies 3 GeV{<=}E{sub {gamma}}{sup LAB}{<=}5 GeV. In particular, we study the role of the K* exchange for the production of {lambda}(1520) within the SU(6) Weinberg-Tomozowa chiral unitary model proposed by Garcia-Recio, Nieves, and Salcedo [Phys. Rev. D 74, 034025 (2006)]. The coupling of the {lambda}(1520) resonance to the NK* pair, which is dynamically generated, turns out to be relatively small and, thus, the K exchange mechanism dominates the reaction. In the higher energy region,more » where experimental data are available, the quark-gluon string mechanism with the K Regge trajectory reproduces both the energy and the angular distribution dependences of the {lambda}(1520) photoproduction reaction.« less

Leading-order determination of the gluon polarisation from semi-inclusive deep inelastic scattering data

NASA Astrophysics Data System (ADS)

Adolph, C.; Aghasyan, M.; Akhunzyanov, R.; Alexeev, M. G.; Alexeev, G. D.; Amoroso, A.; Andrieux, V.; Anfimov, N. V.; Anosov, V.; Augustyniak, W.; Austregesilo, A.; Azevedo, C. D. R.; Badełek, B.; Balestra, F.; Barth, J.; Beck, R.; Bedfer, Y.; Bernhard, J.; Bicker, K.; Bielert, E. R.; Birsa, R.; Bisplinghoff, J.; Bodlak, M.; Boer, M.; Bordalo, P.; Bradamante, F.; Braun, C.; Bressan, A.; Büchele, M.; Chang, W.-C.; Chiosso, M.; Choi, I.; Chung, S.-U.; Cicuttin, A.; Crespo, M. L.; Curiel, Q.; Dalla Torre, S.; Dasgupta, S. S.; Dasgupta, S.; Denisov, O. Yu.; Dhara, L.; Donskov, S. V.; Doshita, N.; Duic, V.; Dünnweber, W.; Dziewiecki, M.; Efremov, A.; Eversheim, P. D.; Eyrich, W.; Faessler, M.; Ferrero, A.; Finger, M.; , M. Finger, Jr.; Fischer, H.; Franco, C.; du Fresne von Hohenesche, N.; Friedrich, J. M.; Frolov, V.; Fuchey, E.; Gautheron, F.; Gavrichtchouk, O. P.; Gerassimov, S.; Giordano, F.; Gnesi, I.; Gorzellik, M.; Grabmüller, S.; Grasso, A.; Grosse Perdekamp, M.; Grube, B.; Grussenmeyer, T.; Guskov, A.; Haas, F.; Hahne, D.; von Harrach, D.; Hashimoto, R.; Heinsius, F. H.; Heitz, R.; Herrmann, F.; Hinterberger, F.; Horikawa, N.; d'Hose, N.; Hsieh, C.-Y.; Huber, S.; Ishimoto, S.; Ivanov, A.; Ivanshin, Yu.; Iwata, T.; Jahn, R.; Jary, V.; Joosten, R.; Jörg, P.; Kabuß, E.; Ketzer, B.; Khaustov, G. V.; Khokhlov, Yu. A.; Kisselev, Yu.; Klein, F.; Klimaszewski, K.; Koivuniemi, J. H.; Kolosov, V. N.; Kondo, K.; Königsmann, K.; Konorov, I.; Konstantinov, V. F.; Kotzinian, A. M.; Kouznetsov, O. M.; Krämer, M.; Kremser, P.; Krinner, F.; Kroumchtein, Z. V.; Kulinich, Y.; Kunne, F.; Kurek, K.; Kurjata, R. P.; Lednev, A. A.; Lehmann, A.; Levillain, M.; Levorato, S.; Lichtenstadt, J.; Longo, R.; Maggiora, A.; Magnon, A.; Makins, N.; Makke, N.; Mallot, G. K.; Marchand, C.; Marianski, B.; Martin, A.; Marzec, J.; Matoušek, J.; Matsuda, H.; Matsuda, T.; Meshcheryakov, G. V.; Meyer, W.; Michigami, T.; Mikhailov, Yu. V.; Mikhasenko, M.; Miyachi, Y.; Montuenga, P.; Nagaytsev, A.; Nerling, F.; Neyret, D.; Nikolaenko, V. I.; Nový, J.; Nowak, W.-D.; Nukazuka, G.; Nunes, A. S.; Olshevsky, A. G.; Orlov, I.; Ostrick, M.; Panzieri, D.; Parsamyan, B.; Paul, S.; Peng, J.-C.; Pereira, F.; Pešek, M.; Peshekhonov, D. V.; Platchkov, S.; Pochodzalla, J.; Polyakov, V. A.; Pretz, J.; Quaresma, M.; Quintans, C.; Ramos, S.; Regali, C.; Reicherz, G.; Riedl, C.; Roskot, M.; Rossiyskaya, N. S.; Ryabchikov, D. I.; Rybnikov, A.; Rychter, A.; Salac, R.; Samoylenko, V. D.; Sandacz, A.; Santos, C.; Sarkar, S.; Savin, I. A.; Sawada, T.; Sbrizzai, G.; Schiavon, P.; Schmidt, K.; Schmieden, H.; Schönning, K.; Schopferer, S.; Seder, E.; Selyunin, A.; Shevchenko, O. Yu.; Silva, L.; Sinha, L.; Sirtl, S.; Slunecka, M.; Smolik, J.; Sozzi, F.; Srnka, A.; Stolarski, M.; Sulc, M.; Suzuki, H.; Szabelski, A.; Szameitat, T.; Sznajder, P.; Takekawa, S.; Tasevsky, M.; Tessaro, S.; Tessarotto, F.; Thibaud, F.; Tosello, F.; Tskhay, V.; Uhl, S.; Veloso, J.; Virius, M.; Vondra, J.; Weisrock, T.; Wilfert, M.; ter Wolbeek, J.; Zaremba, K.; Zavada, P.; Zavertyaev, M.; Zemlyanichkina, E.; Ziembicki, M.; Zink, A.

2017-04-01

Using a novel analysis technique, the gluon polarisation in the nucleon is re-evaluated using the longitudinal double-spin asymmetry measured in the cross section of semi-inclusive single-hadron muoproduction with photon virtuality Q^2>1 (GeV/c)^2. The data were obtained by the COMPASS experiment at CERN using a 160 GeV/ c polarised muon beam impinging on a polarised ^6LiD target. By analysing the full range in hadron transverse momentum p_T, the different p_T-dependences of the underlying processes are separated using a neural-network approach. In the absence of pQCD calculations at next-to-leading order in the selected kinematic domain, the gluon polarisation Δ g/g is evaluated at leading order in pQCD at a hard scale of μ ^2= < Q^2 \\rangle = 3 (GeV/c)^2. It is determined in three intervals of the nucleon momentum fraction carried by gluons, x_g, covering the range 0.04 < x_{g} < 0.28 and does not exhibit a significant dependence on x_g. The average over the three intervals, < Δ g/g \\rangle = 0.113 ± 0.038_(stat.)± 0.036_(syst.) at < x_g \\rangle ≈ 0.10, suggests that the gluon polarisation is positive in the measured x_g range.

A Reappraisal of the Mechanism of Pion Exchange and Its Implications for the Teaching of Particle Physics

ERIC Educational Resources Information Center

Dunne, Peter

2002-01-01

The origins of the pion exchange model of nuclear forces are described and the exchange process is reinterpreted in the light of current views on the quark-gluon structure of nucleons. It is suggested that the reinterpretation might provide a picture of cohesive nuclear forces that is more intellectually satisfying than that produced by the…

Gluon-fusion Higgs production in the Standard Model Effective Field Theory

NASA Astrophysics Data System (ADS)

Deutschmann, Nicolas; Duhr, Claude; Maltoni, Fabio; Vryonidou, Eleni

2017-12-01

We provide the complete set of predictions needed to achieve NLO accuracy in the Standard Model Effective Field Theory at dimension six for Higgs production in gluon fusion. In particular, we compute for the first time the contribution of the chromomagnetic operator {\\overline{Q}}_LΦ σ {q}_RG at NLO in QCD, which entails two-loop virtual and one-loop real contributions, as well as renormalisation and mixing with the Yukawa operator {Φ}^{\\dagger}Φ{\\overline{Q}}_LΦ {q}_R and the gluon-fusion operator Φ†Φ GG. Focusing on the top-quark-Higgs couplings, we consider the phenomenological impact of the NLO corrections in constraining the three relevant operators by implementing the results into the M adG raph5_ aMC@NLO frame-work. This allows us to compute total cross sections as well as to perform event generation at NLO that can be directly employed in experimental analyses.

Regge vertex for quark production in the central rapidity region in the next-to-leading order

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kozlov, M. G., E-mail: M.G.Kozlov@inp.nsk.su; Reznichenko, A. V., E-mail: A.V.Reznichenko@inp.nsk.su

2016-03-15

The effective vertex for quark production in the interaction of a Reggeized quark and a Reggeized gluon is calculated in the next-to-leading order (NLO). The resulting vertex is the missing component of the NLO multi-Regge amplitude featuring quark and gluon exchanges in the t channels. This calculation will make it possible to develop in future the bootstrap approach to proving quark Reggeization in the next-to-leading logarithmic approximation.

From webs to polylogarithms

NASA Astrophysics Data System (ADS)

Gardi, Einan

2014-04-01

We compute a class of diagrams contributing to the multi-leg soft anomalous dimension through three loops, by renormalizing a product of semi-infinite non-lightlike Wilson lines in dimensional regularization. Using non-Abelian exponentiation we directly compute contributions to the exponent in terms of webs. We develop a general strategy to compute webs with multiple gluon exchanges between Wilson lines in configuration space, and explore their analytic structure in terms of α ij , the exponential of the Minkowski cusp angle formed between the lines i and j. We show that beyond the obvious inversion symmetry α ij → 1 /α ij , at the level of the symbol the result also admits a crossing symmetry α ij → - α ij , relating spacelike and timelike kinematics, and hence argue that in this class of webs the symbol alphabet is restricted to α ij and . We carry out the calculation up to three gluons connecting four Wilson lines, finding that the contributions to the soft anomalous dimension are remarkably simple: they involve pure functions of uniform weight, which are written as a sum of products of polylogarithms, each depending on a single cusp angle. We conjecture that this type of factorization extends to all multiple-gluon-exchange contributions to the anomalous dimension.

Scale dependencies of proton spin constituents with a nonperturbative αs

NASA Astrophysics Data System (ADS)

Jia, Shaoyang; Huang, Feng

2012-11-01

By introducing the contribution from dynamically generated gluon mass, we present a brand new parametrized form of QCD beta function to get an inferred limited running behavior of QCD coupling constant αs. This parametrized form is regarded as an essential factor to determine the scale dependencies of the proton spin constituents at the very low scale. In order to compare with experimental results directly, we work within the gauge-invariant framework to decompose the proton spin. Utilizing the updated next-to-next-leading-order evolution equations for angular momentum observables within a modified minimal subtraction scheme, we indicate that gluon contribution to proton spin cannot be ignored. Specifically, by assuming asymptotic limits of the total quark/gluon angular momentum valid, respectively, the scale dependencies of quark angular momentum Jq and gluon angular momentum Jg down to Q2˜1GeV2 are presented, which are comparable with the preliminary analysis of deeply virtual Compton scattering experiments by HERMES and JLab. After solving scale dependencies of quark spin ΔΣq, orbital angular momenta of quarks Lq are given by subtraction, presenting a holistic picture of proton spin partition within up and down quarks at a low scale.

Virtual photon emission from a quark-gluon plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Suryanarayana, S. V.

We present phenomenological formulas for virtual photon emission rates from a thermalized quark-gluon plasma (QGP) that include bremsstrahlung and annihilation with scattering (AWS) mechanisms along with the Landau-Pomeranchuk-Migdal (LPM) effects. For this purpose we follow the approach of generalized emission functions (GEF) for virtual photon emission, we showed earlier for a fixed temperature and strong coupling constant. In the present work, we extend the LPM calculations for several temperatures and strong coupling strengths, photon energies (q{sub 0}), photon mass (Q{sup 2}), and quark energies (p{sub 0}). We generalize the dynamical scaling variables, x{sub T},x{sub L}, for bremsstrahlung and AWS processesmore » that are now functions of variables p{sub 0},q{sub 0},Q{sup 2},T,{alpha}{sub s}. The GEF introduced earlier, g{sub T}{sup b},g{sub T}{sup a},g{sub L}{sup b},g{sub L}{sup a}, are also generalized for any temperatures and coupling strengths. From this, the imaginary part of the photon polarization tensor as a function of photon mass and energy has been calculated as a one-dimensional integral over these GEF and parton distribution functions in the plasma. By fitting these polarization tensors obtained from GEF method, we obtained a phenomenological formula for virtual photon emission rates as a function of (q{sub 0},Q{sup 2},T,{alpha}{sub s}) that includes bremsstrahlung and AWS mechanisms with LPM effects.« less

Heavy-quark production in gluon fusion at two loops in QCD

NASA Astrophysics Data System (ADS)

Czakon, M.; Mitov, A.; Moch, S.

2008-07-01

We present the two-loop virtual QCD corrections to the production of heavy quarks in gluon fusion. The results are exact in the limit when all kinematical invariants are large compared to the mass of the heavy quark up to terms suppressed by powers of the heavy-quark mass. Our derivation uses a simple relation between massless and massive QCD scattering amplitudes as well as a direct calculation of the massive amplitude at two loops. The results presented here together with those obtained previously for quark-quark scattering form important parts of the next-to-next-to-leading order QCD corrections to heavy-quark production in hadron-hadron collisions.

A new numerical method for inverse Laplace transforms used to obtain gluon distributions from the proton structure function

NASA Astrophysics Data System (ADS)

Block, Martin M.; Durand, Loyal

2011-11-01

We recently derived a very accurate and fast new algorithm for numerically inverting the Laplace transforms needed to obtain gluon distributions from the proton structure function F2^{γ p}(x,Q2). We numerically inverted the function g( s), s being the variable in Laplace space, to G( v), where v is the variable in ordinary space. We have since discovered that the algorithm does not work if g( s)→0 less rapidly than 1/ s as s→∞, e.g., as 1/ s β for 0< β<1. In this note, we derive a new numerical algorithm for such cases, which holds for all positive and non-integer negative values of β. The new algorithm is exact if the original function G( v) is given by the product of a power v β-1 and a polynomial in v. We test the algorithm numerically for very small positive β, β=10-6 obtaining numerical results that imitate the Dirac delta function δ( v). We also devolve the published MSTW2008LO gluon distribution at virtuality Q 2=5 GeV2 down to the lower virtuality Q 2=1.69 GeV2. For devolution, β is negative, giving rise to inverse Laplace transforms that are distributions and not proper functions. This requires us to introduce the concept of Hadamard Finite Part integrals, which we discuss in detail.

Horizontal Curve Virtual Peer Exchange : an RSPCB Peer Exchange

DOT National Transportation Integrated Search

2014-06-01

This report summarizes the Horizontal Curve Virtual Peer Exchange sponsored by the Federal Highway Administration (FHWA) Office of Safetys Roadway Safety Professional Capacity Building Program on June 17, 2014. This virtual peer exchange was the f...

A new approach to analytic, non-perturbative and gauge-invariant QCD

NASA Astrophysics Data System (ADS)

Fried, H. M.; Grandou, T.; Sheu, Y.-M.

2012-11-01

Following a previous calculation of quark scattering in eikonal approximation, this paper presents a new, analytic and rigorous approach to the calculation of QCD phenomena. In this formulation a basic distinction between the conventional "idealistic" description of QCD and a more "realistic" description is brought into focus by a non-perturbative, gauge-invariant evaluation of the Schwinger solution for the QCD generating functional in terms of the exact Fradkin representations of Green's functional G(x,y|A) and the vacuum functional L[A]. Because quarks exist asymptotically only in bound states, their transverse coordinates can never be measured with arbitrary precision; the non-perturbative neglect of this statement leads to obstructions that are easily corrected by invoking in the basic Lagrangian a probability amplitude which describes such transverse imprecision. The second result of this non-perturbative analysis is the appearance of a new and simplifying output called "Effective Locality", in which the interactions between quarks by the exchange of a "gluon bundle"-which "bundle" contains an infinite number of gluons, including cubic and quartic gluon interactions-display an exact locality property that reduces the several functional integrals of the formulation down to a set of ordinary integrals. It should be emphasized that "non-perturbative" here refers to the effective summation of all gluons between a pair of quark lines-which may be the same quark line, as in a self-energy graph-but does not (yet) include a summation over all closed-quark loops which are tied by gluon-bundle exchange to the rest of the "Bundle Diagram". As an example of the power of these methods we offer as a first analytic calculation the quark-antiquark binding potential of a pion, and the corresponding three-quark binding potential of a nucleon, obtained in a simple way from relevant eikonal scattering approximations. A second calculation, analytic, non-perturbative and gauge-invariant, of a nucleon-nucleon binding potential to form a model deuteron, will appear separately.

Glauber gluons and multiple parton interactions

NASA Astrophysics Data System (ADS)

Gaunt, Jonathan R.

2014-07-01

We show that for hadronic transverse energy E T in hadron-hadron collisions, the classic Collins-Soper-Sterman (CSS) argument for the cancellation of Glauber gluons breaks down at the level of two Glauber gluons exchanged between the spectators. Through an argument that relates the diagrams with these Glauber gluons to events containing additional soft scatterings, we suggest that this failure of the CSS cancellation actually corresponds to a failure of the `standard' factorisation formula with hard, soft and collinear functions to describe E T at leading power. This is because the observable receives a leading power contribution from multiple parton interaction (or spectator-spectator Glauber) processes. We also suggest that the same argument can be used to show that a whole class of observables, which we refer to as MPI sensitive observables, do not obey the standard factorisation at leading power. MPI sensitive observables are observables whose distributions in hadron-hadron collisions are disrupted strongly by the presence of multiple parton interactions (MPI) in the event. Examples of further MPI sensitive observables include the beam thrust B {/a, b +} and transverse thrust.

Higher order corrections to mixed QCD-EW contributions to Higgs boson production in gluon fusion

NASA Astrophysics Data System (ADS)

Bonetti, Marco; Melnikov, Kirill; Tancredi, Lorenzo

2018-03-01

We present an estimate of the next-to-leading-order (NLO) QCD corrections to mixed QCD-electroweak contributions to the Higgs boson production cross section in gluon fusion, combining the recently computed three-loop virtual corrections and the approximate treatment of real emission in the soft approximation. We find that the NLO QCD corrections to the mixed QCD-electroweak contributions are nearly identical to NLO QCD corrections to QCD Higgs production. Our result confirms an earlier estimate of these O (α αs2) effects by Anastasiou et al. [J. High Energy Phys. 04 (2009) 003, 10.1088/1126-6708/2009/04/003] and provides further support for the factorization approximation of QCD and electroweak corrections.

Non-cancellation of electroweak logarithms in high-energy scattering

DOE PAGES

Manohar, Aneesh V.; Shotwell, Brian; Bauer, Christian W.; ...

2015-01-01

We study electroweak Sudakov corrections in high energy scattering, and the cancellation between real and virtual Sudakov corrections. Numerical results are given for the case of heavy quark production by gluon collisions involving the rates gg→t¯t, b¯b, t¯bW, t¯tZ, b¯bZ, t¯tH, b¯bH. Gauge boson virtual corrections are related to real transverse gauge boson emission, and Higgs virtual corrections to Higgs and longitudinal gauge boson emission. At the LHC, electroweak corrections become important in the TeV regime. At the proposed 100TeV collider, electroweak interactions enter a new regime, where the corrections are very large and need to be resummed.

Electric dipole moment of the electron and of the neutron

NASA Technical Reports Server (NTRS)

Barr, S. M.; Zee, A.

1990-01-01

It is shown that if Higgs-boson exchange mediates CP violation a significant electric dipole moment for the electron can result. Analogous effects can contribute to the neutron's electric dipole moment at a level competitive with Weinberg's three-gluon operator.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Campbell, John M.; Ellis, R. Keith; Czakon, Michal

We present results for the production of a pair of on-shell Z bosons via gluon-gluon fusion. This process occurs both through the production and decay of the Higgs boson, and through continuum production where the Z boson couples to a loop of massless quarks or to a massive quark. We calculate the interference of the two processes and its contribution to the cross section up to and including order O(αmore » $$_{s}^{3}$$ ). The two-loop contributions to the amplitude are all known analytically, except for the continuum production through loops of top quarks of mass m. The latter contribution is important for the invariant mass of the two Z bosons, (as measured by the mass of their leptonic decay products, m$$_{4l}$$), in a regime where m$$_{4l}$$ ≥ 2m because of the contributions of longitudinal bosons. We examine all the contributions to the virtual amplitude involving top quarks, as expansions about the heavy top quark limit combined with a conformal mapping and Padé approximants. Comparison with the analytic results, where known, allows us to assess the validity of the heavy quark expansion, and it extensions. We give results for the NLO corrections to this interference, including both real and virtual radiation.« less

Single jet and prompt-photon inclusive production with multi-Regge kinematics: From Tevatron to LHC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kniehl, B. A.; Saleev, V. A.; Shipilova, A. V.

2011-10-01

We study single jet and prompt-photon inclusive hadroproduction with multi-Regge kinematics invoking the hypothesis of parton Reggeization in t-channel exchanges at high energy. In this approach, the leading contributions are due to the fusion of two Reggeized gluons into a Yang-Mills gluon and the annihilation of a Reggeized quark-antiquark pair into a photon, respectively. Adopting the Kimber-Martin-Ryskin and Bluemlein prescriptions to derive unintegrated gluon and quark distribution functions of the proton from their collinear counterparts, for which we use the Martin-Roberts-Stirling-Thorne set, we evaluate cross section distributions in transverse momentum (p{sub T}) and rapidity. Without adjusting any free parameters, wemore » find good agreement with measurements by the CDF and D0 Collaborations at the Tevatron and by the ATLAS Collaboration at the LHC in the region 2p{sub T}/{radical}(S) < or approx. 0.1, where {radical}(S) is the hadronic c.m. energy.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boroun, G. R., E-mail: boroun@razi.ac.ir; Rezaie, B.

We present a set of formulas using the solution of the QCD Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) evolution equation to extract of the exponents of the gluon distribution, {lambda}{sub g}, and structure function, {lambda}{sub S}, from the Regge-like behavior at low x. The exponents are found to be independent of x and to increase linearly with lnQ{sup 2} and are compared with the most data from the H1 Collaboration. We also calculated the structure function F{sub 2}(x,Q{sup 2}) and the gluon distribution G(x,Q{sup 2}) at low x assuming the Regge-like behavior of the gluon distribution function at this limit and compared them withmore » an NLO-QCD fit to theH1 data, two-Pomeron fit, multipole Pomeron exchange fit, and MRST (A.D. Martin, R.G. Roberts, W.J. Stirling, and R.S. Thorne), DL (A. Donnachie and P.V. Landshoff), and NLO GRV (M. Gluek, E. Reya, and A. Vogt) fit results.« less

Higgs Boson Pair Production in Gluon Fusion at Next-to-Leading Order with Full Top-Quark Mass Dependence.

PubMed

Borowka, S; Greiner, N; Heinrich, G; Jones, S P; Kerner, M; Schlenk, J; Schubert, U; Zirke, T

2016-07-01

We present the calculation of the cross section and invariant mass distribution for Higgs boson pair production in gluon fusion at next-to-leading order (NLO) in QCD. Top-quark masses are fully taken into account throughout the calculation. The virtual two-loop amplitude has been generated using an extension of the program GoSam supplemented with an interface to Reduze for the integral reduction. The occurring integrals have been calculated numerically using the program SecDec. Our results, including the full top-quark mass dependence for the first time, allow us to assess the validity of various approximations proposed in the literature, which we also recalculate. We find substantial deviations between the NLO result and the different approximations, which emphasizes the importance of including the full top-quark mass dependence at NLO.

X(3872), IG(JPC) = 0+(1++), as the χc1(2P) charmonium

NASA Astrophysics Data System (ADS)

Achasov, N. N.; Rogozina, E. V.

2015-09-01

Contrary to almost standard opinion that the X(3872) resonance is the D∗0D¯0 + c.c. molecule or the qcq¯c¯ four-quark state, we discuss the scenario where the X(3872) resonance is the cc¯ = χc1(2P) charmonium which “sits on” the D∗0D¯0 threshold. We explain the shift of the mass of the X(3872) resonance with respect to the prediction of a potential model for the mass of the χc1(2P) charmonium by the contribution of the virtual D∗D¯ + c.c. intermediate states into the self energy of the X(3872) resonance. This allows us to estimate the coupling constant of the X(7872) resonance with the D∗0D¯0 channel, the branching ratio of the X(3872) → D∗0D¯0 + c.c. decay, and the branching ratio of the X(3872) decay into all non-D∗0D¯0 + c.c. states. We predict a significant number of unknown decays of X(3872) via two gluon: X(3872) →gluon gluon →hadrons. We suggest a physically clear program of experimental researches for verification of our assumption.

Two loop correction to interference in $$gg \\to ZZ$$

DOE PAGES

Campbell, John M.; Ellis, R. Keith; Czakon, Michal; ...

2016-08-01

We present results for the production of a pair of on-shell Z bosons via gluon-gluon fusion. This process occurs both through the production and decay of the Higgs boson, and through continuum production where the Z boson couples to a loop of massless quarks or to a massive quark. We calculate the interference of the two processes and its contribution to the cross section up to and including order O(αmore » $$_{s}^{3}$$ ). The two-loop contributions to the amplitude are all known analytically, except for the continuum production through loops of top quarks of mass m. The latter contribution is important for the invariant mass of the two Z bosons, (as measured by the mass of their leptonic decay products, m$$_{4l}$$), in a regime where m$$_{4l}$$ ≥ 2m because of the contributions of longitudinal bosons. We examine all the contributions to the virtual amplitude involving top quarks, as expansions about the heavy top quark limit combined with a conformal mapping and Padé approximants. Comparison with the analytic results, where known, allows us to assess the validity of the heavy quark expansion, and it extensions. We give results for the NLO corrections to this interference, including both real and virtual radiation.« less

Gluon fragmentation into quarkonium at next-to-leading order

DOE PAGES

Artoisenet, Pierre; Braaten, Eric

2015-04-22

Here, we present the first calculation at next-to-leading order (NLO) in α s of a fragmentation function into quarkonium whose form at leading order is a nontrivial function of z, namely the fragmentation function for a gluon into a spin-singlet S-wave state at leading order in the relative velocity. To calculate the real NLO corrections, we introduce a new subtraction scheme that allows the phase-space integrals to be evaluated in 4 dimensions. We extract all ultraviolet and infrared divergences in the real NLO corrections analytically by calculating the phase-space integrals of the subtraction terms in 4 – 2ϵ dimensions. Wemore » also extract the divergences in the virtual NLO corrections analytically, and detail the cancellation of all divergences after renormalization. The NLO corrections have a dramatic effect on the shape of the fragmentation function, and they significantly increase the fragmentation probability.« less

Penguin-mediated exclusive hadronic weak B decays

NASA Astrophysics Data System (ADS)

Deshpande, N. G.; Trampetic, J.

1990-02-01

We estimate a number of exclusive two-body charmless decays of B+ and B- mesons. Some of these are mediated predominantly through one-loop gluon exchange, while others have a comparable or larger contribution from the doubly Cabibbo-suppressed tree diagrams. The rates for several decays are in an observable range and should test the standard model.

High-mass diffraction in the QCD dipole picture

NASA Astrophysics Data System (ADS)

Bialas, A.; Navelet, H.; Peschanski, R.

1998-05-01

Using the QCD dipole picture of the BFKL pomeron, the cross-section of single diffractive dissociation of virtual photons at high energy and large diffractively excited masses is calculated. The calculation takes into account the full impact-parameter phase-space and thus allows to obtain an exact value of the triple BFKL Pomeron vertex. It appears large enough to compensate the perturbative 6-gluon coupling factor (α/π)3 thus suggesting a rather appreciable diffractive cross-section.

The Effects of a Virtual Exchange on Language Skills and Intercultural Competence

ERIC Educational Resources Information Center

Schenker, Theresa

2012-01-01

This dissertation explores the effects of a cross-cultural, cross-lingual virtual exchange on students' foreign language skills and intercultural competence. Specifically, the dissertation investigates the effects of students' participation in a twelve-week telecollaborative exchange on their use of syntactic complexity in foreign language writing…

Searching for the rules that govern hadron construction

DOE PAGES

Shepherd, Matthew R.; Dudek, Jozef J.; Mitchell, Ryan E.

2016-06-22

Just as quantum electrodynamics describes how electrons are bound in atoms by the electromagnetic force, mediated by the exchange of photons, quantum chromodynamics (QCD) describes how quarks are bound inside hadrons by the strong force, mediated by the exchange of gluons. QCD seems to allow hadrons constructed from increasingly many quarks to exist, just as atoms with increasing numbers of electrons exist, yet such complex constructions seemed, until recently, not to be present in nature. In this paper, we describe advances in the spectroscopy of mesons that are refining our understanding of the rules for predicting hadron structure from QCD.

Implementing a Virtual Exchange Project for student nurses in Queensland and Nottingham.

PubMed

Todhunter, Fern; Hallawell, Bob; Pittaway, Debbie

2013-09-01

This paper discusses the design and initial progress made with a virtual learning environment to help student nurses develop an understanding of cultural awareness and globalization. Using a Web-based application the Virtual Exchange Project was designed to facilitate study-elsewhere experiences located in the student's own setting. Promotion of the United Nations' Millennium Development goals provided an opportunity for student nurses to explore changes in global health and disease patterns, nursing education and systems of nurse regulation in the United Kingdom and Australia. A pedagogical framework created for this activity acknowledges the social and academic identities that learners often use, when working together in a virtual environment. The architecture of the Virtual Exchange supports local conversations about nurse education and health and social issues across hemispheres. Copyright © 2012 Elsevier Ltd. All rights reserved.

Low-lying 1/2- hidden strange pentaquark states in the constituent quark model

NASA Astrophysics Data System (ADS)

Li, Hui; Wu, Zong-Xiu; An, Chun-Sheng; Chen, Hong

2017-12-01

We investigate the spectrum of the low-lying 1/2- hidden strange pentaquark states, employing the constituent quark model, and looking at two ways within that model of mediating the hyperfine interaction between quarks - Goldstone boson exchange and one gluon exchange. Numerical results show that the lowest 1/2- hidden strange pentaquark state in the Goldstone boson exchange model lies at ˜1570 MeV, so this pentaquark configuration may form a notable component in S 11(1535) if the Goldstone boson exchange model is applied. This is consistent with the prediction that S 11(1535) couples very strongly to strangeness channels. Supported by National Natural Science Foundation of China (11675131, 11645002), Chongqing Natural Science Foundation (cstc2015jcyjA00032) and Fundamental Research Funds for the Central Universities (SWU115020)

On the two-loop virtual QCD corrections to Higgs boson pair production in the standard model

DOE PAGES

Degrassi, Giuseppe; Giardino, Pier Paolo; Gröber, Ramona

2016-07-21

Here, we compute the next-to-leading order virtual QCD corrections to Higgs-pair production via gluon fusion. We also present analytic results for the two-loop contributions to the spin-0 and spin-2 form factors in the amplitude. The reducible contributions, given by the double-triangle diagrams, are evaluated exactly while the two-loop irreducible diagrams are evaluated by an asymptotic expansion in heavy top-quark mass up to and including terms of O(1/mmore » $$8\\atop{t}$$). We estimate that mass effects can reduce the hadronic cross section by at most 10 %, assuming that the finite top-quark mass effects are of similar size in the entire range of partonic energies.« less

Final state interactions and the transverse structure of the pion using non-perturbative eikonal methods

DOE PAGES

Gamberg, Leonard; Schlegel, Marc

2010-01-18

In the factorized picture of semi-inclusive hadronic processes the naive time reversal-odd parton distributions exist by virtue of the gauge link which renders it color gauge invariant. The link characterizes the dynamical effect of initial/final-state interactions of the active parton due soft gluon exchanges with the target remnant. Though these interactions are non-perturbative, studies of final-state interaction have been approximated by perturbative one-gluon approximation in Abelian models. We include higher-order contributions by applying non-perturbative eikonal methods incorporating color degrees of freedom in a calculation of the Boer-Mulders function of the pion. Lastly, using this framework we explore under what conditionsmore » the Boer Mulders function can be described in terms of factorization of final state interactions and a spatial distribution in impact parameter space.« less

Transition between nuclear and quark-gluon descriptions of hadrons and light nuclei

NASA Astrophysics Data System (ADS)

Holt, R. J.; Gilman, R.

2012-08-01

We provide a perspective on studies aimed at observing the transition between hadronic and quark-gluonic descriptions of reactions involving light nuclei. We begin by summarizing the results for relatively simple reactions such as the pion form factor and the neutral pion transition form factor as well as that for the nucleon and end with exclusive photoreactions in our simplest nuclei. A particular focus will be on reactions involving the deuteron. It is noted that a firm understanding of these issues is essential for unravelling important structure information from processes such as deeply virtual Compton scattering as well as deeply virtual meson production. The connection to exotic phenomena such as color transparency will be discussed. A number of outstanding challenges will require new experiments at modern facilities on the horizon as well as further theoretical developments.

Online Social Support for Patients with Multiple Sclerosis: A Thematic Analysis of Messages Posted to a Virtual Support Community.

PubMed

Shavazi, Masoumeh Abbasi; Morowatisharifabad, Mohammad Ali; Shavazi, Mohammad Taghi Abbasi; Mirzaei, Masoud; Ardekani, Ali Mellat

2016-07-01

Currently with the emergence of the Internet, patients have an opportunity to exchange social support online. However, little attention has been devoted to different dimensions of online social support exchanged in virtual support communities for patients with multiple sclerosis (MS). To provide a rich insight, the aim of this qualitative study was to explore and categorize different dimensions of online social support in messages exchanged in a virtual support community for patients with MS. A total of 548 posted messages created during one year period were selected using purposive sampling to consider the maximum variation sampling. Prior-research-driven thematic analysis was then conducted. In this regard, we used the Cutruna and Suhr's coding system. The messages that could not be categorized with the used coding system were thematically analyzed to explore new additional social support themes. The results showed that various forms of social support including informational, emotional, network, esteem and tangible support were exchanged. Moreover, new additional social support themes including sharing personal experiences, sharing coping strategies and spiritual support emerged in this virtual support community. The wide range of online social support exchanged in the virtual support community can be regarded as a supplementary source of social support for patients with MS. Future researches can examine online social support more comprehensively considering additional social support themes emerging in the present study.

A Virtual Educational Exchange: A North-South Virtually Shared Class on Sustainable Development

ERIC Educational Resources Information Center

Abrahamse, Augusta; Johnson, Mathew; Levinson, Nanette; Medsker, Larry; Pearce, Joshua M.; Quiroga, Carla; Scipione, Ruth

2015-01-01

Increasingly, international competence is considered an important skill to be acquired from an undergraduate education. Because international exchange presents a challenge to many students, there is a need to develop and implement alternative means for incorporating international and cross-cultural experiences into the undergraduate classroom. We…

Online Social Support for Patients with Multiple Sclerosis: A Thematic Analysis of Messages Posted to a Virtual Support Community

PubMed Central

Shavazi, Masoumeh Abbasi; Morowatisharifabad, Mohammad Ali; Shavazi, Mohammad Taghi Abbasi; Mirzaei, Masoud; Ardekani, Ali Mellat

2016-01-01

Background: Currently with the emergence of the Internet, patients have an opportunity to exchange social support online. However, little attention has been devoted to different dimensions of online social support exchanged in virtual support communities for patients with multiple sclerosis (MS). Methods: To provide a rich insight, the aim of this qualitative study was to explore and categorize different dimensions of online social support in messages exchanged in a virtual support community for patients with MS. A total of 548 posted messages created during one year period were selected using purposive sampling to consider the maximum variation sampling. Prior-research-driven thematic analysis was then conducted. In this regard, we used the Cutruna and Suhr’s coding system. The messages that could not be categorized with the used coding system were thematically analyzed to explore new additional social support themes. Results: The results showed that various forms of social support including informational, emotional, network, esteem and tangible support were exchanged. Moreover, new additional social support themes including sharing personal experiences, sharing coping strategies and spiritual support emerged in this virtual support community. Conclusion: The wide range of online social support exchanged in the virtual support community can be regarded as a supplementary source of social support for patients with MS. Future researches can examine online social support more comprehensively considering additional social support themes emerging in the present study. PMID:27382585

Event shape analysis of deep inelastic scattering events with a large rapidity gap at HERA

NASA Astrophysics Data System (ADS)

ZEUS Collaboration; Breitweg, J.; Derrick, M.; Krakauer, D.; Magill, S.; Mikunas, D.; Musgrave, B.; Repond, J.; Stanek, R.; Talaga, R. L.; Yoshida, R.; Zhang, H.; Mattingly, M. C. K.; Anselmo, F.; Antonioli, P.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Cara Romeo, G.; Castellini, G.; Cifarelli, L.; Cindolo, F.; Contin, A.; Corradi, M.; de Pasquale, S.; Gialas, I.; Giusti, P.; Iacobucci, G.; Laurenti, G.; Levi, G.; Margotti, A.; Massam, T.; Nania, R.; Palmonari, F.; Pesci, A.; Polini, A.; Ricci, F.; Sartorelli, G.; Zamora Garcia, Y.; Zichichi, A.; Amelung, C.; Bornheim, A.; Brock, I.; Coböken, K.; Crittenden, J.; Deffner, R.; Eckert, M.; Grothe, M.; Hartmann, H.; Heinloth, K.; Heinz, L.; Hilger, E.; Jakob, H.-P.; Katz, U. F.; Kerger, R.; Paul, E.; Pfeiffer, M.; Rembser, Ch.; Stamm, J.; Wedemeyer, R.; Wieber, H.; Bailey, D. S.; Campbell-Robson, S.; Cottingham, W. N.; Foster, B.; Hall-Wilton, R.; Hayes, M. E.; Heath, G. P.; Heath, H. F.; McFall, J. D.; Piccioni, D.; Roff, D. G.; Tapper, R. J.; Arneodo, M.; Ayad, R.; Capua, M.; Garfagnini, A.; Iannotti, L.; Schioppa, M.; Susinno, G.; Kim, J. Y.; Lee, J. H.; Lim, I. T.; Pac, M. Y.; Caldwell, A.; Cartiglia, N.; Jing, Z.; Liu, W.; Mellado, B.; Parsons, J. A.; Ritz, S.; Sampson, S.; Sciulli, F.; Straub, P. B.; Zhu, Q.; Borzemski, P.; Chwastowski, J.; Eskreys, A.; Figiel, J.; Klimek, K.; Przybycień , M. B.; Zawiejski, L.; Adamczyk, L.; Bednarek, B.; Bukowy, M.; Jeleń , K.; Kisielewska, D.; Kowalski, T.; Przybycień , M.; Rulikowska-Zarȩ Bska, E.; Suszycki, L.; Zaja C, J.; Duliń Ski, Z.; Kotań Ski, A.; Abbiendi, G.; Bauerdick, L. A. T.; Behrens, U.; Beier, H.; Bienlein, J. K.; Cases, G.; Deppe, O.; Desler, K.; Drews, G.; Fricke, U.; Gilkinson, D. J.; Glasman, C.; Göttlicher, P.; Haas, T.; Hain, W.; Hasell, D.; Johnson, K. F.; Kasemann, M.; Koch, W.; Kötz, U.; Kowalski, H.; Labs, J.; Lindemann, L.; Löhr, B.; Löwe, M.; Mań Czak, O.; Milewski, J.; Monteiro, T.; Ng, J. S. T.; Notz, D.; Ohrenberg, K.; Park, I. H.; Pellegrino, A.; Pelucchi, F.; Piotrzkowski, K.; Roco, M.; Rohde, M.; Roldán, J.; Ryan, J. J.; Savin, A. A.; Schneekloth, U.; Selonke, F.; Surrow, B.; Tassi, E.; Voß, T.; Westphal, D.; Wolf, G.; Wollmer, U.; Youngman, C.; Zsolararnecki, A. F.; Zeuner, W.; Burow, B. D.; Grabosch, H. J.; Meyer, A.; Schlenstedt, S.; Barbagli, G.; Gallo, E.; Pelfer, P.; Maccarrone, G.; Votano, L.; Bamberger, A.; Eisenhardt, S.; Markun, P.; Trefzger, T.; Wölfle, S.; Bromley, J. T.; Brook, N. H.; Bussey, P. J.; Doyle, A. T.; MacDonald, N.; Saxon, D. H.; Sinclair, L. E.; Strickland, E.; Waugh, R.; Bohnet, I.; Gendner, N.; Holm, U.; Meyer-Larsen, A.; Salehi, H.; Wick, K.; Gladilin, L. K.; Horstmann, D.; Kçira, D.; Klanner, R.; Lohrmann, E.; Poelz, G.; Schott, W.; Zetsche, F.; Bacon, T. C.; Butterworth, I.; Cole, J. E.; Howell, G.; Hung, B. H. Y.; Lamberti, L.; Long, K. R.; Miller, D. B.; Pavel, N.; Prinias, A.; Sedgbeer, J. K.; Sideris, D.; Walker, R.; Mallik, U.; Wang, S. M.; Wu, J. T.; Cloth, P.; Filges, D.; Fleck, J. I.; Ishii, T.; Kuze, M.; Suzuki, I.; Tokushuku, K.; Yamada, S.; Yamauchi, K.; Yamazaki, Y.; Hong, S. J.; Lee, S. B.; Nam, S. W.; Park, S. K.; Barreiro, F.; Fernández, J. P.; García, G.; Graciani, R.; Hernández, J. M.; Hervás, L.; Labarga, L.; Martínez, M.; del Peso, J.; Puga, J.; Terrón, J.; de Trocóniz, J. F.; Corriveau, F.; Hanna, D. S.; Hartmann, J.; Hung, L. W.; Murray, W. N.; Ochs, A.; Riveline, M.; Stairs, D. G.; St-Laurent, M.; Ullmann, R.; Tsurugai, T.; Bashkirov, V.; Dolgoshein, B. A.; Stifutkin, A.; Bashindzhagyan, G. L.; Ermolov, P. F.; Golubkov, Yu. A.; Khein, L. A.; Korotkova, N. A.; Korzhavina, I. A.; Kuzmin, V. A.; Lukina, O. Yu.; Proskuryakov, A. S.; Shcheglova, L. M.; Solomin, A. N.; Zotkin, S. A.; Bokel, C.; Botje, M.; Brümmer, N.; Chlebana, F.; Engelen, J.; Koffeman, E.; Kooijman, P.; van Sighem, A.; Tiecke, H.; Tuning, N.; Verkerke, W.; Vossebeld, J.; Vreeswijk, M.; Wiggers, L.; de Wolf, E.; Acosta, D.; Bylsma, B.; Durkin, L. S.; Gilmore, J.; Ginsburg, C. M.; Kim, C. L.; Ling, T. Y.; Nylander, P.; Romanowski, T. A.; Blaikley, H. E.; Cashmore, R. J.; Cooper-Sarkar, A. M.; Devenish, R. C. E.; Edmonds, J. K.; Große-Knetter, J.; Harnew, N.; Nath, C.; Noyes, V. A.; Quadt, A.; Ruske, O.; Tickner, J. R.; Uijterwaal, H.; Walczak, R.; Waters, D. S.; Bertolin, A.; Brugnera, R.; Carlin, R.; dal Corso, F.; Dosselli, U.; Limentani, S.; Morandin, M.; Posocco, M.; Stanco, L.; Stroili, R.; Voci, C.; Bulmahn, J.; Oh, B. Y.; Okrasiń Ski, J. R.; Toothacker, W. S.; Whitmore, J. J.; Iga, Y.; D'Agostini, G.; Marini, G.; Nigro, A.; Raso, M.; Hart, J. C.; McCubbin, N. A.; Shah, T. P.; Epperson, D.; Heusch, C.; Rahn, J. T.; Sadrozinski, H. F.-W.; Seiden, A.; Wichmann, R.; Williams, D. C.; Schwarzer, O.; Walenta, A. H.; Abramowicz, H.; Briskin, G.; Dagan, S.; Kananov, S.; Levy, A.; Abe, T.; Fusayasu, T.; Inuzuka, M.; Nagano, K.; Umemori, K.; Yamashita, T.; Hamatsu, R.; Hirose, T.; Homma, K.; Kitamura, S.; Matsushita, T.; Cirio, R.; Costa, M.; Ferrero, M. I.; Maselli, S.; Monaco, V.; Peroni, C.; Petrucci, M. C.; Ruspa, M.; Sacchi, R.; Solano, A.; Staiano, A.; Dardo, M.; Bailey, D. C.; Fagerstroem, C.-P.; Galea, R.; Hartner, G. F.; Joo, K. K.; Levman, G. M.; Martin, J. F.; Orr, R. S.; Polenz, S.; Sabetfakhri, A.; Simmons, D.; Teuscher, R. J.; Butterworth, J. M.; Catterall, C. D.; Jones, T. W.; Lane, J. B.; Saunders, R. L.; Sutton, M. R.; Wing, M.; Ciborowski, J.; Grzelak, G.; Kasprzak, M.; Muchorowski, K.; Nowak, R. J.; Pawlak, J. M.; Pawlak, R.; Tymieniecka, T.; Wróblewski, A. K.; Zakrzewski, J. A.; Adamus, M.; Coldewey, C.; Eisenberg, Y.; Hochman, D.; Karshon, U.; Badgett, W. F.; Chapin, D.; Cross, R.; Dasu, S.; Foudas, C.; Loveless, R. J.; Mattingly, S.; Reeder, D. D.; Smith, W. H.; Vaiciulis, A.; Wodarczyk, M.; Deshpande, A.; Dhawan, S.; Hughes, V. W.; Bhadra, S.; Frisken, W. R.; Khakzad, M.; Schmidke, W. B.

1998-03-01

A global event shape analysis of the multihadronic final states observed in neutral current deep inelastic scattering events with a large rapidity gap with respect to the proton direction is presented. The analysis is performed in the range 5<=Q2<=185 GeV2 and 160<=W<=250 GeV, where Q2 is the virtuality of the photon and W is the virtual-photon proton centre of mass energy. Particular emphasis is placed on the dependence of the shape variables, measured in the γ*-pomeron rest frame, on the mass of the hadronic final state, MX. With increasing MX the multihadronic final state becomes more collimated and planar. The experimental results are compared with several models which attempt to describe diffractive events. The broadening effects exhibited by the data require in these models a significant gluon component of the pomeron.

Measurement of the reaction γ ∗p→φp in deep inelastic e+p scattering at HERA

NASA Astrophysics Data System (ADS)

Derrick, M.; Krakauer, D.; Magill, S.; Mikunas, D.; Musgrave, B.; Okrasinski, J. R.; Repond, J.; Stanek, R.; Talaga, R. L.; Zhang, H.; Mattingly, M. C. K.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Bruni, P.; Cara Romeo, G.; Castellini, G.; Cifarelli, L.; Cindolo, F.; Contin, A.; Corradi, M.; Gialas, I.; Giusti, P.; Iacobucci, G.; Laurenti, G.; Levi, G.; Margotti, A.; Massam, T.; Nania, R.; Palmonari, F.; Polini, A.; Sartorelli, G.; Garcia, Y. Zamora; Zichichi, A.; Amelung, C.; Bornheim, A.; Crittenden, J.; Deffner, R.; Doeker, T.; Eckert, M.; Feld, L.; Frey, A.; Geerts, M.; Grothe, M.; Hartmann, H.; Heinloth, K.; Heinz, L.; Hilger, E.; Jakob, H.-P.; Katz, U. F.; Mengel, S.; Paul, E.; Pfeiffer, M.; Rembser, Ch.; Schramm, D.; Stamm, J.; Wedemeyer, R.; Campbell-Robson, S.; Cassidy, A.; Cottingham, W. N.; Dyce, N.; Foster, B.; George, S.; Hayes, M. E.; Heath, G. P.; Heath, H. F.; Piccioni, D.; Roff, D. G.; Tapper, R. J.; Yoshida, R.; Arneodo, M.; Ayad, R.; Capua, M.; Garfagnini, A.; Iannotti, L.; Schioppa, M.; Susinno, G.; Caldwell, A.; Cartiglia, N.; Jing, Z.; Liu, W.; Parsons, J. A.; Ritz, S.; Sciulli, F.; Straub, P. B.; Wai, L.; Yang, S.; Zhu, Q.; Borzemski, P.; Chwastowski, J.; Eskreys, A.; Jakubowski, Z.; Przybycień, M. B.; Zachara, M.; Zawiejski, L.; Adamczyk, L.; Bednarek, B.; Jeleń, K.; Kisielewska, D.; Kowalski, T.; Przybycień, M.; Rulikowska-Zarȩbska, E.; Suszycki, L.; Zajaç, J.; Duliński, Z.; Kotański, A.; Abbiendi, G.; Bauerdick, L. A. T.; Behrens, U.; Beier, H.; Bienlein, J. K.; Cases, G.; Deppe, O.; Desler, K.; Drews, G.; Flasiński, M.; Gilkinson, D. J.; Glasman, C.; Göttlicher, P.; Große-Knetter, J.; Haas, T.; Hain, W.; Hasell, D.; Heßling, H.; Iga, Y.; Johnson, K. F.; Joos, P.; Kasemann, M.; Klanner, R.; Koch, W.; Kötz, U.; Kowalski, H.; Labs, J.; Ladage, A.; Löhr, B.; Löwe, M.; Lüke, D.; Mainusch, J.; Mańczak, O.; Milewski, J.; Monteiro, T.; Ng, J. S. T.; Notz, D.; Ohrenberg, K.; Piotrzkowski, K.; Roco, M.; Rohde, M.; Roldán, J.; Schneekloth, U.; Schulz, W.; Selonke, F.; Surrow, B.; Voß, T.; Westphal, D.; Wolf, G.; Wollmer, U.; Youngman, C.; Zeuner, W.; Grabosch, H. J.; Kharchilava, A.; Mari, S. M.; Meyer, A.; Schlenstedt, S.; Wulff, N.; Barbagli, G.; Gallo, E.; Pelfer, P.; Maccarrone, G.; De Pasquale, S.; Votano, L.; Bamberger, A.; Eisenhardt, S.; Trefzger, T.; Wölfle, S.; Bromley, J. T.; Brook, N. H.; Bussey, P. J.; Doyle, A. T.; Saxon, D. H.; Sinclair, L. E.; Utley, M. L.; Wilson, A. S.; Dannemann, A.; Holm, U.; Horstmann, D.; Sinkus, R.; Wick, K.; Burow, B. D.; Hagge, L.; Lohrmann, E.; Pavel, N.; Poelz, G.; Schott, W.; Zetsche, F.; Bacon, T. C.; Brümmer, N.; Butterworth, I.; Harris, V. L.; Howell, G.; Hung, B. H. Y.; Lamberti, L.; Long, K. R.; Miller, D. B.; Prinias, A.; Sedgbeer, J. K.; Sideris, D.; Whitfield, A. F.; Mallik, U.; Wang, M. Z.; Wang, S. M.; Wu, J. T.; Cloth, P.; Filges, D.; An, S. H.; Cho, G. H.; Ko, B. J.; Lee, S. B.; Nam, S. W.; Park, H. S.; Park, S. K.; Kartik, S.; Kim, H.-J.; McNeil, R. R.; Metcalf, W.; Nadendla, V. K.; Barreiro, F.; Fernandez, J. P.; Graciani, R.; Hernández, J. M.; Hervás, L.; Labarga, L.; Martinez, M.; del Peso, J.; Puga, J.; Terron, J.; de Trocóniz, J. F.; Corriveau, F.; Hanna, D. S.; Hartmann, J.; Hung, L. W.; Lim, J. N.; Matthews, C. G.; Patel, P. M.; Riveline, M.; Stairs, D. G.; St-Laurent, M.; Ullmann, R.; Zacek, G.; Tsurugai, T.; Bashkirov, V.; Dolgoshein, B. A.; Stifutkin, A.; Bashindzhagyan, G. L.; Ermolov, P. F.; Gladilin, L. K.; Golubkov, Yu. A.; Kobrin, V. D.; Korzhavina, I. A.; Kuzmin, V. A.; Lukina, O. Yu.; Proskuryakov, A. S.; Savin, A. A.; Shcheglova, L. M.; Solomin, A. N.; Zotov, N. P.; Botje, M.; Chlebana, F.; Engelen, J.; de Kamps, M.; Kooijman, P.; Kruse, A.; van Sighem, A.; Tiecke, H.; Verkerke, W.; Vossebeld, J.; Vreeswijk, M.; Wiggers, L.; de Wolf, E.; van Woudenberg, R.; Acosta, D.; Bylsma, B.; Durkin, L. S.; Gilmore, J.; Li, C.; Ling, T. Y.; Nylander, P.; Park, I. H.; Romanowski, T. A.; Bailey, D. S.; Cashmore, R. J.; Cooper-Sarkar, A. M.; Devenish, R. C. E.; Harnew, N.; Lancaster, M.; Lindemann, L.; McFall, J. D.; Nath, C.; Noyes, V. A.; Quadt, A.; Tickner, J. R.; Uijterwaal, H.; Walczak, R.; Waters, D. S.; Wilson, F. F.; Yip, T.; Bertolin, A.; Brugnera, R.; Carlin, R.; Dal Corso, F.; De Giorgi, M.; Dosselli, U.; Limentani, S.; Morandin, M.; Posocco, M.; Stanco, L.; Stroili, R.; Voci, C.; Zuin, F.; Bulmahn, J.; Feild, R. G.; Oh, B. Y.; Whitmore, J. J.; D'Agostini, G.; Marini, G.; Nigro, A.; Tassi, E.; Hart, J. C.; McCubbin, N. A.; Shah, T. P.; Barberis, E.; Dubbs, T.; Heusch, C.; Van Hook, M.; Lockman, W.; Rahn, J. T.; Sadrozinski, H. F.-W.; Seiden, A.; Williams, D. C.; Biltzinger, J.; Seifert, R. J.; Schwarzer, O.; Walenta, A. H.; Zech, G.; Abramowicz, H.; Briskin, G.; Dagan, S.; Levy, A.; Fleck, J. I.; Inuzuka, M.; Ishii, T.; Kuze, M.; Mine, S.; Nakao, M.; Suzuki, I.; Tokushuku, K.; Umemori, K.; Yamada, S.; Yamazaki, Y.; Chiba, M.; Hamatsu, R.; Hirose, T.; Homma, K.; Kitamura, S.; Matsushita, T.; Yamauchi, K.; Cirio, R.; Costa, M.; Ferrero, M. I.; Maselli, S.; Peroni, C.; Sacchi, R.; Solano, A.; Staiano, A.; Dardo, M.; Bailey, D. C.; Benard, F.; Brkic, M.; Fagerstroem, C.-P.; Hartner, G. F.; Joo, K. K.; Levman, G. M.; Martin, J. F.; Orr, R. S.; Polenz, S.; Sampson, C. R.; Simmons, D.; Teuscher, R. J.; Butterworth, J. M.; Catterall, C. D.; Jones, T. W.; Kaziewicz, P. B.; Lane, J. B.; Saunders, R. L.; Shulman, J.; Sutton, M. R.; Lu, B.; Mo, L. W.; Bogusz, W.; Ciborowski, J.; Gajewski, J.; Grzelak, G.; Kasprzak, M.; Krzyżanowski, M.; Muchorowski, K.; Nowak, R. J.; Pawlak, J. M.; Tymieniecka, T.; Wróblewski, A. K.; Zakrzewski, J. A.; Żarnecki, A. F.; Adamus, M.; Coldewey, C.; Eisenberg, Y.; Hochman, D.; Karshon, U.; Revel, D.; Zer-Zion, D.; Badgett, W. F.; Breitweg, J.; Chapin, D.; Cross, R.; Dasu, S.; Foudas, C.; Loveless, R. J.; Mattingly, S.; Reeder, D. D.; Silverstein, S.; Smith, W. H.; Vaiciulis, A.; Wodarczyk, M.; Bhadra, S.; Cardy, M. L.; Frisken, W. R.; Khakzad, M.; Murray, W. N.; Schmidke, W. B.; ZEUS Collaboration

1996-02-01

The production of φ mesons in the reaction e+p → e+φp ( φ → K+K-), for 7 < Q2 < 25 GeV 2 and virtual photon-proton centre of mass energies ( W) in the range 42-134 GeV, has been studied with the ZEUS detector at HERA. When compared to lower energy data at similar Q2, the results show that the γ ∗p → φp cross section rises strongly with W. This behaviour is similar to that previously found for the γ ∗p → ϱ 0p cross section. This strong dependence cannot be explained by production through soft pomeron exchange. It is, however, consistent with perturbative QCD expectations, where it reflects the rise of the gluon momentum density in the proton at small x. The ratio of {σ(φ)}/{σ(ϱ 0) }, which has previously been determined by ZEUS to be 0.065 ± 0.013 (stat.) in photoproduction at a mean W of 70 GeV, is measured to be 0.18 ± 0.05 (stat.) ± 0.03 (syst.) at a mean Q2 of 12.3 GeV 2 and mean W of ≈ 100 GeV and is thus approaching at large Q2 the value of {2}/{9} predicted from the quark charges of the vector mesons and a flavour independent production mechanism.

The Iterative Design of a Virtual Design Studio

ERIC Educational Resources Information Center

Blevis, Eli; Lim, Youn-kyung; Stolterman, Erik; Makice, Kevin

2008-01-01

In this article, the authors explain how they implemented Design eXchange as a shared collaborative online and physical space for design for their students. Their notion for Design eXchange favors a complex mix of key elements namely: (1) a virtual online studio; (2) a forum for review of all things related to design, especially design with the…

Computation of the soft anomalous dimension matrix in coordinate space

NASA Astrophysics Data System (ADS)

Mitov, Alexander; Sterman, George; Sung, Ilmo

2010-08-01

We complete the coordinate space calculation of the three-parton correlation in the two-loop massive soft anomalous dimension matrix. The full answer agrees with the result found previously by a different approach. The coordinate space treatment of renormalized two-loop gluon exchange diagrams exhibits their color symmetries in a transparent fashion. We compare coordinate space calculations of the soft anomalous dimension matrix with massive and massless eikonal lines and examine its nonuniform limit at absolute threshold.

The Role of Community Trust and Altruism in Knowledge Sharing: An Investigation of a Virtual Community of Teacher Professionals

ERIC Educational Resources Information Center

Chen, Hsiu-Ling; Fan, Hsueh-Liang; Tsai, Chin-Chung

2014-01-01

The knowledge sharing process within a virtual community of teacher professionals is viewed as a social exchange process in that the knowledge sharing intention and behavior of individuals are influenced by the exchange relationship among members. However, relatively little research has focused on this approach to exploring the factors that…

The gluon structure of hadrons and nuclei from lattice QCD

NASA Astrophysics Data System (ADS)

Shanahan, Phiala

2018-03-01

I discuss recent lattice QCD studies of the gluon structure of hadrons and light nuclei. After very briefly highlighting new determinations of the gluon contributions to the nucleon's momentum and spin, presented by several collaborations over the last year, I describe first calculations of gluon generalised form factors. The generalised transversity gluon distributions are of particular interest since they are purely gluonic; they do not mix with quark distributions at leading twist. In light nuclei they moreover provide a clean signature of non-nucleonic gluon degrees of freedom, and I present the first evidence for such effects, based on lattice QCD calculations. The planned Electron-Ion Collider, designed to access gluon structure quantities, will have the capability to test this prediction, and measure a range of gluon observables including generalised gluon distributions and transverse momentum dependent gluon distributions, within the next decade.

Bottom-quark forward-backward asymmetry in the standard model and beyond.

PubMed

Grinstein, Benjamín; Murphy, Christopher W

2013-08-09

We computed the bottom-quark forward-backward asymmetry at the Tevatron in the standard model (SM) and for several new physics scenarios. Near the Z pole, the SM bottom asymmetry is dominated by tree level exchanges of electroweak gauge bosons. While above the Z pole, next-to-leading order QCD dominates the SM asymmetry as was the case with the top-quark forward-backward asymmetry. Light new physics, M(NP)≲150  GeV, can cause significant deviations from the SM prediction for the bottom asymmetry. The bottom asymmetry can be used to distinguish between competing new physics (NP) explanations of the top asymmetry based on how the NP interferes with s-channel gluon and Z exchange.

Polarization Transfer in Proton Compton Scattering at High Momentum Transfer

NASA Astrophysics Data System (ADS)

Hamilton, D. J.; Mamyan, V. H.; Aniol, K. A.; Annand, J. R.; Bertin, P. Y.; Bimbot, L.; Bosted, P.; Calarco, J. R.; Camsonne, A.; Chang, G. C.; Chang, T.-H.; Chen, J.-P.; Choi, Seonho; Chudakov, E.; Danagoulian, A.; Degtyarenko, P.; de Jager, C. W.; Deur, A.; Dutta, D.; Egiyan, K.; Gao, H.; Garibaldi, F.; Gayou, O.; Gilman, R.; Glamazdin, A.; Glashausser, C.; Gomez, J.; Hansen, J.-O.; Hayes, D.; Higinbotham, D.; Hinton, W.; Horn, T.; Howell, C.; Hunyady, T.; Hyde-Wright, C. E.; Jiang, X.; Jones, M. K.; Khandaker, M.; Ketikyan, A.; Kubarovsky, V.; Kramer, K.; Kumbartzki, G.; Laveissière, G.; Lerose, J.; Lindgren, R. A.; Margaziotis, D. J.; Markowitz, P.; McCormick, K.; Meziani, Z.-E.; Michaels, R.; Moussiegt, P.; Nanda, S.; Nathan, A. M.; Nikolenko, D. M.; Nelyubin, V.; Norum, B. E.; Paschke, K.; Pentchev, L.; Perdrisat, C. F.; Piasetzky, E.; Pomatsalyuk, R.; Punjabi, V. A.; Rachek, I.; Radyushkin, A.; Reitz, B.; Roche, R.; Roedelbronn, M.; Ron, G.; Sabatie, F.; Saha, A.; Savvinov, N.; Shahinyan, A.; Shestakov, Y.; Širca, S.; Slifer, K.; Solvignon, P.; Stoler, P.; Tajima, S.; Sulkosky, V.; Todor, L.; Vlahovic, B.; Weinstein, L. B.; Wang, K.; Wojtsekhowski, B.; Voskanyan, H.; Xiang, H.; Zheng, X.; Zhu, L.

2005-06-01

Compton scattering from the proton was investigated at s=6.9 GeV2 and t=-4.0 GeV2 via polarization transfer from circularly polarized incident photons. The longitudinal and transverse components of the recoil proton polarization were measured. The results are in disagreement with a prediction of perturbative QCD based on a two-gluon exchange mechanism, but agree well with a prediction based on a reaction mechanism in which the photon interacts with a single quark carrying the spin of the proton.

Bremsstrahlung from colour charges as a source of soft particle production in hadronic collisions

NASA Astrophysics Data System (ADS)

Bialas, A.; Jezabek, M.

2004-06-01

It is proposed that soft particle production in hadronic collisions is dominated by multiple gluon exchanges between partons from the colliding hadrons, followed by radiation of hadronic clusters from the coloured partons distributed uniformly in rapidity. This explains naturally two dominant features of the data: (a) the linear increase of rapidity spectra in the regions of limiting fragmentation and, (b) the proportionality between the increasing width of the limiting fragmentation region and the height of the central plateau.

Comparing the Development of Transversal Skills between Virtual and Physical Exchanges

ERIC Educational Resources Information Center

Van der Velden, Bart; Millner, Sophie; Van der Heijden, Casper

2016-01-01

This paper aims to compare the impact on the development of transversal skills, such as self-esteem, of virtual and physical exchanges. This is done by comparing the Europe on the Edge programme to the results of the Erasmus Impact Study. In doing so it fills the need that has been expressed in the telecollaboration field to study the impact of…

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shanahan, Phiala A.

I discuss recent lattice QCD studies of the gluon structure of hadrons and light nuclei. After very briefly highlighting new determinations of the gluon contributions to the nucleon's momentum and spin, presented by several collaborations over the last year, I describe first calculations of gluon generalised form factors. The generalised transversity gluon distributions are of particular interest since they are purely gluonic; they do not mix with quark distributions at leading twist. In light nuclei they moreover provide a clean signature of non-nucleonic gluon degrees of freedom, and I present the first evidence for such effects, based on lattice QCDmore » calculations. The planned Electron-Ion Collider, designed to access gluon structure quantities, will have the capability to test this prediction, and measure a range of gluon observables including generalised gluon distributions and transverse momentum dependent gluon distributions, within the next decade.« less

Vector Meson Production at Hera

NASA Astrophysics Data System (ADS)

Szuba, Dorota

The diffractive production of vector mesons ep→eVMY, with VM=ρ0, ω, ϕ, J/ψ, ψ‧ or ϒ and with Y being either the scattered proton or a low mass hadronic system, has been extensively investigated at HERA. HERA offers a unique opportunity to study the dependences of diffractive processes on different scales: the mass of the vector meson, mVM, the centre-of-mass energy of the γp system, W, the photon virtuality, Q2 and the four-momentum transfer squared at the proton vertex, |t|. Strong interactions can be investigated in the transition from the hard to the soft regime, where the confinement of quarks and gluons occurs.

The gluon Sivers distribution: Status and future prospects

DOE PAGES

Boer, Daniël; Lorcé, Cédric; Pisano, Cristian; ...

2015-06-28

In this study, we review what is currently known about the gluon Sivers distribution and what are the opportunities to learn more about it. Because single transverse spin asymmetries in p↑p → πX provide only indirect information about the gluon Sivers function through the relation with the quark-gluon and tri-gluon Qiu-Sterman functions, current data from hadronic collisions at RHIC have not yet been translated into a solid constraint on the gluon Sivers function.

Quark ACM with topologically generated gluon mass

NASA Astrophysics Data System (ADS)

Choudhury, Ishita Dutta; Lahiri, Amitabha

2016-03-01

We investigate the effect of a small, gauge-invariant mass of the gluon on the anomalous chromomagnetic moment (ACM) of quarks by perturbative calculations at one-loop level. The mass of the gluon is taken to have been generated via a topological mass generation mechanism, in which the gluon acquires a mass through its interaction with an antisymmetric tensor field Bμν. For a small gluon mass ( < 10 MeV), we calculate the ACM at momentum transfer q2 = -M Z2. We compare those with the ACM calculated for the gluon mass arising from a Proca mass term. We find that the ACM of up, down, strange and charm quarks vary significantly with the gluon mass, while the ACM of top and bottom quarks show negligible gluon mass dependence. The mechanism of gluon mass generation is most important for the strange quarks ACM, but not so much for the other quarks. We also show the results at q2 = -m t2. We find that the dependence on gluon mass at q2 = -m t2 is much less than at q2 = -M Z2 for all quarks.

Numerical analysis of the unintegrated double gluon distribution

NASA Astrophysics Data System (ADS)

Elias, Edgar; Golec-Biernat, Krzysztof; Staśto, Anna M.

2018-01-01

We present detailed numerical analysis of the unintegrated double gluon distribution which includes the dependence on the transverse momenta of partons. The unintegrated double gluon distribution was obtained following the Kimber-Martin-Ryskin method as a convolution of the perturbative gluon splitting function with the collinear integrated double gluon distribution and the Sudakov form factors. We analyze the dependence on the transverse momenta, longitudinal momentum fractions and hard scales. We find that the unintegrated gluon distribution factorizes into a product of two single unintegrated gluon distributions in the region of small values of x, provided the splitting contribution is included and the momentum sum rule is satisfied.

Cross-institutional document exchange system using clinical document architecture (CDA) with virtual printing method.

PubMed

Mihara, Naoki; Ueda, Kanayo; Manabe, Shirou; Takeda, Toshihiro; Shimai, Yoshie; Horishima, Hiroyuki; Murata, Taizo; Fujii, Ayumi; Matsumura, Yasushi

2015-01-01

Recently one patient received care from several hospitals at around the same time. When the patient visited a new hospital, the new hospital's physician tried to get patient information the previous hospital. Thus, patient information is frequently exchanged between them. Many types of healthcare facilities have implemented an electronic medical record system, but in Japan, healthcare information exchange is often done by paper. In other words, after a clinical doctor prints a referral document and sends it to another hospital's physician, another hospital's doctor receives it and scans to store the EMR in his own hospital's system. It is a wasteful way to exchange healthcare information about a patient. In order to solve this problem, we have developed a cross-institutional document exchange system using clinical document architecture (CDA) with a virtual printing method.

78 FR 57921 - Patch International, Inc., QuadTech International, Inc., Strategic Resources, Ltd., and Virtual...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-09-20

... SECURITIES AND EXCHANGE COMMISSION [File No. 500-1] Patch International, Inc., QuadTech International, Inc., Strategic Resources, Ltd., and Virtual Medical Centre, Inc.; Order of Suspension of Trading... lack of current and accurate information concerning the securities of Virtual Medical Centre, Inc...

A direct determination of the gluon density in the proton at low x

NASA Astrophysics Data System (ADS)

Aid, S.; Andreev, V.; Andrieu, B.; Appuhn, R.-D.; Arpagaus, M.; Babaev, A.; Bähr, J.; Bán, J.; Ban, Y.; Baranov, P.; Barrelet, E.; Barschke, R.; Bartel, W.; Barth, M.; Bassler, U.; Beck, H. P.; Behrend, H.-J.; Belousov, A.; Berger, Ch.; Bernardi, G.; Bernet, R.; Bertrand-Coremans, G.; Besançon, M.; Beyer, R.; Biddulph, P.; Bispham, P.; Bizot, J. C.; Blobel, V.; Borras, K.; Botterweck, F.; Boudry, V.; Braemer, A.; Brasse, F.; Braunschweig, W.; Brisson, V.; Bruncko, D.; Brune, C.; Buchholz, R.; Büngener, L.; Bürger, J.; Büsser, F. W.; Buniatian, A.; Burke, S.; Burton, M. J.; Buschhorn, G.; Campbell, A. J.; Carli, T.; Charles, F.; Charlet, M.; Clarke, D.; Clegg, A. B.; Clerbaux, B.; Colombo, M.; Contreras, J. G.; Cormack, C.; Coughlan, J. A.; Courau, A.; Coutures, Ch.; Cozzika, G.; Criegee, L.; Cussans, D. G.; Cvach, J.; Dagoret, S.; Dainton, J. B.; Dau, W. D.; Daum, K.; David, M.; Delcourt, B.; Del Buono, L.; De Roeck, A.; De Wolf, E. A.; Di Nezza, P.; Dollfus, C.; Dowell, J. D.; Dreis, H. B.; Droutskoi, A.; Duboc, J.; Düllmann, D.; Dünger, O.; Duhm, H.; Ebert, J.; Ebert, T. R.; Eckerlin, G.; Efremenko, V.; Egli, S.; Ehrlichmann, H.; Eichenberger, S.; Eichler, R.; Eisele, F.; Eisenhandler, E.; Ellison, R. J.; Elsen, E.; Erdmann, M.; Erdmann, W.; Evrard, E.; Favart, L.; Fedotox, A.; Feeken, D.; Felst, R.; Feltesse, J.; Ferencei, J.; Ferrarotto, F.; Flamm, K.; Fleischer, M.; Flieser, M.; Flügge, G.; Fomenko, A.; Fominykh, B.; Forbush, M.; Formánek, J.; Foster, J. M.; Franke, G.; Fretwurst, E.; Gabathuler, E.; Gabathuler, K.; Garvey, J.; Gayler, J.; Gebauer, M.; Gellrich, A.; Genzel, H.; Gerhards, R.; Glazov, A.; Goerlach, U.; Goerlich, L.; Gogitidze, N.; Goldberg, M.; Goldner, D.; Gonzalez-Pineiro, B.; Gorelov, I.; Goritchev, P.; Grab, C.; Grässler, H.; Grässler, R.; Greenshaw, T.; Grindhammer, G.; Gruber, A.; Gruber, C.; Haack, J.; Haidt, D.; Hajduk, L.; Hamon, O.; Hampel, M.; Hapke, M.; Haynes, W. J.; Heatherington, J.; Heinzelmann, G.; Henderson, R. C. W.; Henschel, H.; Herynek, I.; Hess, M. F.; Hildesheim, W.; Hill, P.; Hiller, K. H.; Hilton, C. D.; Hladký, J.; Hoeger, K. C.; Höppner, M.; Horisberger, R.; Hudgson, V. L.; Huet, Ph.; Hütte, M.; Hufnagel, H.; Ibbotson, M.; Itterbeck, H.; Jabiol, M.-A.; Jacholkowska, A.; Jacobsson, C.; Jaffre, M.; Janoth, J.; Jansen, T.; Jönsson, L.; Johnson, D. P.; Johnson, L.; Jung, H.; Kalmus, P. I. P.; Kant, D.; Kaschowitz, R.; Kasselmann, P.; Kathage, U.; Katzy, J.; Kaufmann, H. H.; Kazarian, S.; Kenyon, I. R.; Kermiche, S.; Keuker, C.; Kiesling, C.; Klein, M.; Kleinwort, C.; Knies, G.; Ko, W.; Köhler, T.; Köhne, J. H.; Kolanoski, H.; Kole, F.; Kolya, S. D.; Korbel, V.; Korn, M.; Kostka, P.; Kotelnikov, S. K.; Krämerkämper, T.; Krasny, M. W.; Krehbiel, H.; Krücker, D.; Krüger, U.; Krüner-Marquis, U.; Küster, H.; Kuhlen, M.; Kurča, T.; Kurzhöfer, J.; Kuznik, B.; Lacour, D.; Lamarche, F.; Lander, R.; Landon, M. P. J.; Lange, W.; Lanius, P.; Laporte, J.-F.; Lebedev, A.; Lehner, F.; Leverenz, C.; Levonian, S.; Ley, Ch.; Lindner, A.; Lindström, G.; Link, J.; Linsel, F.; Lipinski, J.; List, B.; Lobo, G.; Loch, P.; Lohmander, H.; Lomas, J. W.; Lopez, G. C.; Lubimox, V.; Lüke, D.; Magnussen, N.; Malinovski, E.; Mani, S.; Maraček, R.; Marage, P.; Marks, J.; Marshall, R.; Martens, J.; Martin, G.; Martin, R.; Martyn, H.-U.; Martyniak, J.; Masson, S.; Mavroidis, T.; Maxfield, S. J.; McMahon, S. J.; Mehta, A.; Meier, K.; Mercer, D.; Merz, T.; Meyer, A.; Meyer, C. A.; Meyer, H.; Meyer, J.; Migliori, A.; Mikocki, S.; Milstead, D.; Moreau, F.; Morris, J. V.; Mroczko, E.; Müller, G.; Müller, K.; Murín, P.; Nagovizin, V.; Nahnhauer, R.; Naroska, B.; Naumann, Th.; Newman, P. R.; Newton, D.; Neyret, D.; Nguyen, H. K.; Nicholls, T. C.; Niebergall, F.; Niebuhr, C.; Niedzballa, Ch.; Nisius, R.; Nowak, G.; Noyes, G. W.; Nyberg-Werther, M.; Oakden, M.; Oberlack, H.; Obrock, U.; Olsson, J. E.; Ozerov, D.; Panaro, E.; Panitch, A.; Pascaud, C.; Patel, G. D.; Peppel, E.; Perez, E.; Phillips, J. P.; Pichler, Ch.; Pieuchot, A.; Pitzl, D.; Pope, G.; Prell, S.; Prosi, R.; Rabbertz, K.; Rädel, G.; Raupach, F.; Reimer, P.; Reinshagen, S.; Ribarics, P.; Rick, H.; Riech, V.; Riedlberger, J.; Riess, S.; Rietz, M.; Rizvi, E.; Robertson, S. M.; Robmann, P.; Roloff, H. E.; Roosen, R.; Rosenbauer, K.; Rostovtsev, A.; Rouse, F.; Yoyon, C.; Rüter, K.; Rusakov, S.; Rybicki, K.; Rylko, R.; Sahlmann, N.; Sankey, D. P. C.; Schacht, P.; Schiek, S.; Schleif, S.; Schleper, P.; von Schlippe, W.; Schmidt, D.; Schmidt, G.; Schöning, A.; Schröder, V.; Schuhmann, E.; Schwab, B.; Sciacca, G.; Sefkow, F.; Seidel, M.; Sell, R.; Semenov, A.; Shekelyan, V.; Sheviakov, I.; Shtarkov, L. N.; Siegmon, G.; Siewert, U.; Sirois, Y.; Skillicorn, I. O.; Smirnov, P.; Smith, J. R.; Solochenko, V.; Soloviev, Y.; Spiekermann, J.; Spielman, S.; Spitzer, H.; Starosta, R.; Steenbock, M.; Steffen, P.; Steinberg, R.; Stella, B.; Stephens, K.; Stier, J.; Stiewe, J.; Stößlein, U.; Stolze, K.; Strachota, J.; Straumann, U.; Struczinski, W.; Sutton, J. P.; Tapprogge, S.; Tchernyshov, V.; Thiebaux, C.; Thompson, G.; Truöl, P.; Turnau, J.; Tutas, J.; Uelkes, P.; Usik, A.; Valkár, S.; Valkárová, A.; Vallée, C.; Vandenplas, D.; Van Esch, P.; Van Mechelen, P.; Vartapetian, A.; Vazdik, Y.; Verrecchia, P.; Villet, G.; Wacker, K.; Wagener, A.; Wagener, M.; Walther, A.; Weber, G.; Weber, M.; Wegener, D.; Wegner, A.; Wellisch, H. P.; West, L. R.; Willard, S.; Winde, M.; Winter, G.-G.; Wittek, C.; Wright, A. E.; Wünsch, E.; Wulff, N.; Yiou, T. P.; Žáček, J.; Zarbock, D.; Zhang, Z.; Zhokin, A.; Zimmer, M.; Zimmermann, W.; Zomer, F.; Zuber, K.; zur Nedden, M.; H1 Collaboration

1995-02-01

A leading order determination of the gluon density in the proton has been performed in the fractional momentum range 1.9 · 10 -3 < xg/ p < 0.18 by measuring multi-jet events from boson-gluon fusion in deep-inelastic scattering with the H1 detector at the electron-proton collider HERA. This direct determination of the gluon density was performed in a kinematic region previously not accessible. The data show a considerable increase of the gluon density with decreasing fractional momenta of the gluons.

Influence of tensor interactions on masses and decay widths of dibaryons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pang Hourong; Ping Jialun; Chen Lingzhi

The influence of gluon and Goldstone boson induced tensor interactions on the dibaryon masses and D-wave decay widths has been studied in the quark delocalization, color screening model. The effective S-D wave transition interactions induced by gluon and Goldstone boson exchanges decrease rapidly with increasing strangeness of the channel. The tensor contribution of K and {eta} mesons is negligible in this model. There is no six-quark state in the light flavor world studied so far that can become bound by means of these tensor interactions besides the deuteron. The partial D-wave decay widths of the IJ{sup p}=(1/2)2{sup +}N{omega} state tomore » spin 0 and 1 {lambda}{xi} final states are 12.0 and 21.9 keV, respectively. This is a very narrow dibaryon resonance that might be detectable in those production reactions with rich high strangeness particles through the reconstruction of the vertex mass of the decay product {lambda}{xi} by existing detectors at RHIC and COMPASS at CERN or at JHF in Japan and FAIR in Germany in the future.« less

Higgs enhancement for the dark matter relic density

NASA Astrophysics Data System (ADS)

Harz, Julia; Petraki, Kalliopi

2018-04-01

We consider the long-range effect of the Higgs on the density of thermal-relic dark matter. While the electroweak gauge boson and gluon exchange have been previously studied, the Higgs is typically thought to mediate only contact interactions. We show that the Sommerfeld enhancement due to a 125 GeV Higgs can deplete TeV-scale dark matter significantly and describe how the interplay between the Higgs and other mediators influences this effect. We discuss the importance of the Higgs enhancement in the minimal supersymmetric standard model and its implications for experiments.

Heavy quarkonium in a holographic basis

DOE PAGES

Li, Yang; Maris, Pieter; Zhao, Xingbo; ...

2016-05-04

Here, we study the heavy quarkonium within the basis light-front quantization approach. We implement the one-gluon exchange interaction and a confining potential inspired by light-front holography. We adopt the holographic light-front wavefunction (LFWF) as our basis function and solve the non-perturbative dynamics by diagonalizing the Hamiltonian matrix. We obtain the mass spectrum for charmonium and bottomonium. With the obtained LFWFs, we also compute the decay constants and the charge form factors for selected eigenstates. The results are compared with the experimental measurements and with other established methods.

Polarization Transfer in Proton Compton Scattering at High Momentum Transfer

DOE Office of Scientific and Technical Information (OSTI.GOV)

D.J. Hamilton; Vahe Mamyan

2004-10-01

Compton scattering from the proton was investigated at s = 6.9 GeV{sup 2} and t = -4.0 TeV{sup 2} via polarization transfer from circularly polarized incident photons. The longitudinal and transverse components of the recoil proton polarization were measured. The results are in excellent agreement with a prediction based on a reaction mechanism in which the photon interacts with a single quark carrying the spin of the proton and in disagreement with a prediction of pQCD based on a two-gluon exchange mechanism.

Data Quality and Interoperability Challenges for eHealth Exchange Participants: Observations from the Department of Veterans Affairs' Virtual Lifetime Electronic Record Health Pilot Phase.

PubMed

Botts, Nathan; Bouhaddou, Omar; Bennett, Jamie; Pan, Eric; Byrne, Colene; Mercincavage, Lauren; Olinger, Lois; Hunolt, Elaine; Cullen, Theresa

2014-01-01

Authors studied the United States (U.S.) Department of Veterans Affairs' (VA) Virtual Lifetime Electronic Record (VLER) Health pilot phase relative to two attributes of data quality - the adoption of eHealth Exchange data standards, and clinical content exchanged. The VLER Health pilot was an early effort in testing implementation of eHealth Exchange standards and technology. Testing included evaluation of exchange data from the VLER Health pilot sites partners: VA, U.S. Department of Defense (DoD), and private sector health care organizations. Domains assessed data quality and interoperability as it relates to: 1) conformance with data standards related to the underlying structure of C32 Summary Documents (C32) produced by eHealth Exchange partners; and 2) the types of C32 clinical content exchanged. This analysis identified several standards non-conformance issues in sample C32 files and informed further discourse on the methods needed to effectively monitor Health Information Exchange (HIE) data content and standards conformance.

Archive interoperability in the Virtual Observatory

NASA Astrophysics Data System (ADS)

Genova, Françoise

2003-02-01

Main goals of Virtual Observatory projects are to build interoperability between astronomical on-line services, observatory archives, databases and results published in journals, and to develop tools permitting the best scientific usage from the very large data sets stored in observatory archives and produced by large surveys. The different Virtual Observatory projects collaborate to define common exchange standards, which are the key for a truly International Virtual Observatory: for instance their first common milestone has been a standard allowing exchange of tabular data, called VOTable. The Interoperability Work Area of the European Astrophysical Virtual Observatory project aims at networking European archives, by building a prototype using the CDS VizieR and Aladin tools, and at defining basic rules to help archive providers in interoperability implementation. The prototype is accessible for scientific usage, to get user feedback (and science results!) at an early stage of the project. ISO archive participates very actively to this endeavour, and more generally to information networking. The on-going inclusion of the ISO log in SIMBAD will allow higher level links for users.

Virtuous and vicious virtual water trade with application to Italy.

PubMed

Winter, Julia Anna; Allamano, Paola; Claps, Pierluigi

2014-01-01

The current trade of agricultural goods, with connections involving all continents, entails for global exchanges of "virtual" water, i.e. water used in the production process of alimentary products, but not contained within. Each trade link translates into a corresponding virtual water trade, allowing quantification of import and export fluxes of virtual water. The assessment of the virtual water import for a given nation, compared to the national consumption, could give an approximate idea of the country's reliance on external resources from the food and the water resources point of view. A descriptive approach to the understanding of a nation's degree of dependency from overseas food and water resources is first proposed, and indices of water trade virtuosity, as opposed to inefficiency, are devised. Such indices are based on the concepts of self-sufficiency and relative export, computed systematically on all products from the FAOSTAT database, taking Italy as the first case study. Analysis of time series of the self-sufficiency and relative export can demonstrate effects of market tendencies and influence water-related policies at the international level. The goal of this approach is highlighting incongruent terms in the virtual water balances by the viewpoint of single products. Specific products, which are here referred to as "swap products", are in fact identified as those that lead to inefficiencies in the virtual water balance due to their contemporaneously high import and export. The inefficiencies due to the exchanges of the same products between two nations are calculated in terms of virtual water volumes. Furthermore, the cases of swap products are investigated by computing two further indexes denoting the ratio of virtual water exchanged in the swap and the ratio of the economic values of the swapped products. The analysis of these figures can help examine the reasons behind the swap phenomenon in trade.

Horizontal Curves Virtual Peer Exchange

DOT National Transportation Integrated Search

2012-05-01

This report provides a summary of a peer-to-peer videoconference sponsored by : the Federal Highway Administration (FHWA) Office of Safety. The : videoconference, which piloted a virtual event format, is part of a series of : roadway departure-focuse...

Dynamical gluon mass in the instanton vacuum model

NASA Astrophysics Data System (ADS)

Musakhanov, M.; Egamberdiev, O.

2018-04-01

We consider the modifications of gluon properties in the instanton liquid model (ILM) for the QCD vacuum. Rescattering of gluons on instantons generates the dynamical momentum-dependent gluon mass Mg (q). First, we consider the case of a scalar gluon, no zero-mode problem occurs and its dynamical mass Ms (q) can be found. Using the typical phenomenological values of the average instanton size ρ = 1 / 3 fm and average inter-instanton distance R = 1 fm we get Ms (0) = 256 MeV. We then extend this approach to the real vector gluon with zero-modes carefully considered. We obtain the following expression Mg2 (q) = 2 Ms2 (q). This modification of the gluon in the instanton media will shed light on nonperturbative aspect on heavy quarkonium physics.

Transverse momentum and its compensation in current and target jets in deep inelastic muon-proton scattering

NASA Astrophysics Data System (ADS)

Arneodo, M.; Arvidson, A.; Aubert, J. J.; Beaufays, J.; Becks, K. H.; Bee, C.; Benchouk, C.; Bird, I.; Blum, D.; Böhm, E.; de Bouard, X.; Brasse, F. W.; Braun, H.; Broll, C.; Brown, S.; Brück, H.; Calen, H.; Callebaut, D.; Carr, J.; Chima, J. S.; Clifft, R.; Cobb, J. H.; Coignet, G.; Combley, F.; Coughlan, J.; Court, G. R.; D'Agostini, G.; Dahlgren, S.; Davies, J. K.; Dengler, F.; Derado, I.; Dosselli, U.; Dreyer, T.; Drees, J.; Dumont, J. J.; Düren, M.; Eckardt, V.; Edwards, A.; Edwards, M.; Ernst, T.; Eszes, G.; Favier, J.; Ferrero, M. I.; Figiel, J.; Flauger, W.; Foster, J.; Gabathuler, E.; Gamet, R.; Gayler, J.; Geddes, N.; Giubellino, P.; Gössling, C.; Grafström, P.; Grard, F.; Gustafsson, L.; Haas, J.; Hagberg, E.; Hasert, F. J.; Hayman, P.; Heusse, P.; Hoppe, C.; Jaffré, M.; Jacholkowska, A.; Janata, F.; Jancso, G.; Johnson, A. S.; Kabuss, E. M.; Kellner, G.; Korbel, V.; Krüger, J.; Kullander, S.; Landgraf, U.; Lanske, D.; Loken, J.; Long, K.; Maire, M.; Manz, A.; Mohr, W.; Montanet, F.; Montgomery, H. E.; Mount, R. P.; Nagy, E.; Nassalski, J.; Norton, P. R.; Oakham, F. G.; Osborne, A. M.; Pascaud, C.; Paul, L.; Pawlik, B.; Payre, P.; Peroni, C.; Pessard, H.; Pettingale, J.; Pietrzyk, B.; Pötsch, M.; Preissner, H.; Renton, P.; Ribarics, P.; Rith, K.; Rondio, E.; Schlagböhmer, A.; Schmitz, N.; Schneegans, M.; Schröder, T.; Schultze, K.; Shiers, J.; Sloan, T.; Stier, H. E.; Stockhausen, W.; Studt, M.; Taylor, G. N.; Thénard, J. M.; Thompson, J. C.; de La Torre, A.; Toth, J.; Urban, L.; Wahlen, H.; Wallucks, W.; Whalley, M.; Wheeler, S.; Williams, W. S. C.; Wimpenny, S.; Windmolders, R.; Wolf, G.

1984-12-01

Results are presented on the transverse momentum distributions of charged hadrons in 280 GeV muon-proton deep inelastic interactions. The transverse momenta are defined relative to the accurately measured virtual photon direction and the experiment has almost complete angular acceptance for the final state hadrons. Significantly larger values of the average transverse momentum squared are found for the forward going hadrons than for the target remnants. This result, combined with a study of the rapidity region over which the transverse momentum is compensated, can be explained by a significant contribution from soft gluon radiation, but not by a large value of the primordial transverse momentum of the struck quark.

Quark and Gluon Relaxation in Quark-Gluon Plasmas

NASA Technical Reports Server (NTRS)

Heiselberg, H.; Pethick, C. J.

1993-01-01

The quasiparticle decay rates for quarks and gluons in quark-gluon plasmas are calculated by solving the kinetic equation. Introducing an infrared cutoff to allow for nonperturbative effects, we evaluate the quasiparticle lifetime at momenta greater than the inverse Debye screening length to leading order in the coupling constant.

Constraining the double gluon distribution by the single gluon distribution

DOE PAGES

Golec-Biernat, Krzysztof; Lewandowska, Emilia; Serino, Mirko; ...

2015-10-03

We show how to consistently construct initial conditions for the QCD evolution equations for double parton distribution functions in the pure gluon case. We use to momentum sum rule for this purpose and a specific form of the known single gluon distribution function in the MSTW parameterization. The resulting double gluon distribution satisfies exactly the momentum sum rule and is parameter free. Furthermore, we study numerically its evolution with a hard scale and show the approximate factorization into product of two single gluon distributions at small values of x, whereas at large values of x the factorization is always violatedmore » in agreement with the sum rule.« less

Event-by-event picture for the medium-induced jet evolution

NASA Astrophysics Data System (ADS)

Escobedo, Miguel A.; Iancu, Edmond

2017-08-01

We discuss the evolution of an energetic jet which propagates through a dense quark-gluon plasma and radiates gluons due to its interactions with the medium. Within perturbative QCD, this evolution can be described as a stochastic branching process, that we have managed to solve exactly. We present exact, analytic, results for the gluon spectrum (the average gluon distribution) and for the higher n-point functions, which describe correlations and fluctuations. Using these results, we construct the event-by-event picture of the gluon distribution produced via medium-induced gluon branching. In contrast to what happens in a usual QCD cascade in vacuum, the medium-induced branchings are quasi-democratic, with offspring gluons carrying sizable fractions of the energy of their parent parton. We find large fluctuations in the energy loss and in the multiplicity of soft gluons. The multiplicity distribution is predicted to exhibit KNO (Koba-Nielsen-Olesen) scaling. These predictions can be tested in Pb+Pb collisions at the LHC, via event-by-event measurements of the di-jet asymmetry. Based on [1, 2].

Event-by-event picture for the medium-induced jet evolution

NASA Astrophysics Data System (ADS)

Escobedo, Miguel A.; Iancu, Edmond

2017-03-01

We discuss the evolution of an energetic jet which propagates through a dense quark-gluon plasma and radiates gluons due to its interactions with the medium. Within perturbative QCD, this evolution can be described as a stochastic branching process, that we have managed to solve exactly. We present exact, analytic, results for the gluon spectrum (the average gluon distribution) and for the higher n-point functions, which describe correlations and fluctuations. Using these results, we construct the event-by-event picture of the gluon distribution produced via medium-induced gluon branching. In contrast to what happens in a usual QCD cascade in vacuum, the medium-induced branchings are quasi-democratic, with offspring gluons carrying sizable fractions of the energy of their parent parton. We find large fluctuations in the energy loss and in the multiplicity of soft gluons. The multiplicity distribution is predicted to exhibit KNO (Koba-Nielsen-Olesen) scaling. These predictions can be tested in Pb+Pb collisions at the LHC, via event-by-event measurements of the di-jet asymmetry. Based on [1, 2].

Multiplicity distributions of gluon and quark jets and a test of QCD analytic calculations

NASA Astrophysics Data System (ADS)

Gary, J. William

1999-03-01

Gluon jets are identified in e +e - hadronic annihilation events by tagging two quark jets in the same hemisphere of an event. The gluon jet is defined inclusively as all the particles in the opposite hemisphere. Gluon hets defined in this manner have a close correspondence to gluon jets as they are defined for analytic calculations, and are almost independent of a jet finding algorithm. The mean and first few higher moments of the gluon jet charged particle multiplicity distribution are compared to the analogous results found for light quark (uds) jets, also defined inclusively. Large differences are observed between the mean, skew and curtosis values of the gluon and quark jets, but not between their dispersions. The cumulant factorial moments of the distributions are also measured, and are used to test the predictions of QCD analytic calculations. A calculation which includes next-to-next-to-leading order corrections and energy conservation is observed to provide a much improved description of the separated gluon and quark jet cumulant moments compared to a next-to-leading order calculation without energy conservation. There is good quantitative agreement between the data and calculations for the ratios of the cumulant moments between gluon and quark jets. The data sample used is the LEP-1 sample of the OPAL experiment at LEP.

Gluon TMDs in Quarkonium Production

NASA Astrophysics Data System (ADS)

Boer, Daniël

2017-03-01

Quarkonium production offers good possibilities to study gluon TMDs. In this proceedings contribution this topic is explored for the linearly polarized gluons inside unpolarized hadrons and unpolarized gluons inside transversely polarized hadrons. It is argued that χ _{b0/2} and η _b production at LHC are best to study the effects of linearly polarized gluons in hadronic collisions, by means of angular independent ratios of ratios of cross sections. This can be directly compared to cos 2φ asymmetries in heavy quark pair and dijet production in DIS at a future high-energy Electron-Ion Collider (EIC), which probe the same TMDs. In the small- x limit this corresponds to the Weizsäcker-Williams (WW) gluon distributions, which should show a change in behavior for transverse momenta around the saturation scale. Together with investigations of the dipole (DP) gluon distributions, this can provide valuable information about the polarization of the Color Glass Condensate if sufficiently small x-values are reached. Quarkonia can also be useful in the study of single transverse spin asymmetries. For transversely polarized hadrons the gluon distribution can be asymmetric, which is referred to as the Sivers effect. It leads to single spin asymmetries in for instance J{/}ψ (pair) production at AFTER@LHC, which probe the WW or f-type gluon Sivers TMD. It allows for a test of a sign-change relation w.r.t. the gluon Sivers TMD probed at an EIC in open heavy quark pair production. Single spin asymmetries in backward inclusive C-odd quarkonium production, such as J{/}ψ production, may offer probes of the DP or d-type gluon Sivers TMD at small x-values in the polarized proton, which in that limit corresponds to a correlator of a single Wilson loop, describing the spin-dependent odderon.

Defining Virtual Interactions: A Taxonomy for Researchers and Practitioners

DTIC Science & Technology

1999-11-01

Engineering and Management of the Air Force Institute of Technology Air University Air Education and Training Command In Partial Fulfillment of the...information technology and produce the maximum benefits for all virtual components involved. Vlll DEFINING VIRTUAL INTERACTIONS: A TAXONOMY FOR...allow the human factor to maximize information exchange and provide high quality products to intelligence consumers. Applicability of this research In

Enhancing Intercultural Competence of Engineering Students via GVT (Global Virtual Teams)-Based Virtual Exchanges: An International Collaborative Course in Intralogistics Education

ERIC Educational Resources Information Center

Wang, Rui; Rechl, Friederike; Bigontina, Sonja; Fang, Dianjun; Günthner, Willibald A.; Fottner, Johannes

2017-01-01

In order to enhance the intercultural competence of engineering students, an international collaborative course in intralogistics education was initiated and realized between the Technical University of Munich in Germany and the Tongji University in China. In this course, students worked in global virtual teams (GVTs) and solved a concrete case…

Analysis of the social network development of a virtual community for Australian intensive care professionals.

PubMed

Rolls, Kaye Denise; Hansen, Margaret; Jackson, Debra; Elliott, Doug

2014-11-01

Social media platforms can create virtual communities, enabling healthcare professionals to network with a broad range of colleagues and facilitate knowledge exchange. In 2003, an Australian state health department established an intensive care mailing list to address the professional isolation experienced by senior intensive care nurses. This article describes the social network created within this virtual community by examining how the membership profile evolved from 2003 to 2009. A retrospective descriptive design was used. The data source was a deidentified member database. Since 2003, 1340 healthcare professionals subscribed to the virtual community with 78% of these (n = 1042) still members at the end of 2009. The membership profile has evolved from a single-state nurse-specific network to an Australia-wide multidisciplinary and multiorganizational intensive care network. The uptake and retention of membership by intensive care clinicians indicated that they appeared to value involvement in this virtual community. For healthcare organizations, a virtual community may be a communications option for minimizing professional and organizational barriers and promoting knowledge flow. Further research is, however, required to demonstrate a link between these broader social networks, enabling the exchange of knowledge and improved patient outcomes.

Improved decision making in construction using virtual site visits.

DOT National Transportation Integrated Search

2003-01-01

This study explored the dynamics of information exchange involving field issues relating to construction and the assistance that a virtual site visit can provide to the field decision-making process. Such a process can be used for inspection and surv...

Nucleon spin-averaged forward virtual Compton tensor at large Q 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hill, Richard J.; Paz, Gil

The nucleon spin-averaged forward virtual Compton tensor determines important physical quantities such as electromagnetically-induced mass differences of nucleons, and two-photon exchange contributions in hydrogen spectroscopy. It depends on two kinematic variables:more » $$\

Quarkonium-nucleus bound states from lattice QCD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beane, S.  R.; Chang, E.; Cohen, S.  D.

2015-06-11

Quarkonium-nucleus systems are composed of two interacting hadronic states without common valence quarks, which interact primarily through multi-gluon exchanges, realizing a color van der Waals force. We present lattice QCD calculations of the interactions of strange and charm quarkonia with light nuclei. Both the strangeonium-nucleus and charmonium-nucleus systems are found to be relatively deeply bound when the masses of the three light quarks are set equal to that of the physical strange quark. Extrapolation of these results to the physical light-quark masses suggests that the binding energy of charmonium to nuclear matter is B < 40 MeV.

Horizontal Curves Virtual Peer Exchange

DOT National Transportation Integrated Search

2013-05-14

This report provides a summary of a peer-to-peer videoconference sponsored by the Federal Highway Administration (FHWA) Office of Safety. The videoconference was the third in a series of roadway departure-focused peer exchanges sponsored by the Offic...

Four-state virtual research peer exchange 2015 : final report.

DOT National Transportation Integrated Search

2016-01-01

The transportation research programs in Idaho, Nevada, South Dakota, and Wyoming each hosted a multi-state : online webinar-based peer exchange consisting of a series of four webinars addressing four topics: : - Research Quality: optimizing the value...

Horizontal Curves Virtual Peer Exchange

DOT National Transportation Integrated Search

2013-01-01

This report provides a summary of a peer-to-peer videoconference sponsored by the Federal Highway Administration (FHWA) Office of Safety. The videoconference was the third in a series of roadway departure-focused peer exchanges sponsored by the Offic...

Self-Regulated Learning in Virtual Communities

ERIC Educational Resources Information Center

Delfino, Manuela; Dettori, Giuliana; Persico, Donatella

2008-01-01

This paper investigates self-regulated learning (SRL) in a virtual learning community of adults interacting through asynchronous textual communication. The investigation method chosen is interaction analysis, a qualitative/quantitative approach allowing a systematic study of the contents of the messages exchanged within online communities. The…

Using a Classical Gluon Cascade to study the Equilibration of a Gluon-Plasma

NASA Astrophysics Data System (ADS)

McConnell, Lucas

2015-10-01

Using a classical gluon cascade, we study the thermalisation of a gluon-plasma in a homogeneous box by considering the time evolution of the entropy, and in particular how the thermalisation time depends on the strong coupling αs. We then partition the volume into cells with a linearly increasing temperature gradient in one direction, and homogeneous/isotropic in the the other two directions. We allow the gluons to stream in one direction in order to study how they then evolve spatially. We examine cases with and without collisions. We study the entropy as well as the flow-velocity in the z-direction and find that the system initially has a flow which dissipates over time as the gluons become distributed homogeneously throughout the box.

Virtual Patients on the Semantic Web: A Proof-of-Application Study

PubMed Central

Dafli, Eleni; Antoniou, Panagiotis; Ioannidis, Lazaros; Dombros, Nicholas; Topps, David

2015-01-01

Background Virtual patients are interactive computer simulations that are increasingly used as learning activities in modern health care education, especially in teaching clinical decision making. A key challenge is how to retrieve and repurpose virtual patients as unique types of educational resources between different platforms because of the lack of standardized content-retrieving and repurposing mechanisms. Semantic Web technologies provide the capability, through structured information, for easy retrieval, reuse, repurposing, and exchange of virtual patients between different systems. Objective An attempt to address this challenge has been made through the mEducator Best Practice Network, which provisioned frameworks for the discovery, retrieval, sharing, and reuse of medical educational resources. We have extended the OpenLabyrinth virtual patient authoring and deployment platform to facilitate the repurposing and retrieval of existing virtual patient material. Methods A standalone Web distribution and Web interface, which contains an extension for the OpenLabyrinth virtual patient authoring system, was implemented. This extension was designed to semantically annotate virtual patients to facilitate intelligent searches, complex queries, and easy exchange between institutions. The OpenLabyrinth extension enables OpenLabyrinth authors to integrate and share virtual patient case metadata within the mEducator3.0 network. Evaluation included 3 successive steps: (1) expert reviews; (2) evaluation of the ability of health care professionals and medical students to create, share, and exchange virtual patients through specific scenarios in extended OpenLabyrinth (OLabX); and (3) evaluation of the repurposed learning objects that emerged from the procedure. Results We evaluated 30 repurposed virtual patient cases. The evaluation, with a total of 98 participants, demonstrated the system’s main strength: the core repurposing capacity. The extensive metadata schema presentation facilitated user exploration and filtering of resources. Usability weaknesses were primarily related to standard computer applications’ ease of use provisions. Most evaluators provided positive feedback regarding educational experiences on both content and system usability. Evaluation results replicated across several independent evaluation events. Conclusions The OpenLabyrinth extension, as part of the semantic mEducator3.0 approach, is a virtual patient sharing approach that builds on a collection of Semantic Web services and federates existing sources of clinical and educational data. It is an effective sharing tool for virtual patients and has been merged into the next version of the app (OpenLabyrinth 3.3). Such tool extensions may enhance the medical education arsenal with capacities of creating simulation/game-based learning episodes, massive open online courses, curricular transformations, and a future robust infrastructure for enabling mobile learning. PMID:25616272

Virtual patients on the semantic Web: a proof-of-application study.

PubMed

Dafli, Eleni; Antoniou, Panagiotis; Ioannidis, Lazaros; Dombros, Nicholas; Topps, David; Bamidis, Panagiotis D

2015-01-22

Virtual patients are interactive computer simulations that are increasingly used as learning activities in modern health care education, especially in teaching clinical decision making. A key challenge is how to retrieve and repurpose virtual patients as unique types of educational resources between different platforms because of the lack of standardized content-retrieving and repurposing mechanisms. Semantic Web technologies provide the capability, through structured information, for easy retrieval, reuse, repurposing, and exchange of virtual patients between different systems. An attempt to address this challenge has been made through the mEducator Best Practice Network, which provisioned frameworks for the discovery, retrieval, sharing, and reuse of medical educational resources. We have extended the OpenLabyrinth virtual patient authoring and deployment platform to facilitate the repurposing and retrieval of existing virtual patient material. A standalone Web distribution and Web interface, which contains an extension for the OpenLabyrinth virtual patient authoring system, was implemented. This extension was designed to semantically annotate virtual patients to facilitate intelligent searches, complex queries, and easy exchange between institutions. The OpenLabyrinth extension enables OpenLabyrinth authors to integrate and share virtual patient case metadata within the mEducator3.0 network. Evaluation included 3 successive steps: (1) expert reviews; (2) evaluation of the ability of health care professionals and medical students to create, share, and exchange virtual patients through specific scenarios in extended OpenLabyrinth (OLabX); and (3) evaluation of the repurposed learning objects that emerged from the procedure. We evaluated 30 repurposed virtual patient cases. The evaluation, with a total of 98 participants, demonstrated the system's main strength: the core repurposing capacity. The extensive metadata schema presentation facilitated user exploration and filtering of resources. Usability weaknesses were primarily related to standard computer applications' ease of use provisions. Most evaluators provided positive feedback regarding educational experiences on both content and system usability. Evaluation results replicated across several independent evaluation events. The OpenLabyrinth extension, as part of the semantic mEducator3.0 approach, is a virtual patient sharing approach that builds on a collection of Semantic Web services and federates existing sources of clinical and educational data. It is an effective sharing tool for virtual patients and has been merged into the next version of the app (OpenLabyrinth 3.3). Such tool extensions may enhance the medical education arsenal with capacities of creating simulation/game-based learning episodes, massive open online courses, curricular transformations, and a future robust infrastructure for enabling mobile learning.

The cool potential of gluons

NASA Astrophysics Data System (ADS)

Peshier*, André; Giovannoni, Dino

2016-01-01

We put forward the idea that the quark-gluon plasma might exist way below the usual confinement temperature Tc. Our argument rests on the possibility that the plasma produced in heavy-ion collisions could reach a transient quasi-equilibrium with ‘over-occupied’ gluon density, as advocated by Blaizot et al. Taking further into account that gluons acquire an effective mass by interaction effects, they can have a positive chemical potential and therefore behave similarly to non-relativistic bosons. Relevant properties of this dense state of interacting gluons, which we dub serried glue, can then be inferred on rather general grounds from Maxwell's relation.

Small-x asymptotics of the gluon helicity distribution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kovchegov, Yuri V.; Pitonyak, Daniel; Sievert, Matthew D.

2017-10-27

Here, we determine the small-x asymptotics of the gluon helicity distribution in a proton at leading order in perturbative QCD at large N c. To achieve this, we begin by evaluating the dipole gluon helicity TMD at small x. In the process we obtain an interesting new result: in contrast to the unpolarized dipole gluon TMD case, the operator governing the small-x behavior of the dipole gluon helicity TMD is different from the operator corresponding to the polarized dipole scattering amplitude (used in our previous work to determine the small-x asymptotics of the quark helicity distribution).

Dimensional Transmutation by Monopole Condensation in QCD

NASA Astrophysics Data System (ADS)

Cho, Y. M.

2015-01-01

The dimensional transmutation by the monopole condensation in QCD is reviewed. Using Abelian projection of the gauge potential which projects out the monopole potential gauge independently, we we show that there are two types of gluons: the color neutral binding gluons which plays the role of the confining agent and the colored valence gluons which become confined prisoners. With this we calculate the one-loop QCD effective potential and show the monopole condensation becomes the true vacuum of QCD. We propose to test the existence of two types of gluons experimentally by re-analyzing the existing gluon jets data.

vh@nnlo-v2: new physics in Higgs Strahlung

NASA Astrophysics Data System (ADS)

Harlander, Robert V.; Klappert, Jonas; Liebler, Stefan; Simon, Lukas

2018-05-01

Introducing version 2 of the code vh@nnlo [1], we study the effects of a number of new-physics scenarios on the Higgs-Strahlung process. In particular, the cross section is evaluated within a general 2HDM and the MSSM. While the Drell-Yan-like contributions are consistently taken into account by a simple rescaling of the SM result, the gluon-initiated contribution is supplemented by squark-loop mediated amplitudes, and by the s-channel exchange of additional scalars which may lead to conspicuous interference effects. The latter holds as well for bottom-quark initiated Higgs Strahlung, which is also included in the new version of vh@nnlo. Using an orthogonal rotation of the three Higgs CP eigenstates in the 2HDM and the MSSM, vh@nnlo incorporates a simple means of CP mixing in these models. Moreover, the effect of vector-like quarks in the SM on the gluon-initiated contribution can be studied. Beyond concrete models, vh@nnlo allows to include the effect of higher-dimensional operators on the production of CP-even Higgs bosons. Transverse momentum distributions of the final state Higgs boson and invariant mass distributions of the Vϕ final state for the gluon- and bottom-quark initiated contributions can be studied. Distributions for the Drell-Yan-like component of Higgs Strahlung can be included through a link to MCFM. vh@nnlo can also be linked to FeynHiggs and 2HDMC for the calculation of Higgs masses and mixing angles. It can also read these parameters from an SLHA-file as produced by standard spectrum generators. Throughout the manuscript, we highlight new-physics effects in various numerical examples, both at the inclusive level and for distributions.

A VIRTUAL LEARNING COMMUNITY TO FACILITATE SUSTAINABLE BEHAVIOR

EPA Science Inventory

Research to date on virtual learning communities suggests that electronic interaction can be a useful way to impact new skills and to encourage innovative practices by creating networked systems of mutual support. We expect that by being able to exchange information, trade tip...

Digital Resource Exchange About Music (DREAM): Phase 2 Usability Testing

ERIC Educational Resources Information Center

Upitis, Rena; Boese, Karen; Abrami, Philip C.; Anwar, Zaeem

2015-01-01

The Digital Resource Exchange About Music (DREAM) is a virtual space for exchanging information about digital learning tools. The purpose of the present study was to determine how users responded to DREAM in the first four months after its public release. This study is the second phase of usability research on DREAM, and was conducted to guide…

Quark-gluon tagging with shower deconstruction: Unearthing dark matter and Higgs couplings

NASA Astrophysics Data System (ADS)

Ferreira de Lima, Danilo; Petrov, Petar; Soper, Davison; Spannowsky, Michael

2017-02-01

The separation of quark and gluon initiated jets can be an important way to improve the sensitivity in searches for new physics or in measurements of Higgs boson properties. We present a simplified version of the shower deconstruction approach as a novel observable for quark-gluon tagging. Assuming topoclusterlike objects as input, we compare our observable with energy correlation functions and find a favorable performance for a large variety of jet definitions. We address the issue of infrared sensitivity of quark-gluon discrimination. When this approach is applied to dark matter searches in monojet final states, limitations from small signal-to-background ratios can be overcome. We also show that quark-gluon tagging is an alternative way of separating weak boson from gluon-fusion production in the process p +p →H +jet+jet+X .

When gluons go odd: how classical gluon fields generate odd azimuthal harmonics for the two-gluon correlation function in high-energy collisions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kovchegov, Yuri V.; Skokov, Vladimir V.

We show that, in the saturation/Color Glass Condensate framework, odd azimuthal harmonics of the two-gluon correlation function with a long-range separation in rapidity are generated by the higher-order saturation corrections in the interactions with the projectile and the target. At the very least, the odd harmonics require three scatterings in the projectile and three scatterings in the target. We derive the leading-order expression for the two-gluon production cross section which generates odd harmonics: the expression includes all-order interactions with the target and three interactions with the projectile. Here, we evaluate the obtained expression both analytically and numerically, confirming that themore » odd-harmonics contribution to the two-gluon production in the saturation framework is non-zero.« less

When gluons go odd: how classical gluon fields generate odd azimuthal harmonics for the two-gluon correlation function in high-energy collisions

DOE PAGES

Kovchegov, Yuri V.; Skokov, Vladimir V.

2018-04-30

We show that, in the saturation/Color Glass Condensate framework, odd azimuthal harmonics of the two-gluon correlation function with a long-range separation in rapidity are generated by the higher-order saturation corrections in the interactions with the projectile and the target. At the very least, the odd harmonics require three scatterings in the projectile and three scatterings in the target. We derive the leading-order expression for the two-gluon production cross section which generates odd harmonics: the expression includes all-order interactions with the target and three interactions with the projectile. Here, we evaluate the obtained expression both analytically and numerically, confirming that themore » odd-harmonics contribution to the two-gluon production in the saturation framework is non-zero.« less

Nonperturbative quark, gluon, and meson correlators of unquenched QCD

NASA Astrophysics Data System (ADS)

Cyrol, Anton K.; Mitter, Mario; Pawlowski, Jan M.; Strodthoff, Nils

2018-03-01

We present nonperturbative first-principle results for quark, gluon, and meson 1PI correlation functions of two-flavor Landau-gauge QCD in the vacuum. These correlation functions carry the full information about the theory. They are obtained by solving their functional renormalization group equations in a systematic vertex expansion, aiming at apparent convergence. This work represents a crucial prerequisite for quantitative first-principle studies of the QCD phase diagram and the hadron spectrum within this framework. In particular, we have computed the gluon, ghost, quark, and scalar-pseudoscalar meson propagators, as well as gluon, ghost-gluon, quark-gluon, quark, quark-meson, and meson interactions. Our results stress the crucial importance of the quantitatively correct running of different vertices in the semiperturbative regime for describing the phenomena and scales of confinement and spontaneous chiral symmetry breaking without phenomenological input.

Gluon structure function of a color dipole in the light-cone limit of lattice QCD

NASA Astrophysics Data System (ADS)

Grünewald, D.; Ilgenfritz, E.-M.; Pirner, H. J.

2009-10-01

We calculate the gluon structure function of a color dipole in near-light-cone SU(2) lattice QCD as a function of xB. The quark and antiquark are external nondynamical degrees of freedom which act as sources of the gluon string configuration defining the dipole. We compute the color dipole matrix element of transversal chromo-electric and chromo-magnetic field operators separated along a direction close to the light cone, the Fourier transform of which is the gluon structure function. As vacuum state in the pure glue sector, we use a variational ground state of the near-light-cone Hamiltonian. We derive a recursion relation for the gluon structure function on the lattice similar to the perturbative Dokshitzer-Gribov-Lipatov-Altarelli-Parisi equation. It depends on the number of transversal links assembling the Schwinger string of the dipole. Fixing the mean momentum fraction of the gluons to the “experimental value” in a proton, we compare our gluon structure function for a dipole state with four links with the next-to-leading-order MRST 2002 and the CTEQ AB-0 parametrizations at Q2=1.5GeV2. Within the systematic uncertainty we find rather good agreement. We also discuss the low xB behavior of the gluon structure function in our model calculation.

Multiplicity distributions of gluon and quark jets and tests of QCD analytic predictions

NASA Astrophysics Data System (ADS)

OPAL Collaboration; Ackerstaff, K.; et al.

Gluon jets are identified in e+e^- hadronic annihilation events by tagging two quark jets in the same hemisphere of an event. The gluon jet is defined inclusively as all the particles in the opposite hemisphere. Gluon jets defined in this manner have a close correspondence to gluon jets as they are defined for analytic calculations, and are almost independent of a jet finding algorithm. The charged particle multiplicity distribution of the gluon jets is presented, and is analyzed for its mean, dispersion, skew, and curtosis values, and for its factorial and cumulant moments. The results are compared to the analogous results found for a sample of light quark (uds) jets, also defined inclusively. We observe differences between the mean, skew and curtosis values of gluon and quark jets, but not between their dispersions. The cumulant moment results are compared to the predictions of QCD analytic calculations. A calculation which includes next-to-next-to-leading order corrections and energy conservation is observed to provide a much improved description of the data compared to a next-to-leading order calculation without energy conservation. There is agreement between the data and calculations for the ratios of the cumulant moments between gluon and quark jets.

Evidence for the Absence of Gluon Orbital Angular Momentum in the Nucleon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brodsky, S.J.; Gardner, S.

2006-08-23

The Sivers mechanism for the single-spin asymmetry in unpolarized lepton scattering from a transversely polarized nucleon is driven by the orbital angular momentum carried by its quark and gluon constituents, combined with QCD final-state interactions. Both quark and gluon mechanisms can generate such a single-spin asymmetry, though only the quark mechanism can explain the small single-spin asymmetry measured by the COMPASS collaboration on the deuteron, suggesting the gluon mechanism is small relative to the quark mechanism. We detail empirical studies through which the gluon and quark orbital angular momentum contributions, quark-flavor by quark-flavor, can be elucidated.

Analysis of the proton longitudinal structure function from the gluon distribution function

NASA Astrophysics Data System (ADS)

Boroun, G. R.; Rezaei, B.

2012-11-01

We make a critical, next-to-leading order, study of the relationship between the longitudinal structure function F L and the gluon distribution proposed in Cooper-Sarkar et al. (Z. Phys. C 39:281, 1988; Acta Phys. Pol. B 34:2911 2003), which is frequently used to extract the gluon distribution from the proton longitudinal structure function at small x. The gluon density is obtained by expanding at particular choices of the point of expansion and compared with the hard Pomeron behavior for the gluon density. Comparisons with H1 data are made and predictions for the proposed best approach are also provided.

Regularization of the light-cone gauge gluon propagator singularities using sub-gauge conditions

DOE PAGES

Chirilli, Giovanni A.; Kovchegov, Yuri V.; Wertepny, Douglas E.

2015-12-21

Perturbative QCD calculations in the light-cone gauge have long suffered from the ambiguity associated with the regularization of the poles in the gluon propagator. In this work we study sub-gauge conditions within the light-cone gauge corresponding to several known ways of regulating the gluon propagator. By using the functional integral calculation of the gluon propagator, we rederive the known sub-gauge conditions for the θ-function gauges and identify the sub-gauge condition for the principal value (PV) regularization of the gluon propagator’s light-cone poles. The obtained sub-gauge condition for the PV case is further verified by a sample calculation of the classicalmore » Yang-Mills field of two collinear ultrarelativistic point color charges. Our method does not allow one to construct a sub-gauge condition corresponding to the well-known Mandelstam-Leibbrandt prescription for regulating the gluon propagator poles.« less

Are the dressed gluon and ghost propagators in the Landau gauge presently determined in the confinement regime of QCD?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pennington, M. R.; Wilson, D. J.

2011-11-01

The gluon and ghost propagators in Landau gauge QCD are investigated using the Schwinger-Dyson equation approach. Working in Euclidean spacetime, we solve for these propagators using a selection of vertex inputs, initially for the ghost equation alone and then for both propagators simultaneously. The results are shown to be highly sensitive to the choices of vertices. We favor the infrared finite ghost solution from studying the ghost equation alone where we argue for a specific unique solution. In order to solve this simultaneously with the gluon using a dressed-one-loop truncation, we find that a nontrivial full ghost-gluon vertex is requiredmore » in the vanishing gluon momentum limit. The self-consistent solutions we obtain correspond to having a masslike term in the gluon propagator dressing, in agreement with similar studies supporting the long-held proposal of Cornwall.« less

Virtual Project Rooms for Education in Engineering

ERIC Educational Resources Information Center

van Vliet, Rudolf G.; Roeling, Monika M.; de Graaff, Rick; Pilot, Albert

2004-01-01

Virtual project rooms (VPRs) may support collaborative project-based learning groups by facilitating project management, documentation and communication. In this study a set of experiments was carried out at Eindhoven University of Technology using the MS Outlook/Exchange software as a groupware platform for design-oriented group projects. The…

Preadolescent Girls' and Boys' Virtual MUD Play

ERIC Educational Resources Information Center

Calvert, Sandra L.; Strouse, Gabrielle A.; Strong, Bonnie L.; Huffaker, David A.; Lai, Sean

2009-01-01

Same and opposite-sex pairs of preadolescents interacted twice in a MUD, a virtual domain where they created characters known as avatars and socially interacted with one another. Boys interacted primarily through rapid scene shifts and playful exchanges; girls interacted with one another through written dialogue. Opposite-sex pairs lagged behind…

Shear and bulk viscosity of high-temperature gluon plasma

NASA Astrophysics Data System (ADS)

Zhang, Le; Hou, De-Fu

2018-05-01

We calculate the shear viscosity (η) and bulk viscosity (ζ) to entropy density (s) ratios η/s and ζ/s of a gluon plasma system in kinetic theory, including both the elastic {gg}≤ftrightarrow {gg} forward scattering and the inelastic soft gluon bremsstrahlung {gg}≤ftrightarrow {ggg} processes. Due to the suppressed contribution to η and ζ in the {gg}≤ftrightarrow {gg} forward scattering and the effective g≤ftrightarrow {gg} gluon splitting, Arnold, Moore and Yaffe (AMY) and Arnold, Dogan and Moore (ADM) have got the leading order computations for η and ζ in high-temperature QCD matter. In this paper, we calculate the correction to η and ζ in the soft gluon bremsstrahlung {gg}≤ftrightarrow {ggg} process with an analytic method. We find that the contribution of the collision term from the {gg}≤ftrightarrow {ggg} soft gluon bremsstrahlung process is just a small perturbation to the {gg}≤ftrightarrow {gg} scattering process and that the correction is at ∼5% level. Then, we obtain the bulk viscosity of the gluon plasma for the number-changing process. Furthermore, our leading-order result for bulk viscosity is the formula \\zeta \\propto \\tfrac{{α }s2{T}3}{ln}{α }s-1} in high-temperature gluon plasma. Supported by Ministry of Science and Technology of China (MSTC) under the “973” Project (2015CB856904(4)) and National Natural Science Foundation of China (11735007, 11521064)

How to measure the linear polarization of gluons in unpolarized proton using the heavy-quark pair leptoproduction

NASA Astrophysics Data System (ADS)

Efremov, A. V.; Ivanov, N. Ya.; Teryaev, O. V.

2018-02-01

We study the azimuthal cos ⁡ φ and cos ⁡ 2 φ asymmetries in heavy-quark pair leptoproduction, lN →l‧ Q Q bar X, as probes of linearly polarized gluons inside unpolarized proton, where the azimuth φ is the angle between the lepton scattering plane (l ,l‧) and the heavy quark production plane (N , Q). First, we determine the maximal values for the cos ⁡ φ and cos ⁡ 2 φ asymmetries allowed by the photon-gluon fusion with unpolarized gluons; these predictions are large, (√{ 3 } - 1) / 2 and 1/3, respectively. Then we calculate the contribution of the transverse-momentum dependent gluonic counterpart of the Boer-Mulders function, h1⊥g, describing the linear polarization of gluons inside unpolarized proton. Our analysis shows that the maximum values of the azimuthal distributions depend strongly on the gluon polarization; they vary from 0 to 1 depending on h1⊥g. We conclude that the azimuthal cos ⁡ φ and cos ⁡ 2 φ asymmetries in heavy-quark pair leptoproduction are predicted to be large and very sensitive to the contribution of linearly polarized gluons. For this reason, future measurements of the azimuthal distributions in charm and bottom production at the proposed EIC and LHeC colliders seem to be very promising for determination of the linear polarization of gluons inside unpolarized proton.

TMD splitting functions in [Formula: see text] factorization: the real contribution to the gluon-to-gluon splitting.

PubMed

Hentschinski, M; Kusina, A; Kutak, K; Serino, M

2018-01-01

We calculate the transverse momentum dependent gluon-to-gluon splitting function within [Formula: see text]-factorization, generalizing the framework employed in the calculation of the quark splitting functions in Hautmann et al. (Nucl Phys B 865:54-66, arXiv:1205.1759, 2012), Gituliar et al. (JHEP 01:181, arXiv:1511.08439, 2016), Hentschinski et al. (Phys Rev D 94(11):114013, arXiv:1607.01507, 2016) and demonstrate at the same time the consistency of the extended formalism with previous results. While existing versions of [Formula: see text] factorized evolution equations contain already a gluon-to-gluon splitting function i.e. the leading order Balitsky-Fadin-Kuraev-Lipatov (BFKL) kernel or the Ciafaloni-Catani-Fiorani-Marchesini (CCFM) kernel, the obtained splitting function has the important property that it reduces both to the leading order BFKL kernel in the high energy limit, to the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) gluon-to-gluon splitting function in the collinear limit as well as to the CCFM kernel in the soft limit. At the same time we demonstrate that this splitting kernel can be obtained from a direct calculation of the QCD Feynman diagrams, based on a combined implementation of the Curci-Furmanski-Petronzio formalism for the calculation of the collinear splitting functions and the framework of high energy factorization.

Constraints on spin-dependent parton distributions at large x from global QCD analysis

DOE PAGES

Jimenez-Delgado, P.; Avakian, H.; Melnitchouk, W.

2014-09-28

This study investigate the behavior of spin-dependent parton distribution functions (PDFs) at large parton momentum fractions x in the context of global QCD analysis. We explore the constraints from existing deep-inelastic scattering data, and from theoretical expectations for the leading x → 1 behavior based on hard gluon exchange in perturbative QCD. Systematic uncertainties from the dependence of the PDFs on the choice of parametrization are studied by considering functional forms motivated by orbital angular momentum arguments. Finally, we quantify the reduction in the PDF uncertainties that may be expected from future high-x data from Jefferson Lab at 12 GeV.

World Wind: NASA's Virtual Globe

NASA Astrophysics Data System (ADS)

Hogan, P.

2007-12-01

Virtual globes have set the standard for information exchange. Once you've experienced the visually rich and highly compelling nature of data delivered via virtual globes with their highly engaging context of 3D, it's hard to go back to a flat 2D world. Just as the sawbones of not-too-long-ago have given way to sophisticated surgical operating theater, today's medium for information exchange is just beginning to leap from the staid chalkboards and remote libraries to fingertip navigable 3D worlds. How we harness this technology to serve a world inundated with information will describe the quality of our future. Our instincts for discovery and entertainment urge us on. There's so much we could know if the world's knowledge was presented to us in its natural context. Virtual globes are almost magical in their ability to reveal natural wonders. Anyone flying along a chain of volcanoes, a mid-ocean ridge or deep ocean trench, while simultaneously seeing the different depths to the history of earthquakes in those areas, will be delighted to sense Earth's dynamic nature in a way that would otherwise take several paragraphs of "boring" text. The sophisticated concepts related to global climate change would be far more comprehensible when experienced via a virtual globe. There is a large universe of public and private geospatial data sets that virtual globes can bring to light. The benefit derived from access to this data within virtual globes represents a significant return on investment for government, industry, the general public, and especially in the realm of education. Data access remains a key issue. Just as the highway infrastructure allows unimpeded access from point A to point B, an open standards-based infrastructure for data access allows virtual globes to exchange data in the most efficient manner possible. This data can be either free or proprietary. The Open Geospatial Consortium is providing the leadership necessary for this open standards-based data access infrastructure. The open-source community plays a crucial role in advancing virtual globe technology. This world community identifies, tracks and resolves technical problems, suggests new features and source code modifications, and often provides high-resolution data sets and other types of user-generated content, all while extending the functionality of virtual globe technology. NASA World Wind is one example of open source virtual globe technology that provides the world with the ability to build any desired functionality and make any desired data accessible.

Fluctuations of the gluon distribution from the small- x effective action

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dumitru, Adrian; Skokov, Vladimir

The computation of observables in high-energy QCD involves an average over stochastic semiclassical small-x gluon fields. The weight of various configurations is determined by the effective action. We introduce a method to study fluctuations of observables, functionals of the small-x fields, which does not explicitly involve dipoles. We integrate out those fluctuations of the semiclassical gluon field under which a given observable is invariant. Thereby we obtain the effective potential for that observable describing its fluctuations about the average. Here, we determine explicitly the effective potential for the covariant gauge gluon distribution both for the McLerran-Venugopalan (MV) model and formore » a (nonlocal) Gaussian approximation for the small-x effective action. This provides insight into the correlation of fluctuations of the number of hard gluons versus their typical transverse momentum. We find that the spectral shape of the fluctuations of the gluon distribution is fundamentally different in the MV model, where there is a pileup of gluons near the saturation scale, versus the solution of the small-x JIMWLK renormalization group, which generates essentially scale-invariant fluctuations above the absorptive boundary set by the saturation scale.« less

Fluctuations of the gluon distribution from the small- x effective action

DOE PAGES

Dumitru, Adrian; Skokov, Vladimir

2017-09-29

The computation of observables in high-energy QCD involves an average over stochastic semiclassical small-x gluon fields. The weight of various configurations is determined by the effective action. We introduce a method to study fluctuations of observables, functionals of the small-x fields, which does not explicitly involve dipoles. We integrate out those fluctuations of the semiclassical gluon field under which a given observable is invariant. Thereby we obtain the effective potential for that observable describing its fluctuations about the average. Here, we determine explicitly the effective potential for the covariant gauge gluon distribution both for the McLerran-Venugopalan (MV) model and formore » a (nonlocal) Gaussian approximation for the small-x effective action. This provides insight into the correlation of fluctuations of the number of hard gluons versus their typical transverse momentum. We find that the spectral shape of the fluctuations of the gluon distribution is fundamentally different in the MV model, where there is a pileup of gluons near the saturation scale, versus the solution of the small-x JIMWLK renormalization group, which generates essentially scale-invariant fluctuations above the absorptive boundary set by the saturation scale.« less

Small parameters in infrared quantum chromodynamics

NASA Astrophysics Data System (ADS)

Peláez, Marcela; Reinosa, Urko; Serreau, Julien; Tissier, Matthieu; Wschebor, Nicolás

2017-12-01

We study the long-distance properties of quantum chromodynamics in the Landau gauge in an expansion in powers of the three-gluon, four-gluon, and ghost-gluon couplings, but without expanding in the quark-gluon coupling. This is motivated by two observations. First, the gauge sector is well described by perturbation theory in the context of a phenomenological model with a massive gluon. Second, the quark-gluon coupling is significantly larger than those in the gauge sector at large distances. In order to resum the contributions of the remaining infinite set of QED-like diagrams, we further expand the theory in 1 /Nc, where Nc is the number of colors. At leading order, this double expansion leads to the well-known rainbow approximation for the quark propagator. We take advantage of the systematic expansion to get a renormalization-group improvement of the rainbow resummation. A simple numerical solution of the resulting coupled set of equations reproduces the phenomenology of the spontaneous chiral symmetry breaking: for sufficiently large quark-gluon coupling constant, the constituent quark mass saturates when its valence mass approaches zero. We find very good agreement with lattice data for the scalar part of the propagator and explain why the vectorial part is poorly reproduced.

Regional cooperation and transportation planning in Alaska : a regional models of cooperation peer exchange summary report.

DOT National Transportation Integrated Search

2017-01-31

This report summarizes the proceedings of a Regional Models of Cooperation Virtual Peer Exchange Workshop held on March 9 10, 2016 for the State of Alaska. Participants discussed the benefits and challenges of cooperation across jurisdictions and...

Outstanding performance of configuration interaction singles and doubles using exact exchange Kohn-Sham orbitals in real-space numerical grid method

NASA Astrophysics Data System (ADS)

Lim, Jaechang; Choi, Sunghwan; Kim, Jaewook; Kim, Woo Youn

2016-12-01

To assess the performance of multi-configuration methods using exact exchange Kohn-Sham (KS) orbitals, we implemented configuration interaction singles and doubles (CISD) in a real-space numerical grid code. We obtained KS orbitals with the exchange-only optimized effective potential under the Krieger-Li-Iafrate (KLI) approximation. Thanks to the distinctive features of KLI orbitals against Hartree-Fock (HF), such as bound virtual orbitals with compact shapes and orbital energy gaps similar to excitation energies; KLI-CISD for small molecules shows much faster convergence as a function of simulation box size and active space (i.e., the number of virtual orbitals) than HF-CISD. The former also gives more accurate excitation energies with a few dominant configurations than the latter, even with many more configurations. The systematic control of basis set errors is straightforward in grid bases. Therefore, grid-based multi-configuration methods using exact exchange KS orbitals provide a promising new way to make accurate electronic structure calculations.

The gluon condensation at high energy hadron collisions

NASA Astrophysics Data System (ADS)

Zhu, Wei; Lan, Jiangshan

2017-03-01

We report that the saturation/CGC model of gluon distribution is unstable under action of the chaotic solution in a nonlinear QCD evolution equation, and it evolves to the distribution with a sharp peak at the critical momentum. We find that this gluon condensation is caused by a new kind of shadowing-antishadowing effects, and it leads to a series of unexpected effects in high energy hadron collisions including astrophysical events. For example, the extremely intense fluctuations in the transverse-momentum and rapidity distributions of the gluon jets present the gluon-jet bursts; a sudden increase of the proton-proton cross sections may fill the GZK suppression; the blocking QCD evolution will restrict the maximum available energy of the hadron-hadron colliders.

Next-to-leading order transverse momentum-weighted Sivers asymmetry in semi-inclusive deep inelastic scattering: The role of the three-gluon correlator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dai, Ling -Yun; Kang, Zhong -Bo; Prokudin, Alexei

2015-12-22

Here, we study the Sivers asymmetry in semi-inclusive hadron production in deep inelastic scattering. We concentrate on the contribution from the photon-gluon fusion channel at O(α em 2α s), where three-gluon correlation functions play a major role within the twist-3 collinear factorization formalism. We establish the correspondence between such a formalism with three-gluon correlation functions and the usual transverse momentum-dependent (TMD) factorization formalism at moderate hadron transverse momenta. We derive the coefficient functions used in the usual TMD evolution formalism related to the quark Sivers function expansion in terms of the three-gluon correlation functions. We further perform the next-to-leading ordermore » calculation for the transverse momentum-weighted spin-dependent differential cross section and identify the off-diagonal contribution from the three-gluon correlation functions to the QCD collinear evolution of the twist-3 Qiu-Sterman function.« less

SU(3) Landau gauge gluon and ghost propagators using the logarithmic lattice gluon field definition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ilgenfritz, Ernst-Michael; Humboldt-Universitaet zu Berlin, Institut fuer Physik, 12489 Berlin; Menz, Christoph

2011-03-01

We study the Landau gauge gluon and ghost propagators of SU(3) gauge theory, employing the logarithmic definition for the lattice gluon fields and implementing the corresponding form of the Faddeev-Popov matrix. This is necessary in order to consistently compare lattice data for the bare propagators with that of higher-loop numerical stochastic perturbation theory. In this paper we provide such a comparison, and introduce what is needed for an efficient lattice study. When comparing our data for the logarithmic definition to that of the standard lattice Landau gauge we clearly see the propagators to be multiplicatively related. The data of themore » associated ghost-gluon coupling matches up almost completely. For the explored lattice spacings and sizes discretization artifacts, finite size, and Gribov-copy effects are small. At weak coupling and large momentum, the bare propagators and the ghost-gluon coupling are seen to be approached by those of higher-order numerical stochastic perturbation theory.« less

Cooperative Lamb shift and superradiance in an optoelectronic device

NASA Astrophysics Data System (ADS)

Frucci, G.; Huppert, S.; Vasanelli, A.; Dailly, B.; Todorov, Y.; Beaudoin, G.; Sagnes, I.; Sirtori, C.

2017-04-01

When a single excitation is shared between a large number of two-level systems, a strong enhancement of the spontaneous emission appears. This phenomenon is known as superradiance. This enhanced rate can be accompanied by a shift of the emission frequency, the cooperative Lamb shift, issued from the exchange of virtual photons between the emitters. In this work we present a semiconductor optoelectronic device allowing the observation of these two phenomena at room temperature. We demonstrate experimentally and theoretically that plasma oscillations in spatially separated quantum wells interact through real and virtual photon exchange. This gives rise to a superradiant mode displaying a large cooperative Lamb shift.

Gluon transport equation with effective mass and dynamical onset of Bose–Einstein condensation

DOE PAGES

Blaizot, Jean-Paul; Jiang, Yin; Liao, Jinfeng

2016-05-01

In this paper we study the transport equation describing a dense system of gluons, in the small scattering angle approximation, taking into account medium-generated effective masses of the gluons. We focus on the case of overpopulated systems that are driven to Bose–Einstein condensation on their way to thermalization. Lastly, the presence of a mass modifies the dispersion relation of the gluon, as compared to the massless case, but it is shown that this does not change qualitatively the scaling behavior in the vicinity of the onset.

Gluon transport equation with effective mass and dynamical onset of Bose–Einstein condensation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blaizot, Jean-Paul; Jiang, Yin; Liao, Jinfeng

In this paper we study the transport equation describing a dense system of gluons, in the small scattering angle approximation, taking into account medium-generated effective masses of the gluons. We focus on the case of overpopulated systems that are driven to Bose–Einstein condensation on their way to thermalization. Lastly, the presence of a mass modifies the dispersion relation of the gluon, as compared to the massless case, but it is shown that this does not change qualitatively the scaling behavior in the vicinity of the onset.

Boson mapping techniques applied to constant gauge fields in QCD

NASA Technical Reports Server (NTRS)

Hess, Peter Otto; Lopez, J. C.

1995-01-01

Pairs of coordinates and derivatives of the constant gluon modes are mapped to new gluon-pair fields and their derivatives. Applying this mapping to the Hamiltonian of constant gluon fields results for large coupling constants into an effective Hamiltonian which separates into one describing a scalar field and another one for a field with spin two. The ground state is dominated by pairs of gluons coupled to color and spin zero with slight admixtures of color zero and spin two pairs. As color group we used SU(2).

How classical gluon fields generate odd azimuthal harmonics for the two-gluon correlation function in high-energy collisions

NASA Astrophysics Data System (ADS)

Kovchegov, Yuri V.; Skokov, Vladimir V.

2018-05-01

We show that, in the saturation/color glass condensate framework, odd azimuthal harmonics of the two-gluon correlation function with a long-range separation in rapidity are generated by the higher-order saturation corrections in the interactions with the projectile and the target. At the very least, the odd harmonics require three scatterings in the projectile and three scatterings in the target. We derive the leading-order expression for the two-gluon production cross section which generates odd harmonics: the expression includes all-order interactions with the target and three interactions with the projectile. We evaluate the obtained expression both analytically and numerically, confirming that the odd-harmonics contribution to the two-gluon production in the saturation framework is nonzero.

1/Nc expansion and the spin-flavor structure of the quark interaction in the constituent quark model

NASA Astrophysics Data System (ADS)

Pirjol, Dan; Schat, Carlos

2010-12-01

We study the hierarchy of the coefficients in the 1/Nc expansion for the negative parity L=1 excited baryons from the perspective of the constituent quark model. This is related to the problem of determining the spin-flavor structure of the quark interaction. The most general two-body scalar interaction between quarks contains the spin-flavor structures t1at2a,s→1·s→2 and s→1·s→2t1at2a. We show that in the limit of a zero range interaction all these structures are matched onto the same hadronic mass operator Sc2, which gives a possible explanation for the dominance of this operator in the 1/Nc expansion for the L=1 states and implies that in this limit it is impossible to distinguish between these different spin-flavor structures. Modeling a finite range interaction through the exchange of a vector and pseudoscalar meson, we propose a test for the spin-flavor dependence of the quark forces. For the scalar part of the quark interaction, we find that both pion exchange and gluon exchange are compatible with the data.

Social Media and Population Health Virtual Exchange for Senior Nursing Students: An International Collaboration.

PubMed

Procter, Paula M; Brixey, Juliana J; Honey, Michelle L L; Todhunter, Fern

2016-01-01

The authors have all engaged in using social media with students as a means for collaboration across national and international boundaries for various educational purposes. Following the explosion of big data in health the authors are now moving this concept forward within undergraduate and postgraduate nursing curricula for the development of population health virtual exchanges. Nursing has a global presence and yet it appears as though students have little knowledge of the health and social care needs and provision outside their local environment. This development will allow for explorative exchange amongst students in three countries, enhancing their understanding of their own and the selected international population health needs and solutions through asking and responding to questions amongst the learning community involved. The connection of the students will be recorded for their use in reflection; of particular interest will be the use of information included by the students to answer questions about their locality.

The Virtual Data Center Tagged-Format Tool - Introduction and Executive Summary

USGS Publications Warehouse

Evans, John R.; Squibb, Melinda; Stephens, Christopher D.; Savage, W.U.; Haddadi, Hamid; Kircher, Charles A.; Hachem, Mahmoud M.

2008-01-01

This Report introduces and summarizes the new Virtual Data Center (VDC) Tagged Format (VTF) Tool, which was developed by a diverse group of seismologists, earthquake engineers, and information technology professionals for internal use by the COSMOS VDC and other interested parties for the exchange, archiving, and analysis of earthquake strong-ground-motion data.

Gluon and Wilson loop TMDs for hadrons of spin ≤ 1

NASA Astrophysics Data System (ADS)

Boer, Daniël; Cotogno, Sabrina; van Daal, Tom; Mulders, Piet J.; Signori, Andrea; Zhou, Ya-Jin

2016-10-01

In this paper we consider the parametrizations of gluon transverse momentum dependent (TMD) correlators in terms of TMD parton distribution functions (PDFs). These functions, referred to as TMDs, are defined as the Fourier transforms of hadronic matrix elements of nonlocal combinations of gluon fields. The nonlocality is bridged by gauge links, which have characteristic paths (future or past pointing), giving rise to a process dependence that breaks universality. For gluons, the specific correlator with one future and one past pointing gauge link is, in the limit of small x, related to a correlator of a single Wilson loop. We present the parametrization of Wilson loop correlators in terms of Wilson loop TMDs and discuss the relation between these functions and the small- x `dipole' gluon TMDs. This analysis shows which gluon TMDs are leading or suppressed in the small- x limit. We discuss hadronic targets that are unpolarized, vector polarized (relevant for spin-1 /2 and spin-1 hadrons), and tensor polarized (relevant for spin-1 hadrons). The latter are of interest for studies with a future Electron-Ion Collider with polarized deuterons.

Gluon polarization in the proton: Constraints at low x from the measurement of the double longitudinal spin asymmetry for forward-rapidity hadrons with the PHENIX detector at RHIC

NASA Astrophysics Data System (ADS)

McKinney, Cameron Palmer

In the 1980s, polarized deep inelastic lepton-nucleon scattering experiments revealed that only about a third of the proton's spin of ½ h is carried by the quarks and antiquarks, leaving physicists with the puzzle of how to account for the remaining spin. As gluons carry roughly 50% of the proton's momentum, it seemed most logical to look to the gluon spin as another significant contributor. However, lepton-nucleon scattering experiments only access the gluon helicity distribution, Delta g, through effects on the quark distributions via scaling violations. Constraining Deltag through scaling violations requires experiments that together cover a large range of Q 2. Such experiments had been carried out with unpolarized beams, leaving g(x) (the unpolarized gluon distribution) relatively well-known, but the polarized experiments have only thus far provided weak constraints on Deltag in a limited momentum fraction range. With the commissioning in 2000 of the Relativistic Heavy Ion Collider, the first polarized proton-proton (pp) collider, and the first polarized pp running in 2002, the gluon distributions could be accessed directly by studying quark-gluon and gluon-gluon interactions. In 2009, data from measurements of double longitudinal spin asymmetries, ALL, at the STAR and PHENIX experiments through 2006 were included in a QCD global analysis performed by Daniel de Florian, Rodolfo Sassot, Marco Stratmann, and Werner Vogelsang (DSSV), yielding the first direct constraints on the gluon helicity. The DSSV group found that the contribution of the gluon spin to the proton spin was consistent with zero, but the data provided by PHENIX and STAR was all at mid-rapidity, meaning Delta g was constrained by data only a range in x from 0.05 to 0.2, leaving out helicity contributions from the huge number of low- x gluons. A more recent analysis by DSSV from 2014 including RHIC data through 2009 for the first time points to significant gluon polarization at intermediate momentum fractions, meaning gluon polarization measurements may be more interesting than anticipated, especially at momentum fractions where no constraints exist as of yet. A forward detector upgrade in PHENIX, the Muon Piston Calorimeter (MPC), was designed with the purpose of extending the sensitivity to Delta g to lower x. Monte Carlo simulations indicate that measurements of hadrons in the MPC's pseudorapidity of range 3.1 < eta <3.9 probe asymmetric collisions between high-x quarks and low-x gluons, with the x of the gluons reaching below 0.01 at a collision energy √s = 500 GeV. We access Deltag through measurements of ALL for electromagnetic clusters in the MPC; this thesis details the measurement from the Run 11 (2011) data set at √ s = 500GeV. We find ALL≈ 0, but the statistical uncertainties from this measurement mean we likely cannot resolve the small expected asymmetries. However, improved techniques for determining the relative luminosity between bunch crossings with different helicity configurations will allow data from a much larger data set in Run 13 to be most impactful in constraining Deltag, whereas previous measurements of ALL have had difficulties limiting the systematic uncertainty from relative luminosity. In this thesis, we begin by presenting an overview of the physics motivation for this experiment. Then, we discuss the experimental apparatus at RHIC and PHENIX, with a focus on those systems integral to our analysis. The analysis sections of the thesis cover calibration of the Muon Piston Calorimeter, a careful examination of the relative luminosity systematic uncertainty, and the process of obtaining a final physics result.

Higgs production and decay in models of a warped extra dimension with a bulk Higgs

DOE PAGES

Archer, Paul R.; Carena, Marcela; Carmona, Adrian; ...

2015-01-13

Warped extra-dimension models in which the Higgs boson is allowed to propagate in the bulk of a compact AdS 5 space are conjectured to be dual to models featuring a partially composite Higgs boson. They offer a framework with which to investigate the implications of changing the scaling dimension of the Higgs operator, which can be used to reduce the constraints from electroweak precision data. In the context of such models, we calculate the cross section for Higgs production in gluon fusion and the H → γγ decay rate and show that they are finite (at one-loop order) as amore » consequence of gauge invariance. The extended scalar sector comprising the Kaluza-Klein excitations of the Standard Model scalars is constructed in detail. The largest effects are due to virtual KK fermions, whose contributions to the cross section and decay rate introduce a quadratic sensitivity to the maximum allowed value y * of the random complex entries of the 5D anarchic Yukawa matrices. We find an enhancement of the gluon-fusion cross section and a reduction of the H → γγ rate as well as of the tree-level Higgs couplings to fermions and electroweak gauge bosons. As a result, we perform a detailed study of the correlated signal strengths for different production mechanisms and decay channels as functions of y *, the mass scale of Kaluza-Klein resonances and the scaling dimension of the composite Higgs operator.« less

The pressure distribution inside the proton.

PubMed

Burkert, V D; Elouadrhiri, L; Girod, F X

2018-05-01

The proton, one of the components of atomic nuclei, is composed of fundamental particles called quarks and gluons. Gluons are the carriers of the force that binds quarks together, and free quarks are never found in isolation-that is, they are confined within the composite particles in which they reside. The origin of quark confinement is one of the most important questions in modern particle and nuclear physics because confinement is at the core of what makes the proton a stable particle and thus provides stability to the Universe. The internal quark structure of the proton is revealed by deeply virtual Compton scattering 1,2 , a process in which electrons are scattered off quarks inside the protons, which  subsequently emit high-energy photons, which are detected in coincidence with the scattered electrons and recoil protons. Here we report a measurement of the pressure distribution experienced by the quarks in the proton. We find a strong repulsive pressure near the centre of the proton (up to 0.6 femtometres) and a binding pressure at greater distances. The average peak pressure near the centre is about 10 35 pascals, which exceeds the pressure estimated for the most densely packed known objects in the Universe, neutron stars 3 . This work opens up a new area of research on the fundamental gravitational properties of protons, neutrons and nuclei, which can provide access to their physical radii, the internal shear forces acting on the quarks and their pressure distributions.

Production of b and overlineb quarks by photon-gluon fusion in heavy-ion collisions

NASA Astrophysics Data System (ADS)

Hofmann, Ch.; Soff, G.; Schäfer, A.; Greiner, W.

1991-06-01

Electromagnetic Higgs production in ultrarelativistic heavy-ion collisions has been proposed as an alternative for detecting Higgs particles in the mass range mZ< mH<2 mW. We consider the fussion of a photon and a gluon into b and overlineb quarks as background to the b overlineb decay of the Higgs boson. This completely hides the Higgs signal. We also discuss the possibility of utilizing photon-gluon fusion into b overlineb and c overlinec as a sensitive tool to determine the gluon distribution of the nucleon inside the nucleus, e.g., at RHIC.

Search for gluon saturation at Bjorken-x of 10-6-10-5 with the LHCb detector

NASA Astrophysics Data System (ADS)

da Silva, Cesar; LHCb Collaboration

2017-09-01

Gluon saturation at small Byorken- x has been in the minds of particle and nuclear physicists for decades. This state can explain several recent observations such as 1) particle collectivity observed in p+p, p+A and A+A collisions at RHIC and LHC; and 2) depleted yield of particles coming from soft gluons. Previous results from DIS experiments at HERA show a fast increase of gluons as their fractional momentum x decreases. The LHCb experiment is a forward spectrometer with vertexing, tracking, p, K, pi , e, μ identification and calorimetry in the rapidity region 1.6 < η < 4.9. LHCb is the only experiment in the world which can probe x 10-6 -10-5 , up to two orders of magnitude smaller than HERA. A direct probe of gluons at small-x and small Q2 can be performed with γ+jet correlation measurements. The current detector acceptance is not optimized for soft particles coming from Q2 < 10 [GeV/c]2 processes, where gluon saturation is expected. R&D is underway for a new tracking detector to be placed inside the LHCb magnet, the Magnet Station (MS), which will enable measurements of these soft particles. This talk is going to report the status of the analysis efforts aimed at finding the gluon saturation scale at LHCb, and details of the MS. Los Alamos National Lab LDRD program.

Kobayashi-Kondo-Maskawa-'t Hooft interaction in pentaquarks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dmitrasinovic, V.

2005-05-01

We review critically the predictions of pentaquarks in the quark model, in particular, those based on the flavor-spin-dependent (Glozman-Riska) hyperfine interaction and the color-spin (one-gluon-exchange Fermi-Breit) one. We include the antiquark interactions and find that: (1) the exotic SU(3) multiplets are not substantially affected in the flavor-spin model, whereas some of the nonexotic multiplets are; and (2) the variational upper bound on the {xi}{sup --}-{theta}{sup +} mass difference in the color-spin hyperfine interaction model is substantially reduced. This leads us to the U{sub A}(1) symmetry breaking Kobayashi-Kondo-Maskawa-'tHooft interaction. We discuss some of its phenomenological consequences for pentaquarks.

Dijet angular distributions in direct and resolved photoproduction at HERA

NASA Astrophysics Data System (ADS)

Derrick, M.; Krakauer, D.; Magill, S.; Mikunas, D.; Musgrave, B.; Okrasinski, J. R.; Repond, J.; Stanek, R.; Talaga, R. L.; Zhang, H.; Mattingly, M. C. K.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Bruni, P.; Cara Romeo, G.; Castellini, G.; Cifarelli, L.; Cindolo, F.; Contin, A.; Corradi, M.; Gialas, I.; Giusti, P.; Iacobucci, G.; Laurenti, G.; Levi, G.; Margotti, A.; Massam, T.; Nania, R.; Palmonari, F.; Polini, A.; Sartorelli, G.; Zamora Garcia, Y.; Zichichi, A.; Amelung, C.; Bornheim, A.; Crittenden, J.; Deffner, R.; Doeker, T.; Eckert, M.; Feld, L.; Frey, A.; Geerts, M.; Grothe, M.; Hartmann, H.; Heinloth, K.; Heinz, L.; Hilger, E.; Jakob, H.-P.; Katz, U. F.; Mengel, S.; Paul, E.; Pfeiffer, M.; Rembser, Ch.; Schramm, D.; Stamm, J.; Wedemeyer, R.; Campbell-Robson, S.; Cassidy, A.; Cottingham, W. N.; Dyce, N.; Foster, B.; George, S.; Hayes, M. E.; Heath, G. P.; Heath, H. F.; Piccioni, D.; Roff, D. G.; Tapper, R. J.; Yoshida, R.; Arneodo, M.; Ayad, R.; Capua, M.; Garfagnini, A.; Iannotti, L.; Schioppa, M.; Susinno, G.; Caldwell, A.; Cartiglia, N.; Jing, Z.; Liu, W.; Parsons, J. A.; Ritz, S.; Sciulli, F.; Straub, P. B.; Wai, L.; Yang, S.; Zhu, Q.; Borzemski, P.; Chwastowski, J.; Eskreys, A.; Jakubowski, Z.; Przybycień, M. B.; Zachara, M.; Zawiejski, L.; Adamczyk, L.; Bednarek, B.; Jeleń, K.; Kisielewska, D.; Kowalski, T.; Przybycień, M.; Rulikowska-Zarȩbska, E.; Suszycki, L.; Zajaç, J.; Duliński, Z.; Kotański, A.; Abbiendi, G.; Bauerdick, L. A. T.; Behrens, U.; Beier, H.; Bienlein, J. K.; Cases, G.; Deppe, O.; Desler, K.; Drews, G.; Flasiński, M.; Gilkinson, D. J.; Glasman, C.; Göttlicher, P.; Große-Knetter, J.; Haas, T.; Hain, W.; Hasell, D.; Heßling, H.; Iga, Y.; Johnson, K. F.; Joos, P.; Kasemann, M.; Klanner, R.; Koch, W.; Kötz, U.; Kowalski, H.; Labs, J.; Ladage, A.; Löhr, B.; Löwe, M.; Lüke, D.; Mainusch, J.; Mańczak, O.; Milewski, J.; Monteiro, T.; Ng, J. S. T.; Notz, D.; Ohrenberg, K.; Piotrzkowski, K.; Roco, M.; Rohde, M.; Roldán, J.; Schneekloth, U.; Schulz, W.; Selonke, F.; Surrow, B.; Voß, T.; Westphal, D.; Wolf, G.; Wollmer, U.; Youngman, C.; Zeuner, W.; Grabosch, H. J.; Kharchilava, A.; Mari, S. M.; Meyer, A.; Schlenstedt, S.; Wulff, N.; Barbagli, G.; Gallo, E.; Pelfer, P.; Maccarrone, G.; De Pasquale, S.; Votano, L.; Bamberger, A.; Eisenhardt, S.; Trefzger, T.; Wölfle, S.; Bromley, J. T.; Brook, N. H.; Bussey, P. J.; Doyle, A. T.; Saxon, D. H.; Sinclair, L. E.; Utley, M. L.; Wilson, A. S.; Dannemann, A.; Holm, U.; Horstmann, D.; Sinkus, R.; Wick, K.; Burow, B. D.; Hagge, L.; Lohrmann, E.; Poelz, G.; Schott, W.; Zetsche, F.; Bacon, T. C.; Brümmer, N.; Butterworth, I.; Harris, V. L.; Howell, G.; Hung, B. H. Y.; Lamberti, L.; Long, K. R.; Miller, D. B.; Pavel, N.; Prinias, A.; Sedgbeer, J. K.; Sideris, D.; Whitfield, A. F.; Mallik, U.; Wang, M. Z.; Wang, S. M.; Wu, J. T.; Cloth, P.; Filges, D.; An, S. H.; Cho, G. H.; Ko, B. J.; Lee, S. B.; Nam, S. W.; Park, H. S.; Park, S. K.; Kartik, S.; Kim, H.-J.; McNeil, R. R.; Metcalf, W.; Nadendla, V. K.; Barreiro, F.; Fernandez, J. P.; Graciani, R.; Hernández, J. M.; Hervás, L.; Labarga, L.; Martinez, M.; del Peso, J.; Puga, J.; Terron, J.; de Trocóniz, J. F.; Corriveau, F.; Hanna, D. S.; Hartmann, J.; Hung, L. W.; Lim, J. N.; Matthews, C. G.; Patel, P. M.; Riveline, M.; Stairs, D. G.; St-Laurent, M.; Ullmann, R.; Zacek, G.; Tsurugai, T.; Bashkirov, V.; Dolgoshein, B. A.; Stifutkin, A.; Bashindzhagyan, G. L.; Ermolov, P. F.; Gladilin, L. K.; Golubkov, Yu. A.; Kobrin, V. D.; Korzhavina, I. A.; Kuzmin, V. A.; Lukina, O. Yu.; Proskuryakov, A. S.; Savin, A. A.; Shcheglova, L. M.; Solomin, A. N.; Zotov, N. P.; Botje, M.; Chlebana, F.; Engelen, J.; de Kamps, M.; Kooijman, P.; Kruse, A.; van Sighem, A.; Tiecke, H.; Verkerke, W.; Vossebeld, J.; Vreeswijk, M.; Wiggers, L.; de Wolf, E.; van Woudenberg, R.; Acosta, D.; Bylsma, B.; Durkin, L. S.; Gilmore, J.; Li, C.; Ling, T. Y.; Nylander, P.; Park, I. H.; Romanowski, T. A.; Bailey, D. S.; Cashmore, R. J.; Cooper-Sarkar, A. M.; Devenish, R. C. E.; Harnew, N.; Lancaster, M.; Lindemann, L.; McFall, J. D.; Nath, C.; Noyes, V. A.; Quadt, A.; Tickner, J. R.; Uijterwaal, H.; Walczak, R.; Waters, D. S.; Wilson, F. F.; Yip, T.; Bertolin, A.; Brugnera, R.; Carlin, R.; Dal Corso, F.; De Giorgi, M.; Dosselli, U.; Limentani, S.; Morandin, M.; Posocco, M.; Stanco, L.; Stroili, R.; Voci, C.; Zuin, F.; Bulmahn, J.; Feild, R. G.; Oh, B. Y.; Whitmore, J. J.; D'Agostini, G.; Marini, G.; Nigro, A.; Tassi, E.; Hart, J. C.; McCubbin, N. A.; Shah, T. P.; Barberis, E.; Dubbs, T.; Heusch, C.; Van Hook, M.; Lockman, W.; Rahn, J. T.; Sadrozinski, H. F.-W.; Seiden, A.; Williams, D. C.; Biltzinger, J.; Seifert, R. J.; Schwarzer, O.; Walenta, A. H.; Zech, G.; Abramowicz, H.; Briskin, G.; Dagan, S.; Levy, A.; Fleck, J. I.; Inuzuka, M.; ishii, T.; Kuze, M.; Mine, S.; Nakao, M.; Suzuki, I.; Tokushuku, K.; Umemori, K.; Yamada, S.; Yamazaki, Y.; Chiba, M.; Hamatsu, R.; Hirose, T.; Homma, K.; Kitamura, S.; Matsushita, T.; Yamauchi, K.; Cirio, R.; Costa, M.; Ferrero, M. I.; Maselli, S.; Peroni, C.; Sacchi, R.; Solano, A.; Staino, A.; Dardo, M.; Bailey, D. C.; Benard, F.; Brkic, M.; Fagerstroem, C.-P.; Hartner, G. F.; Joo, K. K.; Levman, G. M.; Martin, J. F.; Orr, R. S.; Polenz, S.; Sampson, C. R.; Simmons, D.; Teuscher, R. J.; Butterworth, J. M.; Catterall, C. D.; Jones, T. W.; Kaziewicz, P. B.; Lane, J. B.; Saunders, R. L.; Shulman, J.; Sutton, M. R.; Lu, B.; Mo, L. W.; Bogusz, W.; Ciborowski, J.; Gajewski, J.; Grzelak, G.; Kasprzak, M.; Krzyżanowski, M.; Muchorowski, K.; Nowak, R. J.; Pawlak, J. M.; Tymieniecka, T.; Wróblewski, A. K.; Zakrzewski, J. A.; Żarnecki, A. F.; Adamus, M.; Coldewey, C.; Eisenberg, Y.; Hochman, D.; Karshon, U.; Revel, D.; Zer-Zion, D.; Badgett, W. F.; Breitweg, J.; Chapin, D.; Cross, R.; Dasu, S.; Foudas, C.; Loveless, R. J.; Mattingly, S.; Reeder, D. D.; Silverstein, S.; Smith, W. H.; Vaiciulis, A.; Wodarczyk, M.; Bhadra, S.; Cardy, M. L.; Frisken, W. R.; Khakzad, M.; Murray, W. N.; Schmidke, W. B.; ZEUS Collaboration

1996-02-01

Jet photoproduction, where the two highest transverse energy ( ETjet) jets have ETjet above 6 GeV and a jet-jet invariant mass above 23 GeV, has been studied with the ZEUS detector at the HERA ep collider. Resolved and direct photoproduction samples have been separated. The cross section as a function of the angle between the jet-jet axis and the beam direction in the dijet rest frame has been measured for the two samples. The measured angular distributions differ markedly from each other. They agree with the predictions of QCD calculations, where the different angular distributions reflect the different spins of the quark and gluon exchanged in the hard subprocess.

Searches for anomalous coupling in top-quark interaction with the W boson and b quark, along with searches for quark-flavor-changing neutral currents, in an analysis of data from the CMS experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boos, E. E.; Bunichev, V. E.; Vorotnikov, G. A.

2016-01-15

The results of searches for effects beyond the Standard Model in processes of single top-quark production in the CMS experiment are presented. Anomalous contributions of the vector and magnetic types in top-quark interaction with the W boson and b quark and quark-flavor-changing neutral currents in top-quark interaction with the c or u quark via gluon exchange were studied. The respective analysis was performed with the aid of Bayesian neural networks. No statistically significant deviations were found, and upper limits on anomalous couplings at a 95% confidence level were set.

How to Enable Knowledge Exchange in "Second Life" in Design Education?

ERIC Educational Resources Information Center

Thomassen, Aukje; Rive, Pete

2010-01-01

The theory and lessons of knowledge exchange, in both a physical and virtual environment, suggest a framework for understanding the specific requirements for a digital design class in "Second Life". Through teaching and observing students who were asked to complete a machinima project, our research provided examples of the strengths and…

Virtually Being There: Creating Authentic Experiences through Interactive Exchanges.

ERIC Educational Resources Information Center

Sipe, Rebecca Bowers

2000-01-01

Describes an email writing partner exchange between preservice teachers and high school students in a tenth-grade English class and from various disciplines across the school, designed to help students develop conversations about writing as a tool for learning across the curriculum. Outlines ground rules for the project, and discusses issues that…

One-loop light-cone QCD, effective action for reggeized gluons and QCD RFT calculus

NASA Astrophysics Data System (ADS)

Bondarenko, S.; Lipatov, L.; Pozdnyakov, S.; Prygarin, A.

2017-09-01

The effective action for reggeized gluons is based on the gluodynamic Yang-Mills Lagrangian with external current for longitudinal gluons added, see Lipatov (Nucl Phys B 452:369, 1995; Phys Rep 286:131, 1997; Subnucl Ser 49:131, 2013; Int J Mod Phys Conf Ser 39:1560082, 2015; Int J Mod Phys A 31(28/29):1645011, 2016; EPJ Web Conf 125:01010, 2016). On the base of classical solutions, obtained in Bondarenko et al. (Eur Phys J C 77(8):527, 2017), the one-loop corrections to this effective action in light-cone gauge are calculated. The RFT calculus for reggeized gluons similarly to the RFT introduced in Gribov (Sov Phys JETP 26:414, 1968) is proposed and discussed. The correctness of the results is verified by calculation of the propagators of A+ and A- reggeized gluons fields and application of the obtained results is discussed as well.

Facilitating learning through an international virtual collaborative practice: A case study.

PubMed

Wihlborg, Monne; Friberg, Elizabeth E; Rose, Karen M; Eastham, Linda

2018-02-01

Internationalisation of higher education involving information and communication technology such as e-learning opens opportunities for innovative learning approaches across nations and cultures. Describe a case in practice of collaborative and transformative learning in relation to 'internationalisation on home grounds' with the broader learning objective of 'becoming aware and knowledgeable'. A mutually developed project established a virtual international collaborative exchange for faculty and students using a course management software (MOODLE) and open access technology (Adobe CONNECT). Two research universities in Sweden and the United States. Approximately 90 nursing students from each university per semester over several semesters. A collaborative process to develop a joint learning community to construct a virtual module and learning activity involving academics and nursing students in two countries using principles of meaning construction and negotiated learning. Developed possibilities for dealing with the challenges and finding strategies for a future higher education system that opens dialogues worldwide. Virtual international exchanges open innovative communication and learning contexts across nations and cultures. Internationalisation is so much more than students and teachers' mobility. 'Internationalisation on home grounds' (internationalisation for all) should receive more attention to support faculty and student collaboration, learning, and professional development. Copyright © 2017 Elsevier Ltd. All rights reserved.

Parton shower and NLO-matching uncertainties in Higgs boson pair production

NASA Astrophysics Data System (ADS)

Jones, Stephen; Kuttimalai, Silvan

2018-02-01

We perform a detailed study of NLO parton shower matching uncertainties in Higgs boson pair production through gluon fusion at the LHC based on a generic and process independent implementation of NLO subtraction and parton shower matching schemes for loop-induced processes in the Sherpa event generator. We take into account the full top-quark mass dependence in the two-loop virtual corrections and compare the results to an effective theory approximation. In the full calculation, our findings suggest large parton shower matching uncertainties that are absent in the effective theory approximation. We observe large uncertainties even in regions of phase space where fixed-order calculations are theoretically well motivated and parton shower effects expected to be small. We compare our results to NLO matched parton shower simulations and analytic resummation results that are available in the literature.

Studies of GPDs at Jefferson Lab: results and future experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Biselli, Angela

Here, the Generalized Parton Distributions (GPDs) have emerged as a universal tool to describe hadrons in terms of their elementary constituents, the quarks and the gluons. Deeply Virtual Compton Scattering (DVCS) on a proton or neutron (N), eN → e'N'γ, is one of the simplest processes that can be described in terms of GPDs. The amplitudes of DVCS and Bethe-Heitler, process where a photon is emitted by the incident or scattered electron, can be accessed via cross section measurements or exploiting their interference which give rise to spin asymmetries. Spin asymmetries, cross sections and cross-section differences can be connected to different combinations of the four leading order GPDs (H, E,more » $$\\tilde{H} $$, $$\\tilde{E} $$) for the two quark flavors depending on the observable and the type of target.« less

Studies of GPDs at Jefferson Lab: results and future experiments

DOE PAGES

Biselli, Angela

2018-01-05

Here, the Generalized Parton Distributions (GPDs) have emerged as a universal tool to describe hadrons in terms of their elementary constituents, the quarks and the gluons. Deeply Virtual Compton Scattering (DVCS) on a proton or neutron (N), eN → e'N'γ, is one of the simplest processes that can be described in terms of GPDs. The amplitudes of DVCS and Bethe-Heitler, process where a photon is emitted by the incident or scattered electron, can be accessed via cross section measurements or exploiting their interference which give rise to spin asymmetries. Spin asymmetries, cross sections and cross-section differences can be connected to different combinations of the four leading order GPDs (H, E,more » $$\\tilde{H} $$, $$\\tilde{E} $$) for the two quark flavors depending on the observable and the type of target.« less

Gluon Bremsstrahlung in Weakly-Coupled Plasmas

NASA Astrophysics Data System (ADS)

Arnold, Peter

2009-11-01

I report on some theoretical progress concerning the calculation of gluon bremsstrahlung for very high energy particles crossing a weakly-coupled quark-gluon plasma. (i) I advertise that two of the several formalisms used to study this problem, the BDMPS-Zakharov formalism and the AMY formalism (the latter used only for infinite, uniform media), can be made equivalent when appropriately formulated. (ii) A standard technique to simplify calculations is to expand in inverse powers of logarithms ln(E/T). I give an example where such expansions are found to work well for ω/T≳10 where ω is the bremsstrahlung gluon energy. (iii) Finally, I report on perturbative calculations of q̂.

Three Dimensional Imaging of the Nucleon

NASA Astrophysics Data System (ADS)

More, Jai; Mukherjee, Asmita; Nair, Sreeraj

2018-05-01

We study the Wigner distributions of quarks and gluons in light-front dressed quark model using the overlap of light front wave functions (LFWFs). We take the target to be a dressed quark, this is a composite spin -1/2 state of quark dressed with a gluon. This state allows us to calculate the quark and gluon Wigner distributions analytically in terms of LFWFs using Hamiltonian perturbation theory. We analyze numerically the Wigner distributions of quark and gluon and report their nature in the contour plots. We use an improved numerical technique to remove the cutoff dependence of the Fourier transformed integral over \\varvec{Δ}_\\perp.

Theoretical estimation of Photons flow rate Production in quark gluon interaction at high energies

NASA Astrophysics Data System (ADS)

Al-Agealy, Hadi J. M.; Hamza Hussein, Hyder; Mustafa Hussein, Saba

2018-05-01

photons emitted from higher energetic collisions in quark-gluon system have been theoretical studied depending on color quantum theory. A simple model for photons emission at quark-gluon system have been investigated. In this model, we use a quantum consideration which enhances to describing the quark system. The photons current rate are estimation for two system at different fugacity coefficient. We discussion the behavior of photons rate and quark gluon system properties in different photons energies with Boltzmann model. The photons rate depending on anisotropic coefficient : strong constant, photons energy, color number, fugacity parameter, thermal energy and critical energy of system are also discussed.

A systematic approach to sketch Bethe-Salpeter equation

NASA Astrophysics Data System (ADS)

Qin, Si-xue

2016-03-01

To study meson properties, one needs to solve the gap equation for the quark propagator and the Bethe-Salpeter (BS) equation for the meson wavefunction, self-consistently. The gluon propagator, the quark-gluon vertex, and the quark-anti-quark scattering kernel are key pieces to solve those equations. Predicted by lattice-QCD and Dyson-Schwinger analyses of QCD's gauge sector, gluons are non-perturbatively massive. In the matter sector, the modeled gluon propagator which can produce a veracious description of meson properties needs to possess a mass scale, accordingly. Solving the well-known longitudinal Ward-Green-Takahashi identities (WGTIs) and the less-known transverse counterparts together, one obtains a nontrivial solution which can shed light on the structure of the quark-gluon vertex. It is highlighted that the phenomenologically proposed anomalous chromomagnetic moment (ACM) vertex originates from the QCD Lagrangian symmetries and its strength is proportional to the magnitude of dynamical chiral symmetry breaking (DCSB). The color-singlet vector and axial-vector WGTIs can relate the BS kernel and the dressed quark-gluon vertex to each other. Using the relation, one can truncate the gap equation and the BS equation, systematically, without violating crucial symmetries, e.g., gauge symmetry and chiral symmetry.

Light-quark and gluon jet discrimination in pp collisions at √s = 7 TeV with the ATLAS detector

DOE PAGES

Aad, G.; Abbott, B.; Abdallah, J.; ...

2014-08-21

A likelihood-based discriminant for the identification of quark- and gluon-initiated jets is built and validated using 4.7 fb -1 of proton–proton collision data at √s = 7 TeV collected with the ATLAS detector at the LHC. Data samples with enriched quark or gluon content are used in the construction and validation of templates of jet properties that are the input to the likelihood-based discriminant. The discriminating power of the jet tagger is established in both data and Monte Carlo samples within a systematic uncertainty of ≈ 10–20 %. In data, light-quark jets can be tagged with an efficiency of ≈more » 50% while achieving a gluon-jet mis-tag rate of ≈ 25% in a p T range between 40 GeV and 360 GeV for jets in the acceptance of the tracker. The rejection of gluon-jets found in the data is significantly below what is attainable using a Pythia 6 Monte Carlo simulation, where gluon-jet mis-tag rates of 10 % can be reached for a 50 % selection efficiency of light-quark jets using the same jet properties.« less

Vulnerability of countries to food-production crises propagating in the virtual water trade network

NASA Astrophysics Data System (ADS)

Tamea, S.; Laio, F.; Ridolfi, L.

2015-12-01

In recent years, the international trade of food and agricultural commodities has undergone a marked increase of exchanged volumes and an expansion of the trade network. This globalization of trade has both positive and negative effects, but the interconnectedness and external dependency of countries generate complex dynamics which are often difficult to understand and model. In this study we consider the volume of water used for the production of agricultural commodities, virtually exchanged among countries through commodity trade, i.e. the virtual water trade. Then, we set up a parsimonious mechanistic model describing the propagation, into the global trade network, of food-production crises generated locally by a social, economic or environmental event (such as war, economic crisis, drought, pest). The model, accounting for the network structure and the virtual water balance of all countries, bases on rules derived from observed virtual water flows and on data-based and statistically verified assumption. It is also tested on real case studies that prove its capability to capture the main features of crises propagation. The model is then employed as the basis for the development of an index of country vulnerability, measuring the exposure of countries to crises propagating in the virtual water trade network. Results of the analysis are discussed within the context of socio-economic and environmental conditions of countries, showing that not only water-scarce, but also wealthy and globalized countries, are among the most vulnerable to external crises. The temporal analysis for the period 1986-2011 reveals that the global average vulnerability has strongly increased over time, confirming the increased exposure of countries to external crises which may occur in the virtual water trade network.

De l'enseignement de la grammaire par l'Internet (Grammar Instruction using the Internet).

ERIC Educational Resources Information Center

Beaudoin, Martin

1998-01-01

Examines pedagogical advantages and limitations of the Internet for teaching French grammar, and shows how these factors were taken into consideration in creating a Web site at the University of Alberta (Canada), with special emphasis on the integration of exchanges between learners, and exchanges between learners and the virtual francophone…

Rio De Janeiro to Claremont: Promoting Intercultural Competence through Student-Driven Online Intercultural Exchanges

ERIC Educational Resources Information Center

Aristizábal, Juanita C.; Welch, Patrick McDermott

2017-01-01

This article describes the process by which the authors created a Virtual Learning Community for cultural and linguistic exchange between college students of Portuguese in the United States and undergraduate and graduate students of English in Brazil. In addition to describing the way the so-called tandem model for telecollaboration was adapted to…

Strongly-Interacting Fermi Gases in Reduced Dimensions

DTIC Science & Technology

2009-05-29

effective theories of the strong interactions), astrophysics (compact stellar objects), the physics of quark -gluon plasmas (elliptic flow), and most...strong interactions: Superconductors, neutron stars and quark -gluon plasmas on a desktop," Seminar on Modern Optics and Spectroscopy, M. I. T...interface of quark -gluon plasma physics and cold-atom physics," (Trento, Italy, March 19-23, 2007). Talk given by Andrey Turlapov. 17) J. E. Thomas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kopeliovich, B. Z.; Potashnikova, I. K.; Schmidt, Ivan

A bootstrap equation for self-quenched gluon shadowing leads to a reduced magnitude of broadening for partons propagating through a nucleus. Saturation of small-x gluons in a nucleus, which has the form of transverse momentum broadening of projectile gluons in pA collisions in the nuclear rest frame, leads to a modification of the parton distribution functions in the beam compared with pp collisions. In nucleus-nucleus collisions all participating nucleons acquire enhanced gluon density at small x, which boosts further the saturation scale. Solution of the reciprocity equations for central collisions of two heavy nuclei demonstrate a significant, up to several times,more » enhancement of Q{sub sA}{sup 2}, in AA compared with pA collisions.« less

Hunting the Gluon Orbital Angular Momentum at the Electron-Ion Collider.

PubMed

Ji, Xiangdong; Yuan, Feng; Zhao, Yong

2017-05-12

Applying the connection between the parton Wigner distribution and orbital angular momentum (OAM), we investigate the probe of the gluon OAM in hard scattering processes at the planned electron-ion collider. We show that the single longitudinal target-spin asymmetry in the hard diffractive dijet production is very sensitive to the gluon OAM distribution. The associated spin asymmetry leads to a characteristic azimuthal angular correlation of sin(ϕ_{q}-ϕ_{Δ}), where ϕ_{Δ} and ϕ_{q} are the azimuthal angles of the proton momentum transfer and the relative transverse momentum between the quark-antiquark pair. This study may motivate a first measurement of the gluon OAM in the proton spin sum rule.

Monitoring and Control Interface Based on Virtual Sensors

PubMed Central

Escobar, Ricardo F.; Adam-Medina, Manuel; García-Beltrán, Carlos D.; Olivares-Peregrino, Víctor H.; Juárez-Romero, David; Guerrero-Ramírez, Gerardo V.

2014-01-01

In this article, a toolbox based on a monitoring and control interface (MCI) is presented and applied in a heat exchanger. The MCI was programed in order to realize sensor fault detection and isolation and fault tolerance using virtual sensors. The virtual sensors were designed from model-based high-gain observers. To develop the control task, different kinds of control laws were included in the monitoring and control interface. These control laws are PID, MPC and a non-linear model-based control law. The MCI helps to maintain the heat exchanger under operation, even if a temperature outlet sensor fault occurs; in the case of outlet temperature sensor failure, the MCI will display an alarm. The monitoring and control interface is used as a practical tool to support electronic engineering students with heat transfer and control concepts to be applied in a double-pipe heat exchanger pilot plant. The method aims to teach the students through the observation and manipulation of the main variables of the process and by the interaction with the monitoring and control interface (MCI) developed in LabVIEW©. The MCI provides the electronic engineering students with the knowledge of heat exchanger behavior, since the interface is provided with a thermodynamic model that approximates the temperatures and the physical properties of the fluid (density and heat capacity). An advantage of the interface is the easy manipulation of the actuator for an automatic or manual operation. Another advantage of the monitoring and control interface is that all algorithms can be manipulated and modified by the users. PMID:25365462

Pinning down the large- x gluon with NNLO top-quark pair differential distributions

NASA Astrophysics Data System (ADS)

Czakon, Michał; Hartland, Nathan P.; Mitov, Alexander; Nocera, Emanuele R.; Rojo, Juan

2017-04-01

Top-quark pair production at the LHC is directly sensitive to the gluon PDF at large x. While total cross-section data is already included in several PDF determinations, differential distributions are not, because the corresponding NNLO calculations have become available only recently. In this work we study the impact on the large- x gluon of top-quark pair differential distributions measured by ATLAS and CMS at √{s}=8 TeV. Our analysis, performed in the NNPDF3.0 framework at NNLO accuracy, allows us to identify the optimal combination of LHC top-quark pair measurements that maximize the constraints on the gluon, as well as to assess the compatibility between ATLAS and CMS data. We find that differential distributions from top-quark pair production provide significant constraints on the large- x gluon, comparable to those obtained from inclusive jet production data, and thus should become an important ingredient for the next generation of global PDF fits.

A solution to coupled Dyson-Schwinger equations for gluons and ghosts in Landau gauge.

DOE Office of Scientific and Technical Information (OSTI.GOV)

von Smekal, L.; Alkofer, R.; Hauck, A.

1998-07-20

A truncation scheme for the Dyson-Schwinger equations of QCD in Landau gauge is presented which implements the Slavnov-Taylor identities for the 3-point vertex functions. Neglecting contributions from 4-point correlations such as the 4-gluon vertex function and irreducible scattering kernels, a closed system of equations for the propagators is obtained. For the pure gauge theory without quarks this system of equations for the propagators of gluons and ghosts is solved in an approximation which allows for an analytic discussion of its solutions in the infrared: The gluon propagator is shown to vanish for small spacelike momenta whereas the ghost propagator ismore » found to be infrared enhanced. The running coupling of the non-perturbative subtraction scheme approaches an infrared stable fixed point at a critical value of the coupling alpha c of approx. 9.5. The gluon propagator is shown to have no Lehmann representation. The results for the propagators obtained here compare favorably with recent lattice calculations.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Winter, Frank; Detmold, William; Gambhir, Arjun S.

The role of gluons in the structure of the nucleon and light nuclei is investigated using lattice quantum chromodynamics (QCD) calculations. The first moment of the unpolarised gluon distribution is studied in nuclei up to atomic numbermore » $A=3$ at quark masses corresponding to pion masses of $$m_\\pi\\sim 450$$ and $806$ MeV. Nuclear modification of this quantity defines a gluonic analogue of the EMC effect and is constrained to be less than $$\\sim 10$$% in these nuclei. This is consistent with expectations from phenomenological quark distributions and the momentum sum rule. In the deuteron, the combination of gluon distributions corresponding to the $$b_1$$ structure function is found to have a small first moment compared with the corresponding momentum fraction. The first moment of the gluon transversity structure function is also investigated in the spin-1 deuteron, where a non-zero signal is observed at $$m_\\pi \\sim 806$$ MeV. In conclusion, this is the first indication of gluon contributions to nuclear structure that can not be associated with an individual nucleon.« less

Dilepton production from the quark-gluon plasma using (3 +1 )-dimensional anisotropic dissipative hydrodynamics

NASA Astrophysics Data System (ADS)

Ryblewski, Radoslaw; Strickland, Michael

2015-07-01

We compute dilepton production from the deconfined phase of the quark-gluon plasma using leading-order (3 +1 )-dimensional anisotropic hydrodynamics. The anisotropic hydrodynamics equations employed describe the full spatiotemporal evolution of the transverse temperature, spheroidal momentum-space anisotropy parameter, and the associated three-dimensional collective flow of the matter. The momentum-space anisotropy is also taken into account in the computation of the dilepton production rate, allowing for a self-consistent description of dilepton production from the quark-gluon plasma. For our final results, we present predictions for high-energy dilepton yields as a function of invariant mass, transverse momentum, and pair rapidity. We demonstrate that high-energy dilepton production is extremely sensitive to the assumed level of initial momentum-space anisotropy of the quark-gluon plasma. As a result, it may be possible to experimentally constrain the early-time momentum-space anisotropy of the quark-gluon plasma generated in relativistic heavy-ion collisions using high-energy dilepton yields.

Coupled dynamics in gluon mass generation and the impact of the three-gluon vertex

NASA Astrophysics Data System (ADS)

Binosi, Daniele; Papavassiliou, Joannis

2018-03-01

We present a detailed study of the subtle interplay transpiring at the level of two integral equations that are instrumental for the dynamical generation of a gluon mass in pure Yang-Mills theories. The main novelty is the joint treatment of the Schwinger-Dyson equation governing the infrared behavior of the gluon propagator and of the integral equation that controls the formation of massless bound-state excitations, whose inclusion is instrumental for obtaining massive solutions from the former equation. The self-consistency of the entire approach imposes the requirement of using a single value for the gauge coupling entering in the two key equations; its fulfilment depends crucially on the details of the three-gluon vertex, which contributes to both of them, but with different weight. In particular, the characteristic suppression of this vertex at intermediate and low energies enables the convergence of the iteration procedure to a single gauge coupling, whose value is reasonably close to that extracted from related lattice simulations.

Using Linear Gluon Polarization Inside an Unpolarized Proton to Determine the Higgs Spin and Parity

NASA Astrophysics Data System (ADS)

den Dunnen, Wilco J.

2014-06-01

Gluons inside an unpolarized proton are in general linearly polarized in the direction of their transverse momentum, rendering the LHC effectively a polarized gluon collider. This polarization can be utilized in the determination of the spin and parity of the newly found Higgs-like boson. We focus here on the determination of the spin using the azimuthal Collins-Soper angle distribution.

Thermalization of mini-jets in a quark-gluon plasma

NASA Astrophysics Data System (ADS)

Iancu, Edmond; Wu, Bin

2015-10-01

We complete the physical picture for the evolution of a high-energy jet propagating through a weakly-coupled quark-gluon plasma by investigating the thermalization of the soft components of the jet. We argue that the following scenario should hold: the leading particle emits a significant number of mini-jets which promptly evolve via quasi-democratic branchings and thus degrade into a myriad of soft gluons, with energies of the order of the medium temperature T. Via elastic collisions with the medium constituents, these soft gluons relax to local thermal equilibrium with the plasma over a time scale which is considerably shorter than the typical lifetime of the mini-jet. The thermalized gluons form a tail which lags behind the hard components of the jet. We support this scenario, first, via parametric arguments and, next, by studying a simplified kinetic equation, which describes the jet dynamics in longitudinal phase-space. We solve the kinetic equation using both (semi-)analytical and numerical methods. In particular, we obtain the first exact, analytic, solutions to the ultrarelativistic Fokker-Planck equation in one-dimensional phase-space. Our results confirm the physical picture aforementioned and demonstrate the quenching of the jet via multiple branching followed by the thermalization of the soft gluons in the cascades.

Evidence of ghost suppression in gluon mass scale dynamics

NASA Astrophysics Data System (ADS)

Aguilar, A. C.; Binosi, D.; Figueiredo, C. T.; Papavassiliou, J.

2018-03-01

In this work we study the impact that the ghost sector of pure Yang-Mills theories may have on the generation of a dynamical gauge boson mass scale, which hinges on the appearance of massless poles in the fundamental vertices of the theory, and the subsequent realization of the well-known Schwinger mechanism. The process responsible for the formation of such structures is itself dynamical in nature, and is governed by a set of Bethe-Salpeter type of integral equations. While in previous studies the presence of massless poles was assumed to be exclusively associated with the background-gauge three-gluon vertex, in the present analysis we allow them to appear also in the corresponding ghost-gluon vertex. The full analysis of the resulting Bethe-Salpeter system reveals that the contribution of the poles associated with the ghost-gluon vertex are particularly suppressed, their sole discernible effect being a slight modification in the running of the gluon mass scale, for momenta larger than a few GeV. In addition, we examine the behavior of the (background-gauge) ghost-gluon vertex in the limit of vanishing ghost momentum, and derive the corresponding version of Taylor's theorem. These considerations, together with a suitable Ansatz, permit us the full reconstruction of the pole sector of the two vertices involved.

Transverse-momentum-dependent gluon distributions from JIMWLK evolution

NASA Astrophysics Data System (ADS)

Marquet, C.; Petreska, E.; Roiesnel, C.

2016-10-01

Transverse-momentum-dependent (TMD) gluon distributions have different operator definitions, depending on the process under consideration. We study that aspect of TMD factorization in the small- x limit, for the various unpolarized TMD gluon distributions encountered in the literature. To do this, we consider di-jet production in hadronic collisions, since this process allows to be exhaustive with respect to the possible operator definitions, and is suitable to be investigated at small x. Indeed, for forward and nearly back-to-back jets, one can apply both the TMD factorization and Color Glass Condensate (CGC) approaches to compute the di-jet cross-section, and compare the results. Doing so, we show that both descriptions coincide, and we show how to express the various TMD gluon distributions in terms of CGC correlators of Wilson lines, while keeping N c finite. We then proceed to evaluate them by solving the JIMWLK equation numerically. We obtain that at large transverse momentum, the process dependence essentially disappears, while at small transverse momentum, non-linear saturation effects impact the various TMD gluon distributions in very different ways. We notice the presence of a geometric scaling regime for all the TMD gluon distributions studied: the "dipole" one, the Weizsäcker-Williams one, and the six others involved in forward di-jet production.

Light-quark and gluon jet discrimination in [Formula: see text] collisions at [Formula: see text] with the ATLAS detector.

PubMed

Aad, G; Abbott, B; Abdallah, J; Abdel Khalek, S; Abdinov, O; Aben, R; Abi, B; Abolins, M; AbouZeid, O S; Abramowicz, H; Abreu, H; Abreu, R; Abulaiti, Y; Acharya, B S; Adamczyk, L; Adams, D L; Adelman, J; Adomeit, S; Adye, T; Agatonovic-Jovin, T; Aguilar-Saavedra, J A; Agustoni, M; Ahlen, S P; Ahmad, A; Ahmadov, F; Aielli, G; Åkesson, T P A; Akimoto, G; Akimov, A V; Albert, J; Albrand, S; Alconada Verzini, M J; Aleksa, M; Aleksandrov, I N; Alexa, C; Alexander, G; Alexandre, G; Alexopoulos, T; Alhroob, M; Alimonti, G; Alio, L; Alison, J; Allbrooke, B M M; Allison, L J; Allport, P P; Allwood-Spiers, S E; Almond, J; Aloisio, A; Alonso, A; Alonso, F; Alpigiani, C; Altheimer, A; Alvarez Gonzalez, B; Alviggi, M G; Amako, K; Amaral Coutinho, Y; Amelung, C; Amidei, D; Amor Dos Santos, S P; Amorim, A; Amoroso, S; Amram, N; Amundsen, G; Anastopoulos, C; Ancu, L S; Andari, N; Andeen, T; Anders, C F; Anders, G; Anderson, K J; Andreazza, A; Andrei, V; Anduaga, X S; Angelidakis, S; Angelozzi, I; Anger, P; 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Undrus, A; Unel, G; Ungaro, F C; Unno, Y; Urbaniec, D; Urquijo, P; Usai, G; Usanova, A; Vacavant, L; Vacek, V; Vachon, B; Valencic, N; Valentinetti, S; Valero, A; Valery, L; Valkar, S; Valladolid Gallego, E; Vallecorsa, S; Valls Ferrer, J A; Van Berg, R; Van Der Deijl, P C; van der Geer, R; van der Graaf, H; Van Der Leeuw, R; van der Ster, D; van Eldik, N; van Gemmeren, P; Van Nieuwkoop, J; van Vulpen, I; van Woerden, M C; Vanadia, M; Vandelli, W; Vanguri, R; Vaniachine, A; Vankov, P; Vannucci, F; Vardanyan, G; Vari, R; Varnes, E W; Varol, T; Varouchas, D; Vartapetian, A; Varvell, K E; Vazeille, F; Vazquez Schroeder, T; Veatch, J; Veloso, F; Veneziano, S; Ventura, A; Ventura, D; Venturi, M; Venturi, N; Venturini, A; Vercesi, V; Verducci, M; Verkerke, W; Vermeulen, J C; Vest, A; Vetterli, M C; Viazlo, O; Vichou, I; Vickey, T; Vickey Boeriu, O E; Viehhauser, G H A; Viel, S; Vigne, R; Villa, M; Villaplana Perez, M; Vilucchi, E; Vincter, M G; Vinogradov, V B; Virzi, J; Vivarelli, I; Vives Vaque, F; Vlachos, S; Vladoiu, D; Vlasak, M; Vogel, A; Vokac, P; Volpi, G; Volpi, M; von der Schmitt, H; von Radziewski, H; von Toerne, E; Vorobel, V; Vorobev, K; Vos, M; Voss, R; Vossebeld, J H; Vranjes, N; Vranjes Milosavljevic, M; Vrba, V; Vreeswijk, M; Vu Anh, T; Vuillermet, R; Vukotic, I; Vykydal, Z; Wagner, W; Wagner, P; Wahrmund, S; Wakabayashi, J; Walder, J; Walker, R; Walkowiak, W; Wall, R; Waller, P; Walsh, B; Wang, C; Wang, C; Wang, F; Wang, H; Wang, H; Wang, J; Wang, J; Wang, K; Wang, R; Wang, S M; Wang, T; Wang, X; Wanotayaroj, C; Warburton, A; Ward, C P; Wardrope, D R; Warsinsky, M; Washbrook, A; Wasicki, C; Watanabe, I; Watkins, P M; Watson, A T; Watson, I J; Watson, M F; Watts, G; Watts, S; Waugh, B M; Webb, S; Weber, M S; Weber, S W; Webster, J S; Weidberg, A R; Weigell, P; Weinert, B; Weingarten, J; Weiser, C; Weits, H; Wells, P S; Wenaus, T; Wendland, D; Weng, Z; Wengler, T; Wenig, S; Wermes, N; Werner, M; Werner, P; Wessels, M; Wetter, J; Whalen, K; White, A; White, M J; White, R; White, S; Whiteson, D; Wicke, D; Wickens, F J; Wiedenmann, W; Wielers, M; Wienemann, P; Wiglesworth, C; Wiik-Fuchs, L A M; Wijeratne, P A; Wildauer, A; Wildt, M A; Wilkens, H G; Will, J Z; Williams, H H; Williams, S; Willis, C; Willocq, S; Wilson, J A; Wilson, A; Wingerter-Seez, I; Winklmeier, F; Wittgen, M; Wittig, T; Wittkowski, J; Wollstadt, S J; Wolter, M W; Wolters, H; Wosiek, B K; Wotschack, J; Woudstra, M J; Wozniak, K W; Wright, M; Wu, M; Wu, S L; Wu, X; Wu, Y; Wulf, E; Wyatt, T R; Wynne, B M; Xella, S; Xiao, M; Xu, D; Xu, L; Yabsley, B; Yacoob, S; Yamada, M; Yamaguchi, H; Yamaguchi, Y; Yamamoto, A; Yamamoto, K; Yamamoto, S; Yamamura, T; Yamanaka, T; Yamauchi, K; Yamazaki, Y; Yan, Z; Yang, H; Yang, H; Yang, U K; Yang, Y; Yanush, S; Yao, L; Yao, W-M; Yasu, Y; Yatsenko, E; Yau Wong, K H; Ye, J; Ye, S; Yen, A L; Yildirim, E; Yilmaz, M; Yoosoofmiya, R; Yorita, K; Yoshida, R; Yoshihara, K; Young, C; Young, C J S; Youssef, S; Yu, D R; Yu, J; Yu, J M; Yu, J; Yuan, L; Yurkewicz, A; Zabinski, B; Zaidan, R; Zaitsev, A M; Zaman, A; Zambito, S; Zanello, L; Zanzi, D; Zaytsev, A; Zeitnitz, C; Zeman, M; Zemla, A; Zengel, K; Zenin, O; Ženiš, T; Zerwas, D; Zevi Della Porta, G; Zhang, D; Zhang, F; Zhang, H; Zhang, J; Zhang, L; Zhang, X; Zhang, Z; Zhao, Z; Zhemchugov, A; Zhong, J; Zhou, B; Zhou, L; Zhou, N; Zhu, C G; Zhu, H; Zhu, J; Zhu, Y; Zhuang, X; Zibell, A; Zieminska, D; Zimine, N I; Zimmermann, C; Zimmermann, R; Zimmermann, S; Zimmermann, S; Zinonos, Z; Ziolkowski, M; Zobernig, G; Zoccoli, A; Zur Nedden, M; Zurzolo, G; Zutshi, V; Zwalinski, L

A likelihood-based discriminant for the identification of quark- and gluon-initiated jets is built and validated using 4.7 fb[Formula: see text] of proton-proton collision data at [Formula: see text] [Formula: see text] collected with the ATLAS detector at the LHC. Data samples with enriched quark or gluon content are used in the construction and validation of templates of jet properties that are the input to the likelihood-based discriminant. The discriminating power of the jet tagger is established in both data and Monte Carlo samples within a systematic uncertainty of [Formula: see text] 10-20 %. In data, light-quark jets can be tagged with an efficiency of [Formula: see text] while achieving a gluon-jet mis-tag rate of [Formula: see text] in a [Formula: see text] range between [Formula: see text] and [Formula: see text] for jets in the acceptance of the tracker. The rejection of gluon-jets found in the data is significantly below what is attainable using a Pythia 6 Monte Carlo simulation, where gluon-jet mis-tag rates of 10 % can be reached for a 50 % selection efficiency of light-quark jets using the same jet properties.

Virtual Protein Purification: A Simple Exercise to Introduce pH as A Parameter That Effects Ion Exchange Chromatography

ERIC Educational Resources Information Center

Clark, Daniel D.; Edwards, Daniel J.

2018-01-01

This article describes a simple exercise using a free, easy-to-use, established online program. The exercise helps to reinforce protein purification concepts and introduces undergraduates to pH as a parameter that affects anion-exchange chromatography. The exercise was tested with biochemistry majors at California State University-Chico. Given the…

Virtual Journey Coupled with Face-to-Face Exchange: Enhancing the Cultural Sensitivity and Competence of Graduate Students

ERIC Educational Resources Information Center

Ellenwood, Audrey E.; Snyders, Frederik J. A.

2010-01-01

This study attempted to enhance cultural sensitivity for graduate students at an American and a South African university, using a six-week online List Serv, email buddy exchange, and two-week face-to-face experience. After the course was over, results of the intercultural developmental inventory, using "t"-tests for related samples,…

Circuit QED with qutrits: Coupling three or more atoms via virtual-photon exchange

NASA Astrophysics Data System (ADS)

Zhao, Peng; Tan, Xinsheng; Yu, Haifeng; Zhu, Shi-Liang; Yu, Yang

2017-10-01

We present a model to describe a generic circuit QED system which consists of multiple artificial three-level atoms, namely, qutrits, strongly coupled to a cavity mode. When the state transition of the atoms disobeys the selection rules the process that does not conserve the number of excitations can happen determinatively. Therefore, we can realize coherent exchange interaction among three or more atoms mediated by the exchange of virtual photons. In addition, we generalize the one-cavity-mode mediated interactions to the multicavity situation, providing a method to entangle atoms located in different cavities. Using experimentally feasible parameters, we investigate the dynamics of the model including three cyclic-transition three-level atoms, for which the two lowest energy levels can be treated as qubits. Hence, we have found that two qubits can jointly exchange excitation with one qubit in a coherent and reversible way. In the whole process, the population in the third level of atoms is negligible and the cavity photon number is far smaller than 1. Our model provides a feasible scheme to couple multiple distant atoms together, which may find applications in quantum information processing.

Radiation and the classical double copy for color charges

NASA Astrophysics Data System (ADS)

Goldberger, Walter D.; Ridgway, Alexander K.

2017-06-01

We construct perturbative classical solutions of the Yang-Mills equations coupled to dynamical point particles carrying color charge. By applying a set of color to kinematics replacement rules first introduced by Bern, Carrasco and Johansson, these are shown to generate solutions of d -dimensional dilaton gravity, which we also explicitly construct. Agreement between the gravity result and the gauge theory double copy implies a correspondence between non-Abelian particles and gravitating sources with dilaton charge. When the color sources are highly relativistic, dilaton exchange decouples, and the solutions we obtain match those of pure gravity. We comment on possible implications of our findings to the calculation of gravitational waveforms in astrophysical black hole collisions, directly from computationally simpler gluon radiation in Yang-Mills theory.

HEP Computing

Science.gov Websites

Argonne National Laboratory HEP Laptop Computing Problem Report Service Request Password Help New on ANL Exchange: See section for your OS Printing Available Software for Download VPN: Virtual

Highly improved staggered quarks on the lattice with applications to charm physics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Follana, E.; Davies, C.; Wong, K.

2007-03-01

We use perturbative Symanzik improvement to create a new staggered-quark action (HISQ) that has greatly reduced one-loop taste-exchange errors, no tree-level order a{sup 2} errors, and no tree-level order (am){sup 4} errors to leading order in the quark's velocity v/c. We demonstrate with simulations that the resulting action has taste-exchange interactions that are 3-4 times smaller than the widely used ASQTAD action. We show how to bound errors due to taste exchange by comparing ASQTAD and HISQ simulations, and demonstrate with simulations that such errors are likely no more than 1% when HISQ is used for light quarks at latticemore » spacings of 1/10 fm or less. The suppression of (am){sup 4} errors also makes HISQ the most accurate discretization currently available for simulating c quarks. We demonstrate this in a new analysis of the {psi}-{eta}{sub c} mass splitting using the HISQ action on lattices where am{sub c}=0.43 and 0.66, with full-QCD gluon configurations (from MILC). We obtain a result of 111(5) MeV which compares well with the experiment. We discuss applications of this formalism to D physics and present our first high-precision results for D{sub s} mesons.« less

Neutrinoless double-β decay in effective field theory: The light-Majorana neutrino-exchange mechanism

NASA Astrophysics Data System (ADS)

Cirigliano, Vincenzo; Dekens, Wouter; Mereghetti, Emanuele; Walker-Loud, André

2018-06-01

We present the first chiral effective theory derivation of the neutrinoless double-β decay n n →p p potential induced by light Majorana neutrino exchange. The effective-field-theory framework has allowed us to identify and parametrize short- and long-range contributions previously missed in the literature. These contributions cannot be absorbed into parametrizations of the single-nucleon form factors. Starting from the quark and gluon level, we perform the matching onto chiral effective field theory and subsequently onto the nuclear potential. To derive the nuclear potential mediating neutrinoless double-β decay, the hard, soft, and potential neutrino modes must be integrated out. This is performed through next-to-next-to-leading order in the chiral power counting, in both the Weinberg and pionless schemes. At next-to-next-to-leading order, the amplitude receives additional contributions from the exchange of ultrasoft neutrinos, which can be expressed in terms of nuclear matrix elements of the weak current and excitation energies of the intermediate nucleus. These quantities also control the two-neutrino double-β decay amplitude. Finally, we outline strategies to determine the low-energy constants that appear in the potentials, by relating them to electromagnetic couplings and/or by matching to lattice QCD calculations.

Relativistic shock waves and Mach cones in viscous gluon matter

NASA Astrophysics Data System (ADS)

Bouras, Ioannis; Molnár, Etele; Niemi, Harri; Xu, Zhe; El, Andrej; Fochler, Oliver; Lauciello, Francesco; Greiner, Carsten; Rischke, Dirk H.

2010-06-01

To investigate the formation and the propagation of relativistic shock waves in viscous gluon matter we solve the relativistic Riemann problem using a microscopic parton cascade. We demonstrate the transition from ideal to viscous shock waves by varying the shear viscosity to entropy density ratio η/s. Furthermore we compare our results with those obtained by solving the relativistic causal dissipative fluid equations of Israel and Stewart (IS), in order to show the validity of the IS hydrodynamics. Employing the parton cascade we also investigate the formation of Mach shocks induced by a high-energy gluon traversing viscous gluon matter. For η/s = 0.08 a Mach cone structure is observed, whereas the signal smears out for η/s >= 0.32.

Locating the Gribov horizon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Fei; Qin, Si-Xue; Roberts, Craig D.

We explore whether a tree-level expression for the gluon two-point function, supposed to express effects of an horizon term introduced to eliminate the Gribov ambiguity, is consistent with the propagator obtained in simulations of lattice-regularised quantum chromodynamics (QCD). In doing so, we insist that the gluon two-point function obey constraints that ensure a minimal level of consistency with parton-like behaviour at ultraviolet momenta. In consequence, we are led to a position which supports a conjecture that the gluon mass and horizon scale are equivalent emergent massscales, each with a value of roughly 0.5 GeV; and wherefrom it appears plausible thatmore » the dynamical generation of a running gluon mass may alone be sufficient to remove the Gribov ambiguity.« less

Locating the Gribov horizon

DOE PAGES

Gao, Fei; Qin, Si-Xue; Roberts, Craig D.; ...

2018-02-08

We explore whether a tree-level expression for the gluon two-point function, supposed to express effects of an horizon term introduced to eliminate the Gribov ambiguity, is consistent with the propagator obtained in simulations of lattice-regularised quantum chromodynamics (QCD). In doing so, we insist that the gluon two-point function obey constraints that ensure a minimal level of consistency with parton-like behaviour at ultraviolet momenta. In consequence, we are led to a position which supports a conjecture that the gluon mass and horizon scale are equivalent emergent massscales, each with a value of roughly 0.5 GeV; and wherefrom it appears plausible thatmore » the dynamical generation of a running gluon mass may alone be sufficient to remove the Gribov ambiguity.« less

Off-forward gluonic structure of vector mesons

NASA Astrophysics Data System (ADS)

Detmold, W.; Pefkou, D.; Shanahan, P. E.

2017-06-01

The spin-independent and transversity generalized form factors (GFFs) of the ϕ meson are studied using lattice QCD calculations with light quark masses corresponding to a pion mass mπ˜450 (5 ) MeV . One transversity and three spin-independent GFFs related to the lowest moments of leading-twist spin-independent and transversity gluon distributions are obtained at six nonzero values of the momentum transfer up to 1.2 GeV 2 . These quantities are compared with the analogous spin-independent quark GFFs and the electromagnetic form factors determined on the same lattice ensemble. The results show quantitative distinction between the spatial distribution of transversely polarized gluons, unpolarized gluons, and quarks and point the way towards further investigations of the gluon structure of nucleons and nuclei.

A study of coherence of soft gluons in hadron jets

NASA Astrophysics Data System (ADS)

Akrawy, M. Z.; Alexander, G.; Allison, J.; Allport, P. P.; Anderson, K. J.; Armitage, J. C.; Arnison, G. T. J.; Ashton, P.; Azuelos, G.; Baines, J. T. M.; Ball, A. H.; Banks, J.; Barker, G. J.; Barlow, R. J.; Batley, J. R.; Becker, J.; Behnke, T.; Bell, K. W.; Bella, G.; Bethke, S.; Biebel, O.; Binder, U.; Bloodworth, I. J.; Bock, P.; Breuker, H.; Brown, R. M.; Brun, R.; Buijs, A.; Burckhart, H. J.; Capiluppi, P.; Carnegie, R. K.; Carter, A. A.; Carter, J. R.; Chang, C. Y.; Charlton, D. G.; Chrin, J. T. M.; Clarke, P. E. L.; Cohen, I.; Collins, W. J.; Conboy, J. E.; Couch, M.; Coupland, M.; Cuffiani, M.; Dado, S.; Dallavalle, G. M.; Debu, P.; Deninno, M. M.; Dieckmann, A.; Dittmar, M.; Dixit, M. S.; Duchovni, E.; Duerdoth, I. P.; Dumas, D. J. P.; El Mamouni, H.; Elcombe, P. A.; Estabrooks, P. G.; Etzion, E.; Fabbri, F.; Farthouat, P.; Fischer, H. M.; Fong, D. G.; French, M. T.; Fukunaga, C.; Gaidot, A.; Ganel, O.; Gary, J. W.; Gascon, J.; Geddes, N. I.; Gee, C. N. P.; Geich-Gimbel, C.; Gensler, S. W.; Gentit, F. X.; Giacomelli, G.; Gibson, V.; Gibson, W. R.; Gillies, J. D.; Goldberg, J.; Goodrick, M. J.; Gorn, W.; Granite, D.; Gross, E.; Grunhaus, J.; Hagedorn, H.; Hagemann, J.; Hansroul, M.; Hargrove, C. K.; Harrus, I.; Hart, J.; Hattersley, P. M.; Hauschild, M.; Hawkes, C. M.; Heflin, E.; Hemingway, R. J.; Heuer, R. D.; Hill, J. C.; Hillier, S. J.; Ho, C.; Hobbs, J. D.; Hobson, P. R.; Hochman, D.; Holl, B.; Homer, R. J.; Hou, S. R.; Howarth, C. P.; Hughes-Jones, R. E.; Humbert, R.; Igo-Kemenes, P.; Ihssen, H.; Imrie, D. C.; Jawahery, A.; Jeffreys, P. W.; Jeremie, H.; Jimack, M.; Jobes, M.; Jones, R. W. L.; Jovanovic, P.; Karlen, D.; Kawagoe, K.; Kawamoto, T.; Kellogg, R. G.; Kennedy, B. W.; Kleinwort, C.; Klem, D. E.; Knop, G.; Kobayashi, T.; Kokott, T. P.; Köpke, L.; Kowalewski, R.; Kreutzmann, H.; Kroll, J.; Kuwano, M.; Kyberd, P.; Lafferty, G. D.; Lamarche, F.; Larson, W. J.; Layter, J. G.; Le Du, P.; Leblanc, P.; Lee, A. M.; Lehto, M. H.; Lellouch, D.; Lennert, P.; Lessard, L.; Levinson, L.; Lloyd, S. L.; Loebinger, F. K.; Lorah, J. M.; Lorazo, B.; Losty, M. J.; Ludwig, J.; Ma, J.; Macbeth, A. A.; Mannelli, M.; Marcellini, S.; Maringer, G.; Martin, A. J.; Martin, J. P.; Mashimo, T.; Mättig, P.; Maur, U.; McMahon, T. J.; McNutt, J. R.; McPherson, A. C.; Meijers, F.; Menszner, D.; Merritt, F. S.; Mes, H.; Michelini, A.; Middleton, R. P.; Mikenberg, G.; Miller, D. J.; Milstene, C.; Minowa, M.; Mohr, W.; Montanari, A.; Mori, T.; Moss, M. W.; Murphy, P. G.; Murray, W. J.; Nellen, B.; Nguyen, H. H.; Nozaki, M.; O'Dowd, A. J. P.; O'Neale, S. W.; O'Neill, B. P.; Oakham, F. G.; Odorici, F.; Ogg, M.; Oh, H.; Oreglia, M. J.; Orito, S.; Pansart, J. P.; Patrick, G. N.; Pawley, S. J.; Pfister, P.; Pilcher, J. E.; Pinfold, J. L.; Plane, D. E.; Poli, B.; Pouladdej, A.; Pritchard, T. W.; Quast, G.; Raab, J.; Redmond, M. W.; Rees, D. L.; Regimbald, M.; Riles, K.; Roach, C. M.; Robins, S. A.; Rollnik, A.; Roney, J. M.; Rossberg, S.; Rossi, A. M.; Routenburg, P.; Runge, K.; Runolfsson, O.; Sanghera, S.; Sansum, R. A.; Sasaki, M.; Saunders, B. J.; Schaile, A. D.; Schaile, O.; Schappert, W.; Scharff-Hansen, P.; Schreiber, S.; Schwarz, J.; Shapira, A.; Shen, B. C.; Sherwood, P.; Simon, A.; Singh, P.; Siroli, G. P.; Skuia, A.; Smith, A. M.; Smith, T. J.; Snow, G. A.; Springer, R. W.; Sproston, M.; Stephens, K.; Stier, H. E.; Ströhmer, R.; Strom, D.; Takeda, H.; Takeshita, T.; Tsukamoto, T.; Turner, M. F.; Tysarczyk-Niemeyer, G.; Van den plas, D.; VanDalen, G. J.; Vasseur, G.; Virtue, C. J.; von der Schmitt, H.; von Krogh, J.; Wagner, A.; Wahl, C.; Ward, C. P.; Ward, D. R.; Waterhouse, J.; Watkins, P. M.; Watson, A. T.; Watson, N. K.; Weber, M.; Weisz, S.; Wells, P. S.; Wermes, N.; Weymann, M.; Wilson, G. W.; Wilson, J. A.; Wingerter, I.; Winterer, V.-H.; Wood, N. C.; Wotton, S.; Wuensch, B.; Wyatt, T. R.; Yaari, R.; Yang, Y.; Yekutieli, G.; Yoshida, T.; Zeuner, W.; Zorn, G. T.; OPAL Collaboration

1990-09-01

We study the inclusive momentum distribution of charged particles in multihadronic events produced in e +e - annihilations at ECM∼ M(Z 0). We find agreement with the analytical formulae for gluon production that include the phenomena of soft gluon interference. Using data from CM energies between 14 and 91 GeV, we study the dependence of the inclusive momentum distribution on the centre of momentum energy. We find that the analytical formulae describe the data over the entire energy range. Both the momentum distribution at a fixed energy and the change with energy are described by QCD shower Monte Carlo's which include either coherent gluon branchings or string fragmentation. Simple incoherent models with independent fragmentation fail to reproduce the energy dependence and momentum spectra.

Higgs boson pair production at NNLO with top quark mass effects

NASA Astrophysics Data System (ADS)

Grazzini, M.; Heinrich, G.; Jones, S.; Kallweit, S.; Kerner, M.; Lindert, J. M.; Mazzitelli, J.

2018-05-01

We consider QCD radiative corrections to Higgs boson pair production through gluon fusion in proton collisions. We combine the exact next-to-leading order (NLO) contribution, which features two-loop virtual amplitudes with the full dependence on the top quark mass M t , with the next-to-next-to-leading order (NNLO) corrections computed in the large- M t approximation. The latter are improved with different reweighting techniques in order to account for finite- M t effects beyond NLO. Our reference NNLO result is obtained by combining one-loop double-real corrections with full M t dependence with suitably reweighted real-virtual and double-virtual contributions evaluated in the large- M t approximation. We present predictions for inclusive cross sections in pp collisions at √{s} = 13, 14, 27 and 100 TeV and we discuss their uncertainties due to missing M t effects. Our approximated NNLO corrections increase the NLO result by an amount ranging from +12% at √{s}=13 TeV to +7% at √{s}=100 TeV, and the residual uncertainty of the inclusive cross section from missing M t effects is estimated to be at the few percent level. Our calculation is fully differential in the Higgs boson pair and the associated jet activity: we also present predictions for various differential distributions at √{s}=14 and 100 TeV, and discuss the size of the missing M t effects, which can be larger, especially in the tails of certain observables. Our results represent the most advanced perturbative prediction available to date for this process.

NASA's Solar System Exploration Research Virtual Institute: Building Collaboration Through International Partnerships

NASA Technical Reports Server (NTRS)

Gibbs, K. E.; Schmidt, G. K.

2017-01-01

The NASA Solar System Exploration Research Virtual Institute (SSERVI) is a virtual institute focused on re-search at the intersection of science and exploration, training the next generation of lunar scientists, and community development. As part of the SSERVI mission, we act as a hub for opportunities that engage the larger scientific and exploration communities in order to form new interdisciplinary, research-focused collaborations. This talk will describe the international partner re-search efforts and how we are engaging the international science and exploration communities through workshops, conferences, online seminars and classes, student exchange programs and internships.

The Department of Veterans Affairs' (VA) implementation of the Virtual Lifetime Electronic Record (VLER): findings and lessons learned from Health Information Exchange at 12 sites.

PubMed

Byrne, Colene M; Mercincavage, Lauren M; Bouhaddou, Omar; Bennett, Jamie R; Pan, Eric C; Botts, Nathan E; Olinger, Lois M; Hunolt, Elaine; Banty, Karl H; Cromwell, Tim

2014-08-01

We describe the Department of Veterans Affairs' (VA) Virtual Lifetime Health Electronic Record (VLER) pilot phase in 12 communities to exchange health information with private sector health care organizations and the Department of Defense (DoD), key findings, lessons, and implications for advancing Health Information Exchanges (HIE), nationally. A mixed methods approach was used to monitor and evaluate the status of VLER Health Exchange pilot phase implementation from December 2009 through October 2012. Selected accomplishments, contributions, challenges, and early lessons that are relevant to the growth of nationwide HIE are discussed. Veteran patient and provider acceptance, trust, and perceived value of VLER Health Exchange are found to be high, and usage by providers is steadily growing. Challenges and opportunities to improve provider use are identified, such as better data quality and integration with workflow. Key findings and lessons for advancing HIE are identified. VLER Health Exchange has made great strides in advancing HIE nationally by addressing important technical and policy issues that have impeded scalability, and by increasing trust and confidence in the value and accuracy of HIE among users. VLER Health Exchange has advanced HIE interoperability standards and patient consent policies nationally. Policy, programmatic, technology, and health Information Technology (IT) standards implications to advance HIE for improved delivery and coordination of health care are discussed. The pilot phase success led to VA-wide deployment of this data sharing capability in 2013. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Virtualization of open-source secure web services to support data exchange in a pediatric critical care research network

PubMed Central

Sward, Katherine A; Newth, Christopher JL; Khemani, Robinder G; Cryer, Martin E; Thelen, Julie L; Enriquez, Rene; Shaoyu, Su; Pollack, Murray M; Harrison, Rick E; Meert, Kathleen L; Berg, Robert A; Wessel, David L; Shanley, Thomas P; Dalton, Heidi; Carcillo, Joseph; Jenkins, Tammara L; Dean, J Michael

2015-01-01

Objectives To examine the feasibility of deploying a virtual web service for sharing data within a research network, and to evaluate the impact on data consistency and quality. Material and Methods Virtual machines (VMs) encapsulated an open-source, semantically and syntactically interoperable secure web service infrastructure along with a shadow database. The VMs were deployed to 8 Collaborative Pediatric Critical Care Research Network Clinical Centers. Results Virtual web services could be deployed in hours. The interoperability of the web services reduced format misalignment from 56% to 1% and demonstrated that 99% of the data consistently transferred using the data dictionary and 1% needed human curation. Conclusions Use of virtualized open-source secure web service technology could enable direct electronic abstraction of data from hospital databases for research purposes. PMID:25796596

Core body temperature control by total liquid ventilation using a virtual lung temperature sensor.

PubMed

Nadeau, Mathieu; Micheau, Philippe; Robert, Raymond; Avoine, Olivier; Tissier, Renaud; Germim, Pamela Samanta; Vandamme, Jonathan; Praud, Jean-Paul; Walti, Herve

2014-12-01

In total liquid ventilation (TLV), the lungs are filled with a breathable liquid perfluorocarbon (PFC) while a liquid ventilator ensures proper gas exchange by renewal of a tidal volume of oxygenated and temperature-controlled PFC. Given the rapid changes in core body temperature generated by TLV using the lung has a heat exchanger, it is crucial to have accurate and reliable core body temperature monitoring and control. This study presents the design of a virtual lung temperature sensor to control core temperature. In the first step, the virtual sensor, using expired PFC to estimate lung temperature noninvasively, was validated both in vitro and in vivo. The virtual lung temperature was then used to rapidly and automatically control core temperature. Experimentations were performed using the Inolivent-5.0 liquid ventilator with a feedback controller to modulate inspired PFC temperature thereby controlling lung temperature. The in vivo experimental protocol was conducted on seven newborn lambs instrumented with temperature sensors at the femoral artery, pulmonary artery, oesophagus, right ear drum, and rectum. After stabilization in conventional mechanical ventilation, TLV was initiated with fast hypothermia induction, followed by slow posthypothermic rewarming for 1 h, then by fast rewarming to normothermia and finally a second fast hypothermia induction phase. Results showed that the virtual lung temperature was able to provide an accurate estimation of systemic arterial temperature. Results also demonstrate that TLV can precisely control core body temperature and can be favorably compared to extracorporeal circulation in terms of speed.

Parton shower and NLO-matching uncertainties in Higgs boson pair production

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jones, Stephen; Kuttimalai, Silvan

We perform a detailed study of NLO parton shower matching uncertainties in Higgs boson pair production through gluon fusion at the LHC based on a generic and process independent implementation of NLO subtraction and parton shower matching schemes for loop-induced processes in the Sherpa event generator. We take into account the full top-quark mass dependence in the two-loop virtual corrections and compare the results to an effective theory approximation. In the full calculation, our findings suggest large parton shower matching uncertainties that are absent in the effective theory approximation. Here, we observe large uncertainties even in regions of phase spacemore » where fixed-order calculations are theoretically well motivated and parton shower effects expected to be small. We compare our results to NLO matched parton shower simulations and analytic resummation results that are available in the literature.« less

Parton shower and NLO-matching uncertainties in Higgs boson pair production

DOE PAGES

Jones, Stephen; Kuttimalai, Silvan

2018-02-28

We perform a detailed study of NLO parton shower matching uncertainties in Higgs boson pair production through gluon fusion at the LHC based on a generic and process independent implementation of NLO subtraction and parton shower matching schemes for loop-induced processes in the Sherpa event generator. We take into account the full top-quark mass dependence in the two-loop virtual corrections and compare the results to an effective theory approximation. In the full calculation, our findings suggest large parton shower matching uncertainties that are absent in the effective theory approximation. Here, we observe large uncertainties even in regions of phase spacemore » where fixed-order calculations are theoretically well motivated and parton shower effects expected to be small. We compare our results to NLO matched parton shower simulations and analytic resummation results that are available in the literature.« less

Beam-spin asymmetries from semi-inclusive pion electroproduction

NASA Astrophysics Data System (ADS)

Gohn, W.; Avakian, H.; Joo, K.; Ungaro, M.; Adhikari, K. P.; Aghasyan, M.; Amaryan, M. J.; Anderson, M. D.; Anefalos Pereira, S.; Ball, J.; Baltzell, N. A.; Battaglieri, M.; Biselli, A. S.; Bono, J.; Briscoe, W. J.; Brooks, W. K.; Burkert, V. D.; Carman, D. S.; Celentano, A.; Chandavar, S.; Charles, G.; Cole, P. L.; Contalbrigo, M.; Cortes, O.; Crede, V.; D'Angelo, A.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Djalali, C.; Doughty, D.; Dupre, R.; El Alaoui, A.; El Fassi, L.; Eugenio, P.; Fedotov, G.; Fleming, J. A.; Forest, T.; Garçon, M.; Ghandilyan, Y.; Gilfoyle, G. P.; Giovanetti, K. L.; Girod, F. X.; Gothe, R. W.; Griffioen, K. A.; Guegan, B.; Guo, L.; Hafidi, K.; Hanretty, C.; Harrison, N.; Hattawy, Mohammad; Hicks, K.; Ho, D.; Holtrop, M.; Hyde, C.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Jo, H. S.; Keller, D.; Khandaker, M.; Khetarpal, P.; Kim, W.; Klein, F. J.; Koirala, S.; Kubarovsky, V.; Kuhn, S. E.; Kuleshov, S. V.; Lenisa, P.; Livingston, K.; Lu, H. Y.; MacGregor, I. J. D.; Markov, N.; Mayer, M.; McKinnon, B.; Mineeva, T.; Mirazita, M.; Mokeev, V.; Movsisyan, A.; Nadel-Turonski, P.; Niccolai, S.; Niculescu, I.; Osipenko, M.; Ostrovidov, A. I.; Pappalardo, L. L.; Paremuzyan, R.; Park, K.; Pasyuk, E.; Peng, P.; Phillips, J. J.; Pisano, S.; Pozdniakov, S.; Price, J. W.; Procureur, S.; Prok, Y.; Puckett, A. J. R.; Raue, B. A.; Ripani, M.; Ritchie, B. G.; Rizzo, A.; Rosner, G.; Rossi, P.; Roy, P.; Sabatié, F.; Salgado, C.; Schott, D.; Schumacher, R. A.; Seder, E.; Seraydaryan, H.; Sharabian, Y. G.; Simonyan, A.; Smith, G. D.; Sober, D. I.; Sokhan, D.; Stoler, P.; Strakovsky, I. I.; Stepanyan, S.; Strauch, S.; Tang, W.; Tkachenko, S.; Vernarsky, B.; Voskanyan, H.; Voutier, E.; Walford, N. K.; Watts, D. P.; Weinstein, L. B.; Wood, M. H.; Zachariou, N.; Zana, L.; Zhang, J.; Zonta, I.; CLAS Collaboration

2014-04-01

We have measured the moment ALUsinϕ corresponding to the polarized electron beam-spin asymmetry in semi-inclusive deep inelastic scattering. ALUsinϕ is a twist-3 quantity providing information about quark-gluon correlations. Data were taken with the CLAS Spectrometer at Jefferson Lab using a 5.498 GeV longitudinally polarized electron beam and an unpolarized liquid hydrogen target. All three pion channels (π+, π0 and π-) were measured simultaneously over a large range of kinematics within the virtuality range Q2≈ 1.0-4.5 GeV2. The observable was measured with better than 1% statistical precision over a large range of z, PT, xB, and Q2, which permits comparison with several reaction models. The discussed measurements provide an upgrade in statistics over previous measurements, and serve as the first evidence for the negative sign of the π- sinϕ moment.

Meson electro-/photo-production from QCD

DOE PAGES

Briceno, Raul A.

2016-07-02

I present the calculation of themore » $$\\pi^+\\gamma^\\star\\to\\pi^+\\pi^0$$ transition amplitude from quantum chromodynamics performed by the Hadron Spectrum Collaboration. The amplitude is determined for a range of values of the photon virtuality and the final state energy. One observes a clear dynamical enhancement due to the presence of the $$\\rho$$ resonance. By fitting the transition amplitude and analytically continuing it onto the $$\\rho$$-pole, the $$\\rho\\to\\pi\\gamma^\\star$$ form factor is obtained. This exploratory calculation, performed using lattice quantum chromodynamics, constitutes the very first determination of an electroweak decay of a hadronic resonance directly from the fundamental theory of quarks and gluons. In this talk, I highlight some of the necessary steps that made this calculation possible, placing emphasis on recently developed formalism. In conclusion, I discuss the status and outlook of the field for the study of $$N\\gamma^\\star\\to N^\\star\\to N\\pi$$ transitions.« less

Classical geometry to quantum behavior correspondence in a virtual extra dimension

NASA Astrophysics Data System (ADS)

Dolce, Donatello

2012-09-01

In the Lorentz invariant formalism of compact space-time dimensions the assumption of periodic boundary conditions represents a consistent semi-classical quantization condition for relativistic fields. In Dolce (2011) [18] we have shown, for instance, that the ordinary Feynman path integral is obtained from the interference between the classical paths with different winding numbers associated with the cyclic dynamics of the field solutions. By means of the boundary conditions, the kinematical information of interactions can be encoded on the relativistic geometrodynamics of the boundary, see Dolce (2012) [8]. Furthermore, such a purely four-dimensional theory is manifestly dual to an extra-dimensional field theory. The resulting correspondence between extra-dimensional geometrodynamics and ordinary quantum behavior can be interpreted in terms of AdS/CFT correspondence. By applying this approach to a simple Quark-Gluon-Plasma freeze-out model we obtain fundamental analogies with basic aspects of AdS/QCD phenomenology.

Les Houches ''Physics at TeV Colliders 2003'' Beyond the Standard Model Working Group: Summary Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Allanach, B

2004-03-01

The work contained herein constitutes a report of the ''Beyond the Standard Model'' working group for the Workshop ''Physics at TeV Colliders'', Les Houches, France, 26 May-6 June, 2003. The research presented is original, and was performed specifically for the workshop. Tools for calculations in the minimal supersymmetric standard model are presented, including a comparison of the dark matter relic density predicted by public codes. Reconstruction of supersymmetric particle masses at the LHC and a future linear collider facility is examined. Less orthodox supersymmetric signals such as non-pointing photons and R-parity violating signals are studied. Features of extra dimensional modelsmore » are examined next, including measurement strategies for radions and Higgs', as well as the virtual effects of Kaluza Klein modes of gluons. Finally, there is an update on LHC Z' studies.« less

Gluon amplitudes as 2 d conformal correlators

NASA Astrophysics Data System (ADS)

Pasterski, Sabrina; Shao, Shu-Heng; Strominger, Andrew

2017-10-01

Recently, spin-one wave functions in four dimensions that are conformal primaries of the Lorentz group S L (2 ,C ) were constructed. We compute low-point, tree-level gluon scattering amplitudes in the space of these conformal primary wave functions. The answers have the same conformal covariance as correlators of spin-one primaries in a 2 d CFT. The Britto-Cachazo-Feng-Witten (BCFW) recursion relation between three- and four-point gluon amplitudes is recast into this conformal basis.

The singular behavior of one-loop massive QCD amplitudes with one external soft gluon

NASA Astrophysics Data System (ADS)

Bierenbaum, Isabella; Czakon, Michał; Mitov, Alexander

2012-03-01

We calculate the one-loop correction to the soft-gluon current with massive fermions. This current is process independent and controls the singular behavior of one-loop massive QCD amplitudes in the limit when one external gluon becomes soft. The result derived in this work is the last missing process-independent ingredient needed for numerical evaluation of observables with massive fermions at hadron colliders at the next-to-next-to-leading order.

Semi-inclusive polarised lepton-nucleon scattering and the anomalous gluon contribution

NASA Astrophysics Data System (ADS)

Güllenstern, St.; Veltri, M.; Górnicki, P.; Mankiewicz, L.; Schäfer, A.

1993-08-01

We discuss a new observable for semi-inclusive pion production in polarised lepton-nucleon collisions. This observable is sensitive to the polarised and unpolarised strange quark distribution and the anomalous gluon contribution, provided that their fragmentation functions into pions differ substantially from that of light quarks. From Monte Carlo data generated with our PEPSI code we conclude that HERMES might be able to decide whether the polarized strange quark and gluon distributions are large.

Measurements of double-helicity asymmetries in inclusive J /ψ production in longitudinally polarized p +p collisions at √{s }=510 GeV

NASA Astrophysics Data System (ADS)

Adare, A.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Akimoto, R.; Alfred, M.; Apadula, N.; Aramaki, Y.; Asano, H.; Atomssa, E. T.; Awes, T. C.; Azmoun, B.; Babintsev, V.; Bai, M.; Bandara, N. S.; Bannier, B.; Barish, K. N.; Bathe, S.; Bazilevsky, A.; Beaumier, M.; Beckman, S.; Belmont, R.; Berdnikov, A.; Berdnikov, Y.; Black, D.; Blau, D. S.; Bok, J. S.; Boyle, K.; Brooks, M. L.; Bryslawskyj, J.; Buesching, H.; Bumazhnov, V.; Campbell, S.; Chen, C.-H.; Chi, C. Y.; Chiu, M.; Choi, I. J.; Choi, J. B.; Chujo, T.; Citron, Z.; Csanád, M.; Csörgő, T.; Danley, T. W.; Datta, A.; Daugherity, M. S.; David, G.; Deblasio, K.; Dehmelt, K.; Denisov, A.; Deshpande, A.; Desmond, E. J.; Ding, L.; Dion, A.; Diss, P. B.; Do, J. H.; Drees, A.; Drees, K. A.; Durham, J. M.; Durum, A.; Enokizono, A.; En'yo, H.; Esumi, S.; Fadem, B.; Feege, N.; Fields, D. E.; Finger, M.; Finger, M.; Fokin, S. L.; Frantz, J. E.; Franz, A.; Frawley, A. D.; Gal, C.; Gallus, P.; Garg, P.; Ge, H.; Giordano, F.; Glenn, A.; Goto, Y.; Grau, N.; Greene, S. V.; Grosse Perdekamp, M.; Gu, Y.; Gunji, T.; Guragain, H.; Hachiya, T.; Haggerty, J. S.; Hahn, K. I.; Hamagaki, H.; Hamilton, H. F.; Han, S. Y.; Hanks, J.; Hasegawa, S.; Haseler, T. O. S.; Hashimoto, K.; He, X.; Hemmick, T. K.; Hill, J. C.; Hollis, R. S.; Homma, K.; Hong, B.; Hoshino, T.; Hotvedt, N.; Huang, J.; Huang, S.; Ikeda, Y.; Imai, K.; Imazu, Y.; Inaba, M.; Iordanova, A.; Isenhower, D.; Ivanishchev, D.; Jacak, B. V.; Jeon, S. J.; Jezghani, M.; Jia, J.; Jiang, X.; Johnson, B. M.; Joo, E.; Joo, K. S.; Jouan, D.; Jumper, D. S.; Kanda, S.; Kang, J. H.; Kang, J. S.; Kawall, D.; Kazantsev, A. V.; Key, J. A.; Khachatryan, V.; Khanzadeev, A.; Kihara, K.; Kim, C.; Kim, D. H.; Kim, D. J.; Kim, E.-J.; Kim, G. W.; Kim, H.-J.; Kim, M.; Kim, Y. K.; Kimelman, B.; Kistenev, E.; Kitamura, R.; Klatsky, J.; Kleinjan, D.; Kline, P.; Koblesky, T.; Kofarago, M.; Komkov, B.; Koster, J.; Kotov, D.; Kurita, K.; Kurosawa, M.; Kwon, Y.; Lacey, R.; Lajoie, J. G.; Lebedev, A.; Lee, K. B.; Lee, S.; Lee, S. H.; Leitch, M. J.; Leitgab, M.; Li, X.; Lim, S. H.; Liu, M. X.; Lynch, D.; Makdisi, Y. I.; Makek, M.; Manion, A.; Manko, V. I.; Mannel, E.; McCumber, M.; McGaughey, P. L.; McGlinchey, D.; McKinney, C.; Meles, A.; Mendoza, M.; Meredith, B.; Miake, Y.; Mignerey, A. C.; Miller, A. J.; Milov, A.; Mishra, D. K.; Mitchell, J. T.; Miyasaka, S.; Mizuno, S.; Mohanty, A. K.; Montuenga, P.; Moon, T.; Morrison, D. P.; Moukhanova, T. V.; Murakami, T.; Murata, J.; Mwai, A.; Nagamiya, S.; Nagashima, K.; Nagle, J. L.; Nagy, M. I.; Nakagawa, I.; Nakagomi, H.; Nakano, K.; Nattrass, C.; Netrakanti, P. K.; Nihashi, M.; Niida, T.; Nishimura, S.; Nouicer, R.; Novák, T.; Novitzky, N.; Nyanin, A. S.; O'Brien, E.; Ogilvie, C. A.; Orjuela Koop, J. D.; Osborn, J. D.; Oskarsson, A.; Ozawa, K.; Pak, R.; Pantuev, V.; Papavassiliou, V.; Park, J. S.; Park, S.; Pate, S. F.; Patel, L.; Patel, M.; Peng, J.-C.; Perepelitsa, D. V.; Perera, G. D. N.; Peressounko, D. Yu.; Perry, J.; Petti, R.; Pinkenburg, C.; Pinson, R.; Pisani, R. P.; Purschke, M. L.; Rak, J.; Ramson, B. J.; Ravinovich, I.; Read, K. F.; Reynolds, D.; Riabov, V.; Riabov, Y.; Rinn, T.; Riveli, N.; Roach, D.; Rolnick, S. D.; Rosati, M.; Rowan, Z.; Rubin, J. G.; Sahlmueller, B.; Saito, N.; Sakaguchi, T.; Sako, H.; Samsonov, V.; Sarsour, M.; Sato, S.; Sawada, S.; Schaefer, B.; Schmoll, B. K.; Sedgwick, K.; Seele, J.; Seidl, R.; Sen, A.; Seto, R.; Sett, P.; Sexton, A.; Sharma, D.; Shein, I.; Shibata, T.-A.; Shigaki, K.; Shimomura, M.; Shukla, P.; Sickles, A.; Silva, C. L.; Silvermyr, D.; Singh, B. K.; Singh, C. P.; Singh, V.; Slunečka, M.; Snowball, M.; Soltz, R. A.; Sondheim, W. E.; Sorensen, S. P.; Sourikova, I. V.; Stankus, P. W.; Stepanov, M.; Stoll, S. P.; Sugitate, T.; Sukhanov, A.; Sumita, T.; Sun, J.; Sziklai, J.; Takahara, A.; Taketani, A.; Tanida, K.; Tannenbaum, M. J.; Tarafdar, S.; Taranenko, A.; Tieulent, R.; Timilsina, A.; Todoroki, T.; Tomášek, M.; Torii, H.; Towell, C. L.; Towell, M.; Towell, R.; Towell, R. S.; Tserruya, I.; van Hecke, H. W.; Vargyas, M.; Velkovska, J.; Virius, M.; Vrba, V.; Vznuzdaev, E.; Wang, X. R.; Watanabe, D.; Watanabe, Y.; Watanabe, Y. S.; Wei, F.; Whitaker, S.; White, A. S.; Wolin, S.; Woody, C. L.; Wysocki, M.; Xia, B.; Xue, L.; Yalcin, S.; Yamaguchi, Y. L.; Yanovich, A.; Yoo, J. H.; Yoon, I.; Younus, I.; Yu, H.; Yushmanov, I. E.; Zajc, W. A.; Zelenski, A.; Zhou, S.; Zou, L.; Phenix Collaboration

2016-12-01

We report the double-helicity asymmetry, ALL J /ψ, in inclusive J /ψ production at forward rapidity as a function of transverse momentum pT and rapidity |y |. The data analyzed were taken during √{s }=510 GeV longitudinally polarized p +p collisions at the Relativistic Heavy Ion Collider in the 2013 run using the PHENIX detector. At this collision energy, J /ψ particles are predominantly produced through gluon-gluon scatterings, thus ALL J /ψ is sensitive to the gluon polarization inside the proton. We measured ALL J /ψ by detecting the decay daughter muon pairs μ+μ- within the PHENIX muon spectrometers in the rapidity range 1.2 <|y |<2.2 . In this kinematic range, we measured the ALL J /ψ to be 0.012 ±0.010 (stat) ±0.003 (syst). The ALL J /ψ can be expressed to be proportional to the product of the gluon polarization distributions at two distinct ranges of Bjorken x : one at moderate range x ≈5 ×10-2 where recent data of jet and π0 double helicity spin asymmetries have shown evidence for significant gluon polarization, and the other one covering the poorly known small-x region x ≈2 ×10-3. Thus our new results could be used to further constrain the gluon polarization for x <5 ×10-2.

First lattice QCD study of the gluonic structure of light nuclei

NASA Astrophysics Data System (ADS)

Winter, Frank; Detmold, William; Gambhir, Arjun S.; Orginos, Kostas; Savage, Martin J.; Shanahan, Phiala E.; Wagman, Michael L.; Nplqcd Collaboration

2017-11-01

The role of gluons in the structure of the nucleon and light nuclei is investigated using lattice quantum chromodynamics (QCD) calculations. The first moment of the unpolarized gluon distribution is studied in nuclei up to atomic number A =3 at quark masses corresponding to pion masses of mπ˜450 and 806 MeV. Nuclear modification of this quantity defines a gluonic analogue of the EMC effect and is constrained to be less than ˜10 % in these nuclei. This is consistent with expectations from phenomenological quark distributions and the momentum sum rule. In the deuteron, the combination of gluon distributions corresponding to the b1 structure function is found to have a small first moment compared with the corresponding momentum fraction. The first moment of the gluon transversity structure function is also investigated in the spin-1 deuteron, where a nonzero signal is observed at mπ˜806 MeV . This is the first indication of gluon contributions to nuclear structure that can not be associated with an individual nucleon.

First lattice QCD study of the gluonic structure of light nuclei

DOE PAGES

Winter, Frank; Detmold, William; Gambhir, Arjun S.; ...

2017-11-28

The role of gluons in the structure of the nucleon and light nuclei is investigated using lattice quantum chromodynamics (QCD) calculations. The first moment of the unpolarised gluon distribution is studied in nuclei up to atomic numbermore » $A=3$ at quark masses corresponding to pion masses of $$m_\\pi\\sim 450$$ and $806$ MeV. Nuclear modification of this quantity defines a gluonic analogue of the EMC effect and is constrained to be less than $$\\sim 10$$% in these nuclei. This is consistent with expectations from phenomenological quark distributions and the momentum sum rule. In the deuteron, the combination of gluon distributions corresponding to the $$b_1$$ structure function is found to have a small first moment compared with the corresponding momentum fraction. The first moment of the gluon transversity structure function is also investigated in the spin-1 deuteron, where a non-zero signal is observed at $$m_\\pi \\sim 806$$ MeV. In conclusion, this is the first indication of gluon contributions to nuclear structure that can not be associated with an individual nucleon.« less

A solution to coupled Dyson{endash}Schwinger equations for gluons and ghosts in Landau gauge

DOE Office of Scientific and Technical Information (OSTI.GOV)

von Smekal, L.; Hauck, A.; Alkofer, R.

1998-07-01

A truncation scheme for the Dyson{endash}Schwinger equations of QCD in Landau gauge is presented which implements the Slavnov{endash}Taylor identities for the 3-point vertex functions. Neglecting contributions from 4-point correlations such as the 4-gluon vertex function and irreducible scattering kernels, a closed system of equations for the propagators is obtained. For the pure gauge theory without quarks this system of equations for the propagators of gluons and ghosts is solved in an approximation which allows for an analytic discussion of its solutions in the infrared: The gluon propagator is shown to vanish for small spacelike momenta whereas the ghost propagator ismore » found to be infrared enhanced. The running coupling of the non-perturbative subtraction scheme approaches an infrared stable fixed point at a critical value of the coupling, {alpha}{sub c}{approx_equal}9.5. The gluon propagator is shown to have no Lehmann representation. The results for the propagators obtained here compare favorably with recent lattice calculations. {copyright} 1998 Academic Press, Inc.« less

Using Longitudinally Polarized Proton+Proton Collisions To Constrain the Polarized Gluon Distribution Through Dijet Measurements at √{ s} = 510 GeV at STAR

NASA Astrophysics Data System (ADS)

Olvitt, Daniel, Jr.; STAR Collaboration

2017-09-01

The production of jets from polarized p+p collisions at STAR is dominated by quark-gluon and gluon-gluon scattering. The dijet double spin asymmetry (ALL) is sensitive to the polarized gluon distribution (Δg (x)). Dijets are also advantageous because the parton momentum fraction, x, of initial partons may be reconstructed to first order from the final state measurements. New data from 2013 with an estimated 250 pb-1, at a beam polarization of 55% at √{ s} = 510 GeV, has a figure of merit 3 times that of the 2012 data collected at √{ s} = 510 GeV. This talk will discuss the new dijet ALL preliminary results, this data use 40% of the total 2013 data. The 2013 results are consistent with the published STAR dijet ALL measurements at √{ s} = 200 GeV, and the preliminary 2012 dijet ALL. The 2013 dijet ALL is also consistent with global fits from DSSV and NNPDF collaborations, that incorporate the published STAR inclusive jet ALL at √{ s} = 200 GeV.

The small-x gluon distribution in centrality biased pA and pp collisions

NASA Astrophysics Data System (ADS)

Dumitru, Adrian; Kapilevich, Gary; Skokov, Vladimir

2018-06-01

The nuclear modification factor RpA (pT) provides information on the small-x gluon distribution of a nucleus at hadron colliders. Several experiments have recently measured the nuclear modification factor not only in minimum bias but also for central pA collisions. In this paper we analyze the bias on the configurations of soft gluon fields introduced by a centrality selection via the number of hard particles. Such bias can be viewed as reweighting of configurations of small-x gluons. We find that the biased nuclear modification factor QpA (pT) for central collisions is above RpA (pT) for minimum bias events, and that it may redevelop a "Cronin peak" even at small x. The magnitude of the peak is predicted to increase approximately like 1 /A⊥ ν, ν ∼ 0.6 ± 0.1, if one is able to select more compact configurations of the projectile proton where its gluons occupy a smaller transverse area A⊥. We predict an enhanced Qpp (pT) - 1 ∼ 1 /(pT2) ν and a Cronin peak even for central pp collisions.

Effective kinetic description of the expanding overoccupied glasma

DOE PAGES

Tanji, Naoto; Venugopalan, Raju

2017-05-19

Here, we report on a numerical study of the Boltzmann equation including 2↔2 scatterings of gluons and quarks in an overoccupied glasma undergoing longitudinal expansion. We find that when a cascade of gluon number to the infrared occurs, corresponding to an infrared enhancement analogous to a transient Bose-Einstein condensate, gluon distributions qualitatively reproduce the results of classical-statistical simulations for the expanding glasma. These include key features of the distributions that are not anticipated in the “bottom-up” thermalization scenario. We also find that quark distributions, like those of gluons, satisfy self-similar scaling distributions in the overoccupied glasma. We discuss the implicationsmore » of these results for a deeper understanding of the self-similarity and universality of parton distributions in the glasma.« less

Leading multi-soft limits from scattering equations

NASA Astrophysics Data System (ADS)

Zlotnikov, Michael

2017-10-01

A Cachazo-He-Yuan (CHY) type formula is derived for the leading gluon, bi-adjoint scalar ϕ 3, Yang-Mills-scalar and non-linear sigma model m-soft factors S m in arbitrary dimension. The general formula is used to evaluate explicit examples for up to three soft legs analytically and up to four soft legs numerically via comparison with amplitude ratios under soft kinematics. A structural pattern for gluon m-soft factor is inferred and a simpler formula for its calculation is conjectured. In four dimensions, a Cachazo-Svrček-Witten (CSW) recursive procedure producing the leading m-soft gluon factor in spinor helicity formalism is developed as an alternative, and Britto-Cachazo-Feng-Witten (BCFW) recursion is used to obtain the leading four-soft gluon factor for all analytically distinct helicity configurations.

Two loop QCD vertices at the symmetric point

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gracey, J. A.

2011-10-15

We compute the triple gluon, quark-gluon and ghost-gluon vertices of QCD at the symmetric subtraction point at two loops in the MS scheme. In addition we renormalize each of the three vertices in their respective momentum subtraction schemes, MOMggg, MOMq and MOMh. The conversion functions of all the wave functions, coupling constant and gauge parameter renormalization constants of each of the schemes relative to MS are determined analytically. These are then used to derive the three loop anomalous dimensions of the gluon, quark, Faddeev-Popov ghost and gauge parameter as well as the {beta} function in an arbitrary linear covariant gaugemore » for each MOM scheme. There is good agreement of the latter with earlier Landau gauge numerical estimates of Chetyrkin and Seidensticker.« less

Effective kinetic description of the expanding overoccupied glasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tanji, Naoto; Venugopalan, Raju

Here, we report on a numerical study of the Boltzmann equation including 2↔2 scatterings of gluons and quarks in an overoccupied glasma undergoing longitudinal expansion. We find that when a cascade of gluon number to the infrared occurs, corresponding to an infrared enhancement analogous to a transient Bose-Einstein condensate, gluon distributions qualitatively reproduce the results of classical-statistical simulations for the expanding glasma. These include key features of the distributions that are not anticipated in the “bottom-up” thermalization scenario. We also find that quark distributions, like those of gluons, satisfy self-similar scaling distributions in the overoccupied glasma. We discuss the implicationsmore » of these results for a deeper understanding of the self-similarity and universality of parton distributions in the glasma.« less

Local Area Network Strategies and Guidelines for a Peruvian Air Force Computer Center

DTIC Science & Technology

1991-03-01

service elements to support application processes such as job management, and financial data exchange. The layer also supports the virtual terminal and... virtual file concept. [Ref.3 :p. 285] Essentially, the lowest three layers are concerned with the communication protocols associated with the data...General de la Fuerza Aerea Peruana Lima, Republica del Peru 5. Escuela de Oficiales de la Fuerza Aerea Peruana 2 Biblioteca del Grupo del Instruccion Base

The gluon density of the proton at low x from a QCD analysis of F2

NASA Astrophysics Data System (ADS)

Aid, S.; Andreev, V.; Andrieu, B.; Appuhn, R.-D.; Arpagaus, M.; Babaev, A.; Baehr, J.; Bán, J.; Ban, Y.; Baranov, P.; Barrelet, E.; Barschke, R.; Bartel, W.; Barth, M.; Bassler, U.; Beck, H. P.; Behrend, H.-J.; Belousov, A.; Berger, Ch.; Bernardi, G.; Bernet, R.; Bertrand-Coremans, G.; Besançon, M.; Beyer, R.; Biddulph, P.; Bispham, P.; Bizot, J. C.; Blobel, V.; Borras, K.; Botterweck, F.; Boudry, V.; Braemer, A.; Brasse, F.; Braunschweig, W.; Brisson, V.; Bruncko, D.; Brune, C.; Buchholz, R.; Büngener, L.; Bürger, J.; Büsser, F. W.; Buniatian, A.; Burke, S.; Burton, M.; Buschhorn, G.; Campbell, A. J.; Carli, T.; Charles, F.; Charlet, M.; Clarke, D.; Clegg, A. B.; Clerbaux, B.; Colombo, M.; Contreras, J. G.; Cormack, C.; Coughlan, J. A.; Courau, A.; Coutures, Ch.; Cozzika, G.; Criegee, L.; Cussans, D. G.; Cvach, J.; Dagoret, S.; Dainton, J. B.; Dau, W. D.; Daum, K.; David, M.; Delcourt, B.; Del Buono, L.; De Roeck, A.; De Wolf, E. A.; Di Nezza, P.; Dollfus, C.; Dowell, J. D.; Dreis, H. B.; Droutskoi, A.; Duboc, J.; Düllmann, D.; Dünger, O.; Duhm, H.; Ebert, J.; Ebert, T. R.; Eckerlin, G.; Efremenko, V.; Egli, S.; Ehrlichmann, H.; Eichenberger, S.; Eichler, R.; Eisele, F.; Eisenhandler, E.; Ellison, R. J.; Elsen, E.; Erdmann, M.; Erdmann, W.; Evrard, E.; Favart, L.; Fedotov, A.; Feeken, D.; Felst, R.; Feltesse, J.; Ferencei, J.; Ferrarotto, F.; Flamm, K.; Fleischer, M.; Flieser, M.; Flügge, G.; Fomenko, A.; Fominykh, B.; Forbush, M.; Formánek, J.; Foster, J. M.; Franke, G.; Fretwurst, E.; Gabathuler, E.; Gabathuler, K.; Gamerdinger, K.; Garvey, J.; Gayler, J.; Gebauer, M.; Gellrich, A.; Genzel, H.; Gerhards, R.; Goerlach, U.; Goerlich, L.; Gogitidze, N.; Goldberg, M.; Goldner, D.; Gonzalez-Pineiro, B.; Gorelov, I.; Goritchev, P.; Grab, C.; Grässler, H.; Grässler, R.; Greenshaw, T.; Grindhammer, G.; Gruber, A.; Gruber, C.; Haack, J.; Haidt, D.; Hajduk, L.; Hamon, O.; Hampel, M.; Hanlon, E. M.; Hapke, M.; Haynes, W. J.; Heatherington, J.; Heinzelmann, G.; Henderson, R. C. W.; Henschel, H.; Herynek, I.; Hess, M. F.; Hildesheim, W.; Hill, P.; Hiller, K. H.; Hilton, C. D.; Hladký, J.; Hoeger, K. C.; Höppner, M.; Horisberger, R.; Hudgson, V. L.; Huet, Ph.; Hütte, M.; Hufnagel, H.; Ibbotson, M.; Itterbeck, H.; Jabiol, M.-A.; Jacholkowska, A.; Jacobsson, C.; Jaffre, M.; Janoth, J.; Jansen, T.; Jönsson, L.; Johnson, D. P.; Johnson, L.; Jung, H.; Kalmus, P. I. P.; Kant, D.; Kaschowitz, R.; Kasselmann, P.; Kathage, U.; Katzy, J.; Kaufmann, H. H.; Kazarian, S.; Kenyon, I. R.; Kermiche, S.; Keuker, C.; Kiesling, C.; Klein, M.; Kleinwort, C.; Knies, G.; Ko, W.; Köhler, T.; Köhne, J. H.; Kolanoski, H.; Kole, F.; Kolya, S. D.; Korbel, V.; Korn, M.; Kostka, P.; Kotelnikov, S. K.; Krämerkämper, T.; Krasny, M. W.; Krehbiel, H.; Krücker, D.; Krüger, U.; Krüner-Marquis, U.; Kubenka, J. P.; Küster, H.; Kuhlen, M.; Kurča, T.; Kurzhöfer, J.; Kuznik, B.; Lacour, D.; Lamarche, F.; Lander, R.; Landon, M. P. J.; Lange, W.; Lanius, P.; Laporte, J.-F.; Lebedev, A.; Leverenz, C.; Levonian, S.; Ley, Ch.; Lindner, A.; Lindström, G.; Link, J.; Linsel, F.; Lipinski, J.; List, B.; Lobo, G.; Loch, P.; Lohmander, H.; Lomas, J.; Lopez, G. C.; Lubimov, V.; Lüke, D.; Magnussen, N.; Malinovski, E.; Mani, S.; Maraček, R.; Marage, P.; Marks, J.; Marshall, R.; Martens, J.; Martin, R.; Martyn, H.-U.; Martyniak, J.; Masson, S.; Mavroidis, T.; Maxfield, S. J.; McMahon, S. J.; Mehta, A.; Meier, K.; Mercer, D.; Merz, T.; Meyer, C. A.; Meyer, H.; Meyer, J.; Migliori, A.; Mikocki, S.; Milstead, D.; Moreau, F.; Morris, J. V.; Mroczko, E.; Müller, G.; Müller, K.; Murín, P.; Nagovizin, V.; Nahnhauer, R.; Naroska, B.; Naumann, Th.; Newman, P. R.; Newton, D.; Neyret, D.; Nguyen, H. K.; Nicholls, T. C.; Niebergall, F.; Niebuhr, C.; Niedzballa, Ch.; Nisius, R.; Nowak, G.; Noyes, G. W.; Nyberg-Werther, M.; Oakden, M.; Oberlack, H.; Obrock, U.; Olsson, J. E.; Ozerov, D.; Panaro, E.; Panitch, A.; Pascaud, C.; Patel, G. D.; Peppel, E.; Perez, E.; Phillips, J. P.; Pichler, Ch.; Pieuchot, A.; Pitzl, D.; Pope, G.; Prell, S.; Prosi, R.; Rabbertz, K.; Rädel, G.; Raupach, F.; Reimer, P.; Reinshagen, S.; Ribarics, P.; Rick, H.; Riech, V.; Riedlberger, J.; Riess, S.; Rietz, M.; Rizvi, E.; Robertson, S. M.; Robmann, P.; Roloff, H. E.; Roosen, R.; Rosenbauer, K.; Rostovtsev, A.; Rouse, F.; Royon, C.; Rüter, K.; Rusakov, S.; Rybicki, K.; Rylko, R.; Sahlmann, N.; Sanchez, E.; Sankey, D. P. C.; Schacht, P.; Schiek, S.; Schleper, P.; von Schlippe, W.; Schmidt, C.; Schmidt, D.; Schmidt, G.; Schöning, A.; Schröder, V.; Schuhmann, E.; Schwab, B.; Schwind, A.; Sefkow, F.; Seidel, M.; Sell, R.; Semenov, A.; Shekelyan, V.; Sheviakov, I.; Shooshtari, H.; Shtarkov, L. N.; Siegmon, G.; Siewert, U.; Sirois, Y.; Skillicorn, I. O.; Smirnov, P.; Smith, J. R.; Solochenko, V.; Soloviev, Y.; Spiekermann, J.; Spielman, S.; Spitzer, H.; Starosta, R.; Steenbock, M.; Steffen, P.; Steinberg, R.; Stella, B.; Stephens, K.; Stier, J.; Stiewe, J.; Stösslein, U.; Stolze, K.; Strachota, J.; Straumann, U.; Struczinski, W.; Sutton, J. P.; Tapprogge, S.; Tchernyshov, V.; Thiebaux, C.; Thompson, G.; Truöl, P.; Turnau, J.; Tutas, J.; Uelkes, P.; Usik, A.; Valkár, S.; Valkárová, A.; Vallée, C.; Van Esch, P.; Van Mechelen, P.; Vartapetian, A.; Vazdik, Y.; Verrecchia, P.; Villet, G.; Wacker, K.; Wagener, A.; Wagener, M.; Walker, I. W.; Walther, A.; Weber, G.; Weber, M.; Wegener, D.; Wegner, A.; Wellisch, H. P.; West, L. R.; Willard, S.; Willard, S.; Winde, M.; Winter, G.-G.; Wittek, C.; Wright, A. E.; Wünsch, E.; Wulff, N.; Yiou, T. P.; Žáček, J.; Zarbock, D.; Zhang, Z.; Zhokin, A.; Zimmer, M.; Zimmermann, W.; Zomer, F.; Zuber, K.; H1 Collaboration

1995-02-01

We present a QCD analysis of the proton structure function F2 measured by the H1 experiment at HERA, combined with data from previous fixed target experiments. The gluon density is extracted from the scaling violations of F2 in the range 2 · 10 -4 < x < 3 · 10 -2 and compared with an approximate solution of the QCD evolution equations. The gluon density is found to rise steeply with decreasing x.

Nonperturbative finite-temperature Yang-Mills theory

NASA Astrophysics Data System (ADS)

Cyrol, Anton K.; Mitter, Mario; Pawlowski, Jan M.; Strodthoff, Nils

2018-03-01

We present nonperturbative correlation functions in Landau-gauge Yang-Mills theory at finite temperature. The results are obtained from the functional renormalisation group within a self-consistent approximation scheme. In particular, we compute the magnetic and electric components of the gluon propagator, and the three- and four-gluon vertices. We also show the ghost propagator and the ghost-gluon vertex at finite temperature. Our results for the propagators are confronted with lattice simulations and our Debye mass is compared to hard thermal loop perturbation theory.

REVIEWS OF TOPICAL PROBLEMS The quark-gluon medium

NASA Astrophysics Data System (ADS)

Dremin, Igor M.; Leonidov, Andrei V.

2011-02-01

The properties of the quark-gluon medium observed in high-energy nucleus-nucleus collisions are discussed. The main experimental facts about these collisions are briefly described and compared with data about proton-proton collisions. Both microscopic and macroscopic approaches to their description are reviewed. The chromodynamics of the quark-gluon medium at high energies is mainly considered. The energy loss of partons moving in this medium is treated. The principal conclusion is that the medium possesses some collective properties which are crucial for understanding the experimental observations.

Virtually Out of This World!

NASA Technical Reports Server (NTRS)

2002-01-01

Ames Research Center granted Reality Capture Technologies (RCT), Inc., a license to further develop NASA's Mars Map software platform. The company incorporated NASA#s innovation into software that uses the Virtual Plant Model (VPM)(TM) to structure, modify, and implement the construction sites of industrial facilities, as well as develop, validate, and train operators on procedures. The VPM orchestrates the exchange of information between engineering, production, and business transaction systems. This enables users to simulate, control, and optimize work processes while increasing the reliability of critical business decisions. Engineers can complete the construction process and test various aspects of it in virtual reality before building the actual structure. With virtual access to and simulation of the construction site, project personnel can manage, access control, and respond to changes on complex constructions more effectively. Engineers can also create operating procedures, training, and documentation. Virtual Plant Model(TM) is a trademark of Reality Capture Technologies, Inc.

PROCEEDINGS OF RIKEN BNL RESEARCH CENTER WORKSHOP ENTITLED "ODDERON SEARCHES AT RHIC" (VOLUME 76)

DOE Office of Scientific and Technical Information (OSTI.GOV)

ORGANIZERS: GURYN, W.; KOVCHEGOV, Y.; VOGELSANG, W.

The Odderon, a charge-conjugation-odd partner of the Pomeron, has been a puzzle ever since its introduction in 1973. The Pomeron describes a colorless exchange with vacuum quantum numbers in the t-channel of hadronic scattering at high energies. The concept was originally formulated for the non-perturbative regime of Quantum Chromodynamics (QCD). In perturbation theory, the simplest picture of the Poineron is that of a two-gluon exchange process, whereas an Odderon can be thought of as an exchange of three gluons. Both the Pomeron and the Odderon are expected in QCD. However, while there exists plenty of experimental data that could bemore » successfully described by Pomeron exchanges (for example in electron-proton and hadron-hadron scattering at high energies), no experimental sign of the Odderon has been observed. One of the very few hints so far is the difference in the diffractive minima of elastic proton-proton and proton-antiproton scattering measured at the ISR. The Odderon has recently received renewed attention by QCD researchers, mainly for the following two reasons. First of all, RHIC has entered the scene, offering exciting unique new opportunities for Odderon searches. RHIC provides collisions of nuclei at center-of-mass energies far exceeding those at all previous experiments. RHIC also provides collisions of protons of the highest center-of-mass energy, and in the interval, which has not been explored previously in p {bar p} collisions. In addition, it also has the unique feature of polarization for the proton beams, promising to become a crucial tool in Odderon searches. Indeed, theorists have proposed possible signatures of the Odderon in some spin asymmetries measurable at RHIC. Qualitatively unique signals should be seen in these observables if the Odderon coupling is large. Secondly, the Odderon has recently been shown to naturally emerge from the Color Glass Condensate (CGC), a theory for the high-energy asymptotics of QCD. It has been argued that saturation/CGC effects tend to decrease the Odderon intercept, possibly providing an explanation for the lack of experimental evidence for the Odderon so far. This has added further motivation for pursuing searches for the Odderon. During the workshop the status of the Odderon in QCD and its phenomenology were reviewed. The participants also agreed on the most promising observables for the Odderon search at RHIC, which we list. The conclusion of the workshop is that the best available setup to address experimental questions related to the search for the Odderon at RHIC is the proposed combination of STAR experiment and Roman pots of pp2pp experiment, described in the proposal ''Physics with Tagged Forward Protons with the STAR detector at RHIC''.« less

Gluon TMD in particle production from low to moderate x

DOE PAGES

Balitsky, I.; Tarasov, A.

2016-06-28

We study the rapidity evolution of gluon transverse momentum dependent distributions appearing in processes of particle production and show how this evolution changes from small to moderate Bjorken x.

NASA's Solar System Exploration Research Virtual Institute: Combining Science and Exploration

NASA Astrophysics Data System (ADS)

Bailey, B.; Schmidt, G.; Daou, D.; Pendleton, Y.

2015-10-01

The NASA Solar System Exploration Research Virtual Institute (SSERVI) is a virtual institute focused on research at the intersection of science andexploration, training the next generation of lunar scientists, and community development. As part of the SSERVI mission, we act as a hub for opportunities that engage the larger scientific and exploration communities in order to form new interdisciplinary, research-focused collaborations. This talk will describe the research efforts of the nine domestic teams that constitute the U.S. complement of the Institute and how we will engage the international science and exploration communities through workshops, conferences, online seminars and classes, student exchange programs and internships.

Gauge invariant gluon spin operator for spinless nonlinear wave solutions

NASA Astrophysics Data System (ADS)

Lee, Bum-Hoon; Kim, Youngman; Pak, D. G.; Tsukioka, Takuya; Zhang, P. M.

2017-04-01

We consider nonlinear wave type solutions with intrinsic mass scale parameter and zero spin in a pure SU(2) quantum chromodynamics (QCD). A new stationary solution which can be treated as a system of static Wu-Yang monopole dressed in off-diagonal gluon field is proposed. A remarkable feature of such a solution is that it possesses a finite energy density everywhere. All considered nonlinear wave type solutions have common features: presence of the mass scale parameter, nonvanishing projection of the color fields along the propagation direction and zero spin. The last property requires revision of the gauge invariant definition of the spin density operator which is supposed to produce spin one states for the massless vector gluon field. We construct a gauge invariant definition of the classical gluon spin density operator which is unique and Lorentz frame independent.

Measurements of double-helicity asymmetries in inclusive J / ψ production in longitudinally polarized p + p collisions at s = 510 GeV

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adare, A.; Aidala, C.; Ajitanand, N. N.

We report the double-helicity asymmetry, A J/ψ LL, in inclusive J/ψ production at forward rapidity as a function of transverse momentum p T and rapidity |y|. The data analyzed were taken during √s = 510 GeV longitudinally polarized p + p collisions at the Relativistic Heavy Ion Collider in the 2013 run using the PHENIX detector. At this collision energy, J/ψ particles are predominantly produced through gluon-gluon scatterings, thus A J/ψ LL is sensitive to the gluon polarization inside the proton. We measured A J/ψ LL by detecting the decay daughter muon pairs μ +μ – within the PHENIX muonmore » spectrometers in the rapidity range 1.2 < |y| < 2.2. In this kinematic range, we measured the A J/ψ LL to be 0.012 ± 0.010 (stat) ±0.003 (syst). The A J/ψ LL can be expressed to be proportional to the product of the gluon polarization distributions at two distinct ranges of Bjorken x: one at moderate range x ≈ 5 × 10 –2 where recent data of jet and π 0 double helicity spin asymmetries have shown evidence for significant gluon polarization, and the other one covering the poorly known small-x region x ≈ 2 × 10 –3. Furthermore, our new results could be used to further constrain the gluon polarization for x < 5 × 10 –2.« less

Measurements of double-helicity asymmetries in inclusive J / ψ production in longitudinally polarized p + p collisions at s = 510 GeV

DOE PAGES

Adare, A.; Aidala, C.; Ajitanand, N. N.; ...

2016-12-29

We report the double-helicity asymmetry, A J/ψ LL, in inclusive J/ψ production at forward rapidity as a function of transverse momentum p T and rapidity |y|. The data analyzed were taken during √s = 510 GeV longitudinally polarized p + p collisions at the Relativistic Heavy Ion Collider in the 2013 run using the PHENIX detector. At this collision energy, J/ψ particles are predominantly produced through gluon-gluon scatterings, thus A J/ψ LL is sensitive to the gluon polarization inside the proton. We measured A J/ψ LL by detecting the decay daughter muon pairs μ +μ – within the PHENIX muonmore » spectrometers in the rapidity range 1.2 < |y| < 2.2. In this kinematic range, we measured the A J/ψ LL to be 0.012 ± 0.010 (stat) ±0.003 (syst). The A J/ψ LL can be expressed to be proportional to the product of the gluon polarization distributions at two distinct ranges of Bjorken x: one at moderate range x ≈ 5 × 10 –2 where recent data of jet and π 0 double helicity spin asymmetries have shown evidence for significant gluon polarization, and the other one covering the poorly known small-x region x ≈ 2 × 10 –3. Furthermore, our new results could be used to further constrain the gluon polarization for x < 5 × 10 –2.« less

The National Virtual Observatory

NASA Astrophysics Data System (ADS)

Hanisch, Robert J.

2001-06-01

The National Virtual Observatory is a distributed computational facility that will provide access to the ``virtual sky''-the federation of astronomical data archives, object catalogs, and associated information services. The NVO's ``virtual telescope'' is a common framework for requesting, retrieving, and manipulating information from diverse, distributed resources. The NVO will make it possible to seamlessly integrate data from the new all-sky surveys, enabling cross-correlations between multi-Terabyte catalogs and providing transparent access to the underlying image or spectral data. Success requires high performance computational systems, high bandwidth network services, agreed upon standards for the exchange of metadata, and collaboration among astronomers, astronomical data and information service providers, information technology specialists, funding agencies, and industry. International cooperation at the onset will help to assure that the NVO simultaneously becomes a global facility. .

Virtual expansion of the technical vision system for smart vehicles based on multi-agent cooperation model

NASA Astrophysics Data System (ADS)

Krapukhina, Nina; Senchenko, Roman; Kamenov, Nikolay

2017-12-01

Road safety and driving in dense traffic flows poses some challenges in receiving information about surrounding moving object, some of which can be in the vehicle's blind spot. This work suggests an approach to virtual monitoring of the objects in a current road scene via a system with a multitude of cooperating smart vehicles exchanging information. It also describes the intellectual agent model, and provides methods and algorithms of identifying and evaluating various characteristics of moving objects in video flow. Authors also suggest ways for integrating the information from the technical vision system into the model with further expansion of virtual monitoring for the system's objects. Implementation of this approach can help to expand the virtual field of view for a technical vision system.

Implementation of a World Wide Web server for the oil and gas industry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blaylock, R.E.; Martin, F.D.; Emery, R.

1995-12-31

The Gas and Oil Technology Exchange and Communication Highway, (GO-TECH), provides an electronic information system for the petroleum community for the purpose of exchanging ideas, data, and technology. The personal computer-based system fosters communication and discussion by linking oil and gas producers with resource centers, government agencies, consulting firms, service companies, national laboratories, academic research groups, and universities throughout the world. The oil and gas producers are provided access to the GO-TECH World Wide Web home page via modem links, as well as Internet. The future GO-TECH applications will include the establishment of{open_quote}Virtual corporations {close_quotes} consisting of consortiums of smallmore » companies, consultants, and service companies linked by electronic information systems. These virtual corporations will have the resources and expertise previously found only in major corporations.« less

Implementation of a World Wide Web server for the oil and gas industry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blaylock, R.E.; Martin, F.D.; Emery, R.

1996-10-01

The Gas and Oil Technology Exchange and Communication Highway (GO-TECH) provides an electronic information system for the petroleum community for exchanging ideas, data, and technology. The PC-based system fosters communication and discussion by linking the oil and gas producers with resource centers, government agencies, consulting firms, service companies, national laboratories, academic research groups, and universities throughout the world. The oil and gas producers can access the GO-TECH World Wide Web (WWW) home page through modem links, as well as through the Internet. Future GO-TECH applications will include the establishment of virtual corporations consisting of consortia of small companies, consultants, andmore » service companies linked by electronic information systems. These virtual corporations will have the resources and expertise previously found only in major corporations.« less

Hadron production in diffractive deep-inelastic scattering

NASA Astrophysics Data System (ADS)

H1 Collaboration; Adloff, C.; Aid, S.; Anderson, M.; Andreev, V.; Andrieu, B.; Arkadov, V.; Arndt, C.; Ayyaz, I.; Babaev, A.; Bähr, J.; Bán, J.; Baranov, P.; Barrelet, E.; Barschke, R.; Bartel, W.; Bassler, U.; Bate, P.; Beck, M.; Beglarian, A.; Behrend, H.-J.; Beier, C.; Belousov, A.; Berger, Ch.; Bernardi, G.; Bertrand-Coremans, G.; Beyer, R.; Biddulph, P.; Bizot, J. C.; Borras, K.; Boudry, V.; Braemer, A.; Braunschweig, W.; Brisson, V.; Brown, D. P.; Brückner, W.; Bruel, P.; Bruncko, D.; Brune, C.; Bürger, J.; Büsser, F. W.; Buniatian, A.; Burke, S.; Buschhorn, G.; Calvet, D.; Campbell, A. J.; Carli, T.; Chabert, E.; Charlet, M.; Clarke, D.; Clerbaux, B.; Cocks, S.; Contreras, J. G.; Cormack, C.; Coughlan, J. A.; Cousinou, M.-C.; Cox, B. E.; Cozzika, G.; Cvach, J.; Dainton, J. B.; Dau, W. D.; Daum, K.; David, M.; de Roeck, A.; de Wolf, E. A.; Delcourt, B.; Diaconu, C.; Dirkmann, M.; Dixon, P.; Dlugosz, W.; Donovan, K. T.; Dowell, J. D.; Droutskoi, A.; Ebert, J.; Eckerlin, G.; Eckstein, D.; Efremenko, V.; Egli, S.; Eichler, R.; Eisele, F.; Eisenhandler, E.; Elsen, E.; Enzenberger, M.; Erdmann, M.; Fahr, A. B.; Favart, L.; Fedotov, A.; Felst, R.; Feltesse, J.; Ferencei, J.; Ferrarotto, F.; Flamm, K.; Fleischer, M.; Flügge, G.; Fomenko, A.; Formánek, J.; Foster, J. M.; Franke, G.; Gabathuler, E.; Gabathuler, K.; Gaede, F.; Garvey, J.; Gayler, J.; Gebauer, M.; Gerhards, R.; Glazov, A.; Goerlich, L.; Gogitidze, N.; Goldberg, M.; Gorelov, I.; Grab, C.; Grässler, H.; Greenshaw, T.; Griffiths, R. K.; Grindhammer, G.; Gruber, C.; Hadig, T.; Haidt, D.; Hajduk, L.; Haller, T.; Hampel, M.; Haustein, V.; Haynes, W. J.; Heinemann, B.; Heinzelmann, G.; Henderson, R. C. W.; Hengstmann, S.; Henschel, H.; Heremans, R.; Herynek, I.; Hewitt, K.; Hiller, K. H.; Hilton, C. D.; Hladký, J.; Höppner, M.; Hoffmann, D.; Holtom, T.; Horisberger, R.; Hudgson, V. L.; Hütte, M.; Ibbotson, M.; Isolarş Sever, Ç.; Itterbeck, H.; Jacquet, M.; Jaffre, M.; Janoth, J.; Jansen, D. M.; Jönsson, L.; Johnson, D. P.; Jung, H.; Kander, M.; Kant, D.; Kathage, U.; Katzy, J.; Kaufmann, H. H.; Kaufmann, O.; Kausch, M.; Kazarian, S.; Kenyon, I. R.; Kermiche, S.; Keuker, C.; Kiesling, C.; Klein, M.; Kleinwort, C.; Knies, G.; Köhne, J. H.; Kolanoski, H.; Kolya, S. D.; Korbel, V.; Kostka, P.; Kotelnikov, S. K.; Krämerkämper, T.; Krasny, M. W.; Krehbiel, H.; Krücker, D.; Küpper, A.; Küster, H.; Kuhlen, M.; Kurča, T.; Laforge, B.; Lahmann, R.; Landon, M. P. J.; Lange, W.; Langenegger, U.; Lebedev, A.; Lehmann, M.; Lehner, F.; Lemaitre, V.; Levonian, S.; Lindstroem, M.; Lipinski, J.; List, B.; Lobo, G.; Lubimov, V.; Lüke, D.; Lytkin, L.; Magnussen, N.; Mahlke-Krüger, H.; Malinovski, E.; Maraček, R.; Marage, P.; Marks, J.; Marshall, R.; Martin, G.; Martin, R.; Martyn, H.-U.; Martyniak, J.; Maxfield, S. J.; McMahon, S. J.; McMahon, T. R.; Mehta, A.; Meier, K.; Merkel, P.; Metlica, F.; Meyer, A.; Meyer, A.; Meyer, H.; Meyer, J.; Meyer, P.-O.; Migliori, A.; Mikocki, S.; Milstead, D.; Moeck, J.; Mohr, R.; Mohrdieck, S.; Moreau, F.; Morris, J. V.; Mroczko, E.; Müller, D.; Müller, K.; Murín, P.; Nagovizin, V.; Nahnhauer, R.; Naroska, B.; Naumann, Th.; Négri, I.; Newman, P. R.; Newton, D.; Nguyen, H. K.; Nicholls, T. C.; Niebergall, F.; Niebuhr, C.; Niedzballa, Ch.; Niggli, H.; Nix, O.; Nowak, G.; Nunnemann, T.; Oberlack, H.; Olsson, J. E.; Ozerov, D.; Palmen, P.; Panaro, E.; Panitch, A.; Pascaud, C.; Passaggio, S.; Patel, G. D.; Pawletta, H.; Peppel, E.; Perez, E.; Phillips, J. P.; Pieuchot, A.; Pitzl, D.; Pöschl, R.; Pope, G.; Povh, B.; Rabbertz, K.; Reimer, P.; Reisert, B.; Rick, H.; Riess, S.; Rizvi, E.; Robmann, P.; Roosen, R.; Rosenbauer, K.; Rostovtsev, A.; Rouse, F.; Royon, C.; Rusakov, S.; Rybicki, K.; Sankey, D. P. C.; Schacht, P.; Scheins, J.; Schiek, S.; Schleif, S.; Schleper, P.; von Schlippe, W.; Schmidt, D.; Schmidt, G.; Schoeffel, L.; Schöning, A.; Schröder, V.; Schultz-Coulon, H.-C.; Schwab, B.; Sefkow, F.; Semenov, A.; Shekelyan, V.; Sheviakov, I.; Shtarkov, L. N.; Siegmon, G.; Siewert, U.; Sirois, Y.; Skillicorn, I. O.; Sloan, T.; Smirnov, P.; Smith, M.; Solochenko, V.; Soloviev, Y.; Specka, A.; Spiekermann, J.; Spitzer, H.; Squinabol, F.; Steffen, P.; Steinberg, R.; Steinhart, J.; Stella, B.; Stellberger, A.; Stiewe, J.; Stolze, K.; Straumann, U.; Struczinski, W.; Sutton, J. P.; Swart, M.; Tapprogge, S.; Taševský, M.; Tchernyshov, V.; Tchetchelnitski, S.; Theissen, J.; Thompson, G.; Thompson, P. D.; Tobien, N.; Todenhagen, R.; Truöl, P.; Tsipolitis, G.; Turnau, J.; Tzamariudaki, E.; Udluft, S.; Usik, A.; Valkár, S.; Valkárová, A.; Vallée, C.; van Esch, P.; van Mechelen, P.; Vazdik, Y.; Villet, G.; Wacker, K.; Wallny, R.; Walter, T.; Waugh, B.; Weber, G.; Weber, M.; Wegener, D.; Wegner, A.; Wengler, T.; Werner, M.; West, L. R.; Wiesand, S.; Wilksen, T.; Willard, S.; Winde, M.; Winter, G.-G.; Wittek, C.; Wittmann, E.; Wobisch, M.; Wollatz, H.; Wünsch, E.; Žáček, J.; Zálešák, J.; Zhang, Z.; Zhokin, A.; Zini, P.; Zomer, F.; Zsembery, J.; Zurnedden, M.

1998-05-01

Characteristics of hadron production in diffractive deep-inelastic positron-proton scattering are studied using data collected in 1994 by the H1 experiment at HERA. The following distributions are measured in the centre-of-mass frame of the photon dissociation system: the hadronic energy flow, the Feynman-x (xF) variable for charged particles, the squared transverse momentum of charged particles (pT*2), and the mean pT*2 as a function of xF. These distributions are compared with results in the γ*p centre-of-mass frame from inclusive deep-inelastic scattering in the fixed-target experiment EMC, and also with the predictions of several Monte Carlo calculations. The data are consistent with a picture in which the partonic structure of the diffractive exchange is dominated at low Q2 by hard gluons.

Heavy and Heavy-Light Mesons in the Covariant Spectator Theory

NASA Astrophysics Data System (ADS)

Stadler, Alfred; Leitão, Sofia; Peña, M. T.; Biernat, Elmar P.

2018-05-01

The masses and vertex functions of heavy and heavy-light mesons, described as quark-antiquark bound states, are calculated with the Covariant Spectator Theory (CST). We use a kernel with an adjustable mixture of Lorentz scalar, pseudoscalar, and vector linear confining interaction, together with a one-gluon-exchange kernel. A series of fits to the heavy and heavy-light meson spectrum were calculated, and we discuss what conclusions can be drawn from it, especially about the Lorentz structure of the kernel. We also apply the Brodsky-Huang-Lepage prescription to express the CST wave functions for heavy quarkonia in terms of light-front variables. They agree remarkably well with light-front wave functions obtained in the Hamiltonian basis light-front quantization approach, even in excited states.

Correct definition of color singlet P-wave non-perturbative matrix element of heavy quarkonium production

NASA Astrophysics Data System (ADS)

Nayak, Gouranga C.

2017-09-01

Recently we have proved factorization of infrared divergences in NRQCD S-wave heavy quarkonium production at high energy colliders at all orders in coupling constant. One of the problem which still exists in the higher order pQCD calculation of color singlet P-wave heavy quarkonium production/anihillation is the appearance of noncanceling infrared divergences due to real soft gluons exchange, although no such infrared divergences are present in the color singlet S-wave heavy quarkonium. In this paper we find that since the non-perturbative matrix element of the color singlet P-wave heavy quarkonium production contains derivative operators, the gauge links are necessary to make it gauge invariant and be consistent with the factorization of such non-canceling infrared divergences at all orders in coupling constant.

The small-x gluon distribution in centrality biased pA and pp collisions

DOE PAGES

Dumitru, Adrian; Kapilevich, Gary; Skokov, Vladimir

2018-04-04

Here, the nuclear modification factor R pA(p T) provides information on the small- x gluon distribution of a nucleus at hadron colliders. Several experiments have recently measured the nuclear modification factor not only in minimum bias but also for central pA collisions. In this paper we analyze the bias on the configurations of soft gluon fields introduced by a centrality selection via the number of hard particles. Such bias can be viewed as reweighting of configurations of small- x gluons. We find that the biased nuclear modification factor Q pA(p T) for central collisions is above R pA(p T) formore » minimum bias events, and that it may redevelop a “Cronin peak” even at small x . The magnitude of the peak is predicted to increase approximately like 1/A ⊥ ν, ν~0.6±0.1 , if one is able to select more compact configurations of the projectile proton where its gluons occupy a smaller transverse area A ⊥. We predict an enhanced Q pp(p T)–1~1/(p T 2) ν and a Cronin peak even for central pp collisions.« less

The small-x gluon distribution in centrality biased pA and pp collisions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dumitru, Adrian; Kapilevich, Gary; Skokov, Vladimir

Here, the nuclear modification factor R pA(p T) provides information on the small- x gluon distribution of a nucleus at hadron colliders. Several experiments have recently measured the nuclear modification factor not only in minimum bias but also for central pA collisions. In this paper we analyze the bias on the configurations of soft gluon fields introduced by a centrality selection via the number of hard particles. Such bias can be viewed as reweighting of configurations of small- x gluons. We find that the biased nuclear modification factor Q pA(p T) for central collisions is above R pA(p T) formore » minimum bias events, and that it may redevelop a “Cronin peak” even at small x . The magnitude of the peak is predicted to increase approximately like 1/A ⊥ ν, ν~0.6±0.1 , if one is able to select more compact configurations of the projectile proton where its gluons occupy a smaller transverse area A ⊥. We predict an enhanced Q pp(p T)–1~1/(p T 2) ν and a Cronin peak even for central pp collisions.« less

Creating the Primordial Quark-Gluon Plasma at the LHC

NASA Astrophysics Data System (ADS)

Harris, John W.

2013-04-01

Ultra-relativistic collisions of heavy ions at the Large Hadron Collider (LHC) and the Relativistic Heavy Ion Collider (RHIC) create an extremely hot system at temperatures (T) expected only within the first microseconds after the Big Bang. At these temperatures (T ˜ 2 x 10^12 K), a few hundred thousand times hotter than the sun's core, the known ``elementary'' particles cannot exist and matter ``melts'' to form a ``soup'' of quarks and gluons, called the quark-gluon plasma (QGP). This ``soup'' flows easily, with extremely low viscosity, suggesting a nearly perfect hot liquid of quarks and gluons. Furthermore, the liquid is dense, highly interacting and opaque to energetic probes (fast quarks or gluons). RHIC has been in operation for twelve years and has established an impressive set of findings. Recent results from heavy ion collisions at the LHC extend the study of the QGP to higher temperatures and harder probes, such as jets (energetic clusters of particles), particles with extremely large transverse momenta and those containing heavy quarks. I will present a motivation for physics in the field and an overview of the new LHC heavy ion results in relation to results from RHIC.

Inclusive Higgs boson production at the LHC in the kT -factorization approach

NASA Astrophysics Data System (ADS)

Abdulov, N. A.; Lipatov, A. V.; Malyshev, M. A.

2018-03-01

We investigate the inclusive Higgs boson production in proton-proton collisions at the CERN LHC conditions using the kT-factorization approach. Our analysis is based on the dominant off-shell gluon-gluon fusion subprocess (where the transverse momenta of initial gluons are taken into account) and covers H →γ γ , H →Z Z*→4 l (where l =e , μ ) and H →W+W-→e±μ∓ν ν ¯ decay channels. The transverse momentum dependent (or unintegrated) gluon densities in a proton were derived from Ciafaloni-Catani-Fiorani-Marchesini equation, which resums large logarithmic terms proportional to ln s ˜ln 1 /x , important at high energies. As an alternative choice, we apply the Kimber-Martin-Ryskin prescription, where the transverse momentum dependent gluon density is constructed from the known conventional parton distributions. We estimate the theoretical uncertainties of our calculations and compare our results with next-to-next-to-leading-order plus next-to-next-to-leading-logarithmic ones obtained using collinear QCD factorization. Our predictions agree well with the latest experimental data taken by the CMS and ATLAS Collaborations at √{s }=8 and 13 TeV.

Fractal Properties in Economics

DTIC Science & Technology

2000-01-01

being the exchange rate at T-th tick time, and <...> shows average over tick times To. The correlation is virtually 0 even at T=2, which corresponds to...t)(r(t) - r(t - At)) (5.b) where r*(t) is a virtual equilibrium price that is determined by the balanced price of demand and supply when all dealers...Pareto, Le Cour d’Economie Politique, (Macmillan, London, 1896). 13. C. Gim, Indici di concentrazione e di dipendenza, Biblioteca delli’economista

Department of Defense Training Technology Technical Group (T2TG) Minutes and Briefings of 6th Meeting

DTIC Science & Technology

1992-03-01

the Services or "What are the Research Issues in the use of Virtual Reality in Training?" 173 Visual Communication In Multi-Media Virtual Realities...This basic research project in visual communication examines how visual knowledge should be structured to take full advantage of advanced computer...theoretical framework to begin to analyze the comparative strengths of speech communication versus visual communication in the exchange of shared mental

Virtual Satellite

NASA Technical Reports Server (NTRS)

Hammrs, Stephan R.

2008-01-01

Virtual Satellite (VirtualSat) is a computer program that creates an environment that facilitates the development, verification, and validation of flight software for a single spacecraft or for multiple spacecraft flying in formation. In this environment, enhanced functionality and autonomy of navigation, guidance, and control systems of a spacecraft are provided by a virtual satellite that is, a computational model that simulates the dynamic behavior of the spacecraft. Within this environment, it is possible to execute any associated software, the development of which could benefit from knowledge of, and possible interaction (typically, exchange of data) with, the virtual satellite. Examples of associated software include programs for simulating spacecraft power and thermal- management systems. This environment is independent of the flight hardware that will eventually host the flight software, making it possible to develop the software simultaneously with, or even before, the hardware is delivered. Optionally, by use of interfaces included in VirtualSat, hardware can be used instead of simulated. The flight software, coded in the C or C++ programming language, is compilable and loadable into VirtualSat without any special modifications. Thus, VirtualSat can serve as a relatively inexpensive software test-bed for development test, integration, and post-launch maintenance of spacecraft flight software.

Elliptic flow in small systems due to elliptic gluon distributions?

DOE PAGES

Hagiwara, Yoshikazu; Hatta, Yoshitaka; Xiao, Bo-Wen; ...

2017-05-31

We investigate the contributions from the so-called elliptic gluon Wigner distributions to the rapidity and azimuthal correlations of particles produced in high energy pp and pA collisions by applying the double parton scattering mechanism. We compute the ‘elliptic flow’ parameter v 2 as a function of the transverse momentum and rapidity, and find qualitative agreement with experimental observations. This shall encourage further developments with more rigorous studies of the elliptic gluon distributions and their applications in hard scattering processes in pp and pA collisions.

Elliptic flow in small systems due to elliptic gluon distributions?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hagiwara, Yoshikazu; Hatta, Yoshitaka; Xiao, Bo-Wen

We investigate the contributions from the so-called elliptic gluon Wigner distributions to the rapidity and azimuthal correlations of particles produced in high energy pp and pA collisions by applying the double parton scattering mechanism. We compute the ‘elliptic flow’ parameter v 2 as a function of the transverse momentum and rapidity, and find qualitative agreement with experimental observations. This shall encourage further developments with more rigorous studies of the elliptic gluon distributions and their applications in hard scattering processes in pp and pA collisions.

Comparison of particle production in quark and gluon fragmentation at s˜10GeV

NASA Astrophysics Data System (ADS)

Briere, R. A.; Ferguson, T.; Tatishvili, G.; Vogel, H.; Watkins, M. E.; Rosner, J. L.; Adam, N. E.; Alexander, J. P.; Cassel, D. G.; Duboscq, J. E.; Ehrlich, R.; Fields, L.; Galik, R. S.; Gibbons, L.; Gray, R.; Gray, S. W.; Hartill, D. L.; Heltsley, B. K.; Hertz, D.; Jones, C. D.; Kandaswamy, J.; Kreinick, D. L.; Kuznetsov, V. E.; Mahlke-Krüger, H.; Onyisi, P. U. E.; Patterson, J. R.; Peterson, D.; Pivarski, J.; Riley, D.; Ryd, A.; Sadoff, A. J.; Schwarthoff, H.; Shi, X.; Stroiney, S.; Sun, W. M.; Wilksen, T.; Weinberger, M.; Athar, S. B.; Patel, R.; Potlia, V.; Yelton, J.; Rubin, P.; Cawlfield, C.; Eisenstein, B. I.; Karliner, I.; Kim, D.; Lowrey, N.; Naik, P.; Selen, M.; White, E. J.; Wiss, J.; Mitchell, R. E.; Shepherd, M. R.; Besson, D.; Swift, H. K.; Pedlar, T. K.; Cronin-Hennessy, D.; Gao, K. Y.; Hietala, J.; Kubota, Y.; Klein, T.; Lang, B. W.; Poling, R.; Scott, A. W.; Smith, A.; Zweber, P.; Dobbs, S.; Metreveli, Z.; Seth, K. K.; Tomaradze, A.; Ernst, J.; Ecklund, K. M.; Severini, H.; Love, W.; Savinov, V.; Aquines, O.; Li, Z.; Lopez, A.; Mehrabyan, S.; Mendez, H.; Ramirez, J.; Huang, G. S.; Miller, D. H.; Pavlunin, V.; Sanghi, B.; Shipsey, I. P. J.; Xin, B.; Adams, G. S.; Anderson, M.; Cummings, J. P.; Danko, I.; Hu, D.; Moziak, B.; Napolitano, J.; He, Q.; Insler, J.; Muramatsu, H.; Park, C. S.; Thorndike, E. H.; Yang, F.; Coan, T. E.; Gao, Y. S.; Artuso, M.; Blusk, S.; Butt, J.; Li, J.; Menaa, N.; Moneti, G. C.; Mountain, R.; Nisar, S.; Randrianarivony, K.; Sia, R.; Skwarnicki, T.; Stone, S.; Wang, J. C.; Zhang, K.; Bonvicini, G.; Cinabro, D.; Dubrovin, M.; Lincoln, A.; Asner, D. M.; Edwards, K. W.

2007-07-01

Using e+e-→hadrons data collected with the CLEO-III detector at the Cornell Electron Storage Ring, we study the inclusive production of baryons/antibaryons (p,Λ) and mesons (ϕ and f2(1270)) in gluon-fragmentation and quark-fragmentation processes. We first corroborate previous per-event total particle yields in Υ(1S)→ggg compared with nearby continuum (e+e-→qq¯) indicating greater (˜×2) per-event yields of baryons in 3-gluon fragmentation. We find similar results when we extend that comparison to include the Υ(2S) and Υ(3S) resonances. With higher statistics, we now also probe the momentum dependence of these per-event particle yields. Next, we compare particle production in the photon-tagged process Υ(1S)→ggγ with that in e+e-→qq¯γ events, to allow comparison of two-parton with three-parton particle-specific fragmentation. For each particle, we determine the “enhancement” ratio, defined as the ratio of particle yields per gluon-fragmentation event compared to quark-fragmentation event. Thus defined, an enhancement of 1.0 implies equal per-event production in gluon and quark fragmentation. In the photon-tagged analysis (Υ(1S)→ggγ compared to e+e-→qq¯γ), we find almost no enhancement for protons (˜1.2±0.1), but a significant enhancement (˜1.9±0.3) for Λ’s. This small measured proton enhancement rate is supported by a study of baryon production in χb2→gg→p+X relative to χb1→qq¯g→p+X. Overall, per-event baryon production in radiative two-gluon fragmentation is somewhat smaller than that observed in three-gluon decays of the Υ(1S). Our results for baryon production are inconsistent with the predictions of the JETSET (7.3) fragmentation model.

Systematics of quark/gluon tagging

DOE PAGES

Gras, Philippe; Höche, Stefan; Kar, Deepak; ...

2017-07-18

By measuring the substructure of a jet, one can assign it a “quark” or “gluon” tag. In the eikonal (double-logarithmic) limit, quark/gluon discrimination is determined solely by the color factor of the initiating parton (C F versus C A). In this paper, we confront the challenges faced when going beyond this leading-order understanding, using both parton-shower generators and first-principles calculations to assess the impact of higher-order perturbative and nonperturbative physics. Working in the idealized context of electron-positron collisions, where one can define a proxy for quark and gluon jets based on the Lorentz structure of the production vertex, we findmore » a fascinating interplay between perturbative shower effects and nonperturbative hadronization effects. Turning to proton-proton collisions, we highlight a core set of measurements that would constrain current uncertainties in quark/gluon tagging and improve the overall modeling of jets at the Large Hadron Collider.« less

Medium-Induced QCD Cascade: Democratic Branching and Wave Turbulence

NASA Astrophysics Data System (ADS)

Blaizot, J.-P.; Iancu, E.; Mehtar-Tani, Y.

2013-08-01

We study the average properties of the gluon cascade generated by an energetic parton propagating through a quark-gluon plasma. We focus on the soft, medium-induced emissions which control the energy transport at large angles with respect to the leading parton. We show that the effect of multiple branchings is important. In contrast with what happens in a usual QCD cascade in vacuum, medium-induced branchings are quasidemocratic, with offspring gluons carrying sizable fractions of the energy of their parent gluon. This results in an efficient mechanism for the transport of energy toward the medium, which is akin to wave turbulence with a scaling spectrum ˜1/ω. We argue that the turbulent flow may be responsible for the excess energy carried by very soft quanta, as revealed by the analysis of the dijet asymmetry observed in Pb-Pb collisions at the LHC.

Systematics of quark/gluon tagging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gras, Philippe; Höche, Stefan; Kar, Deepak

By measuring the substructure of a jet, one can assign it a “quark” or “gluon” tag. In the eikonal (double-logarithmic) limit, quark/gluon discrimination is determined solely by the color factor of the initiating parton (C F versus C A). In this paper, we confront the challenges faced when going beyond this leading-order understanding, using both parton-shower generators and first-principles calculations to assess the impact of higher-order perturbative and nonperturbative physics. Working in the idealized context of electron-positron collisions, where one can define a proxy for quark and gluon jets based on the Lorentz structure of the production vertex, we findmore » a fascinating interplay between perturbative shower effects and nonperturbative hadronization effects. Turning to proton-proton collisions, we highlight a core set of measurements that would constrain current uncertainties in quark/gluon tagging and improve the overall modeling of jets at the Large Hadron Collider.« less

Precision Determination of the Small-x Gluon from Charm Production at LHCb.

PubMed

Gauld, Rhorry; Rojo, Juan

2017-02-17

The small-x gluon in global fits of parton distributions is affected by large uncertainties from the lack of direct experimental constraints. In this Letter, we provide a precision determination of the small-x gluon from the exploitation of forward charm production data provided by LHCb for three different center-of-mass (c.m.) energies: 5 TeV, 7 TeV, and 13 TeV. The LHCb measurements are included in the parton distribution function (PDF) fit by means of normalized distributions and cross-section ratios between data taken at different c.m. values, R_{13/7} and R_{13/5}. We demonstrate that forward charm production leads to a reduction of the PDF uncertainties of the gluon down to x≃10^{-6} by up to an order of magnitude, with implications for high-energy colliders, cosmic ray physics, and neutrino astronomy.

Low-momentum ghost dressing function and the gluon mass

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boucaud, Ph.; Leroy, J. P.; Le Yaouanc, A.

2010-09-01

We study the low-momentum ghost propagator Dyson-Schwinger equation in the Landau gauge, assuming for the truncation a constant ghost-gluon vertex, as it is extensively done, and a simple model for a massive gluon propagator. Then, regular Dyson-Schwinger equation solutions (the zero-momentum ghost dressing function not diverging) appear to emerge, and we show the ghost propagator to be described by an asymptotic expression reliable up to the order O(q{sup 2}). That expression, depending on the gluon mass and the zero-momentum Taylor-scheme effective charge, is proven to fit pretty well some low-momentum ghost propagator data [I. L. Bogolubsky, E. M. Ilgenfritz, M.more » Muller-Preussker, and A. Sternbeck, Phys. Lett. B 676, 69 (2009); Proc. Sci., LAT2007 (2007) 290] from big-volume lattice simulations where the so-called ''simulated annealing algorithm'' is applied to fix the Landau gauge.« less

Event-by-Event Simulations of Early Gluon Fields in High Energy Nuclear Collisions

NASA Astrophysics Data System (ADS)

Nickel, Matthew; Rose, Steven; Fries, Rainer

2017-09-01

Collisions of heavy ions are carried out at ultra relativistic speeds at the Relativistic Heavy Ion Collider and the Large Hadron Collider to create Quark Gluon Plasma. The earliest stages of such collisions are dominated by the dynamics of classical gluon fields. The McLerran-Venugopalan (MV) model of color glass condensate provides a model for this process. Previous research has provided an analytic solution for event averaged observables in the MV model. Using the High Performance Research Computing Center (HPRC) at Texas A&M, we have developed a C++ code to explicitly calculate the initial gluon fields and energy momentum tensor event by event using the analytic recursive solution. The code has been tested against previously known analytic results up to fourth order. We have also have been able to test the convergence of the recursive solution at high orders in time and studied the time evolution of color glass condensate.

Next-to-leading logarithmic QCD contribution of the electromagnetic dipole operator to B¯→Xsγγ with a massive strange quark

NASA Astrophysics Data System (ADS)

Asatrian, H. M.; Greub, C.

2014-05-01

We calculate the O(αs) corrections to the double differential decay width dΓ77/(ds1ds2) for the process B¯→Xsγγ, originating from diagrams involving the electromagnetic dipole operator O7. The kinematical variables s1 and s2 are defined as si=(pb-qi)2/mb2, where pb, q1, q2 are the momenta of the b quark and two photons. We introduce a nonzero mass ms for the strange quark to regulate configurations where the gluon or one of the photons become collinear with the strange quark and retain terms which are logarithmic in ms, while discarding terms which go to zero in the limit ms→0. When combining virtual and bremsstrahlung corrections, the infrared and collinear singularities induced by soft and/or collinear gluons drop out. By our cuts the photons do not become soft, but one of them can become collinear with the strange quark. This implies that in the final result a single logarithm of ms survives. In principle, the configurations with collinear photon emission could be treated using fragmentation functions. In a related work we find that similar results can be obtained when simply interpreting ms appearing in the final result as a constituent mass. We do so in the present paper and vary ms between 400 and 600 MeV in the numerics. This work extends a previous paper by us, where only the leading power terms with respect to the (normalized) hadronic mass s3=(pb-q1-q2)2/mb2 were taken into account in the underlying triple differential decay width dΓ77/(ds1ds2ds3).

77 FR 42305 - Agency Information Collection Activities; Proposed Collection; Comment Request; Regulations.gov...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-07-18

... rulemaking activities. The `feedback exchange' serves as a learning laboratory for open government, enabling... of persistent cookies. Comment Threads allow the public to enter into virtual conversations with one...

Virtual Exchange Services and Shared CROMERR Services

EPA Pesticide Factsheets

Define the objectives, leadership, and membership of an IPT that will guide the requirements definition for a cloud-based Node installation and describe the anticipated architecture and example scenario implementations available to the EN community

Rapidity evolution of gluon TMD from low to moderate x

DOE PAGES

Balitsky, Ian; Tarasov, A.

2015-10-05

In this article, we study how the rapidity evolution of gluon transverse momentum dependent distribution changes from nonlinear evolution at smallmore » $$x \\ll 1$$ to linear evolution at moderate $$x \\sim 1$$.« less

Design and application of BIM based digital sand table for construction management

NASA Astrophysics Data System (ADS)

Fuquan, JI; Jianqiang, LI; Weijia, LIU

2018-05-01

This paper explores the design and application of BIM based digital sand table for construction management. Aiming at the demands and features of construction management plan for bridge and tunnel engineering, the key functional features of digital sand table should include three-dimensional GIS, model navigation, virtual simulation, information layers, and data exchange, etc. That involving the technology of 3D visualization and 4D virtual simulation of BIM, breakdown structure of BIM model and project data, multi-dimensional information layers, and multi-source data acquisition and interaction. Totally, the digital sand table is a visual and virtual engineering information integrated terminal, under the unified data standard system. Also, the applications shall contain visual constructing scheme, virtual constructing schedule, and monitoring of construction, etc. Finally, the applicability of several basic software to the digital sand table is analyzed.

SmallTool - a toolkit for realizing shared virtual environments on the Internet

NASA Astrophysics Data System (ADS)

Broll, Wolfgang

1998-09-01

With increasing graphics capabilities of computers and higher network communication speed, networked virtual environments have become available to a large number of people. While the virtual reality modelling language (VRML) provides users with the ability to exchange 3D data, there is still a lack of appropriate support to realize large-scale multi-user applications on the Internet. In this paper we will present SmallTool, a toolkit to support shared virtual environments on the Internet. The toolkit consists of a VRML-based parsing and rendering library, a device library, and a network library. This paper will focus on the networking architecture, provided by the network library - the distributed worlds transfer and communication protocol (DWTP). DWTP provides an application-independent network architecture to support large-scale multi-user environments on the Internet.

Novel graphical environment for virtual and real-world operations of tracked mobile manipulators

NASA Astrophysics Data System (ADS)

Chen, ChuXin; Trivedi, Mohan M.; Azam, Mir; Lassiter, Nils T.

1993-08-01

A simulation, animation, visualization and interactive control (SAVIC) environment has been developed for the design and operation of an integrated mobile manipulator system. This unique system possesses the abilities for (1) multi-sensor simulation, (2) kinematics and locomotion animation, (3) dynamic motion and manipulation animation, (4) transformation between real and virtual modes within the same graphics system, (5) ease in exchanging software modules and hardware devices between real and virtual world operations, and (6) interfacing with a real robotic system. This paper describes a working system and illustrates the concepts by presenting the simulation, animation and control methodologies for a unique mobile robot with articulated tracks, a manipulator, and sensory modules.

403rd Brookhaven Lecture

ScienceCinema

Saskia Mioduszewski

2017-12-09

"Probing the Matter Created at RHIC." Mioduszewski discusses the results from RHIC's experimental collaborations and how researchers hope to create a form of matter in which the basic building blocks of matter -- quarks and gluons -- interact freely in what is called quark gluon plasma.

The subtle interplay of elastic and inelastic collisions in the thermalization of the quark–gluon plasma

DOE PAGES

Blaizot, Jean-Paul; Liao, Jinfeng; Mehtar-Tani, Yacine

2016-12-01

We analyze the interplay of elastic and inelastic collisions in the thermalization of the quark-gluon plasma, using kinetic theory. Our main focus is the dynamics and equilibration of long wavelength modes.

Sambamurti Memorial Lecture: Spotlight on the Gluon

ScienceCinema

Michael Begelas

2017-12-09

Begel uses results from the Fermilab D0 and E706 experiments to explain how the production rate and energy spectrum of photons produced during proton collisions helped to clarify how the energy inside the proton is shared between quarks and gluons.

Quark scalar, axial and tensor charges in the Schwinger-Dyson formalism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamanaka, Nodoka

2016-01-22

The quark scalar, axial and tensor charges of nucleon are calculated in the Schwinger-Dyson formalism. We first calculate these charges in the rainbow-ladder truncation using the IR cut quark-gluon vertex, and show that the result is in agreement with the known data. We then perform the same calculation with the phenomenological IR singular quark-gluon vertex. In this case, the Schwinger-Dyson equation does not converge. We show that this result suggests the requirement of additional corrections to the rainbow-ladder truncation, due to the interaction between quark and gluons in the deep IR region.

Stopping distance for high energy jets in weakly coupled quark-gluon plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arnold, Peter; Cantrell, Sean; Xiao Wei

2010-02-15

We derive a simple formula for the stopping distance for a high-energy quark traveling through a weakly coupled quark-gluon plasma. The result is given to next-to-leading order in an expansion in inverse logarithms ln(E/T), where T is the temperature of the plasma. We also define a stopping distance for gluons and give a leading-log result. Discussion of stopping distance has a theoretical advantage over discussion of energy loss rates in that stopping distances can be generalized to the case of strong coupling, where one may not speak of individual partons.

Gluon and ghost correlation functions of 2-color QCD at finite density

NASA Astrophysics Data System (ADS)

Hajizadeh, Ouraman; Boz, Tamer; Maas, Axel; Skullerud, Jon-Ivar

2018-03-01

2-color QCD, i. e. QCD with the gauge group SU(2), is the simplest non-Abelian gauge theory without sign problem at finite quark density. Therefore its study on the lattice is a benchmark for other non-perturbative approaches at finite density. To provide such benchmarks we determine the minimal-Landau-gauge 2-point and 3-gluon correlation functions of the gauge sector and the running gauge coupling at finite density. We observe no significant effects, except for some low-momentum screening of the gluons at and above the supposed high-density phase transition.

The Exploration of Hot Nuclear Matter

NASA Astrophysics Data System (ADS)

Jacak, Barbara V.; Müller, Berndt

2012-07-01

When nuclear matter is heated beyond 2 trillion degrees, it becomes a strongly coupled plasma of quarks and gluons. Experiments using highly energetic collisions between heavy nuclei have revealed that this new state of matter is a nearly ideal, highly opaque liquid. A description based on string theory and black holes in five dimensions has made the quark-gluon plasma an archetypical strongly coupled quantum system. Open questions about the structure and theory of the quark-gluon plasma are under active investigation. Many of the insights are also relevant to ultracold fermionic atoms and strongly correlated condensed matter.

The evolution of the small x gluon TMD

NASA Astrophysics Data System (ADS)

Zhou, Jian

2016-06-01

We study the evolution of the small x gluon transverse momentum dependent (TMD) distribution in the dilute limit. The calculation has been carried out in the Ji-Ma-Yuan scheme using a simple quark target model. As expected, we find that the resulting small x gluon TMD simultaneously satisfies both the Collins-Soper (CS) evolution equation and the Balitsky-Fadin-Kuraev-Lipatov (BFKL) evolution equation. We thus confirmed the earlier finding that the high energy factorization (HEF) and the TMD factorization should be jointly employed to resum the different type large logarithms in a process where three relevant scales are well separated.

Estimating nonlinear effects in forward dijet production in ultra-peripheral heavy ion collisions at the LHC

NASA Astrophysics Data System (ADS)

Kotko, P.; Kutak, K.; Sapeta, S.; Stasto, A. M.; Strikman, M.

2017-05-01

Using the framework that interpolates between the leading power limit of the color glass condensate and the high energy (or kT) factorization we calculate the direct component of the forward dijet production in ultra-peripheral Pb-Pb collisions at CM energy 5.1 TeV per nucleon pair. The formalism is applicable when the average transverse momentum of the dijet system PT is much bigger than the saturation scale Qs, PT≫ Qs, while the imbalance of the dijet system can be arbitrary. The cross section is uniquely sensitive to the Weizsäcker-Williams (WW) unintegrated gluon distribution, which is far less known from experimental data than the most common dipole gluon distribution appearing in inclusive small- x processes. We have calculated cross sections and nuclear modification ratios using WW gluon distribution obtained from the dipole gluon density through the Gaussian approximation. The dipole gluon distribution used to get WW was fitted to the inclusive HERA data with the nonlinear extension of unified BFKL + DGLAP evolution equation. The saturation effects are visible but rather weak for realistic pT cut on the dijet system, reaching about 20% with the cut as low as 6 GeV. We find that the LO collinear factorization with nuclear leading-twist shadowing predicts quite similar effects.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kotko, P.; Kutak, K.; Sapeta, S.

Using the framework that interpolates between the leading power limit of the color glass condensate and the high energy (or k T ) factorization we calculate the direct component of the forward dijet production in ultra-peripheral Pb–Pb collisions atCMenergy 5.1 TeV per nucleon pair. The formalism is applicablewhen the average transversemomentum of the dijet system P T is much bigger than the saturation scale Q s , P T >> Qs , while the imbalance of the dijet system can be arbitrary. The cross section is uniquely sensitive to theWeizsäcker–Williams (WW) unintegrated gluon distribution, which is far less known frommore » experimental data than the most common dipole gluon distribution appearing in inclusive small-x processes. We also calculated cross sections and nuclear modification ratios using WW gluon distribution obtained from the dipole gluon density through the Gaussian approximation. The dipole gluon distribution used to get WW was fitted to the inclusive HERA data with the nonlinear extension of unified BFKL+DGLAP evolution equation. The saturation effects are visible but rather weak for realistic p T cut on the dijet system, reaching about 20% with the cut as low as 6 GeV. Finally, we find that the LO collinear factorization with nuclear leading-twist shadowing predicts quite similar effects.« less

Penguin-like diagrams from the standard model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ping, Chia Swee

2015-04-24

The Standard Model is highly successful in describing the interactions of leptons and quarks. There are, however, rare processes that involve higher order effects in electroweak interactions. One specific class of processes is the penguin-like diagram. Such class of diagrams involves the neutral change of quark flavours accompanied by the emission of a gluon (gluon penguin), a photon (photon penguin), a gluon and a photon (gluon-photon penguin), a Z-boson (Z penguin), or a Higgs-boson (Higgs penguin). Such diagrams do not arise at the tree level in the Standard Model. They are, however, induced by one-loop effects. In this paper, wemore » present an exact calculation of the penguin diagram vertices in the ‘tHooft-Feynman gauge. Renormalization of the vertex is effected by a prescription by Chia and Chong which gives an expression for the counter term identical to that obtained by employing Ward-Takahashi identity. The on-shell vertex functions for the penguin diagram vertices are obtained. The various penguin diagram vertex functions are related to one another via Ward-Takahashi identity. From these, a set of relations is obtained connecting the vertex form factors of various penguin diagrams. Explicit expressions for the gluon-photon penguin vertex form factors are obtained, and their contributions to the flavor changing processes estimated.« less

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Two Impurities in a Bose-Einstein Condensate: From Yukawa to Efimov Attracted Polarons

NASA Astrophysics Data System (ADS)

Naidon, Pascal

2018-04-01

The well-known Yukawa and Efimov potentials are two different mediated interaction potentials. The first one arises in quantum field theory from the exchange of virtual particles. The second one is mediated by a real particle resonantly interacting with two other particles. This Letter shows how two impurities immersed in a Bose-Einstein condensate can exhibit both phenomena. For a weak attraction with the condensate, the two impurities form two polarons that interact through a weak Yukawa attraction mediated by virtual excitations. For a resonant attraction with the condensate, the exchanged excitation becomes a real boson and the mediated interaction changes to a strong Efimov attraction that can bind the two polarons. The resulting bipolarons turn into in-medium Efimov trimers made of the two impurities and one boson. Evidence of this physics could be seen in ultracold mixtures of atoms.

Virtualization of open-source secure web services to support data exchange in a pediatric critical care research network.

PubMed

Frey, Lewis J; Sward, Katherine A; Newth, Christopher J L; Khemani, Robinder G; Cryer, Martin E; Thelen, Julie L; Enriquez, Rene; Shaoyu, Su; Pollack, Murray M; Harrison, Rick E; Meert, Kathleen L; Berg, Robert A; Wessel, David L; Shanley, Thomas P; Dalton, Heidi; Carcillo, Joseph; Jenkins, Tammara L; Dean, J Michael

2015-11-01

To examine the feasibility of deploying a virtual web service for sharing data within a research network, and to evaluate the impact on data consistency and quality. Virtual machines (VMs) encapsulated an open-source, semantically and syntactically interoperable secure web service infrastructure along with a shadow database. The VMs were deployed to 8 Collaborative Pediatric Critical Care Research Network Clinical Centers. Virtual web services could be deployed in hours. The interoperability of the web services reduced format misalignment from 56% to 1% and demonstrated that 99% of the data consistently transferred using the data dictionary and 1% needed human curation. Use of virtualized open-source secure web service technology could enable direct electronic abstraction of data from hospital databases for research purposes. © The Author 2015. Published by Oxford University Press on behalf of the American Medical Informatics Association. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Trust-based Access Control in Virtual Learning Community

NASA Astrophysics Data System (ADS)

Wang, Shujuan; Liu, Qingtang

The virtual learning community is an important application pattern of E-Learning. It emphasizes the cooperation of the members in the community, the members would like to share their learning resources, to exchange their experience and complete the study task together. This instructional mode has already been proved as an effective way to improve the quality and efficiency of instruction. At the present time, the virtual learning communities are mostly designed using static access control policy by which the access permission rights are authorized by the super administrator, the super administrator assigns different rights to different roles, but the virtual and social characteristics of virtual learning community make information sharing and collaboration a complex problem, the community realizes its instructional goal only if the members in it believe that others will offer the knowledge they owned and believe the knowledge others offered is well-meaning and worthy. This paper tries to constitute an effective trust mechanism, which could promise favorable interaction and lasting knowledge sharing.

To trade or not to trade: Link prediction in the virtual water network

NASA Astrophysics Data System (ADS)

Tuninetti, Marta; Tamea, Stefania; Laio, Francesco; Ridolfi, Luca

2017-12-01

In the international trade network, links express the (temporary) presence of a commercial exchange of goods between any two countries. Given the dynamical behaviour of the trade network, where links are created and dismissed every year, predicting the link activation/deactivation is an open research question. Through the international trade network of agricultural goods, water resources are 'virtually' transferred from the country of production to the country of consumption. We propose a novel methodology for link prediction applied to the network of virtual water trade. Starting from the assumption of having links between any two countries, we estimate the associated virtual water flows by means of a gravity-law model using country and link characteristics as drivers. We consider the links with estimated flows higher than 1000 m3/year as active links, while the others as non-active links. Flows traded along estimated active links are then re-estimated using a similar but differently-calibrated gravity-law model. We were able to correctly model 84% of the existing links and 93% of the non-existing links in year 2011. It is worth to note that the predicted active links carry 99% of the global virtual water flow; hence, missed links are mainly those where a minimum volume of virtual water is exchanged. Results indicate that, over the period from 1986 to 2011, population, geographical distances between countries, and agricultural efficiency (through fertilizers use) are the major factors driving the link activation and deactivation. As opposed to other (network-based) models for link prediction, the proposed method is able to reconstruct the network architecture without any prior knowledge of the network topology, using only the nodes and links attributes; it thus represents a general method that can be applied to other networks such as food or value trade networks.

All orders results for self-crossing Wilson loops mimicking double parton scattering

DOE PAGES

Dixon, Lance J.; Esterlis, Ilya

2016-07-21

Loop-level scattering amplitudes for massless particles have singularities in regions where tree amplitudes are perfectly smooth. For example, a 2 → 4 gluon scattering process has a singularity in which each incoming gluon splits into a pair of gluons, followed by a pair of 2 → 2 collisions between the gluon pairs. This singularity mimics double parton scattering because it occurs when the transverse momentum of a pair of outgoing gluons vanishes. The singularity is logarithmic at fixed order in perturbation theory. We exploit the duality between scattering amplitudes and polygonal Wilson loops to study six-point amplitudes in this limitmore » to high loop order in planar N = 4 super-Yang-Mills theory. The singular configuration corresponds to the limit in which a hexagonal Wilson loop develops a self-crossing. The singular terms are governed by an evolution equation, in which the hexagon mixes into a pair of boxes; the mixing back is suppressed in the planar (large N c) limit. Because the kinematic dependence of the box Wilson loops is dictated by (dual) conformal invariance, the complete kinematic dependence of the singular terms for the self-crossing hexagon on the one nonsingular variable is determined to all loop orders. The complete logarithmic dependence on the singular variable can be obtained through nine loops, up to a couple of constants, using a correspondence with the multi-Regge limit. As a byproduct, we obtain a simple formula for the leading logs to all loop orders. Furthermore, we also show that, although the MHV six-gluon amplitude is singular, remarkably, the transcendental functions entering the non-MHV amplitude are finite in the same limit, at least through four loops.« less

All orders results for self-crossing Wilson loops mimicking double parton scattering

NASA Astrophysics Data System (ADS)

Dixon, Lance J.; Esterlis, Ilya

2016-07-01

Loop-level scattering amplitudes for massless particles have singularities in regions where tree amplitudes are perfectly smooth. For example, a 2 → 4 gluon scattering process has a singularity in which each incoming gluon splits into a pair of gluons, followed by a pair of 2 → 2 collisions between the gluon pairs. This singularity mimics double parton scattering because it occurs when the transverse momentum of a pair of outgoing gluons vanishes. The singularity is logarithmic at fixed order in perturbation theory. We exploit the duality between scattering amplitudes and polygonal Wilson loops to study six-point amplitudes in this limit to high loop order in planar {N} = 4 super-Yang-Mills theory. The singular configuration corresponds to the limit in which a hexagonal Wilson loop develops a self-crossing. The singular terms are governed by an evolution equation, in which the hexagon mixes into a pair of boxes; the mixing back is suppressed in the planar (large N c) limit. Because the kinematic dependence of the box Wilson loops is dictated by (dual) conformal invariance, the complete kinematic dependence of the singular terms for the self-crossing hexagon on the one nonsingular variable is determined to all loop orders. The complete logarithmic dependence on the singular variable can be obtained through nine loops, up to a couple of constants, using a correspondence with the multi-Regge limit. As a byproduct, we obtain a simple formula for the leading logs to all loop orders. We also show that, although the MHV six-gluon amplitude is singular, remarkably, the transcendental functions entering the non-MHV amplitude are finite in the same limit, at least through four loops.

The analytic structure of non-global logarithms: Convergence of the dressed gluon expansion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Larkoski, Andrew J.; Moult, Ian; Neill, Duff Austin

Non-global logarithms (NGLs) are the leading manifestation of correlations between distinct phase space regions in QCD and gauge theories and have proven a challenge to understand using traditional resummation techniques. Recently, the dressed gluon ex-pansion was introduced that enables an expansion of the NGL series in terms of a “dressed gluon” building block, defined by an all-orders factorization theorem. Here, we clarify the nature of the dressed gluon expansion, and prove that it has an infinite radius of convergence as a solution to the leading logarithmic and large-N c master equation for NGLs, the Banfi-Marchesini-Smye (BMS) equation. The dressed gluonmore » expansion therefore provides an expansion of the NGL series that can be truncated at any order, with reliable uncertainty estimates. In contrast, manifest in the results of the fixed-order expansion of the BMS equation up to 12-loops is a breakdown of convergence at a finite value of α slog. We explain this finite radius of convergence using the dressed gluon expansion, showing how the dynamics of the buffer region, a region of phase space near the boundary of the jet that was identified in early studies of NGLs, leads to large contributions to the fixed order expansion. We also use the dressed gluon expansion to discuss the convergence of the next-to-leading NGL series, and the role of collinear logarithms that appear at this order. Finally, we show how an understanding of the analytic behavior obtained from the dressed gluon expansion allows us to improve the fixed order NGL series using conformal transformations to extend the domain of analyticity. Furthermore, this allows us to calculate the NGL distribution for all values of α slog from the coefficients of the fixed order expansion.« less

QCD evolution of (un)polarized gluon TMDPDFs and the Higgs q T -distribution

NASA Astrophysics Data System (ADS)

Echevarria, Miguel G.; Kasemets, Tomas; Mulders, Piet J.; Pisano, Cristian

2015-07-01

We provide the proper definition of all the leading-twist (un)polarized gluon transverse momentum dependent parton distribution functions (TMDPDFs), by considering the Higgs boson transverse momentum distribution in hadron-hadron collisions and deriving the factorization theorem in terms of them. We show that the evolution of all the (un)polarized gluon TMDPDFs is driven by a universal evolution kernel, which can be resummed up to next-to-next-to-leading-logarithmic accuracy. Considering the proper definition of gluon TMDPDFs, we perform an explicit next-to-leading-order calculation of the unpolarized ( f {1/ g }), linearly polarized ( h {1/⊥ g }) and helicity ( g {1/L g }) gluon TMDPDFs, and show that, as expected, they are free from rapidity divergences. As a byproduct, we obtain the Wilson coefficients of the refactorization of these TMDPDFs at large transverse momentum. In particular, the coefficient of g {1/L g }, which has never been calculated before, constitutes a new and necessary ingredient for a reliable phenomenological extraction of this quantity, for instance at RHIC or the future AFTER@LHC or Electron-Ion Collider. The coefficients of f {1/ g } and h {1/⊥ g } have never been calculated in the present formalism, although they could be obtained by carefully collecting and recasting previous results in the new TMD formalism. We apply these results to analyze the contribution of linearly polarized gluons at different scales, relevant, for instance, for the inclusive production of the Higgs boson and the C-even pseudoscalar bottomonium state η b . Applying our resummation scheme we finally provide predictions for the Higgs boson q T -distribution at the LHC.

The analytic structure of non-global logarithms: Convergence of the dressed gluon expansion

DOE PAGES

Larkoski, Andrew J.; Moult, Ian; Neill, Duff Austin

2016-11-15

Non-global logarithms (NGLs) are the leading manifestation of correlations between distinct phase space regions in QCD and gauge theories and have proven a challenge to understand using traditional resummation techniques. Recently, the dressed gluon ex-pansion was introduced that enables an expansion of the NGL series in terms of a “dressed gluon” building block, defined by an all-orders factorization theorem. Here, we clarify the nature of the dressed gluon expansion, and prove that it has an infinite radius of convergence as a solution to the leading logarithmic and large-N c master equation for NGLs, the Banfi-Marchesini-Smye (BMS) equation. The dressed gluonmore » expansion therefore provides an expansion of the NGL series that can be truncated at any order, with reliable uncertainty estimates. In contrast, manifest in the results of the fixed-order expansion of the BMS equation up to 12-loops is a breakdown of convergence at a finite value of α slog. We explain this finite radius of convergence using the dressed gluon expansion, showing how the dynamics of the buffer region, a region of phase space near the boundary of the jet that was identified in early studies of NGLs, leads to large contributions to the fixed order expansion. We also use the dressed gluon expansion to discuss the convergence of the next-to-leading NGL series, and the role of collinear logarithms that appear at this order. Finally, we show how an understanding of the analytic behavior obtained from the dressed gluon expansion allows us to improve the fixed order NGL series using conformal transformations to extend the domain of analyticity. Furthermore, this allows us to calculate the NGL distribution for all values of α slog from the coefficients of the fixed order expansion.« less

Sivers asymmetries for inclusive pion and kaon production in deep-inelastic scattering

NASA Astrophysics Data System (ADS)

Ellis, John; Hwang, Dae Sung; Kotzinian, Aram

2009-10-01

We calculate the Sivers distribution functions induced by the final-state interaction due to one-gluon exchange in diquark models of a nucleon structure, treating the cases of scalar and axial-vector diquarks with both dipole and Gaussian form factors. We use these distribution functions to calculate the Sivers single-spin asymmetries for inclusive pion and kaon production in deep-inelastic scattering. We compare our calculations with the results of HERMES and COMPASS, finding good agreement for π+ production at HERMES, and qualitative agreement for π0 and K+ production. Our predictions for pion and kaon production at COMPASS could be probed with increased statistics. The successful comparison of our calculations with the HERMES data constitutes prima facie evidence that the quarks in the nucleon have some orbital angular momentum in the infinite-momentum frame.

A phenomenological model of the glasma and photon production

DOE PAGES

McLerran, Larry

2014-12-01

There have been many talks at this meeting concerning the Color Glass Condensate[1]-[5] and the Glasma[6]-[13], so I will not present an extended review the subject in this talk. I will concentrate here on providing a simplified description of the evolution of the Glasma. The Glasma is a strongly interacting Quark Gluon Plasma. It is not thermalized. It is produced very shortly after the collision of two nuclei, thought of as sheets of Color Glass Condensate, and evolves into the Thermalized Quark Gluon Plasma. The Glasma is strongly interacting because the gluon distributions are over occupied, and this overoccupation enhancesmore » the interaction strength due to Bose coherence. There may or may not be a Bose condensate of gluons in the Glasma, but this interesting feature will not be the subject of this talk[14]-[22]. In fact, I will ignore the possibility of such condensation when I analyze the Glasma, although the result I present may be generalized to the case where condensation is present.« less

Measurement of D ∗ meson cross sections at HERA and determination of the gluon density in the proton using NLO QCD

NASA Astrophysics Data System (ADS)

Adloff, C.; Anderson, M.; Andreev, V.; Andrieu, B.; Arkadov, V.; Arndt, C.; Ayyaz, I.; Babaev, A.; Bähr, J.; Baranov, P.; Barrelet, E.; Bartel, W.; Bassler, U.; Bate, P.; Beck, M.; Beglarian, A.; Behnke, O.; Behrend, H.-J.; Beier, C.; Belousov, A.; Berger, Ch.; Bernardi, G.; Bertrand-Coremans, G.; Biddulph, P.; Bizot, J. C.; Boudry, V.; Braunschweig, W.; Brisson, V.; Brown, D. P.; Brückner, W.; Bruel, P.; Bruncko, D.; Bürger, J.; Büsser, F. W.; Buniatian, A.; Burke, S.; Burrage, A.; Buschhorn, G.; Calvet, D.; Campbell, A. J.; Carli, T.; Chabert, E.; Charlet, M.; Clarke, D.; Clerbaux, B.; Contreras, J. G.; Cormack, C.; Coughlan, J. A.; Cousinou, M.-C.; Cox, B. E.; Cozzika, G.; Cvach, J.; Dainton, J. B.; Dau, W. D.; Daum, K.; David, M.; Davidsson, M.; De Roeck, A.; De Wolf, E. A.; Delcourt, B.; Demirchyan, R.; Diaconu, C.; Dirkmann, M.; Dixon, P.; Dlugosz, W.; Donovan, K. T.; Dowell, J. D.; Droutskoi, A.; Ebert, J.; Eckerlin, G.; Eckstein, D.; Efremenko, V.; Egli, S.; Eichler, R.; Eisele, F.; Eisenhandler, E.; Elsen, E.; Enzenberger, M.; Erdmann, M.; Fahr, A. B.; Favart, L.; Fedotov, A.; Felst, R.; Feltesse, J.; Ferencei, J.; Ferrarotto, F.; Fleischer, M.; Flügge, G.; Fomenko, A.; Formánek, J.; Foster, J. M.; Franke, G.; Gabathuler, E.; Gabathuler, K.; Gaede, F.; Garvey, J.; Gassner, J.; Gayler, J.; Gerhards, R.; Ghazaryan, S.; Glazov, A.; Goerlich, L.; Gogitidze, N.; Goldberg, M.; Gorelov, I.; Grab, C.; Grässler, H.; Greenshaw, T.; Griffiths, R. K.; Grindhammer, G.; Hadig, T.; Haidt, D.; Hajduk, L.; Haller, T.; Hampel, M.; Haustein, V.; Haynes, W. J.; Heinemann, B.; Heinzelmann, G.; Henderson, R. C. W.; Hengstmann, S.; Henschel, H.; Heremans, R.; Herynek, I.; Hewitt, K.; Hiller, K. H.; Hilton, C. D.; Hladký, J.; Hoffmann, D.; Horisberger, R.; Hurling, S.; Ibbotson, M.; İşsever, Ç.; Jacquet, M.; Jaffre, M.; Jansen, D. M.; Jönsson, L.; Johnson, D. P.; Jones, M.; Jung, H.; Kästli, H. K.; Kander, M.; Kant, D.; Kapichine, M.; Karlsson, M.; Karschnik, O.; Katzy, J.; Kaufmann, O.; Kausch, M.; Kenyon, I. R.; Kermiche, S.; Keuker, C.; Kiesling, C.; Klein, M.; Kleinwort, C.; Knies, G.; Köhne, J. H.; Kolanoski, H.; Kolya, S. D.; Korbel, V.; Kostka, P.; Kotelnikov, S. K.; Krämerkämper, T.; Krasny, M. W.; Krehbiel, H.; Krücker, D.; Krüger, K.; Küpper, A.; Küster, H.; Kuhlen, M.; Kurča, T.; Lahmann, R.; Landon, M. P. J.; Lange, W.; Langenegger, U.; Lebedev, A.; Lehner, F.; Lemaitre, V.; Lendermann, V.; Levonian, S.; Lindstroem, M.; List, B.; Lobo, G.; Lobodzinska, E.; Lubimov, V.; Lüders, S.; Lüke, D.; Lytkin, L.; Magnussen, N.; Mahlke-Krüger, H.; Malinovski, E.; Maraček, R.; Marage, P.; Marks, J.; Marshall, R.; Martin, G.; Martyn, H.-U.; Martyniak, J.; Maxfield, S. J.; McMahon, T. R.; Mehta, A.; Meier, K.; Merkel, P.; Metlica, F.; Meyer, A.; Meyer, A.; Meyer, H.; Meyer, J.; Meyer, P.-O.; Mikocki, S.; Milstead, D.; Moeck, J.; Mohr, R.; Mohrdieck, S.; Moreau, F.; Morris, J. V.; Müller, D.; Müller, K.; Murin, P.; Nagovizin, V.; Naroska, B.; Naumann, Th.; Négri, I.; Newman, P. R.; Nguyen, H. K.; Nicholls, T. C.; Niebergall, F.; Niebuhr, C.; Niedzballa, Ch.; Niggli, H.; Nikitin, D.; Nix, O.; Nowak, G.; Nunnemann, T.; Oberlack, H.; Olsson, J. E.; Ozerov, D.; Palmen, P.; Panassik, V.; Pascaud, C.; Passaggio, S.; Patel, G. D.; Pawletta, H.; Perez, E.; Phillips, J. P.; Pieuchot, A.; Pitzl, D.; Pöschl, R.; Pope, G.; Povh, B.; Rabbertz, K.; Rauschenberger, J.; Reimer, P.; Reisert, B.; Reyna, D.; Rick, H.; Riess, S.; Rizvi, E.; Robmann, P.; Roosen, R.; Rosenbauer, K.; Rostovtsev, A.; Rouse, F.; Royon, C.; Rusakov, S.; Rybicki, K.; Sankey, D. P. C.; Schacht, P.; Scheins, J.; Schilling, F.-P.; Schleif, S.; Schleper, P.; Schmidt, D.; Schmidt, D.; Schoeffel, L.; Schröder, V.; Schultz-Coulon, H.-C.; Schwab, B.; Sefkow, F.; Semenov, A.; Shekelyan, V.; Sheviakov, I.; Shtarkov, L. N.; Siegmon, G.; Sirois, Y.; Sloan, T.; Smirnov, P.; Smith, M.; Solochenko, V.; Soloviev, Y.; Spaskov, V.; Specka, A.; Spiekermann, J.; Spitzer, H.; Squinabol, F.; Steffen, P.; Steinberg, R.; Steinhart, J.; Stella, B.; Stellberger, A.; Stiewe, J.; Straumann, U.; Struczinski, W.; Sutton, J. P.; Swart, M.; Tapprogge, S.; Taševský, M.; Tchernshov, V.; Tchetchelnitski, S.; Theissen, J.; Thompson, G.; Thompson, P. D.; Tobien, N.; Todenhagen, R.; Truöl, P.; Tsipolitis, G.; Turnau, J.; Tzamariudaki, E.; Udluft, S.; Usik, A.; Valkár, S.; Valkárová, A.; Vallée, C.; Van Esch, P.; Van Haecke, A.; Van Mechelen, P.; Vazdik, Y.; Villet, G.; Wacker, K.; Wallny, R.; Walter, T.; Waugh, B.; Weber, G.; Weber, M.; Wegener, D.; Wegner, A.; Wengler, T.; Werner, M.; West, L. R.; Wiesand, S.; Wilksen, T.; Willard, S.; Winde, M.; Winter, G.-G.; Wittek, C.; Wittmann, E.; Wobisch, M.; Wollatz, H.; Wünsch, E.; Žaček, J.; Zálešak, J.; Zhang, Z.; Zhokin, A.; Zini, P.; Zomer, F.; Zsembery, J.; zurNedden, M.; H1 Collaboration

1999-04-01

With the H1 detector at the ep collider HERA, D ∗ meson production cross sections have been measured in deep inelastic scattering with four-momentum transfers Q2 > 3 GeV 2 and in photoproduction at energies around Wγp ≈ 88 GeV and 194 GeV. Next-to-Leading Order QCD calculations are found to describe the differential cross sections within theoretical and experimental uncertainties. Using these calculations, the NLO gluon momentum distribution in the proton, xgg( xg), has been extracted in the momentum fraction range 7.5 × 10 -4 < xg < 4 × 10 -2 at average scales μ2 = 25 to 50 GeV 2. The gluon momentum fraction xg has been obtained from the measured kinematics of the scattered electron and the D ∗ meson in the final state. The results compare well with the gluon distribution obtained from the analysis of scaling violations of the proton structure function F2.

Electromagnetic Probes: A Chronometer of Heavy Ion Collision

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sinha, Bikash

I have known Predhiman for quite some time and I consider his friendship a great privilege. He along with some of his colleagues made the almost unique transition time to time from Quantum Electrodynamics of his (almost classical) electromagnetic plasma to Quantum Chromodynamics of quarks and gluons. Some of the papers are unique in the sense they surface up to the centre stage of the field of quarks and gluons giving us a new insight; the particular paper of Bannur and Kaw discussing the stability of quark gluon plasma is a particularly interesting one.I wish Predhiman the very best onmore » this occasion and sincerely hope for a long vital and fruitful life that lies ahead.Interestingly enough this transition from QED (electromagnetic plasma) to QCD plasma (Quark Gluon Plasma) was motivated by consuming a very special kind of Indian soft nuts on Sunday afternoons, the consumers consisted of two persons, P. K. Kaw and Jitendra Parikh - some nuts!« less

Open charm production and low x gluons

NASA Astrophysics Data System (ADS)

de Oliveira, E. G.; Martin, A. D.; Ryskin, M. G.

2018-04-01

We compare the rapidity, y , and the beam energy, √{s } , behaviors of the cross section of the data for D meson production in the forward direction that were measured by the LHCb Collaboration. We describe the observed cross sections using NLO perturbative QCD, and choose the optimal factorization scale for the LO contribution which provides the resummation of the large double logarithms. We emphasize the inconsistency observed in the y and √{s } behaviors of the D meson cross sections. The y behavior indicates a very flat x dependence of the gluon PDF in the unexplored low x region around x ˜1 0-5 . However, to describe the √{s } dependence of the data we need a steeper gluon PDF with decreasing x . Moreover, an even steeper behavior is needed to provide an extrapolation which matches on to the well known gluons found in the global PDF analyses for x ˜1 0-3 . The possible role of nonperturbative effects is briefly discussed.

Comprehensive Parameterization of the p-Meson Spectral Function in Hot and Dense Matter

NASA Astrophysics Data System (ADS)

Onyango, Thomas; Rapp, Ralf

2017-09-01

The goal of this research is to study how hadronic matter transitions into quark-gluon plasma. This transition is believed to have occurred in the early universe about 10 microseconds after the big bang. In particular, this transition created more than 95% of the visible mass in the universe, and confined quarks and gluons into hadrons. Hot nuclear matter can be recreated in the laboratory by colliding heavy atomic nuclei at very high energies. This transition into the quark-gluon plasma can be probed by analyzing the invariant mass distributions of ρ-mesons. The ρ-meson was chosen because it decays into dilepton pairs, e.g. or . Dilepton pairs are a preferred observable because they do not interact through the strong nuclear force inside the strongly interacting fireball, therefore ρ-mesons decay into dileptons in the medium and can be measured during heavy ion collisions. In this project, we developed a parameterization of this process which will help to describe quark-gluon plasma which filled the early universe.

Search for a heavy vector boson decaying to two gluons in pp̄ collisions at √s=1.96 TeV

DOE PAGES

Aaltonen, T.; Adelman, J.; Álvarez González, B.; ...

2012-12-05

We present a search for a new heavy vector boson Z' that decays to gluons. Decays to on-shell gluons are suppressed, leading to a dominant decay mode of Z'→g*g. We study the case where the off-shell gluon g* converts to a pair of top quarks, leading to a final state of tt¯g. In a sample of events with exactly one charged lepton, large missing transverse momentum and at least five jets, corresponding to an integrated luminosity of 8.7 fb⁻¹ collected by the CDF II detector, we find the data to be consistent with the standard model. We set upper limitsmore » on the production cross section times branching ratio of this chromophilic Z' at 95% confidence level from 300 to 40 fb for Z' masses ranging from 400 to 1000 GeV/c², respectively.« less

On non-primitively divergent vertices of Yang-Mills theory

NASA Astrophysics Data System (ADS)

Huber, Markus Q.

2017-11-01

Two correlation functions of Yang-Mills beyond the primitively divergent ones, the two-ghost-two-gluon and the four-ghost vertices, are calculated and their influence on lower vertices is examined. Their full (transverse) tensor structure is taken into account. As input, a solution of the full two-point equations - including two-loop terms - is used that respects the resummed perturbative ultraviolet behavior. A clear hierarchy is found with regard to the color structure that reduces the number of relevant dressing functions. The impact of the two-ghost-two-gluon vertex on the three-gluon vertex is negligible, which is explained by the fact that all non-small dressing functions drop out due to their color factors. Only in the ghost-gluon vertex a small net effect below 2% is seen. The four-ghost vertex is found to be extremely small in general. Since these two four-point functions do not enter into the propagator equations, these findings establish their small overall effect on lower correlation functions.

Jet Topics: Disentangling Quarks and Gluons at Colliders

NASA Astrophysics Data System (ADS)

Metodiev, Eric M.; Thaler, Jesse

2018-06-01

We introduce jet topics: a framework to identify underlying classes of jets from collider data. Because of a close mathematical relationship between distributions of observables in jets and emergent themes in sets of documents, we can apply recent techniques in "topic modeling" to extract jet topics from the data with minimal or no input from simulation or theory. As a proof of concept with parton shower samples, we apply jet topics to determine separate quark and gluon jet distributions for constituent multiplicity. We also determine separate quark and gluon rapidity spectra from a mixed Z -plus-jet sample. While jet topics are defined directly from hadron-level multidifferential cross sections, one can also predict jet topics from first-principles theoretical calculations, with potential implications for how to define quark and gluon jets beyond leading-logarithmic accuracy. These investigations suggest that jet topics will be useful for extracting underlying jet distributions and fractions in a wide range of contexts at the Large Hadron Collider.

sPHENIX: The next generation heavy ion detector at RHIC

NASA Astrophysics Data System (ADS)

Campbell, Sarah; sPHENIX Collaboration

2017-04-01

sPHENIX is a new collaboration and future detector project at Brookhaven National Laboratory’s Relativistic Heavy Ion Collider (RHIC). It seeks to answer fundamental questions on the nature of the quark gluon plasma (QGP), including its coupling strength and temperature dependence, by using a suite of precision jet and upsilon measurements that probe different length scales of the QGP. This is possible with a full acceptance, |η| < 1 and 0-2π in φ, electromagentic and hadronic calorimeters and precision tracking enabled by a 1.5 T superconducting magnet. With the increased luminosity afforded by accelerator upgrades, sPHENIX is going to perform high statistics measurements extending the kinematic reach at RHIC to overlap the LHC’s. This overlap is going to facilitate a better understanding of the role of temperature, density and parton virtuality in QGP dynamics and, specifically, jet quenching. This paper focuses on key future measurements and the current state of the sPHENIX project.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fischer, Nadine; Prestel, S.; Ritzmann, M.

We present the first public implementation of antenna-based QCD initial- and final-state showers. The shower kernels are 2→3 antenna functions, which capture not only the collinear dynamics but also the leading soft (coherent) singularities of QCD matrix elements. We define the evolution measure to be inversely proportional to the leading poles, hence gluon emissions are evolved in a p ⊥ measure inversely proportional to the eikonal, while processes that only contain a single pole (e.g., g → qq¯) are evolved in virtuality. Non-ordered emissions are allowed, suppressed by an additional power of 1/Q 2. Recoils and kinematics are governed bymore » exact on-shell 2 → 3 phase-space factorisations. This first implementation is limited to massless QCD partons and colourless resonances. Tree-level matrix-element corrections are included for QCD up to O(α 4 s) (4 jets), and for Drell–Yan and Higgs production up to O(α 3 s) (V / H + 3 jets). Finally, the resulting algorithm has been made publicly available in Vincia 2.0.« less

Color-octet scalars of N = 2 supersymmetry at the LHC

NASA Astrophysics Data System (ADS)

Choi, S. Y.; Drees, M.; Kalinowski, J.; Kim, J. M.; Popenda, E.; Zerwas, P. M.

2009-02-01

The color gauge hyper-multiplet in N = 2 supersymmetry consists of the usual N = 1 gauge vector/gaugino super-multiplet, joined with a novel gaugino/scalar super-multiplet. Large cross sections are predicted for the production of pairs of the color-octet scalars σ [sgluons] at the LHC: gg, qqbar → σσ*. Single σ production is possible at one-loop level, but the gg → σ amplitude vanishes in the limit of degenerate L and R squarks. When kinematically allowed, σ decays predominantly into two gluinos, whose cascade decays give rise to a burst of eight or more jets together with four LSP's as signature for σ pair events at the LHC. σ can also decay into a squark-antisquark pair at tree level. At one-loop level σ decays into gluons or a ttbar pair are predicted, generating exciting resonance signatures in the final states. The corresponding partial widths are very roughly comparable to that for three body final states mediated by one virtual squark at tree level.

Modern Elementary Particle Physics

NASA Astrophysics Data System (ADS)

Kane, Gordon

2017-02-01

1. Introduction; 2. Relativistic notation, Lagrangians, and interactions; 3. Gauge invariance; 4. Non-abelian gauge theories; 5. Dirac notation for spin; 6. The Standard Model Lagrangian; 7. The electroweak theory and quantum chromodynamics; 8. Masses and the Higgs mechanism; 9. Cross sections, decay widths, and lifetimes: W and Z decays; 10. Production and properties of W± and Zᴼ; 11. Measurement of electroweak and QCD parameters: the muon lifetime; 12. Accelerators - present and future; 13. Experiments and detectors; 14. Low energy and non-accelerator experiments; 15. Observation of the Higgs boson at the CERN LHC: is it the Higgs boson?; 16. Colliders and tests of the Standard Model: particles are pointlike; 17. Quarks and gluons, confinement and jets; 18. Hadrons, heavy quarks, and strong isospin invariance; 19. Coupling strengths depend on momentum transfer and on virtual particles; 20. Quark (and lepton) mixing angles; 21. CP violation; 22. Overview of physics beyond the Standard Model; 23. Grand unification; 24. Neutrino masses; 25. Dark matter; 26. Supersymmetry.

Two-loop hard-thermal-loop thermodynamics with quarks

NASA Astrophysics Data System (ADS)

Andersen, Jens O.; Petitgirard, Emmanuel; Strickland, Michael

2004-08-01

We calculate the quark contribution to the free energy of a hot quark-gluon plasma to two-loop order using hard-thermal-loop (HTL) perturbation theory. All ultraviolet divergences can be absorbed into renormalizations of the vacuum energy and the HTL quark and gluon mass parameters. The quark and gluon HTL mass parameters are determined self-consistently by a variational prescription. Combining the quark contribution with the two-loop HTL perturbation theory free energy for pure glue we obtain the total two-loop QCD free energy. Comparisons are made with lattice estimates of the free energy for Nf=2 and with exact numerical results obtained in the large-Nf limit.

Next-to-leading order weighted Sivers asymmetry in semi-inclusive deep inelastic scattering: three-gluon correlator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dai, Lingyun; Prokudin, Alexei; Kang, Zhong-Bo

2015-09-01

We study the three-gluon correlation function contribution to the Sivers asymmetry in semi-inclusive deep inelastic scattering. We first establish the matching between the usual twist-3 collinear factorization approach and transverse momentum dependent factorization formalism for the moderate transverse momentum region. We then derive the so-called coefficient functions used in the usual TMD evolution formalism. Finally, we perform the next-to-leading order calculation for the transverse-momentum-weighted spin-dependent differential cross section, from which we identify the QCD collinear evolution of the twist-3 Qiu-Sterman function: the off-diagonal contribution from the three-gluon correlation functions.

Reformulations of Yang–Mills theories with space–time tensor fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, Zhi-Qiang, E-mail: gzhqedu@gmail.com

2016-01-15

We provide the reformulations of Yang–Mills theories in terms of gauge invariant metric-like variables in three and four dimensions. The reformulations are used to analyze the dimension two gluon condensate and give gauge invariant descriptions of gluon polarization. In three dimensions, we obtain a non-zero dimension two gluon condensate by one loop computation, whose value is similar to the square of photon mass in the Schwinger model. In four dimensions, we obtain a Lagrangian with the dual property, which shares the similar but different property with the dual superconductor scenario. We also make discussions on the effectiveness of one loopmore » approximation.« less

Production of a pseudoscalar Higgs boson with a Z boson from gluon fusion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kao, C.

1992-12-01

The minimal supersymmetric model is adopted to study the production of a pseudoscalar Higgs boson ({ital A}) in association with a {ital Z} gauge boson from gluon fusion ({ital gg}{r arrow}{ital ZA}) at future hadron supercolliders. Its production rate is determined and compared to that of the associated production of the standard model Higgs boson ({ital H}{sub SM}) with a {ital Z} boson from quark-antiquark annihilation ({ital q{bar q}}{r arrow}{ital ZH}{sub SM}) and gluon fusion ({ital gg}{r arrow}{ital ZH}{sub SM}). Some promising decay modes are suggested for detection.

Dynamical chiral symmetry breaking and confinement with an infrared-vanishing gluon propagator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hawes, F.T.; Roberts, C.D.; Williams, A.G.

1994-05-01

We study a model Dyson-Schwinger equation for the quark propagator closed using an [ital Ansatz] for the gluon propagator of the form [ital D]([ital q])[similar to][ital q][sup 2]/[([ital q][sup 2])[sup 2]+[ital b][sup 4

Hadronic and nuclear interactions in QCD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

Despite the evidence that QCD - or something close to it - gives a correct description of the structure of hadrons and their interactions, it seems paradoxical that the theory has thus far had very little impact in nuclear physics. One reason for this is that the application of QCD to distances larger than 1 fm involves coherent, non-perturbative dynamics which is beyond present calculational techniques. For example, in QCD the nuclear force can evidently be ascribed to quark interchange and gluon exchange processes. These, however, are as complicated to analyze from a fundamental point of view as is themore » analogous covalent bond in molecular physics. Since a detailed description of quark-quark interactions and the structure of hadronic wavefunctions is not yet well-understood in QCD, it is evident that a quantitative first-principle description of the nuclear force will require a great deal of theoretical effort. Another reason for the limited impact of QCD in nuclear physics has been the conventional assumption that nuclear interactions can for the most part be analyzed in terms of an effective meson-nucleon field theory or potential model in isolation from the details of short distance quark and gluon structure of hadrons. These lectures, argue that this view is untenable: in fact, there is no correspondence principle which yields traditional nuclear physics as a rigorous large-distance or non-relativistic limit of QCD dynamics. On the other hand, the distinctions between standard nuclear physics dynamics and QCD at nuclear dimensions are extremely interesting and illuminating for both particle and nuclear physics.« less

Distribution Locational Real-Time Pricing Based Smart Building Control and Management

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hao, Jun; Dai, Xiaoxiao; Zhang, Yingchen

This paper proposes an real-virtual parallel computing scheme for smart building operations aiming at augmenting overall social welfare. The University of Denver's campus power grid and Ritchie fitness center is used for demonstrating the proposed approach. An artificial virtual system is built in parallel to the real physical system to evaluate the overall social cost of the building operation based on the social science based working productivity model, numerical experiment based building energy consumption model and the power system based real-time pricing mechanism. Through interactive feedback exchanged between the real and virtual system, enlarged social welfare, including monetary cost reductionmore » and energy saving, as well as working productivity improvements, can be achieved.« less

Virtual- and real-world operation of mobile robotic manipulators: integrated simulation, visualization, and control environment

NASA Astrophysics Data System (ADS)

Chen, ChuXin; Trivedi, Mohan M.

1992-03-01

This research is focused on enhancing the overall productivity of an integrated human-robot system. A simulation, animation, visualization, and interactive control (SAVIC) environment has been developed for the design and operation of an integrated robotic manipulator system. This unique system possesses the abilities for multisensor simulation, kinematics and locomotion animation, dynamic motion and manipulation animation, transformation between real and virtual modes within the same graphics system, ease in exchanging software modules and hardware devices between real and virtual world operations, and interfacing with a real robotic system. This paper describes a working system and illustrates the concepts by presenting the simulation, animation, and control methodologies for a unique mobile robot with articulated tracks, a manipulator, and sensory modules.

Estimating nonlinear effects in forward dijet production in ultra-peripheral heavy ion collisions at the LHC

DOE PAGES

Kotko, P.; Kutak, K.; Sapeta, S.; ...

2017-05-27

Using the framework that interpolates between the leading power limit of the color glass condensate and the high energy (or k T ) factorization we calculate the direct component of the forward dijet production in ultra-peripheral Pb–Pb collisions atCMenergy 5.1 TeV per nucleon pair. The formalism is applicablewhen the average transversemomentum of the dijet system P T is much bigger than the saturation scale Q s , P T >> Qs , while the imbalance of the dijet system can be arbitrary. The cross section is uniquely sensitive to theWeizsäcker–Williams (WW) unintegrated gluon distribution, which is far less known frommore » experimental data than the most common dipole gluon distribution appearing in inclusive small-x processes. We also calculated cross sections and nuclear modification ratios using WW gluon distribution obtained from the dipole gluon density through the Gaussian approximation. The dipole gluon distribution used to get WW was fitted to the inclusive HERA data with the nonlinear extension of unified BFKL+DGLAP evolution equation. The saturation effects are visible but rather weak for realistic p T cut on the dijet system, reaching about 20% with the cut as low as 6 GeV. Finally, we find that the LO collinear factorization with nuclear leading-twist shadowing predicts quite similar effects.« less

Color Confinement and Screening in the θ Vacuum of QCD.

PubMed

Kharzeev, Dmitri E; Levin, Eugene M

2015-06-19

QCD perturbation theory ignores the compact nature of the SU(3) gauge group that gives rise to the periodic θ vacuum of the theory. We propose to modify the gluon propagator to reconcile perturbation theory with the anomalous Ward identities for the topological current in the θ vacuum. As a result, the gluon couples to the Veneziano ghost describing the tunneling transitions between different Chern-Simons sectors of the vacuum; we call the emerging gluon dressed by ghost loops a "glost." We evaluate the glost propagator and find that it has the form G(p)=(p(2)+χ(top)/p(2))(-1) where χ(top) is the Yang-Mills topological susceptibility related to the η' mass by the Witten-Veneziano relation; this propagator describes the confinement of gluons at distances ∼χ(top)(-1/4)≃1  fm. The same functional form of the propagator was originally proposed by Gribov as a solution to the gauge copies problem that plagues perturbation theory. The resulting running coupling coincides with the perturbative one at p(2)≫√[χ(top)], but in the infrared region either freezes (in pure Yang-Mills theory) or vanishes (in full QCD with light quarks), in accord with experimental evidence. Our scenario makes explicit the connection between confinement and topology of the QCD vacuum; we discuss the implications for spin physics, high energy scattering, and the physics of quark-gluon plasma.

Propagation of crises in the virtual water trade network

NASA Astrophysics Data System (ADS)

Tamea, Stefania; Laio, Francesco; Ridolfi, Luca

2015-04-01

The international trade of agricultural goods is associated to the displacement of the water used to produce such goods and embedded in trade as a factor of production. Water virtually exchanged from producing to consuming countries, named virtual water, defines flows across an international network of 'virtual water trade' which enable the assessment of environmental forcings and implications of trade, such as global water savings or country dependencies on foreign water resources. Given the recent expansion of commodity (and virtual water) trade, in both displaced volumes and network structure, concerns have been raised about the exposure to crises of individuals and societies. In fact, if one country had to markedly decrease its export following a socio-economical or environmental crisis, such as a war or a drought, many -if not all- countries would be affected due to a cascade effect within the trade network. The present contribution proposes a mechanistic model describing the propagation of a local crisis into the virtual water trade network, accounting for the network structure and the virtual water balance of all countries. The model, built on data-based assumptions, is tested on the real case study of the Argentinean crisis in 2008-09, when the internal agricultural production (measured as virtual water volume) decreased by 26% and the virtual water export of Argentina dropped accordingly. Crisis propagation and effects on the virtual water trade are correctly captured, showing the way forward to investigations of crises impact and country vulnerability based on the results of the model proposed.

Follow Me, Like Me, Tweet Me! Implementing Social Media Into Occupational Health.

PubMed

Olszewski, Kimberly; Wolf, Debra M

2015-06-01

Occupational health nurses can advance their professional practices through virtual platforms (e.g., social media and mobile applications). Virtual platforms allow occupational health nurses to disseminate occupational safety and health information efficiently to employees, families, and other stakeholders. Occupational health nurses exchange information with employees, enhancing communication and disseminating appropriate and accurate safety and health information to workers and their families. This article assists occupational health nurses in understanding how to use social media and other mobile applications to enhance their practices. © 2015 The Author(s).

Virtual file system on NoSQL for processing high volumes of HL7 messages.

PubMed

Kimura, Eizen; Ishihara, Ken

2015-01-01

The Standardized Structured Medical Information Exchange (SS-MIX) is intended to be the standard repository for HL7 messages that depend on a local file system. However, its scalability is limited. We implemented a virtual file system using NoSQL to incorporate modern computing technology into SS-MIX and allow the system to integrate local patient IDs from different healthcare systems into a universal system. We discuss its implementation using the database MongoDB and describe its performance in a case study.

Squeezed colour states in gluon jet

NASA Technical Reports Server (NTRS)

Kilin, S. YA.; Kuvshinov, V. I.; Firago, S. A.

1993-01-01

The possibility of the formation of squeezed states of gluon fields in quantum chromodynamics due to nonlinear nonperturbative self interaction during jet evolution in the process of e(+)e(-) annihilation into hadrons, which are analogous to the quantum photon squeezed states in quantum electrodynamics, is demonstrated. Additionally, the squeezing parameters are calculated.

Designing of a technological line in the context of controlling with the use of integration of the virtual controller with the mechatronics concept designer module of the PLM Siemens NX software

NASA Astrophysics Data System (ADS)

Herbuś, K.; Ociepka, P.

2017-08-01

In the work is examined the sequential control system of a technological line in the form of the final part of a system of an internal transport. The process of designing this technological line using the computer-aided approach ran concurrently in two different program environments. In the Mechatronics Concept Designer module of the PLM Siemens NX software was developed the 3D model of the technological line prepared for verification the logic interrelations implemented in the control system. For this purpose, from the whole system of the technological line, it was distinguished the sub-system of actuators and sensors, because their correct operation determines the correct operation of the whole system. Whereas in the application of the virtual controller have been implemented the algorithms of work of the planned line. Then both program environments have been integrated using the OPC server, which enables the exchange of data between the considered systems. The data on the state of the object and the data defining the way and sequence of operation of the technological line are exchanged between the virtual controller and the 3D model of the technological line in real time.

A Proof of Factorization Theorem of Drell-Yan Process at Operator Level

NASA Astrophysics Data System (ADS)

Zhou, Gao-Liang

2016-02-01

An alternative proof of factorization theorem for Drell-Yan process that works at operator level is presented in this paper. Contributions of interactions after the hard collision for such inclusive processes are proved to be canceled at operator level according to the unitarity of time evolution operator. After this cancellation, there are no longer leading pinch singular surface in Glauber region in the time evolution of electromagnetic currents. Effects of soft gluons are absorbed into Wilson lines of scalar-polarized gluons. Cancelation of soft gluons is attribute to unitarity of time evolution operator and such Wilson lines. Supported by the National Natural Science Foundation of China under Grant No. 11275242

Waves in magnetized quark matter

NASA Astrophysics Data System (ADS)

Fogaça, D. A.; Sanches, S. M.; Navarra, F. S.

2018-05-01

We study wave propagation in a non-relativistic cold quark-gluon plasma immersed in a constant magnetic field. Starting from the Euler equation we derive linear wave equations and investigate their stability and causality. We use a generic form for the equation of state, the EOS derived from the MIT bag model and also a variant of the this model which includes gluon degrees of freedom. The results of this analysis may be relevant for perturbations propagating through the quark matter phase in the core of compact stars and also for perturbations propagating in the low temperature quark-gluon plasma formed in low energy heavy ion collisions, to be carried out at FAIR and NICA.

Helicity amplitudes for QCD with massive quarks

NASA Astrophysics Data System (ADS)

Ochirov, Alexander

2018-04-01

The novel massive spinor-helicity formalism of Arkani-Hamed, Huang and Huang provides an elegant way to calculate scattering amplitudes in quantum chromodynamics for arbitrary quark spin projections. In this note we compute two families of tree-level QCD amplitudes with one massive quark pair and n - 2 gluons. The two cases include all gluons with identical helicity and one opposite-helicity gluon being color-adjacent to one of the quarks. Our results naturally incorporate the previously known amplitudes for both quark spins quantized along one of the gluonic momenta. In the all-multiplicity formulae presented here the spin quantization axes can be tuned at will, which includes the case of the definite-helicity quark states.

Spatially modulated phase in the holographic description of quark-gluon plasma.

PubMed

Ooguri, Hirosi; Park, Chang-Soon

2011-02-11

We present a string theory construction of a gravity dual of a spatially modulated phase. Our earlier work shows that the Chern-Simons term in the five-dimensional Maxwell theory destabilizes the Reissner-Nordström black holes in anti-de Sitter space if the Chern-Simons coupling is sufficiently high. In this Letter, we show that a similar instability is realized on the world volume of 8-branes in the Sakai-Sugimoto model in the quark-gluon plasma phase. Our result suggests a new spatially modulated phase in quark-gluon plasma when the baryon density is above 0.8Nf  fm(-3) at temperature 150 MeV.

The two-loop symbol of all multi-Regge regions

DOE PAGES

Bargheer, Till; Papathanasiou, Georgios; Schomerus, Volker

2016-05-02

Here, we study the symbol of the two-loop n-gluon MHV amplitude for all Mandelstam regions in multi-Regge kinematics in N=4 super Yang-Mills theory. While the number of distinct Mandelstam regions grows exponentially with n, the increase of independent symbols turns out to be merely quadratic. We uncover how to construct the symbols for any number of external gluons from just two building blocks which are naturally associated with the six- and seven-gluon amplitude, respectively. The second building block is entirely new, and in addition to its symbol, we also construct a prototype function that correctly reproduces all terms of maximalmore » functional transcendentality.« less

Higgs Boson Production in Association with a Jet at Next-to-Next-to-Leading Order.

PubMed

Boughezal, Radja; Caola, Fabrizio; Melnikov, Kirill; Petriello, Frank; Schulze, Markus

2015-08-21

We present precise predictions for Higgs boson production in association with a jet. We work in the Higgs effective field theory framework and compute next-to-next-to-leading order QCD corrections to the gluon-gluon and quark-gluon channels, which is sufficient for reliable LHC phenomenology. We present fully differential results as well as total cross sections for the LHC. Our next-to-next-to-leading order predictions reduce the unphysical scale dependence by more than a factor of 2 and enhance the total rate by about twenty percent compared to next-to-leading order QCD predictions. Our results demonstrate for the first time satisfactory convergence of the perturbative series.

Microscopic theory of the Coulomb based exchange coupling in magnetic tunnel junctions.

PubMed

Udalov, O G; Beloborodov, I S

2017-05-04

We study interlayer exchange coupling based on the many-body Coulomb interaction between conduction electrons in magnetic tunnel junction. This mechanism complements the known interaction between magnetic layers based on virtual electron hopping (or spin currents). We find that these two mechanisms have different behavior on system parameters. The Coulomb based coupling may exceed the hopping based exchange. We show that the Coulomb based exchange interaction, in contrast to the hopping based coupling, depends strongly on the dielectric constant of the insulating layer. The dependence of the interlayer exchange interaction on the dielectric properties of the insulating layer in magnetic tunnel junction is similar to magneto-electric effect where electric and magnetic degrees of freedom are coupled. We calculate the interlayer coupling as a function of temperature and electric field for magnetic tunnel junction with ferroelectric layer and show that the exchange interaction between magnetic leads has a sharp decrease in the vicinity of the ferroelectric phase transition and varies strongly with external electric field.

Connecting QGP-Heavy Ion Physics to the Early Universe

NASA Astrophysics Data System (ADS)

Rafelski, Johann

2013-10-01

We discuss properties and evolution of quark-gluon plasma in the early Universe and compare to laboratory heavy ion experiments. We describe how matter and antimatter emerged from a primordial soup of quarks and gluons. We focus our discussion on similarities and differences between the early Universe and the laboratory experiments.

Exploring Quarks, Gluons and the Higgs Boson

ERIC Educational Resources Information Center

Johansson, K. Erik

2013-01-01

With real particle collision data available on the web, the amazing dynamics of the fundamental particles of the standard model can be explored in classrooms. Complementing the events from the ATLAS experiment with animations of the fundamental processes on the quark and gluon level makes it possible to better understand the invisible world of…

The static hard-loop gluon propagator to all orders in anisotropy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nopoush, Mohammad; Guo, Yun; Strickland, Michael

We calculate the (semi-)static hard-loop self-energy and propagator using the Keldysh formalism in a momentum-space anisotropic quark-gluon plasma. The static retarded, advanced, and Feynman (symmetric) self-energies and propagators are calculated to all orders in the momentum-space anisotropy parameter ξ. For the retarded and advanced self-energies/propagators, we present a concise derivation and comparison with previouslyobtained results and extend the calculation of the self-energies to next-to-leading order in the gluon energy, ω. For the Feynman self-energy/propagator, we present new results which are accurate to all orders in ξ. We compare our exact results with prior expressions for the Feynman self-energy/propagator which weremore » obtained using Taylor-expansions around an isotropic state. Here, we show that, unlike the Taylor-expanded results, the all-orders expression for the Feynman propagator is free from infrared singularities. Finally, we discuss the application of our results to the calculation of the imaginary-part of the heavy-quark potential in an anisotropic quark-gluon plasma.« less

The LPM effect in sequential bremsstrahlung 2: factorization

DOE PAGES

Arnold, Peter; Chang, Han-Chih; Iqbal, Shahin

2016-09-13

The splitting processes of bremsstrahlung and pair production in a medium are coherent over large distances in the very high energy limit, which leads to a suppression known as the Landau-Pomeranchuk-Migdal (LPM) effect. In this paper, we continue analysis of the case when the coherence lengths of two consecutive splitting processes overlap (which is important for understanding corrections to standard treatments of the LPM effect in QCD), avoiding soft-gluon approximations. In particular, this paper analyzes the subtle problem of how to precisely separate overlapping double splitting (e.g. overlapping double bremsstrahlung) from the case of consecutive, independent bremsstrahlung (which is themore » case that would be implemented in a Monte Carlo simulation based solely on single splitting rates). As an example of the method, we consider the rate of real double gluon bremsstrahlung from an initial gluon with various simplifying assumptions (thick media; q approximation; large N c; and neglect for the moment of processes involving 4-gluon ver-tices) and explicitly compute the correction Δ dΓ/dx dy due to overlapping formation times.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ent, Rolf

With two options studied at Brookhaven National Lab and Jefferson Laboratory the U.S., an Electron-Ion Collider (EIC) of energy √s=20-100 GeV was under design. Furthermore, the recent 2015 US Nuclear Science Long-Range Planning effort included a future EIC as a recommendation for future construction. The EIC will be unique in colliding polarised electrons off polarised protons and light nuclei, providing the spin degrees of freedom essential to pursue its physics program driven by spin structure, multi-dimensional tomographic images of protons and nuclei, and discovery of the role of collective effects of gluons in nuclei. The foreseen luminosity of the EIC,more » coupled with its energy variability and reach, will allow unprecedented three-dimensional imaging of the gluon and sea quark distributions, via both TMDs and GPDs, and to explore correlations amongst them. Its hermetic detection capability of correlated fragments promises to similar allow for precise tomographic images of the quark-gluon landscape in nuclei, transcending from light few-body nuclei to the heaviest nuclei, and could uncover how the TMD and GPD landscape changes when gluons display an anticipated collective behavior at the higher energies.« less

Promp photon yield and υ2 coefficent from gluon fusion induced by magnetic field in heavy-ion collisions

NASA Astrophysics Data System (ADS)

Castaño-Yepes, Jorge David; Ayala, Alejandro; Dominguez, C. A.; Hernández, L. A.; Hernández-Ortíz, Saúl; Tejeda-Yeomans, María Elena

2018-01-01

We compute the production of prompt photons and the υ2 harmonic coefficient in relativistic heavy-ion collisions induced by gluon fusion in the presence of an intense magnetic field, during the early stages of the reaction. The calculations take into account several parameters which are relevant to the description of the experimental transverse momentum distribution, and elliptic flow for RHIC and LHC energies. The main imput is the strenght of the magnetic field which varies in magnitude from 1 to 3 times the pion mass squared, and allows the gluon fusion that otherwise is forbidden in the absence of the field. The high gluon occupation number and the value of the saturation scale also play an important role in our calculation, as well as a flow velocity and geometrical factors. Our results support the idea that the origin of at least some of the photon excess observed in heavy-ion experiments may arise from magnetic field induced processes, and gives a good description of the experimental data.

HTL resummation in the light cone gauge

NASA Astrophysics Data System (ADS)

Chen, Qi; Hou, De-fu

2018-04-01

The light cone gauge with light cone variables is often used in pQCD calculations in relativistic heavy-ion collision physics. The Hard Thermal Loops (HTL) resummation is an indispensable technique for hot QCD calculation. It was developed in covariant gauges with conventional Minkowski varaiables; we shall extend this method to the light cone gauge. In the real time formalism, using the Mandelstam-Leibbrant prescription of (n·K)‑1, we calculate the transverse and longitudinal components of the gluon HTL self energy, and prove that there are no infrared divergences. With this HTL self energy, we derive the HTL resummed gluon propagator in the light cone gauge. We also calculate the quark HTL self energy and the resummed quark propagator in the light cone gauge and find it is gauge independent. As application examples, we analytically calculate the damping rates of hard quarks and gluons with the HTL resummed gluon propagator in the light cone gauge and showed that they are gauge independent. The final physical results are identical to those computed in covariant gauge, as they should be. Supported by National Natural Science Foundation of China (11375070, 11735007, 11521064)

Abelian non-global logarithms from soft gluon clustering

NASA Astrophysics Data System (ADS)

Kelley, Randall; Walsh, Jonathan R.; Zuberi, Saba

2012-09-01

Most recombination-style jet algorithms cluster soft gluons in a complex way. This leads to previously identified correlations in the soft gluon phase space and introduces logarithmic corrections to jet cross sections, which are known as clustering logarithms. The leading Abelian clustering logarithms occur at least at next-to leading logarithm (NLL) in the exponent of the distribution. Using the framework of Soft Collinear Effective Theory (SCET), we show that new clustering effects contributing at NLL arise at each order. While numerical resummation of clustering logs is possible, it is unlikely that they can be analytically resummed to NLL. Clustering logarithms make the anti-kT algorithm theoretically preferred, for which they are power suppressed. They can arise in Abelian and non-Abelian terms, and we calculate the Abelian clustering logarithms at O ( {α_s^2} ) for the jet mass distribution using the Cambridge/Aachen and kT algorithms, including jet radius dependence, which extends previous results. We find that clustering logarithms can be naturally thought of as a class of non-global logarithms, which have traditionally been tied to non-Abelian correlations in soft gluon emission.

Quark and gluon production from a boost-invariantly expanding color electric field

NASA Astrophysics Data System (ADS)

Taya, Hidetoshi

2017-07-01

Particle production from an expanding classical color electromagnetic field is extensively studied, motivated by the early stage dynamics of ultrarelativistic heavy ion collisions. We develop a formalism at one-loop order to compute the particle spectra by canonically quantizing quark, gluon, and ghost fluctuations under the presence of such an expanding classical color background field; the canonical quantization is done in the τ -η coordinates in order to take into account manifestly the expanding geometry. As a demonstration, we model the expanding classical color background field by a boost-invariantly expanding homogeneous color electric field with lifetime T , for which we obtain analytically the quark and gluon production spectra by solving the equations of motion of QCD nonperturbatively with respect to the color electric field. In this paper we study (i) the finite lifetime effect, which is found to modify significantly the particle spectra from those expected from the Schwinger formula; (ii) the difference between the quark and gluon production; and (iii) the quark mass dependence of the production spectra. Implications of these results to ultrarelativistic heavy ion collisions are also discussed.

The Shape and Flow of Heavy Ion Collisions (490th Brookhaven Lecture)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schenke, Bjoern

2014-12-18

The sun can’t do it, but colossal machines like the Relativistic Heavy Ion Collider (RHIC) at Brookhaven Lab and Large Hadron Collider (LHC) in Europe sure can. Quarks and gluons make up protons and neutrons found in the nucleus of every atom in the universe. At heavy ion colliders like RHIC and the LHC, scientists can create matter more than 100,000 times hotter than the center of the sun—so hot that protons and neutrons melt into a plasma of quarks and gluons. The particle collisions and emerging quark-gluon plasma hold keys to understanding how these fundamental particles interact with eachmore » other, which helps explain how everything is held together—from atomic nuclei to human beings to the biggest stars—how all matter has mass, and what the universe looked like microseconds after the Big Bang. Dr. Schenke discusses theory that details the shape and structure of heavy ion collisions. He will also explain how this theory and data from experiments at RHIC and the LHC are being used to determine properties of the quark-gluon plasma.« less

The static hard-loop gluon propagator to all orders in anisotropy

DOE PAGES

Nopoush, Mohammad; Guo, Yun; Strickland, Michael

2017-09-15

We calculate the (semi-)static hard-loop self-energy and propagator using the Keldysh formalism in a momentum-space anisotropic quark-gluon plasma. The static retarded, advanced, and Feynman (symmetric) self-energies and propagators are calculated to all orders in the momentum-space anisotropy parameter ξ. For the retarded and advanced self-energies/propagators, we present a concise derivation and comparison with previouslyobtained results and extend the calculation of the self-energies to next-to-leading order in the gluon energy, ω. For the Feynman self-energy/propagator, we present new results which are accurate to all orders in ξ. We compare our exact results with prior expressions for the Feynman self-energy/propagator which weremore » obtained using Taylor-expansions around an isotropic state. Here, we show that, unlike the Taylor-expanded results, the all-orders expression for the Feynman propagator is free from infrared singularities. Finally, we discuss the application of our results to the calculation of the imaginary-part of the heavy-quark potential in an anisotropic quark-gluon plasma.« less

Distributed collaborative environments for virtual capability-based planning

NASA Astrophysics Data System (ADS)

McQuay, William K.

2003-09-01

Distributed collaboration is an emerging technology that will significantly change how decisions are made in the 21st century. Collaboration involves two or more geographically dispersed individuals working together to share and exchange data, information, knowledge, and actions. The marriage of information, collaboration, and simulation technologies provides the decision maker with a collaborative virtual environment for planning and decision support. This paper reviews research that is focusing on the applying open standards agent-based framework with integrated modeling and simulation to a new Air Force initiative in capability-based planning and the ability to implement it in a distributed virtual environment. Virtual Capability Planning effort will provide decision-quality knowledge for Air Force resource allocation and investment planning including examining proposed capabilities and cost of alternative approaches, the impact of technologies, identification of primary risk drivers, and creation of executable acquisition strategies. The transformed Air Force business processes are enabled by iterative use of constructive and virtual modeling, simulation, and analysis together with information technology. These tools are applied collaboratively via a technical framework by all the affected stakeholders - warfighter, laboratory, product center, logistics center, test center, and primary contractor.

Color Confinement and Screening in the θ Vacuum of QCD

DOE PAGES

Kharzeev, Dmitri E.; Levin, Eugene M.

2015-06-16

QCD perturbation theory ignores the compact nature of the SU(3) gauge group that gives rise to the periodic θ vacuum of the theory. In this paper, we propose to modify the gluon propagator to reconcile perturbation theory with the anomalous Ward identities for the topological current in the θ vacuum. As a result, the gluon couples to the Veneziano ghost describing the tunneling transitions between different Chern-Simons sectors of the vacuum; we call the emerging gluon dressed by ghost loops a “glost.” We evaluate the glost propagator and find that it has the form G(p)=(p 2+χ top/p 2) -1 wheremore » χ top is the Yang-Mills topological susceptibility related to the η" mass by the Witten-Veneziano relation; this propagator describes the confinement of gluons at distances ~χ top -1/4≃1 fm. The same functional form of the propagator was originally proposed by Gribov as a solution to the gauge copies problem that plagues perturbation theory. The resulting running coupling coincides with the perturbative one at p 2>>√χtop, but in the infrared region either freezes (in pure Yang-Mills theory) or vanishes (in full QCD with light quarks), in accord with experimental evidence. In conclusion, our scenario makes explicit the connection between confinement and topology of the QCD vacuum; we discuss the implications for spin physics, high energy scattering, and the physics of quark-gluon plasma.« less

Influence of government controls over the currency exchange rate in the evolution of Hurst's exponent: An autonomous agent-based model

NASA Astrophysics Data System (ADS)

Chávez Muñoz, Pablo; Fernandes da Silva, Marcus; Vivas Miranda, José; Claro, Francisco; Gomez Diniz, Raimundo

2007-12-01

We have studied the performance of the Hurst's index associated with the currency exchange rate in Brazil and Chile. It is shown that this index maps the degree of government control in the exchange rate. A model of supply and demand based in an autonomous agent is proposed, that simulates a virtual market of sale and purchase, where buyer or seller are forced to negotiate through an intermediary. According to this model, the average of the price of daily transactions correspond to the theoretical balance proposed by the law of supply and demand. The influence of an added tendency factor is also analyzed.

Information Technology and Disabilities, 1997.

ERIC Educational Resources Information Center

McNulty, Tom, Ed.

1997-01-01

Articles published during 1997 include: "The Multi-Disability Workstation for Small Libraries" (Dick Banks and Steve Noble); "Talking Books: Toward a Digital Model" (John Cookson and others); "World Wide Access: Focus on Libraries" (Sheryl Burgstahler); "The Virtual Library: Collaborative Data Exchange and Electronic Text Delivery" (Steve Noble);…

Learning without Borders

ERIC Educational Resources Information Center

Anderson, Sue

2013-01-01

In 2010, State College Area School District (SCASD) in Pennsylvania, USA, agreed to help develop a virtual international classroom exchange called the Schoolwires Greenleaf program. The program's project-based curriculum paired U.S. students with Chinese learners to collaborate, foster global citizenship, and prepare students for the digital work…

Type 2 Diabetes Education and Support in a Virtual Environment: A Secondary Analysis of Synchronously Exchanged Social Interaction and Support

PubMed Central

2018-01-01

Background Virtual environments (VEs) facilitate interaction and support among individuals with chronic illness, yet the characteristics of these VE interactions remain unknown. Objective The objective of this study was to describe social interaction and support among individuals with type 2 diabetes (T2D) who interacted in a VE. Methods Data included VE-mediated synchronous conversations and text-chat and asynchronous emails and discussion board posts from a study that facilitated interaction among individuals with T2D and diabetes educators (N=24) in 2 types of sessions: education and support. Results VE interactions consisted of communication techniques (how individuals interact in the VE), expressions of self-management (T2D-related topics), depth (personalization of topics), and breadth (number of topics discussed). Individuals exchanged support more often in the education (723/1170, 61.79%) than in the support (406/1170, 34.70%) sessions or outside session time (41/1170, 3.50%). Of all support exchanges, 535/1170 (45.73%) were informational, 377/1170 (32.22%) were emotional, 217/1170 (18.55%) were appraisal, and 41/1170 (3.50%) were instrumental. When comparing session types, education sessions predominately provided informational support (357/723, 49.4%), and the support sessions predominately provided emotional (159/406, 39.2%) and informational (159/406, 39.2%) support. Conclusions VE-mediated interactions resemble those in face-to-face environments, as individuals in VEs engage in bidirectional exchanges with others to obtain self-management education and support. Similar to face-to-face environments, individuals in the VE revealed personal information, sought information, and exchanged support during the moderated education sessions and unstructured support sessions. With this versatility, VEs are able to contribute substantially to support for those with diabetes and, very likely, other chronic diseases. PMID:29467118

Structure of rapidity divergences in multi-parton scattering soft factors

NASA Astrophysics Data System (ADS)

Vladimirov, Alexey

2018-04-01

We discuss the structure of rapidity divergences that are presented in the soft factors of transverse momentum dependent (TMD) factorization theorems. To provide the discussion on the most general level we consider soft factors for multi-parton scattering. We show that the rapidity divergences are result of the gluon exchanges with the distant transverse plane, and are structurally equivalent to the ultraviolet divergences. It allows to formulate and to prove the renormalization theorem for rapidity divergences. The proof is made with the help the conformal transformation which maps rapidity divergences to ultraviolet divergences. The theorem is the systematic form of the factorization of rapidity divergences, which is required for the definition of TMD parton distributions. In particular, the definition of multi parton distributions is presented. The equivalence of ultraviolet and rapidity divergences leads to the exact relation between soft and rapidity anomalous dimensions. Using this relation we derive the rapidity anomalous dimension at the three-loop order.

Sivers asymmetries for inclusive pion and kaon production in deep-inelastic scattering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ellis, John; Hwang, Dae Sung; Kotzinian, Aram

2009-10-01

We calculate the Sivers distribution functions induced by the final-state interaction due to one-gluon exchange in diquark models of a nucleon structure, treating the cases of scalar and axial-vector diquarks with both dipole and Gaussian form factors. We use these distribution functions to calculate the Sivers single-spin asymmetries for inclusive pion and kaon production in deep-inelastic scattering. We compare our calculations with the results of HERMES and COMPASS, finding good agreement for {pi}{sup +} production at HERMES, and qualitative agreement for {pi}{sup 0} and K{sup +} production. Our predictions for pion and kaon production at COMPASS could be probed withmore » increased statistics. The successful comparison of our calculations with the HERMES data constitutes prima facie evidence that the quarks in the nucleon have some orbital angular momentum in the infinite-momentum frame.« less

Electroproduction of ϕ(1020) mesons at 1.4⩽Q2⩽3.8 GeV2 measured with the CLAS spectrometer

NASA Astrophysics Data System (ADS)

Santoro, J. P.; Smith, E. S.; Garçon, M.; Guidal, M.; Laget, J. M.; Weiss, C.; Adams, G.; Amaryan, M. J.; Anghinolfi, M.; Asryan, G.; Audit, G.; Avakian, H.; Bagdasaryan, H.; Baillie, N.; Ball, J.; Ball, J. P.; Baltzell, N. A.; Barrow, S.; Battaglieri, M.; Bedlinskiy, I.; Bektasoglu, M.; Bellis, M.; Benmouna, N.; Berman, B. L.; Biselli, A. S.; Blaszczyk, L.; Bonner, B. E.; Bookwalter, C.; Bouchigny, S.; Boiarinov, S.; Bradford, R.; Branford, D.; Briscoe, W. J.; Brooks, W. K.; Bültmann, S.; Burkert, V. D.; Butuceanu, C.; Calarco, J. R.; Careccia, S. L.; Carman, D. S.; Casey, L.; Cazes, A.; Chen, S.; Cheng, L.; Cole, P. L.; Collins, P.; Coltharp, P.; Cords, D.; Corvisiero, P.; Crabb, D.; Crannell, H.; Crede, V.; Cummings, J. P.; Dale, D.; Dashyan, N.; de Masi, R.; de Sanctis, E.; de Vita, R.; Degtyarenko, P. V.; Denizli, H.; Dennis, L.; Deur, A.; Dhamija, S.; Dharmawardane, K. V.; Dhuga, K. S.; Dickson, R.; Djalali, C.; Dodge, G. E.; Doughty, D.; Dugger, M.; Dytman, S.; Dzyubak, O. P.; Egiyan, H.; Egiyan, K. S.; El Fassi, L.; Elouadrhiri, L.; Eugenio, P.; Fatemi, R.; Fedotov, G.; Feuerbach, R. J.; Ficenec, J.; Forest, T. A.; Fradi, A.; Funsten, H.; Gavalian, G.; Gevorgyan, N.; Gilfoyle, G. P.; Giovanetti, K. L.; Girod, F. X.; Goetz, J. T.; Gohn, W.; Gordon, C. I. O.; Gothe, R. W.; Graham, L.; Griffioen, K. A.; Guillo, M.; Guler, N.; Guo, L.; Gyurjyan, V.; Hadjidakis, C.; Hafidi, K.; Hakobyan, H.; Hanretty, C.; Hardie, J.; Hassall, N.; Heddle, D.; Hersman, F. W.; Hicks, K.; Hleiqawi, I.; Holtrop, M.; Hyde-Wright, C. E.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Isupov, E. L.; Ito, M. M.; Jenkins, D.; Jo, H. S.; Johnstone, J. R.; Joo, K.; Juengst, H. G.; Kalantarians, N.; Keller, D.; Kellie, J. D.; Khandaker, M.; Kim, W.; Klein, A.; Klein, F. J.; Klimenko, A. V.; Kossov, M.; Krahn, Z.; Kramer, L. H.; Kubarovsky, V.; Kuhn, J.; Kuhn, S. E.; Kuleshov, S. V.; Kuznetsov, V.; Lachniet, J.; Langheinrich, J.; Lawrence, D.; Li, Ji; Livingston, K.; Lu, H. Y.; MacCormick, M.; Marchand, C.; Markov, N.; Mattione, P.; McAleer, S.; McKinnon, B.; McNabb, J. W. C.; Mecking, B. A.; Mehrabyan, S.; Melone, J. J.; Mestayer, M. D.; Meyer, C. A.; Mibe, T.; Mikhailov, K.; Minehart, R.; Mirazita, M.; Miskimen, R.; Mokeev, V.; Morand, L.; Moreno, B.; Moriya, K.; Morrow, S. A.; Moteabbed, M.; Mueller, J.; Munevar, E.; Mutchler, G. S.; Nadel-Turonski, P.; Nasseripour, R.; Niccolai, S.; Niculescu, G.; Niculescu, I.; Niczyporuk, B. B.; Niroula, M. R.; Niyazov, R. A.; Nozar, M.; O'Rielly, G. V.; Osipenko, M.; Ostrovidov, A. I.; Park, K.; Park, S.; Pasyuk, E.; Paterson, C.; Pereira, S. Anefalos; Philips, S. A.; Pierce, J.; Pivnyuk, N.; Pocanic, D.; Pogorelko, O.; Popa, I.; Pozdniakov, S.; Preedom, B. M.; Price, J. W.; Procureur, S.; Prok, Y.; Protopopescu, D.; Qin, L. M.; Raue, B. A.; Riccardi, G.; Ricco, G.; Ripani, M.; Ritchie, B. G.; Rosner, G.; Rossi, P.; Sabatié, F.; Saini, M. S.; Salamanca, J.; Salgado, C.; Sapunenko, V.; Schott, D.; Schumacher, R. A.; Serov, V. S.; Sharabian, Y. G.; Sharov, D.; Shvedunov, N. V.; Skabelin, A. V.; Smith, L. C.; Sober, D. I.; Sokhan, D.; Stavinsky, A.; Stepanyan, S. S.; Stepanyan, S.; Stokes, B. E.; Stoler, P.; Strakovsky, I. I.; Strauch, S.; Taiuti, M.; Tedeschi, D. J.; Tkabladze, A.; Tkachenko, S.; Todor, L.; Tur, C.; Ungaro, M.; Vineyard, M. F.; Vlassov, A. V.; Watts, D. P.; Weinstein, L. B.; Weygand, D. P.; Williams, M.; Wolin, E.; Wood, M. H.; Yegneswaran, A.; Yurov, M.; Zana, L.; Zhang, J.; Zhao, B.; Zhao, Z. W.

2008-08-01

Electroproduction of exclusive ϕ vector mesons has been studied with the CLAS detector in the kinematic range 1.4⩽Q2⩽3.8 GeV2,0.0⩽t'⩽3.6 GeV2, and 2.0⩽W⩽3.0 GeV. The scaling exponent for the total cross section as 1/(Q2+Mϕ2)n was determined to be n=2.49±0.33. The slope of the four-momentum transfer t' distribution is bϕ=0.98±0.17 GeV-2. Under the assumption of s-channel helicity conservation, we determine the ratio of longitudinal to transverse cross sections to be R=0.86±0.24. A two-gluon exchange model is able to reproduce the main features of the data.

Exclusive ϱ0 production in deep inelastic electron-proton scattering at HERA

NASA Astrophysics Data System (ADS)

Derrick, M.; Krakauer, D.; Magill, S.; Mikunas, D.; Musgrave, B.; Repond, J.; Stanek, R.; Talaga, R. L.; Zhang, H.; Ayad, R.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Bruni, P.; Cara Romeo, G.; Castellini, G.; Chiarini, M.; Cifarelli, L.; Cindolo, F.; Contin, A.; Corradi, M.; Gialas, I.; Giusti, P.; Iacobucci, G.; Laurenti, G.; Levi, G.; Margotti, A.; Massam, T.; Nania, R.; Nemoz, C.; Palmonari, F.; Polini, A.; Sartorelli, G.; Timellini, R.; Zamora Garcia, Y.; Zichichi, A.; Bargende, A.; Crittenden, J.; Desch, K.; Diekmann, B.; Doeker, T.; Eckert, M.; Feld, L.; Frey, A.; Geerts, M.; Grothe, M.; Hartmann, H.; Heinloth, K.; Hilger, E.; Jakob, H.-P.; Katz, U. F.; Mari, S. M.; Mengel, S.; Mollen, J.; Paul, E.; Pfeiffer, M.; Rembser, Ch.; Schramm, D.; Stamm, J.; Wedemeyer, R.; Campbell-Robson, S.; Cassidy, A.; Dyce, N.; Foster, B.; George, S.; Gilmore, R.; Heath, G. P.; Heath, H. F.; Llewellyn, T. J.; Morgado, C. J. S.; Norman, D. J. P.; O'Mara, J. A.; Tapper, R. J.; Wilson, S. S.; Yoshida, R.; Rau, R. R.; Arneodo, M.; Capua, M.; Garfagnini, A.; Iannotti, L.; Schioppa, M.; Susinno, G.; Bernstein, A.; Caldwell, A.; Cartiglia, N.; Parsons, J. A.; Ritz, S.; Sciulli, F.; Straub, P. B.; Wai, L.; Yang, S.; Zhu, Q.; Borzemski, P.; Chwastowski, J.; Eskreys, A.; Piotrzkowski, K.; Zachara, M.; Zawiejski, L.; Adamczyk, L.; Bednarek, B.; Jeleń, K.; Kisielewska, D.; Kowalski, T.; Rulikowska-Zarȩbska, E.; Suszycki, L.; Zajaç, J.; Kotański, A.; Przybycień, M.; Bauerdick, L. A. T.; Behrens, U.; Beier, H.; Bienlein, J. K.; Coldewey, C.; Deppe, O.; Desler, K.; Drews, G.; Flasiński, M.; Gilkinson, D. J.; Glasman, C.; Göttlicher, P.; Große-Knetter, J.; Gutjahr, B.; Haas, T.; Hain, W.; Hasell, D.; Heßling, H.; Iga, Y.; Johnson, K.; Joos, P.; Kasemann, M.; Klanner, R.; Koch, W.; Köpke, L.; Kötz, U.; Kowalski, H.; Labs, J.; Ladage, A.; Löhr, B.; Löwe, M.; Lüke, D.; Mainusch, J.; Mańczak, O.; Monteiro, T.; Ng, J. S. T.; Nickel, S.; Notz, D.; Ohrenberg, K.; Roco, M.; Rohde, M.; Roldán, J.; Schneekloth, U.; Schulz, W.; Selonke, F.; Stiliaris, E.; Surrow, B.; Voß, T.; Westphal, D.; Wolf, G.; Youngman, C.; Zeuner, W.; Zhou, J. F.; Grabosch, H. J.; Kharchilava, A.; Leich, A.; Mattingly, M. C. K.; Meyer, A.; Schlenstedt, S.; Wulff, N.; Barbagli, G.; Pelfer, P.; Anzivino, G.; Maccarrone, G.; De Pasquale, S.; Votano, L.; Bamberger, A.; Eisenhardt, S.; Freidhof, A.; Söldner-Rembold, S.; Schroeder, J.; Trefzger, T.; Brook, N. H.; Bussey, P. J.; Doyle, A. T.; Fleck, J. I.; Saxon, D. H.; Utley, M. L.; Wilson, A. S.; Dannemann, A.; Holm, U.; Horstmann, D.; Neumann, T.; Sinkus, R.; Wick, K.; Badura, E.; Burow, B. D.; Hagge, L.; Lohrmann, E.; Milewski, J.; Nakahata, M.; Pavel, N.; Poelz, G.; Schott, W.; Zetsche, F.; Bacon, T. C.; Bruemmer, N.; Butterworth, I.; Gallo, E.; Harris, V. L.; Hung, B. Y. H.; Long, K. R.; Miller, D. B.; Morawitz, P. P. O.; Prinias, A.; Sedgbeer, J. K.; Whitfield, A. F.; Mallik, U.; McCliment, E.; Wang, M. Z.; Wang, S. M.; Wu, J. T.; Cloth, P.; Filges, D.; An, S. H.; Hong, S. M.; Nam, S. W.; Park, S. K.; Suh, M. H.; Yon, S. H.; Imlay, R.; Kartik, S.; Kim, H.-J.; McNeil, R. R.; Metcalf, W.; Nadendla, V. K.; Barreiro, F.; Cases, G.; Fernandez, J. P.; Graciani, R.; Hernández, J. M.; Hervás, L.; Labarga, L.; Martinez, M.; del Peso, J.; Puga, J.; Terron, J.; de Trocóniz, J. F.; Smith, G. R.; Corriveau, F.; Hanna, D. S.; Hartmann, J.; Hung, L. W.; Lim, J. N.; Matthews, C. G.; Patel, P. M.; Sinclair, L. E.; Stairs, D. G.; St. Laurent, M.; Ullmann, R.; Zacek, G.; Bashkirov, V.; Dolgoshein, B. A.; Stifutkin, A.; Bashindzhagyan, G. L.; Ermolov, P. F.; Gladilin, L. K.; Golubkov, Yu. A.; Kobrin, V. D.; Korzhavina, I. A.; Kurzhavina, V. A.; Kuzmin, V. A.; Lukina, O. Yu.; Proskuryakov, A. S.; Savin, A. A.; Shcheglova, L. M.; Solomin, A. N.; Zotov, N. P.; Botje, M.; Chlebana, F.; Dake, A.; Engelen, J.; de Kamps, M.; Kooijman, P.; Kruse, A.; Tiecke, H.; Verkerke, W.; Veeswijk, M.; Wiggers, L.; de Wolf, E.; van Woudenberg, R.; Acosta, D.; Bylsma, B.; Durkin, L. S.; Honscheid, K.; Li, C.; Ling, T. Y.; McLean, K. W.; Murray, W. N.; Park, I. H.; Romanowski, T. A.; Seidlein, R.; Bailey, D. S.; Byrne, A.; Cashmore, R. J.; Cooper-Sarkar, A. M.; Devenish, R. C. E.; Harnew, N.; Lancaster, M.; Lindemann, L.; McFall, J. D.; Nath, C.; Noyes, V. A.; Quadt, A.; Tickner, J. R.; Uijterwaal, H.; Walczak, R.; Waters, D. S.; Wilson, F. F.; Yip, T.; Abbiendi, G.; Bertolin, A.; Brugnera, R.; Carlin, R.; Dal Corso, F.; De Giorgi, M.; Dosselli, U.; Limentani, S.; Morandin, M.; Posocco, M.; Stanco, L.; Stroili, R.; Voci, C.; Bulmahn, J.; Butterworth, J. M.; Feild, R. G.; Oh, B. Y.; Whitmore, J. J.; D'Agostini, G.; Marini, G.; Nigro, A.; Tassi, E.; Hart, J. C.; McCubbin, N. A.; Prytz, K.; Shah, T. P.; Short, T. L.; Barberis, E.; Dubbs, T.; Heusch, C.; Van Hook, M.; Lockman, W.; Rahn, J. T.; Sadrozinski, H. F.-W.; Seiden, A.; Williams, D. C.; Biltzinger, J.; Seifert, R. J.; Schwarzer, O.; Walenta, A. H.; Zech, G.; Abramowicz, H.; Briskin, G.; Dagan, S.; Levy, A.; Hasegawa, T.; Hazumi, M.; Ishii, T.; Kuze, M.; Mine, S.; Nagasawa, Y.; Nakao, M.; Suzuki, I.; Tokushuku, K.; Yamada, S.; Yamazaki, Y.; Chiba, M.; Hamatsu, R.; Hirose, T.; Homma, K.; Kitamura, S.; Nakamitsu, Y.; Yamauchi, K.; Cirio, R.; Costa, M.; Ferrero, M. I.; Lamberti, L.; Maselli, S.; Peroni, C.; Sacchi, R.; Solano, A.; Staiano, A.; Dardo, M.; Bailey, D. C.; Bandyopadhyay, D.; Benard, F.; Brkic, M.; Gingrich, D. M.; Hartner, G. F.; Joo, K. K.; Levman, G. M.; Martin, J. F.; Orr, R. S.; Polenz, S.; Sampson, C. R.; Teuscher, R. J.; Catterall, C. D.; Jones, T. W.; Kaziewicz, P. B.; Lane, J. B.; Saunders, R. L.; Shulman, J.; Blankenship, K.; Lu, B.; Mo, L. W.; Bogusz, W.; Charchuła, K.; Ciborowski, J.; Gajewski, J.; Grzelak, G.; Kasprzak, M.; Krzyżanowski, M.; Muchorowski, K.; Nowak, R. J.; Pawlak, J. M.; Tymieniecka, T.; Wróblewski, A. K.; Zakrzewski, J. A.; Żarnecki, A. F.; Adamus, M.; Eisenberg, Y.; Karshon, U.; Revel, D.; Zer-Zion, D.; Ali, I.; Badgett, W. F.; Behrens, B.; Dasu, S.; Fordham, C.; Foudas, C.; Goussiou, A.; Loveless, R. J.; Reeder, D. D.; Silverstein, S.; Smith, W. H.; Vaiciulis, A.; Wodarczyk, M.; Tsurugai, T.; Bhadra, S.; Cardy, M. L.; Fagerstroem, C.-P.; Frisken, W. R.; Furutani, K. M.; Khakzad, M.; Schmidke, W. B.; ZEUS Collaboration

1995-02-01

The exclusive production of ϱ0 mesons in deep inelastic electron-proton scattering has been studied using the ZEUS detector. Cross sections have been measured in the range 7 < Q2 < 25 GeV 2 for λ ∗p centre of mass (c.m.) energies 40 to 130 GeV. The λ ∗p → ϱ 0p cross section exhibits a Q-(4.2±0.8 -0.5+1.4) dependence and both longitudinally and transversely polarised ϱ0's are observed. The λ ∗p → ϱ 0p cross section rises strongly with increasing c.m. energy, when compared with NMC data at lower energy, which cannot be explained by production through soft pomeron exchange. The data are compared with perturbative QCD calculations where the rise in the cross section reflects the increase in the gluon density at low x.

L. V. Al'tshuler, and High Energy Density Research

NASA Astrophysics Data System (ADS)

Gibson, Carl H.; Krikorian, Nerses H.; Keeler, R. Norris

2012-03-01

Knowledge of high energy densities critical to cosmology and astrophysics was achieved and exchanged among a very few scientists at a time when science was even more constrained by political considerations that it is today. Resources for the early studies necessarily involved atomic weaponry. A history of L. V. Al'tshuler and some others in his science is given in cosmological context. In the beginning of cosmology and the Universe, negative Fortov-Planck1 pressures c7h-1G-2 of 4.6 10115 Pa are overcome by inertial-vortex anti-gravity (dark energy) pressures to achieve a turbulent big bang and the first turbulent combustion with power 1066 watts at the Kolmogorov-Planck scale 10-35 meters. The big bang event ceased when negative- pressure gluon-viscous-forces extracted 10100 kg of mass-energy from the vacuum to produce the observed fossil vorticity turbulence Universe and its inflation with power 10145 watts.

Diffractive charmonium spectrum in high energy collisions in the basis light-front quantization approach

DOE PAGES

Chen, Guangyao; Li, Yang; Maris, Pieter; ...

2017-04-14

Using the charmonium light-front wavefunctions obtained by diagonalizing an effective Hamiltonian with the one-gluon exchange interaction and a confining potential inspired by light-front holography in the basis light-front quantization formalism, we compute production of charmonium states in diffractive deep inelastic scattering and ultra-peripheral heavy ion collisions within the dipole picture. Our method allows us to predict yields of all vector charmonium states below the open flavor thresholds in high-energy deep inelastic scattering, proton-nucleus and ultra-peripheral heavy ion collisions, without introducing any new parameters in the light-front wavefunctions. The obtained charmonium cross section is in reasonable agreement with experimental data atmore » HERA, RHIC and LHC. We observe that the cross-section ratio σΨ(2s)/σJ/Ψ reveals significant independence of model parameters« less

Elastic collisions of low-energy electrons with SiY4 (Y = Cl, Br, I) molecules

NASA Astrophysics Data System (ADS)

Bettega, M. H. F.

2011-11-01

We employed the Schwinger multichannel method to compute elastic integral, differential, and momentum transfer cross sections for low-energy electron collisions with SiY4 (Y = Cl, Br, I) molecules. The calculations were carried out in the static-exchange and static-exchange plus polarization approximations for energies up to 10 eV. The elastic integral cross section for SiCl4 and SiBr4, computed in the static-exchange plus polarization approximation, shows two shape resonances belonging to the T2 and E symmetries of the Td group, and for SiI4 shows one shape resonance belonging to the E symmetry of the Td group. The present results agree well in shape with experimental total cross sections. The positions of the resonances observed in the calculated integral cross sections are also in agreement with the experimental positions. We have found the presence of a virtual state for SiCl4 and a Ramsauer-Townsend minimum for SiI4 at 0.5 eV. The present results show that the proper inclusion of polarization effects is crucial in order to correctly describe the resonance spectra of these molecules and also to identify a Ramsauer-Townsend minimum for SiI4 and a virtual state for SiCl4.

Assessment of the usability and impact of the Idaho Health Data Exchange (IHDE).

PubMed

Reis, Janet; MacKenzie, Lisa; Soelberg, Terri; Smith, Jennifer

2016-04-01

Eighty four health care professionals participated in an online survey assessing the usability, and clinical and administrative impact of the Idaho Health Data Exchange's (IHDE) Virtual Health Record (VHR). The IHDE VHR allows authorized users to use a secure web interface to view lab, radiology and transcribed reports from multiple facilities and view medical histories on patients in the data exchange. Results indicate the usability of the IHDE VHR was almost universally positively rated with the Software Usability Measurement Inventory (SUMI) utilized as the assessment method. Medical providers however had the lowest rating of the exchange, raising concerns about the need for additional training and support. The addition of other Idaho health care organizations to the health data exchange was most widely desired, with the most frequently cited benefit being more comprehensive access to patients' records. In contrast to other published evaluations of health data exchanges in the U.S., few of the concerns emerged about cost of implementation of the data exchange or trust in the quality of information contained therein.

Quark-gluon plasma (Selected Topics)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zakharov, V. I., E-mail: vzakharov@itep.ru

Introductory lectures to the theory of (strongly interacting) quark-gluon plasma given at the Winter School of Physics of ITEP (Moscow, February 2010). We emphasize theoretical issues highlighted by the discovery of the low viscosity of the plasma. The topics include relativistic hydrodynamics, manifestations of chiral anomaly in hydrodynamics, superfluidity, relativistic superfluid hydrodynamics, effective stringy scalars, holographic models of Yang-Mills theories.

From strangeness enhancement to quark-gluon plasma discovery

NASA Astrophysics Data System (ADS)

Koch, Peter; Müller, Berndt; Rafelski, Johann

2017-11-01

This is a short survey of signatures and characteristics of the quark-gluon plasma in the light of experimental results that have been obtained over the past three decades. In particular, we present an in-depth discussion of the strangeness observable, including a chronology of the experimental effort to detect QGP at CERN-SPS, BNL-RHIC, and CERN-LHC.

Production of multiply heavy flavoured baryons from Quark Gluon Plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Becattini, F.; INFN Sezione di Firenze, Via G. Sansone 1, I-50019, Sesto F.no

We show that in heavy ion collisions at LHC there could be a measurable production of baryons containing two or three heavy quarks from statistical coalescence. This production mechanism is peculiar of Quark Gluon Plasma and the predicted rates, in heavy ion collisions at LHC energy, exceed those from a purely hadronic scenario, particularly for {xi}bc and {omega}ccc. Thus, besides the interest in the discovery of these new states, enhanced ratios of these baryons over singly heavy flavoured hadrons, like B or D, in heavy ion collisions with respect to pp at the same energy, would be a clear indicationmore » of kinetical equilibration of heavy quarks in the Quark Gluon Plasma.« less

The phi-meson and Chiral-mass-meson production in heavy-ion collisions as potential probes of quark-gluon-plasma and Chiral symmetry transitions

NASA Technical Reports Server (NTRS)

Takahashi, Y.; Eby, P. B.

1985-01-01

Possibilities of observing abundances of phi mesons and narrow hadronic pairs, as results of QGP and Chiral transitions, are considered for nucleus-nucleus interactions. Kinematical requirements in forming close pairs are satisfied in K+K decays of S(975) and delta (980) mesons with small phi, and phi (91020) mesons with large PT, and in pi-pi decays of familiar resonance mesons only in a partially restored chiral symmetry. Gluon-gluon dominance in QGP can enhance phi meson production. High hadronization rates of primordial resonance mesons which form narrow hadronic pairs are not implausible. Past cosmic ray evidences of anomalous phi production and narrow pair abundances are considered.

Search for dijet resonances in 7 TeV pp collisions at CMS.

PubMed

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Klein, K; Merz, J; Mohr, N; Ostapchuk, A; Perieanu, A; Raupach, F; Sammet, J; Schael, S; Sprenger, D; Weber, H; Weber, M; Wittmer, B; Ata, M; Bender, W; Erdmann, M; Frangenheim, J; Hebbeker, T; Hinzmann, A; Hoepfner, K; Hof, C; Klimkovich, T; Klingebiel, D; Kreuzer, P; Lanske, D; Magass, C; Masetti, G; Merschmeyer, M; Meyer, A; Papacz, P; Pieta, H; Reithler, H; Schmitz, S A; Sonnenschein, L; Steggemann, J; Teyssier, D; Bontenackels, M; Davids, M; Duda, M; Flügge, G; Geenen, H; Giffels, M; Haj Ahmad, W; Heydhausen, D; Kress, T; Kuessel, Y; Linn, A; Nowack, A; Perchalla, L; Pooth, O; Rennefeld, J; Sauerland, P; Stahl, A; Thomas, M; Tornier, D; Zoeller, M H; Aldaya Martin, M; Behrenhoff, W; Behrens, U; Bergholz, M; Borras, K; Campbell, A; Castro, E; Dammann, D; Eckerlin, G; Flossdorf, A; Flucke, G; Geiser, A; Glushkov, I; Hauk, J; Jung, H; Kasemann, M; Katkov, I; Katsas, P; Kleinwort, C; Kluge, H; Knutsson, A; Krücker, D; Kuznetsova, E; Lange, W; Lohmann, W; Mankel, R; Marienfeld, M; Melzer-Pellmann, I-A; 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Onel, Y; Ozok, F; Sen, S; Wetzel, J; Yetkin, T; Yi, K; Barnett, B A; Blumenfeld, B; Bonato, A; Eskew, C; Fehling, D; Giurgiu, G; Gritsan, A V; Guo, Z J; Hu, G; Maksimovic, P; Rappoccio, S; Swartz, M; Tran, N V; Whitbeck, A; Baringer, P; Bean, A; Benelli, G; Grachov, O; Murray, M; Noonan, D; Radicci, V; Sanders, S; Wood, J S; Zhukova, V; Bandurin, D; Bolton, T; Chakaberia, I; Ivanov, A; Makouski, M; Maravin, Y; Shrestha, S; Svintradze, I; Wan, Z; Gronberg, J; Lange, D; Wright, D; Baden, A; Boutemeur, M; Eno, S C; Ferencek, D; Gomez, J A; Hadley, N J; Kellogg, R G; Kirn, M; Lu, Y; Mignerey, A C; Rossato, K; Rumerio, P; Santanastasio, F; Skuja, A; Temple, J; Tonjes, M B; Tonwar, S C; Twedt, E; Alver, B; Bauer, G; Bendavid, J; Busza, W; Butz, E; Cali, I A; Chan, M; Dutta, V; Everaerts, P; Gomez Ceballos, G; Goncharov, M; Hahn, K A; Harris, P; Kim, Y; Klute, M; Lee, Y-J; Li, W; Loizides, C; Luckey, P D; Ma, T; Nahn, S; Paus, C; Roland, C; Roland, G; Rudolph, M; Stephans, G S F; Sumorok, K; Sung, K; Wenger, E A; Wyslouch, B; Xie, S; Yang, M; Yilmaz, Y; Yoon, A S; Zanetti, M; Cole, P; Cooper, S I; Cushman, P; Dahmes, B; De Benedetti, A; Dudero, P R; Franzoni, G; Haupt, J; Klapoetke, K; Kubota, Y; Mans, J; Rekovic, V; Rusack, R; Sasseville, M; Singovsky, A; Cremaldi, L M; Godang, R; Kroeger, R; Perera, L; Rahmat, R; Sanders, D A; Summers, D; Bloom, K; Bose, S; Butt, J; Claes, D R; Dominguez, A; Eads, M; Keller, J; Kelly, T; Kravchenko, I; Lazo-Flores, J; Lundstedt, C; Malbouisson, H; Malik, S; Snow, G R; Baur, U; Godshalk, A; Iashvili, I; Kharchilava, A; Kumar, A; Smith, K; Zennamo, J; Alverson, G; Barberis, E; Baumgartel, D; Boeriu, O; Chasco, M; Kaadze, K; Reucroft, S; Swain, J; Wood, D; Zhang, J; Anastassov, A; Kubik, A; Odell, N; Ofierzynski, R A; Pollack, B; Pozdnyakov, A; Schmitt, M; Stoynev, S; Velasco, M; Won, S; Antonelli, L; Berry, D; Hildreth, M; Jessop, C; Karmgard, D J; Kolb, J; Kolberg, T; Lannon, K; Luo, W; Lynch, S; Marinelli, N; Morse, D M; Pearson, T; Ruchti, R; Slaunwhite, J; Valls, N; Warchol, J; Wayne, M; Ziegler, J; Bylsma, B; Durkin, L S; Gu, J; Hill, C; Killewald, P; Ling, T Y; Rodenburg, M; Williams, G; Adam, N; Berry, E; Elmer, P; Gerbaudo, D; Halyo, V; Hebda, P; Hunt, A; Jones, J; Laird, E; Lopes Pegna, D; Marlow, D; Medvedeva, T; Mooney, M; Olsen, J; Piroué, P; Saka, H; Stickland, D; Tully, C; Werner, J S; Zuranski, A; Acosta, J G; Huang, X T; Lopez, A; Mendez, H; Oliveros, S; Ramirez Vargas, J E; Zatserklyaniy, A; Alagoz, E; Barnes, V E; Bolla, G; Borrello, L; Bortoletto, D; Everett, A; Garfinkel, A F; Gecse, Z; Gutay, L; Jones, M; Koybasi, O; Laasanen, A T; Leonardo, N; Liu, C; Maroussov, V; Meier, M; Merkel, P; Miller, D H; Neumeister, N; Potamianos, K; Shipsey, I; Silvers, D; Svyatkovskiy, A; Yoo, H D; Zablocki, J; Zheng, Y; Jindal, P; Parashar, N; Boulahouache, C; Cuplov, V; Ecklund, K M; Geurts, F J M; Liu, J H; Morales, J; Padley, B P; Redjimi, R; Roberts, J; Zabel, J; Betchart, B; Bodek, A; Chung, Y S; de Barbaro, P; Demina, R; Eshaq, Y; Flacher, H; Garcia-Bellido, A; Goldenzweig, P; Gotra, Y; Han, J; Harel, A; Miner, D C; Orbaker, D; Petrillo, G; Vishnevskiy, D; Zielinski, M; Bhatti, A; Demortier, L; Goulianos, K; Lungu, G; Mesropian, C; Yan, M; Atramentov, O; Barker, A; Duggan, D; Gershtein, Y; Gray, R; Halkiadakis, E; Hidas, D; Hits, D; Lath, A; Panwalkar, S; Patel, R; Richards, A; Rose, K; Schnetzer, S; Somalwar, S; Stone, R; Thomas, S; Cerizza, G; Hollingsworth, M; Spanier, S; Yang, Z C; York, A; Asaadi, J; Eusebi, R; Gilmore, J; Gurrola, A; Kamon, T; Khotilovich, V; Montalvo, R; Nguyen, C N; Pivarski, J; Safonov, A; Sengupta, S; Tatarinov, A; Toback, D; Weinberger, M; Akchurin, N; Bardak, C; Damgov, J; Jeong, C; Kovitanggoon, K; Lee, S W; Mane, P; Roh, Y; Sill, A; Volobouev, I; Wigmans, R; Yazgan, E; Appelt, E; Brownson, E; Engh, D; Florez, C; Gabella, W; Johns, W; Kurt, P; Maguire, C; Melo, A; Sheldon, P; Velkovska, J; Arenton, M W; Balazs, M; Boutle, S; Buehler, M; Conetti, S; Cox, B; Francis, B; Hirosky, R; Ledovskoy, A; Lin, C; Neu, C; Patel, T; Yohay, R; Gollapinni, S; Harr, R; Karchin, P E; Loggins, V; Mattson, M; Milstène, C; Sakharov, A; Anderson, M; Bachtis, M; Bellinger, J N; Carlsmith, D; Dasu, S; Efron, J; Gray, L; Grogg, K S; Grothe, M; Hall-Wilton, R; Herndon, M; Klabbers, P; Klukas, J; Lanaro, A; Lazaridis, C; Leonard, J; Liu, J; Lomidze, D; Loveless, R; Mohapatra, A; Parker, W; Reeder, D; Ross, I; Savin, A; Smith, W H; Swanson, J; Weinberg, M

2010-11-19

A search for narrow resonances in the dijet mass spectrum is performed using data corresponding to an integrated luminosity of 2.9 pb⁻¹ collected by the CMS experiment at the Large Hadron Collider. Upper limits at the 95% confidence level are presented on the product of the resonance cross section, branching fraction into dijets, and acceptance, separately for decays into quark-quark, quark-gluon, or gluon-gluon pairs. The data exclude new particles predicted in the following models at the 95% confidence level: string resonances, with mass less than 2.50 TeV, excited quarks, with mass less than 1.58 TeV, and axigluons, colorons, and E6 diquarks, in specific mass intervals. This extends previously published limits on these models.

Quark self-energy in an ellipsoidally anisotropic quark-gluon plasma

NASA Astrophysics Data System (ADS)

Kasmaei, Babak S.; Nopoush, Mohammad; Strickland, Michael

2016-12-01

We calculate the quark self-energy in a quark-gluon plasma that possesses an ellipsoidal momentum-space anisotropy in the local rest frame. By introducing additional transverse-momentum anisotropy parameters into the parton distribution functions, we generalize previous results which were obtained for the case of a spheroidal anisotropy. Our results demonstrate that the presence of anisotropies in the transverse directions affects the real and imaginary parts of quark self-energy and, consequently, the self-energy depends on both the polar and azimuthal angles in the local rest frame of the matter. Our results for the quark self-energy set the stage for the calculation of the effects of ellipsoidal momentum-space anisotropy on quark-gluon plasma photon spectra and collective flow.

The Internet Culture: Transitions and Problems.

ERIC Educational Resources Information Center

Weiner, Robert G.

Originally begun as a government-sponsored project for scientists, engineers, and military personnel to exchange information with great speed and efficiency, the Internet has become a virtual community, an online culture arisen from the depths of computerized networking and communication. This paper presents positive and negative aspects of the…

DWTP: a basis for networked VR on the Internet

NASA Astrophysics Data System (ADS)

Broll, Wolfgang; Schick, Daniel

1998-04-01

Shared virtual worlds are one of today's major research topics. While limited to particular application areas and high speed networks in the past, they become more and more available to a large number of users. One reason for this development was the introduction of VRML (the Virtual Reality Modeling Language), which has been established as a standard of the exchange of 3D worlds on the Internet. Although a number of prototype systems have been developed to realize shared multi-user worlds based on VRML, no suitable network protocol to support the demands of such environments has yet been established. In this paper we will introduce our approach of a network protocol for shared virtual environments: DWTP--the Distributed Worlds Transfer and communication Protocol. We will show how DWTP meets the demands of shared virtual environments on the Internet. We will further present SmallView, our prototype of a distributed multi-user VR system, to show how DWTP can be used to realize shared worlds.

Evaluating Predictive Uncertainty of Hyporheic Exchange Modelling

NASA Astrophysics Data System (ADS)

Chow, R.; Bennett, J.; Dugge, J.; Wöhling, T.; Nowak, W.

2017-12-01

Hyporheic exchange is the interaction of water between rivers and groundwater, and is difficult to predict. One of the largest contributions to predictive uncertainty for hyporheic fluxes have been attributed to the representation of heterogeneous subsurface properties. This research aims to evaluate which aspect of the subsurface representation - the spatial distribution of hydrofacies or the model for local-scale (within-facies) heterogeneity - most influences the predictive uncertainty. Also, we seek to identify data types that help reduce this uncertainty best. For this investigation, we conduct a modelling study of the Steinlach River meander, in Southwest Germany. The Steinlach River meander is an experimental site established in 2010 to monitor hyporheic exchange at the meander scale. We use HydroGeoSphere, a fully integrated surface water-groundwater model, to model hyporheic exchange and to assess the predictive uncertainty of hyporheic exchange transit times (HETT). A highly parameterized complex model is built and treated as `virtual reality', which is in turn modelled with simpler subsurface parameterization schemes (Figure). Then, we conduct Monte-Carlo simulations with these models to estimate the predictive uncertainty. Results indicate that: Uncertainty in HETT is relatively small for early times and increases with transit times. Uncertainty from local-scale heterogeneity is negligible compared to uncertainty in the hydrofacies distribution. Introducing more data to a poor model structure may reduce predictive variance, but does not reduce predictive bias. Hydraulic head observations alone cannot constrain the uncertainty of HETT, however an estimate of hyporheic exchange flux proves to be more effective at reducing this uncertainty. Figure: Approach for evaluating predictive model uncertainty. A conceptual model is first developed from the field investigations. A complex model (`virtual reality') is then developed based on that conceptual model. This complex model then serves as the basis to compare simpler model structures. Through this approach, predictive uncertainty can be quantified relative to a known reference solution.

Nonperturbative study of the four gluon vertex

NASA Astrophysics Data System (ADS)

Binosi, D.; Ibañez, D.; Papavassiliou, J.

2014-09-01

In this paper we study the nonperturbative structure of the SU(3) four-gluon vertex in the Landau gauge, concentrating on contributions quadratic in the metric. We employ an approximation scheme where "one-loop" diagrams are computed using fully dressed gluon and ghost propagators, and tree-level vertices. When a suitable kinematical configuration depending on a single momentum scale p is chosen, only two structures emerge: the tree-level four-gluon vertex, and a tensor orthogonal to it. A detailed numerical analysis reveals that the form factor associated with this latter tensor displays a change of sign (zero-crossing) in the deep infrared, and finally diverges logarithmically. The origin of this characteristic behavior is proven to be entirely due to the masslessness of the ghost propagators forming the corresponding ghost-loop diagram, in close analogy to a similar effect established for the three-gluon vertex. However, in the case at hand, and under the approximations employed, this particular divergence does not affect the form factor proportional to the tree-level tensor, which remains finite in the entire range of momenta, and deviates moderately from its naive tree-level value. It turns out that the kinematic configuration chosen is ideal for carrying out lattice simulations, because it eliminates from the connected Green's function all one-particle reducible contributions, projecting out the genuine one-particle irreducible vertex. Motivated by this possibility, we discuss in detail how a hypothetical lattice measurement of this quantity would compare to the results presented here, and the potential interference from an additional tensorial structure, allowed by Bose symmetry, but not encountered within our scheme.

Nucleon Resonance Structure from Exclusive Meson Electroproduction with CLAS

DOE PAGES

Mokeev, Victor I.

2018-04-06

Studies of the nucleon resonance electroexcitation amplitudes in a wide range of photon virtualities offer unique information on many facets of strong QCD behind the generation of all prominent excited nucleon states of distinctively different structure. Advances in the evaluation of resonance electroexcitation amplitudes from the data measured with the CLAS detector and the future extension of these studies with the CLAS12 detector at Jefferson Lab are presented in this paper. For the first time, analyses ofmore » $$\\pi^0p$$, $$\\pi^+n$$, $$\\eta p$$, and $$\\pi^+\\pi^-p$$ electroproduction off proton channels have provided electroexcitation amplitudes of most resonances in the mass range up to 1.8 GeV and at photon virtualities $Q^2 < 5$ GeV$^2$. Consistent results on resonance electroexcitation amplitudes determined from different exclusive channels validate a credible extraction of these fundamental quantities. Studies of the resonance electroexcitation amplitudes revealed the $N^*$ structure as a complex interplay between the inner core of three dressed quarks and the external meson-baryon cloud. The successful description of the $$\\Delta(1232)3/2^+$$ and $N(1440)1/2^+$ electrocouplings achieved within the Dyson-Schwinger Equation approach under a traceable connection to the QCD Lagrangian and supported by the novel light front quark model demonstrated the relevance of dressed quarks with dynamically generated masses as an active structural component in baryons. Future experiments with the CLAS12 detector will offer insight into the structure of all prominent resonances at the highest photon virtualities, $Q^2 < 12$ GeV$^2$, ever achieved in exclusive reactions, thus addressing the most challenging problems of the Standard Model on the nature of hadron mass, quark-gluon confinement, and the emergence of nucleon resonance structures from QCD. Finally, a search for new states of hadronic matter, the so-called hybrid-baryons with glue as a structural component, will complete the long term efforts on the resonance spectrum exploration.« less

Nucleon Resonance Structure from Exclusive Meson Electroproduction with CLAS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mokeev, Victor I.

Studies of the nucleon resonance electroexcitation amplitudes in a wide range of photon virtualities offer unique information on many facets of strong QCD behind the generation of all prominent excited nucleon states of distinctively different structure. Advances in the evaluation of resonance electroexcitation amplitudes from the data measured with the CLAS detector and the future extension of these studies with the CLAS12 detector at Jefferson Lab are presented in this paper. For the first time, analyses ofmore » $$\\pi^0p$$, $$\\pi^+n$$, $$\\eta p$$, and $$\\pi^+\\pi^-p$$ electroproduction off proton channels have provided electroexcitation amplitudes of most resonances in the mass range up to 1.8 GeV and at photon virtualities $Q^2 < 5$ GeV$^2$. Consistent results on resonance electroexcitation amplitudes determined from different exclusive channels validate a credible extraction of these fundamental quantities. Studies of the resonance electroexcitation amplitudes revealed the $N^*$ structure as a complex interplay between the inner core of three dressed quarks and the external meson-baryon cloud. The successful description of the $$\\Delta(1232)3/2^+$$ and $N(1440)1/2^+$ electrocouplings achieved within the Dyson-Schwinger Equation approach under a traceable connection to the QCD Lagrangian and supported by the novel light front quark model demonstrated the relevance of dressed quarks with dynamically generated masses as an active structural component in baryons. Future experiments with the CLAS12 detector will offer insight into the structure of all prominent resonances at the highest photon virtualities, $Q^2 < 12$ GeV$^2$, ever achieved in exclusive reactions, thus addressing the most challenging problems of the Standard Model on the nature of hadron mass, quark-gluon confinement, and the emergence of nucleon resonance structures from QCD. Finally, a search for new states of hadronic matter, the so-called hybrid-baryons with glue as a structural component, will complete the long term efforts on the resonance spectrum exploration.« less

Integrated Access to Heliospheric and Magnetospheric Data

NASA Astrophysics Data System (ADS)

Merka, J.; Szabo, A.; Narock, T. W.

2007-05-01

Heliospheric and magnetospheric data are provided by a variety of diverse sources. For space physics scientists, knowing that such data sources exist and where they are located are only the first hurdles to overcome before they can utilize the data for research. As a solution, the NASA Heliophysics Division has established a group of virtual observatories (VOs) to provide the scientific community with integrated access to well documented data and related services. The VOs are organized by scientific discipline and yet their essential characteristic is cross-discipline data discovery and exchange. In this talk, we will demonstrate the architecture and features of two distributed data systems, the Virtual Heliospheric Observatory (VHO) and the Virtual Magnetospheric Observatory at NASA Goddard Space Flight Center (VMO/G). The VHO and VMO/G are designed to share most of the components to facilitate faster development and to ease communication between the two VxOs. Since different communities are served by the two observatories, slightly, and sometimes even significantly, different terms and expectations must be accommodated and correctly processed. In our approach the interfaces are tuned for a particular community while the standard SPASE data model is employed internally. Together with other VxOs, we are also developing a standard query language for metadata exchange among the VxOs, data providers, and VxO-related services. Specific examples will be given. http:vho.nasa.gov

How Effective Is a Virtual Consultation Process in Facilitating Multidisciplinary Decision-Making for Malignant Epidural Spinal Cord Compression?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fitzpatrick, David; St Luke's Hospital, Dublin; Grabarz, Daniel

Purpose: The purpose of this study was to assess the accuracy of a virtual consultation (VC) process in determining treatment strategy for patients with malignant epidural spinal cord compression (MESCC). Methods and Materials: A prospective clinical database was maintained for patients with MESCC. A virtual consultation process (involving exchange of key predetermined clinical information and diagnostic imaging) facilitated rapid decision-making between oncologists and spinal surgeons. Diagnostic imaging was reviewed retrospectively (by R.R.) for surgical opinions in all patients. The primary outcome was the accuracy of virtual consultation opinion in predicting the final treatment recommendation. Results: After excluding 20 patients whomore » were referred directly to the spinal surgeon, 125 patients were eligible for virtual consultation. Of the 46 patients who had a VC, surgery was recommended in 28 patients and actually given to 23. A retrospective review revealed that 5/79 patients who did not have a VC would have been considered surgical candidates. The overall accuracy of the virtual consultation process was estimated at 92%. Conclusion: The VC process for MESCC patients provides a reliable means of arriving at a multidisciplinary opinion while minimizing patient transfer. This can potentially shorten treatment decision time and enhance clinical outcomes.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

KRASNITZ,A.; VENUGOPALAN,R.

The dynamics of low-x partons in the transverse plane of a high-energy nuclear collision is classical, and therefore admits a fully non-perturbative numerical treatment. The authors report results of a recent study estimating the initial energy density in the central region of a collision. Preliminary estimates of the number of gluons per unit rapidity, and the initial transverse momentum distribution of gluons, are also provided.

Color instabilities in the quark-gluon plasma

NASA Astrophysics Data System (ADS)

Mrówczyński, Stanisław; Schenke, Björn; Strickland, Michael

2017-04-01

When the quark-gluon plasma (QGP) - a system of deconfined quarks and gluons - is in a nonequilibrium state, it is usually unstable with respect to color collective modes. The instabilities, which are expected to strongly influence dynamics of the QGP produced in relativistic heavy-ion collisions, are extensively discussed under the assumption that the plasma is weakly coupled. We begin by presenting the theoretical approaches to study the QGP, which include: field theory methods based on the Keldysh-Schwinger formalism, classical and quantum kinetic theories, and fluid techniques. The dispersion equations, which give the spectrum of plasma collective excitations, are analyzed in detail. Particular attention is paid to a momentum distribution of plasma constituents which is obtained by deforming an isotropic momentum distribution. Mechanisms of chromoelectric and chromomagnetic instabilities are explained in terms of elementary physics. The Nyquist analysis, which allows one to determine the number of solutions of a dispersion equation without explicitly solving it, and stability criteria are also discussed. We then review various numerical approaches - purely classical or quantum - to simulate the temporal evolution of an unstable quark-gluon plasma. The dynamical role of instabilities in the processes of plasma equilibration is analyzed.

How nonperturbative is the infrared regime of Landau gauge Yang-Mills correlators?

NASA Astrophysics Data System (ADS)

Reinosa, U.; Serreau, J.; Tissier, M.; Wschebor, N.

2017-07-01

We study the Landau gauge correlators of Yang-Mills fields for infrared Euclidean momenta in the context of a massive extension of the Faddeev-Popov Lagrangian which, we argue, underlies a variety of continuum approaches. Standard (perturbative) renormalization group techniques with a specific, infrared-safe renormalization scheme produce so-called decoupling and scaling solutions for the ghost and gluon propagators, which correspond to nontrivial infrared fixed points. The decoupling fixed point is infrared stable and weakly coupled, while the scaling fixed point is unstable and generically strongly coupled except for low dimensions d →2 . Under the assumption that such a scaling fixed point exists beyond one-loop order, we find that the corresponding ghost and gluon scaling exponents are, respectively, 2 αF=2 -d and 2 αG=d at all orders of perturbation theory in the present renormalization scheme. We discuss the relation between the ghost wave function renormalization, the gluon screening mass, the scale of spectral positivity violation, and the gluon mass parameter. We also show that this scaling solution does not realize the standard Becchi-Rouet-Stora-Tyutin symmetry of the Faddeev-Popov Lagrangian. Finally, we discuss our findings in relation to the results of nonperturbative continuum methods.

Color instabilities in the quark–gluon plasma

DOE PAGES

Mrówczyński, Stanisław; Schenke, Björn; Strickland, Michael

2017-04-09

When the quark–gluon plasma (QGP) – a system of deconfined quarks and gluons – is in a nonequilibrium state, it is usually unstable with respect to color collective modes. The instabilities, which are expected to strongly influence dynamics of the QGP produced in relativistic heavy-ion collisions, are extensively discussed under the assumption that the plasma is weakly coupled. Here, we begin by presenting the theoretical approaches to study the QGP, which include: field theory methods based on the Keldysh–Schwinger formalism, classical and quantum kinetic theories, and fluid techniques. The dispersion equations, which give the spectrum of plasma collective excitations, aremore » analyzed in detail. We pay particular attention to a momentum distribution of plasma constituents which is obtained by deforming an isotropic momentum distribution. Mechanisms of chromoelectric and chromomagnetic instabilities are explained in terms of elementary physics. The Nyquist analysis, which allows one to determine the number of solutions of a dispersion equation without explicitly solving it, and stability criteria are also discussed. We then review various numerical approaches – purely classical or quantum – to simulate the temporal evolution of an unstable quark–gluon plasma. The dynamical role of instabilities in the processes of plasma equilibration is analyzed.« less

Hot QCD equations of state and relativistic heavy ion collisions

NASA Astrophysics Data System (ADS)

Chandra, Vinod; Kumar, Ravindra; Ravishankar, V.

2007-11-01

We study two recently proposed equations of state obtained from high-temperature QCD and show how they can be adapted to use them for making predictions for relativistic heavy ion collisions. The method involves extracting equilibrium distribution functions for quarks and gluons from the equation of state (EOS), which in turn will allow a determination of the transport and other bulk properties of the quark gluon-plasma. Simultaneously, the method also yields a quasiparticle description of interacting quarks and gluons. The first EOS is perturbative in the QCD coupling constant and has contributions of O(g5). The second EOS is an improvement over the first, with contributions up to O[g6ln(1/g)]; it incorporates the nonperturbative hard thermal contributions. The interaction effects are shown to be captured entirely by the effective chemical potentials for the gluons and the quarks, in both cases. The chemical potential is seen to be highly sensitive to the EOS. As an application, we determine the screening lengths, which are, indeed, the most important diagnostics for QGP. The screening lengths are seen to behave drastically differently depending on the EOS considered and therefore yield a way to distinguish the two equations of state in heavy ion collisions.

TMDs and GPDs at a future Electron-Ion Collider

DOE PAGES

Ent, Rolf

2016-06-21

With two options studied at Brookhaven National Lab and Jefferson Laboratory the U.S., an Electron-Ion Collider (EIC) of energy √s=20-100 GeV was under design. Furthermore, the recent 2015 US Nuclear Science Long-Range Planning effort included a future EIC as a recommendation for future construction. The EIC will be unique in colliding polarised electrons off polarised protons and light nuclei, providing the spin degrees of freedom essential to pursue its physics program driven by spin structure, multi-dimensional tomographic images of protons and nuclei, and discovery of the role of collective effects of gluons in nuclei. The foreseen luminosity of the EIC,more » coupled with its energy variability and reach, will allow unprecedented three-dimensional imaging of the gluon and sea quark distributions, via both TMDs and GPDs, and to explore correlations amongst them. Its hermetic detection capability of correlated fragments promises to similar allow for precise tomographic images of the quark-gluon landscape in nuclei, transcending from light few-body nuclei to the heaviest nuclei, and could uncover how the TMD and GPD landscape changes when gluons display an anticipated collective behavior at the higher energies.« less

Safety Strategies While Surfing Online in the Classroom.

ERIC Educational Resources Information Center

Demirbilek, Muhammet; Cilesiz, Sebnem; Tozoglu, Dogan

The Internet has become an indispensable medium of the 21st century. Millions of people are using the Internet for exchanging information, surfing for information on virtually any topic, communicating all over the world, participating in discussion groups, shopping, traveling, and many other online activities. The World Wide Web is constantly…

Qualitative Research on "Mediated Dialogism" among Educators and Pupils

ERIC Educational Resources Information Center

Hansson, Thomas

2004-01-01

The relevance of qualitative research to virtual practices rests on subject knowledge and practical know-how on operations for exchange, growth, learning, and dialogue. Highlighting the discursive perspective, this paper covers theory on emerging didactics for online learning. In doing so, the contents show how computer-mediated learning…

Proton Form Factor Puzzle and the CEBAF Large Acceptance Spectrometer (CLAS) Two-Photon Exchange Experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rimal, Dipak

2014-05-01

The electromagnetic form factors are the most fundamental observables that encode information about the internal structure of the nucleon. This dissertation explored dependence of R on kinematic variables such as squared four-momentum transfer (Q 2) and the virtual photon polarization parameter (ε).

Information Control in the Virtual Office: Preparing Intermediaries To Facilitate Information Exchange in the Home Work Environment.

ERIC Educational Resources Information Center

Fulton, Crystal

2002-01-01

Discusses work done by information professionals and the increase in teleworking, using telecommunications technology; considers teleworkers' information needs; examines ways in which library and information science professionals can facilitate teleworkers' information access; and investigates information environments of 20 teleworkers and 20…

Socio-Emotional Connections: Identity, Belonging and Learning in Online Interactions--A Literature Review

ERIC Educational Resources Information Center

Delahunty, Janine; Verenikina, Irina; Jones, Pauline

2014-01-01

This review focuses on three interconnected socio-emotional aspects of online learning: interaction, sense of community and identity formation. In the intangible social space of the virtual classroom, students come together to learn through dialogic, often asynchronous, exchanges. This creates distinctive learning environments where learning…

Novel QCD Phenomenology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brodsky, Stanley J.; /SLAC /Southern Denmark U., CP3-Origins

2011-08-12

I review a number of topics where conventional wisdom in hadron physics has been challenged. For example, hadrons can be produced at large transverse momentum directly within a hard higher-twist QCD subprocess, rather than from jet fragmentation. Such 'direct' processes can explain the deviations from perturbative QCD predictions in measurements of inclusive hadron cross sections at fixed x{sub T} = 2p{sub T}/{radical}s, as well as the 'baryon anomaly', the anomalously large proton-to-pion ratio seen in high centrality heavy ion collisions. Initial-state and final-state interactions of the struck quark, the soft-gluon rescattering associated with its Wilson line, lead to Bjorken-scaling single-spinmore » asymmetries, diffractive deep inelastic scattering, the breakdown of the Lam-Tung relation in Drell-Yan reactions, as well as nuclear shadowing and antishadowing. The Gribov-Glauber theory predicts that antishadowing of nuclear structure functions is not universal, but instead depends on the flavor quantum numbers of each quark and antiquark, thus explaining the anomalous nuclear dependence measured in deep-inelastic neutrino scattering. Since shadowing and antishadowing arise from the physics of leading-twist diffractive deep inelastic scattering, one cannot attribute such phenomena to the structure of the nucleus itself. It is thus important to distinguish 'static' structure functions, the probability distributions computed from the square of the target light-front wavefunctions, versus 'dynamical' structure functions which include the effects of the final-state rescattering of the struck quark. The importance of the J = 0 photon-quark QCD contact interaction in deeply virtual Compton scattering is also emphasized. The scheme-independent BLM method for setting the renormalization scale is discussed. Eliminating the renormalization scale ambiguity greatly improves the precision of QCD predictions and increases the sensitivity of searches for new physics at the LHC. Other novel features of QCD are discussed, including the consequences of confinement for quark and gluon condensates.« less

Local and global perspectives on the virtual water trade

NASA Astrophysics Data System (ADS)

Tamea, S.; Allamano, P.; Carr, J. A.; Claps, P.; Laio, F.; Ridolfi, L.

2012-11-01

Recent studies on fluxes of virtual water are showing how the global food and goods trade interconnects the water resources of different and distant countries, conditioning the local water balances. This paper presents and discusses the assessment of virtual water fluxes between a single country and its network of trading partners, delineating a country's virtual water budget in space and time (years 1986-2010). The fluxes between the country under study and its importing/exporting partners are visualized with a geographical representation shaping the trade network as a virtual river/delta. Time variations of exchanged fluxes are quantified to show possible trends in the virtual water balance, while characterizing the time evolution of the trade network and its composition in terms of product categories (plant-based, animal-based, luxury and non-edible). The average distance traveled by virtual water to arrive to the place of consumption is also introduced as a new measure for the analysis of globalization of the virtual water trade. Using Italy as an example, we find that food trade has a steadily growing importance compared to domestic production, with a major component represented by plan-based products, and luxury products taking an increasingly larger share (26% in 2010). In 2010 Italy had an average net import of 55 km3 of virtual water (38 km3 in 1986), a value which poses the country among the top net importers in the world. On average each cubic meter of virtual water travels nearly 4000 km before entering Italy, while export goes to relatively closer countries (average distance: 2600 km), with increasing trends in time which are almost unique among the world countries. Analyses proposed for Italy are replicated for 10 other world countries, triggering similar investigations on different socio-economic actualities.

Local and global perspectives on the virtual water trade

NASA Astrophysics Data System (ADS)

Tamea, S.; Allamano, P.; Carr, J. A.; Claps, P.; Laio, F.; Ridolfi, L.

2013-03-01

Recent studies on fluxes of virtual water are showing how the global food and goods trade interconnects the water resources of different and distant countries, conditioning the local water balances. This paper presents and discusses the assessment of virtual water fluxes between a single country and its network of trading partners, delineating a country's virtual water budget in space and time (years 1986-2010). The fluxes between the country under study and its importing/exporting partners are visualized with a geographical representation shaping the trade network as a virtual river/delta. Time variations of exchanged fluxes are quantified to show possible trends in the virtual water balance, while characterizing the time evolution of the trade network and its composition in terms of product categories (plant-based, animal-based, luxury food, and non-edible). The average distance traveled by virtual water to arrive to the place of consumption is also introduced as a new measure for the analysis of globalization of the virtual water trade. Using Italy as an example, we find that food trade has a steadily growing importance compared to domestic production, with a major component represented by plant-based products, and luxury products taking an increasingly larger share (26% in 2010). In 2010 Italy had an average net import of 55 km3 of virtual water (38 km3 in 1986), a value which poses the country among the top net importers in the world. On average each cubic meter of virtual water travels nearly 4000 km before entering Italy, while export goes to relatively closer countries (average distance: 2600 km), with increasing trends in time which are almost unique among the world countries. Analyses proposed for Italy are replicated for 10 other world countries, triggering similar investigations on different socio-economic actualities.

Bulk viscous corrections to screening and damping in QCD at high temperatures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Du, Qianqian; Dumitru, Adrian; Guo, Yun

2017-01-01

Non-equilibrium corrections to the distribution functions of quarks and gluons in a hot and dense QCD medium modify the \\hard thermal loops" (HTL). The HTLs determine the retarded, advanced, and symmetric (time-ordered) propagators for gluons with soft momenta as well as the Debye screening and Landau damping mass scales. Here, we compute such corrections to a thermal as well as to a non-thermal fixed point. The screening and damping mass scales are sensitive to the bulk pressure and hence to (pseudo-) critical dynamical scaling of the bulk viscosity in the vicinity of a second-order critical point. This could be reectedmore » in the properties of quarkonium bound states in the deconfined phase and in the dynamics of soft gluon fields.« less

On the zero-crossing of the three-gluon Green's function from lattice simulations

NASA Astrophysics Data System (ADS)

Athenodorou, Andreas; Boucaud, Philippe; de Soto, Feliciano; Rodríguez-Quintero, José; Zafeiropoulos, Savvas

2018-03-01

We report on some efforts recently made in order to gain a better understanding of some IR properties of the 3-point gluon Green's function by exploiting results from large-volume quenched lattice simulations. These lattice results have been obtained by using both tree-level Symanzik and the standard Wilson action, in the aim of assessing the possible impact of effects presumably resulting from a particular choice for the discretization of the action. The main resulting feature is the existence of a negative log-aritmic divergence at zero-momentum, which pulls the 3-gluon form factors down at low momenta and, consequently, yields a zero-crossing at a given deep IR momentum. The results can be correctly explained by analyzing the relevant Dyson-Schwinger equations and appropriate truncation schemes.

Extraction of the gluon density of the proton at x

NASA Astrophysics Data System (ADS)

Derrick, M.; Krakauer, D.; Magill, S.; Musgrave, B.; Repond, J.; Schlereth, J.; Stanek, R.; Talaga, R. L.; Thron, J.; Arzarello, F.; Ayad, R.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Bruni, P.; Cara Romeo, G.; Castellini, G.; Chiarini, M.; Cifarelli, L.; Cindolo, F.; Ciralli, F.; Contin, A.; D'Auria, S.; Frasconi, F.; Gialas, I.; Giusti, P.; Iacobucci, G.; Laurenti, G.; Levi, G.; Margotti, A.; Massam, T.; Nania, R.; Nemoz, C.; Palmonari, F.; Polini, A.; Sartorelli, G.; Timellini, R.; Zamora Garcia, Y.; Zichichi, A.; Bargende, A.; Crittenden, J.; Desch, K.; Diekmann, B.; Doeker, T.; Eckert, M.; Feld, L.; Frey, A.; Geerts, M.; Geitz, G.; Grothe, M.; Hartmann, H.; Haun, D.; Heinloth, K.; Hilger, E.; Jakob, H.-P.; Katz, U. F.; Mari, S. M.; Mass, A.; Mengel, S.; Mollen, J.; Paul, E.; Rembser, Ch.; Schattevoy, R.; Schramm, D.; Stamm, J.; Wedemeyer, R.; Campbell-Robson, S.; Cassidy, A.; Dyce, N.; Foster, B.; George, S.; Gilmore, R.; Heath, G. P.; Heath, H. F.; Llewellyn, T. J.; Morgado, C. J. S.; Norman, D. J. P.; O'Mara, J. A.; Tapper, R. J.; Wilson, S. S.; Yoshida, R.; Rau, R. R.; Arneodo, M.; Iannotti, L.; Schioppa, M.; Susinno, G.; Bernstein, A.; Caldwell, A.; Parsons, J. A.; Ritz, S.; Sciulli, F.; Straub, P. B.; Wai, L.; Yang, S.; Borzemski, P.; Chwastowski, J.; Eskreys, A.; Piotrzkowski, K.; Zachara, M.; Zawiejski, L.; Adamczyk, L.; Bednarek, B.; Eskreys, K.; Jelén, K.; Kisielewska, D.; Kowalski, T.; Rulikowska-Zarȩbska, E.; Suszycki, L.; Zajaç, J.; Kȩdzierski, T.; Kotański, A.; Przybycień, M.; Bauerdick, L. A. T.; Behrens, U.; Bienlein, J. K.; Böttcher, S.; Coldewey, C.; Drews, G.; Flasiński, M.; Gilkinson, D. J.; Göttlicher, P.; Gutjahr, B.; Haas, T.; Hain, W.; Hasell, D.; Heβling, H.; Hultschig, H.; Iga, Y.; Joos, P.; Kasemann, M.; Klanner, R.; Koch, W.; Köpke, L.; Kötz, U.; Kowalski, H.; Kröger, W.; Krüger, J.; Labs, J.; Ladage, A.; Löhr, B.; Löwe, M.; Lüke, D.; Mańczak, O.; Ng, J. S. T.; Nickel, S.; Notz, D.; Ohrenberg, K.; Roco, M.; Rohde, M.; Roldán, J.; Schneekloth, U.; Schulz, W.; Selonke, F.; Stiliaris, E.; Voβ, T.; Westphal, D.; Wolf, G.; Youngman, C.; Grabosch, H. J.; Leich, A.; Meyer, A.; Rethfeldt, C.; Schlenstedt, S.; Barbagli, G.; Pelfer, P.; Anzivino, G.; Maccarrone, G.; De Pasquale, S.; Qian, S.; Votano, L.; Bamberger, A.; Freidhof, A.; Poser, T.; Söldner-Rembold, S.; Schroeder, J.; Theisen, G.; Trefzger, T.; Brook, N. H.; Bussey, P. J.; Doyle, A. T.; Fleck, I.; Jamieson, V. A.; Saxon, D. H.; Utley, M. L.; Wilson, A. S.; Dannemann, A.; Holm, U.; Horstmann, D.; Kammerlocher, H.; Krebs, B.; Neumann, T.; Sinkus, R.; Wick, K.; Badura, E.; Burow, B. D.; Fürtjes, A.; Hagge, L.; Lohrmann, E.; Mainusch, J.; Milewski, J.; Nakahata, M.; Pavel, N.; Poelz, G.; Schott, W.; Terron, J.; Zetsche, F.; Bacon, T. C.; Beuselinck, R.; Butterworth, I.; Gallo, E.; Harris, V. L.; Hung, B. H.; Long, K. R.; Miller, D. B.; Morawitz, P. P. O.; Prinias, A.; Sedgbeer, J. K.; Whitfield, A. F.; Mallik, U.; McCliment, E.; Wang, M. Z.; Wang, S. M.; Wu, J. T.; Zhang, Y.; Cloth, P.; Filges, D.; An, S. H.; Hong, S. M.; Nam, S. W.; Park, S. K.; Suh, M. H.; Yon, S. H.; Imlay, R.; Kartik, S.; Kim, H.-J.; McNeil, R. R.; Metcalf, W.; Nadendla, V. K.; Barreiro, F.; Cases, G.; Graciani, R.; Hernández, J. M.; Hervás, L.; Labarga, L.; del Peso, J.; Puga, J.; de Trocóniz, J. F.; Ikraiam, F.; Mayer, J. K.; Smith, G. R.; Corriveau, F.; Hanna, D. S.; Hartmann, J.; Hung, L. W.; Lim, J. N.; Matthews, C. G.; Patel, P. M.; Sinclair, L. E.; Stairs, D. G.; St. Laurent, M.; Ullmann, R.; Zacek, G.; Bashkirov, V.; Dolgoshein, B. A.; Stifutkin, A.; Bashindzhagyan, G. L.; Ermolov, P. F.; Gladilin, L. K.; Golubkov, Y. A.; Kobrin, V. D.; Kuzmin, V. A.; Proskuryakov, A. S.; Savin, A. A.; Shcheglova, L. M.; Solomin, A. N.; Zotov, N. P.; Bentvelsen, S.; Botje, M.; Chlebana, F.; Dake, A.; Engelen, J.; de Jong, P.; de Kamps, M.; Kooijman, P.; Kruse, A.; O'Dell, V.; Tenner, A.; Tiecke, H.; Verkerke, W.; Vreeswijk, M.; Wiggers, L.; de Wolf, E.; van Woudenberg, R.; Acosta, D.; Bylsma, B.; Durkin, L. S.; Honscheid, K.; Li, C.; Ling, T. Y.; McLean, K. W.; Murray, W. N.; Park, I. H.; Romanowski, T. A.; Seidlein, R.; Bailey, D. S.; Blair, G. A.; Byrne, A.; Cashmore, R. J.; Cooper-Sarkar, A. M.; Daniels, D.; Devenish, R. C. E.; Harnew, N.; Lancaster, M.; Luffman, P. E.; Lindemann, L.; McFall, J.; Nath, C.; Quadt, A.; Uijterwaal, H.; Walczak, R.; Wilson, F. F.; Yip, T.; Abbiendi, G.; Bertolin, A.; Brugnera, R.; Carlin, R.; Dal Corso, F.; De Giorgi, M.; Dosselli, U.; Limentani, S.; Morandin, M.; Posocco, M.; Stanco, L.; Stroili, R.; Voci, C.; Bulmahn, J.; Butterworth, J. M.; Feild, R. G.; Oh, B. Y.; Whitmore, J. J.; D'Agostini, G.; Iori, M.; Marini, G.; Mattioli, M.; Nigro, A.; Tassi, E.; Hart, J. C.; McCubbin, N. A.; Prytz, K.; Shah, T. P.; Short, T. L.; Barberis, E.; Cartiglia, N.; Dubbs, T.; Heusch, C.; Van Hook, M.; Hubbard, B.; Lockman, W.; Rahn, J. T.; Sadrozinski, H. F.-W.; Seiden, A.; Biltzinger, J.; Seifert, R. J.; Walenta, A. H.; Zech, G.; Abramowicz, H.; Briskin, G.; Dagan, S.; Levy, A.; Hasegawa, T.; Hazumi, M.; Ishii, T.; Kuze, M.; Mine, S.; Nagasawa, Y.; Nagira, T.; Nakao, M.; Suzuki, I.; Tokushuku, K.; Yamada, S.; Yamazaki, Y.; Chiba, M.; Hamatsu, R.; Hirose, T.; Homma, K.; Kitamura, S.; Nagayama, S.; Nakamitsu, Y.; Cirio, R.; Costa, M.; Ferrero, M. I.; Lamberti, L.; Maselli, S.; Peroni, C.; Sacchi, R.; Solano, A.; Staiano, A.; Dardo, M.; Bailey, D. C.; Bandyopadhyay, D.; Benard, F.; Brkic, M.; Crombie, M. B.; Gingrich, D. M.; Hartner, G. F.; Joo, K. K.; Levman, G. M.; Martin, J. F.; Orr, R. S.; Sampson, C. R.; Teuscher, R. J.; Catterall, C. D.; Jones, T. W.; Kaziewicz, P. B.; Lane, J. B.; Saunders, R. L.; Shulman, J.; Blankenship, K.; Kochocki, J.; Lu, B.; Mo, L. W.; Bogusz, W.; Charchuł; a, K.; Ciborowski, J.; Gajewski, J.; Grzelak, G.; Kasprzak, M.; Krzyżanowski, M.; Muchorowski, K.; Nowak, R. J.; Pawlak, J. M.; Tymieniecka, T.; Wróblewski, A. K.; Zakrzewski, J. A.; Zarnecki, A. F.; Adamus, M.; Eisenberg, Y.; Glasman, C.; Karshon, U.; Revel, D.; Shapira, A.; Ali, I.; Behrens, B.; Dasu, S.; Fordham, C.; Foudas, C.; Goussiou, A.; Loveless, R. J.; Reeder, D. D.; Silverstein, S.; Smith, W. H.; Tsurugai, T.; Bhadra, S.; Frisken, W. R.; Furutani, K. M.; Zeus Collaboration

1995-02-01

The gluon momentum density xg( x, Q2) of the proton was extracted at Q2 = 20 GeV 2 for small values of x between 4 × 10 -4 and 10 -2 from the scaling violations of the proton structure function F2 measured recently by ZEUS in deep inelastic neutral current ep scattering at HERA. The extraction was performed in two ways. Firstly, using a global NLO fit to the ZEUS data on F2 at low x constrained by measurementsfrom NMC at larger x; and secondly using published approximate methods for the solution of the GLAP QCD evolution equations. Consistent results are obtained. A substantial increase of the gluon density is found at small x in comparison with the NMC result obtained at larger values of x.

Quark-gluon discrimination in the search for gluino pair production at the LHC

DOE PAGES

Bhattacherjee, Biplob; Mukhopadhyay, Satyanarayan; Nojiri, Mihoko M.; ...

2017-01-11

Here, we study the impact of including quark- and gluon-initiated jet discrimination in the search for strongly interacting supersymmetric particles at the LHC. Taking the example of gluino pair production, considerable improvement is observed in the LHC search reach on including the jet substructure observables to the standard kinematic variables within a multivariate analysis. In particular, quark and gluon jet separation has higher impact in the region of intermediate mass-gap between the gluino and the lightest neutralino, as the difference between the signal and the standard model background kinematic distributions is reduced in this region. We also compare the predictionsmore » from different Monte Carlo event generators to estimate the uncertainty originating from the modelling of the parton shower and hadronization processes.« less

Spin Qubits in Germanium Structures with Phononic Gap

NASA Technical Reports Server (NTRS)

Smelyanskiy, V. N.; Vasko, F. T.; Hafiychuk, V. V.; Dykman, M. I.; Petukhov, A. G.

2014-01-01

We propose qubits based on shallow donor electron spins in germanium structures with phononic gap. We consider a phononic crystal formed by periodic holes in Ge plate or a rigid cover / Ge layer / rigid substrate structure with gaps approximately a few GHz. The spin relaxation is suppressed dramatically, if the Zeeman frequency omegaZ is in the phononic gap, but an effective coupling between the spins of remote donors via exchange of virtual phonons remains essential. If omegaZ approaches to a gap edge in these structures, a long-range (limited by detuning of omegaZ) resonant exchange interaction takes place. We estimate that ratio of the exchange integral to the longitudinal relaxation rate exceeds 10(exp 5) and lateral scale of resonant exchange 0.1 mm. The exchange contribution can be verified under microwave pumping through oscillations of spin echo signal or through the differential absorption measurements. Efficient manipulation of spins due to the Rabi oscillations opens a new way for quantum information applications.

Use titanium tubes to create higher-capacity, corrosion-resistant exchangers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pase, G.K.; O`Donnell, J.

1995-10-01

Revamping heat exchangers with titanium-finned tubes provided an 11.7% production increase for a liquefied natural gas (LNG) plant at Bontang, East Kalimantan, Indonesia. The technology was chosen due to its high resistance to corrosive seawater, which is used as a cooling medium. With the end of the cold war, supplies of titanium became much more readily available and more reasonably priced. As a result, within the past few years, titanium has become the metal of choice for tubing whenever seawater is used for cooling. Its high resistance to corrosion and erosion in marine environments, and virtual elimination of tubeside foulingmore » and scaling make it a prime candidate for heat exchanger tube replacement in coastal plants. Titanium is still not inexpensive. However, this is compensated for by using a low-profile finned-tube design. The paper describe the heat exchanger retrofit in the LNG plant.« less

NLO evolution of color dipole

DOE PAGES

Balitsky, Ian; Chirilli, Giovanni A.

2008-09-01

The small-x deep inelastic scattering in the saturation region is governed by the non-linear evolution of Wilson-line operators. In the leading logarithmic approximation it is given by the BK equation for the evolution of color dipoles. In the next-to-leading order the BK equation gets contributions from quark and gluon loops as well as from the tree gluon diagrams with quadratic and cubic nonlinearities.

Study of Spin through Gluon Poles

NASA Astrophysics Data System (ADS)

Anikin, I. V.; Szymanowski, L.; Teryaev, O. V.; Volchanskiy, N.

2017-12-01

Based on the use of contour gauge and collinear factorization, we propose a new set of single spin asymmetry which can be measured in polarized Drell-Yan process by SPD@NICA. We stress that all of discussed single spin asymmetries exist owing to the gluon poles manifesting in the twist-3 or twist-2⊗twist-3 parton distributions related to the transverse-polarized Drell-Yan process.

Entropy production during hadronization of a quark-gluon plasma

NASA Astrophysics Data System (ADS)

Biró, Tamás S.; Schram, Zsolt; Jenkovszky, László

2018-02-01

We revisit some physical pictures for the hadronization of quark-gluon plasma, concentrating on the problem of entropy production during processes where the number of degrees of freedom is seemingly reduced due to color confinement. Based on observations on Regge trajectories we propose not having an infinite tower of hadronic resonances. We discuss possible entropy production mechanisms far from equilibrium in terms of stochastic dynamics.

Is q̂ a physical quantity or just a parameter? and other unanswered questions in high-pT physics

NASA Astrophysics Data System (ADS)

Tannenbaum, M. J.

2017-02-01

The many different theoretical studies of energy loss of a quark or gluon traversing a medium have one thing in common: the transport coefficient of a gluon in the medium, denoted q̂, which is defined as the mean 4-momentum transfer-square, q 2, by a gluon to the medium per gluon mean free path, λmfp. In the original BDMPSZ formalism, the energy loss of an outgoing parton, -dE/dx, per unit length (x) of a medium with total length L, due to coherent gluon bremsstrahlung is proportional to the q 2 and takes the form: where µ, is the mean momentum transfer per collision. Thus, the total energy loss in the medium goes like L 2. Additionally, the accumulated momentum-square, ≤ft< {k_T^2} \\right> , transverse to a gluon traversing a length L in the medium is well approximated by < k_T^2> ≈ < {q^2}(L)> = \\hat qL. A simple estimate shows that the < k_T^2> ≈ \\hat qL should be observable at RHIC at \\sqrt {{s{{NN}}}} = 200{{ GeV}} via the broadening of di-hadron azimuthal correlations resulting in an azimuthal width ˜ \\sqrt 2 larger in Au+Au than in p + p collisions. Measurements relevant to this issue will be discussed as well as recent STAR jet results presented at QM2014 [1]. Other topics to be discussed include the danger of using forward energy to define centrality in p(d)+A collisions for high pT measurements, the danger of not using comparison p + p data at the same \\sqrt s in the same detector for R AA or lately for R pA measurements. Also, based on a comment at last year’s 9th workshop that the parton energy loss is proportional to dN ch /dη [2], new results on the dependence of the shift in the pT spectra in A+A collisions from the T AA-scaled p + p spectrum (to be discussed in detail in another presentation [3]) will be shown.

VINCIA for hadron colliders

DOE PAGES

Fischer, Nadine; Prestel, S.; Ritzmann, M.; ...

2016-10-28

We present the first public implementation of antenna-based QCD initial- and final-state showers. The shower kernels are 2→3 antenna functions, which capture not only the collinear dynamics but also the leading soft (coherent) singularities of QCD matrix elements. We define the evolution measure to be inversely proportional to the leading poles, hence gluon emissions are evolved in a p ⊥ measure inversely proportional to the eikonal, while processes that only contain a single pole (e.g., g → qq¯) are evolved in virtuality. Non-ordered emissions are allowed, suppressed by an additional power of 1/Q 2. Recoils and kinematics are governed bymore » exact on-shell 2 → 3 phase-space factorisations. This first implementation is limited to massless QCD partons and colourless resonances. Tree-level matrix-element corrections are included for QCD up to O(α 4 s) (4 jets), and for Drell–Yan and Higgs production up to O(α 3 s) (V / H + 3 jets). Finally, the resulting algorithm has been made publicly available in Vincia 2.0.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Naganoma, Junji

The study of the top quark pair production mechanism in proton-antiproton collisions at a center-of-mass energy of 1.96 TeV is described. The main subjects are the measurements of the top quark pair production cross section, the top quark mass and a search for a new particle decaying to the top quark pair. The analyses are based on 1.9 fb -1 of data collected by the Collider Detector at Fermilab (CDF) Run II experiment between March 2002 and May 2007, using the lepton+jets events. The measured top quark pair production cross section is 8.2 ± 0.5 (stat.) ± 0.8 (syst.) ± 0.5 (lum.) pb, which is slightly higher than the standard model prediction at the top mass of 175 GeV/c 2. The top quark mass is an important parameter in the standard model, and also in the experimental studies. The measured top quark mass if 171.6 ± 2.0 (stat.) ± 1.3(syst.) GeV/c 2. Finally, they report on a search for a new gauge boson decaying to tmore » $$\\bar{t}$$, which interferes with the standard model gluon in the q$$\\bar{q}$$ → t$$\\bar{t}$$ production process. They call such a hypothetical particle a 'Massive Gluon'. The observed t$$\\bar{t}$$ invariant mass distribution is consistent with the standard model expectations, and also the measured massive gluon coupling strength with quarks is consistent within a statistical fluctuation of the standard model expectation in the wide range of the massive gluon masses and widths. They set the upper and lower limits on the coupling strength of the massive gluon.« less

Time-dependent observables in heavy ion collisions. Part I. Setting up the formalism

NASA Astrophysics Data System (ADS)

Wu, Bin; Kovchegov, Yuri V.

2018-03-01

We adapt the Schwinger-Keldysh formalism to study heavy-ion collisions in perturbative QCD. Employing the formalism, we calculate the two-point gluon correlation function G 22 aμ, bν due to the lowest-order classical gluon fields in the McLerran-Venugopalan model of heavy ion collisions and observe an interesting transition from the classical fields to the quasi-particle picture at later times. Motivated by this observation, we push the formalism to higher orders in the coupling and calculate the contribution to G 22 aμ, bν coming from the diagrams representing a single rescattering between two of the produced gluons. We assume that the two gluons go on mass shell both before and after the rescattering. The result of our calculation depends on which region of integration over the proper time of the rescattering τ Z gives the correct correlation function at late proper time τ when the gluon distribution is measured. For (i) τ Z ≫ 1 /Q s and τ - τ Z ≫ 1 /Q s (with Q s the saturation scale) we obtain the same results as from the Boltzmann equation. For (ii) τ - τ Z ≫ τ Z ≫ 1 /Q s we end up with a result very different from kinetic theory and consistent with a picture of "free-streaming" particles. Due to the approximations made, our calculation is too coarse to indicate whether the region (i) or (ii) is the correct one: to resolve this controversy, we shall present a detailed diagrammatic calculation of the rescattering correction in the φ 4 theory in the second paper of this duplex.

Introduction to the physics of the total cross section at LHC. A review of data and models

NASA Astrophysics Data System (ADS)

Pancheri, Giulia; Srivastava, Yogendra N.

2017-03-01

This review describes the development of the physics of hadronic cross sections up to recent LHC results and cosmic ray experiments. We present here a comprehensive review - written with a historical perspective - about total cross sections from medium to the highest energies explored experimentally and studied through a variety of methods and theoretical models for over 60 years. We begin by recalling the analytic properties of the elastic amplitude and the theorems about the asymptotic behavior of the total cross section. A discussion of how proton-proton cross sections are extracted from cosmic rays at higher than accelerator energies and help the study of these asymptotic limits, is presented. This is followed by a description of the advent of particle colliders, through which high energies and unmatched experimental precisions have been attained. Thus the measured hadronic elastic and total cross sections have become crucial instruments to probe the so called soft part of QCD physics, where quarks and gluons are confined, and have led to test and refine Regge behavior and a number of diffractive models. As the c.m. energy increases, the total cross section also probes the transition into hard scattering describable with perturbative QCD, the so-called mini-jet region. Further tests are provided by cross section measurements of γ p, γ ^* p and γ ^* γ ^* for models based on vector meson dominance, scaling limits of virtual photons at high Q^2 and the BFKL formalism. Models interpolating from virtual to real photons are also tested.

Study of generalized parton distributions and deeply virtual compton scattering on the nucleon with the CLAS and CLAS12 detectors at the Jefferson Laboratory

NASA Astrophysics Data System (ADS)

Guegan, Baptiste

The Generalized Parton Distributions (GPDs) provide a new description of the nucleon structure in terms of its elementary constituents, the quarks and the gluons. The GPDs give access to a unified picture of the nucleon, correlating the information obtained from the measurements of the Form Factors and the Parton Distribution Functions. They describe the correlation between the transverse position and the longitudinal momentum fraction of the partons in the nucleon. Deeply Virtual Compton Scattering (DVCS), the electroproduction of a real photon on a single quark of the nucleon eN → eN'gamma , is the most straightforward exclusive process allowing access to the GPDs. The DVCS process interferes with the Bethe-Heitler (BH) process, in which the real photon is emitted by either the incoming or the scattered electron instead of the nucleon. A dedicated experiment to study DVCS with the CLAS detector of Jefferson Lab has been carried out using a 5.883 GeV polarized electron beam and an unpolarized hydrogen target, allowing to collect DVCS events in the widest kinematic range ever explored in the valence region : 1 < Q2 < 4.6 GeV2, 0.1 < xB < 0.58, 0.09 < -t < 3 GeV2. We will present preliminary results on the extraction of the unpolarized and the difference of polarized DVCS cross sections. We will show a preliminary extraction of the GPDs using the latest fitting code procedure on our data, and a preliminary interpretation of the results.

Poincare recurrence theorem and the strong CP problem

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kalloniatis, Alex C.; Nedelko, Sergei N.; Bogoliubov Laboratory of Theoretical Physics, JINR, 141980 Dubna

2006-02-01

The existence in the physical QCD vacuum of nonzero gluon condensates, such as , requires dominance of gluon fields with finite mean action density. This naturally allows any real number value for the unit 'topological charge' q characterizing the fields approximating the gluon configurations which should dominate the QCD partition function. If q is an irrational number then the critical values of the {theta} parameter for which CP is spontaneously broken are dense in R, which provides for a mechanism of resolving the strong CP problem simultaneously with a correct implementation of U{sub A}(1) symmetry. We present anmore » explicit realization of this mechanism within a QCD motivated domain model. Some model independent arguments are given that suggest the relevance of this mechanism also to genuine QCD.« less

On the zero-crossing of the three-gluon Green's function from lattice simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Athenodorou, Andreas; Boucaud, Philippe; de Soto, Feliciano

We report on some efforts recently made in order to gain a better understanding of some IR properties of the 3-point gluon Green’s function by exploiting results from large-volume quenched lattice simulations. These lattice results have been obtained by using both tree-level Symanzik and the standard Wilson action, in the aim of assessing the possible impact of effects presumably resulting from a particular choice for the discretization of the action. The main resulting feature is the existence of a negative log-aritmic divergence at zero-momentum, which pulls the 3-gluon form factors down at low momenta and, consequently, yields a zero-crossing atmore » a given deep IR momentum. The results can be correctly explained by analyzing the relevant Dyson-Schwinger equations and appropriate truncation schemes.« less

Quark-Gluon Soup -- The Perfectly Liquid Phase of QCD

NASA Astrophysics Data System (ADS)

Heinz, Ulrich

2015-03-01

At temperatures above about 150 MeV and energy densities exceeding 500 MeV/fm3, quarks and gluons exist in the form of a plasma of free color charges that is about 1000 times hotter and a billion times denser than any other plasma ever created in the laboratory. This quark-gluon plasma (QGP) turns out to be strongly coupled, flowing like a liquid. About 35 years ago, the nuclear physics community started a program of relativistic heavy-ion collisions with the goal of producing and studying QGP under controlled laboratory conditions. This article recounts the story of its successful creation in collider experiments at Brookhaven National Laboratory and CERN and the subsequent discovery of its almost perfectly liquid nature, and reports on the recent quantitatively precise determination of its thermodynamic and transport properties.

Quark-gluon soup — The perfectly liquid phase of QCD

NASA Astrophysics Data System (ADS)

Heinz, Ulrich

2015-01-01

At temperatures above about 150 MeV and energy densities exceeding 500 MeV/fm3, quarks and gluons exist in the form of a plasma of free color charges that is about 1000 times hotter and a billion times denser than any other plasma ever created in the laboratory. This quark-gluon plasma (QGP) turns out to be strongly coupled, flowing like a liquid. About 35 years ago, the nuclear physics community started a program of relativistic heavy-ion collisions with the goal of producing and studying QGP under controlled laboratory conditions. This article recounts the story of its successful creation in collider experiments at Brookhaven National Laboratory and CERN and the subsequent discovery of its almost perfectly liquid nature, and reports on the recent quantitatively precise determination of its thermodynamic and transport properties.

Light-cone singularities and transverse-momentum-dependent factorization at twist-3

NASA Astrophysics Data System (ADS)

Chen, A. P.; Ma, J. P.

2017-05-01

We study transverse-momentum-dependent factorization at twist-3 for Drell-Yan processes. The factorization can be derived straightforwardly at leading order of αs. But at this order we find that light-cone singularities already exist and effects of soft gluons are not correctly factorized. We regularize the singularities with gauge links off the light-cone and introduce a soft factor to factorize the effects of soft gluons. Interestingly, the soft factor must be included in the definition of subtracted TMD parton distributions to correctly factorize the effects of soft gluons. We derive the Collins-Soper equation for one of twist-3 TMD parton distributions. The equation can be useful for resummation of large logarithms terms appearing in the corresponding structure function in collinear factorization. However, the derived equation is nonhomogeneous. This will make the resummation complicated.

Propagation of cosmic rays through the atmosphere in the quark-gluon strings model

NASA Technical Reports Server (NTRS)

Erlykin, A. D.; Krutikova, N. P.; Shabelski, Y. M.

1985-01-01

The quark-gluon strings model succeeds in the description of multiple hadron production in the central rapidity region of nucleon-nucleon interctions. This model was developed for hadron-nucleus interactions and used for calculation of the cosmic ray propagation through the atmosphere. It is shown that at energies 10 to the 11th power to the 12th power eV, this model gives a satisfactory description of experimental data. But with the increase of the energy up to approximately 10 to the 14th power eV, results of calculations and of experiments begin to differ and this difference rises with the energy. It may indicate that the scaling violation in the fragmentation region of inclusive spectra for hadron-nucleus interactions is stronger than in the quark-gluon strings model.

Reciprocal Exchange: Understanding the Community Partner Perspective in Higher Education Service-Learning

ERIC Educational Resources Information Center

Petri, Alexis Nicolle

2012-01-01

This study investigates service-learning from the community partners' perspective, especially in terms of reciprocity. As a central construct in the theory of service-learning, reciprocity for community partners is virtually unknown. Little scholarship exists that explains or explores the benefits and opportunity costs of service-learning. One…

Virtual Collaborations in the Spanish Class: From E-Mail to Web Design and CD-ROM Development.

ERIC Educational Resources Information Center

Hellebrandt, Josef

1999-01-01

Modern technologies can provide language students with authentic content and contextualized, collaborative learning situations. This article illustrates how e-mail exchanges, Web exercises, and CD-ROM development between students in the United States and organizations in Ecuador can promote contextualized and authentic practice of Spanish language…

Social Network Analysis in E-Learning Environments: A Preliminary Systematic Review

ERIC Educational Resources Information Center

Cela, Karina L.; Sicilia, Miguel Ángel; Sánchez, Salvador

2015-01-01

E-learning occupies an increasingly prominent place in education. It provides the learner with a rich virtual network where he or she can exchange ideas and information and create synergies through interactions with other members of the network, whether fellow learners or teachers. Social network analysis (SNA) has proven extremely powerful at…

Virtual Communities of Practice: Bridging Research and Practice Using Web 2.0

ERIC Educational Resources Information Center

Lewis, Laura A.; Koston, Zoe; Quartley, Marjorie; Adsit, Jason

2011-01-01

A significant dilemma for the health and human service professions continues to be the question of how best to bridge the divide between academic research and practice. Communities of practice have traditionally been a vehicle for collaborative research and for information exchange (Moore, 2008). Through collaboration, communities of practice have…

School Districts, Communications, and Freedom of Information

ERIC Educational Resources Information Center

Mawdsley, Ralph D.

2012-01-01

Virtually every state has a stature entitling public access to meetings of governing bodies, including school boards. The exchange of information between the district and the public is governed by a variety of statutes. These statutes reflect a policy whereby the business of school boards is to be transparent and exposed to public scrutiny. Three…

The Effect of Communicative Impediments on Interpersonal Attachment and Deviance

ERIC Educational Resources Information Center

Richardson, Nick J.; Barnum, Christopher C.

2010-01-01

This article introduces a theory describing the relationship between factors that increase social isolation and deviance. The theory is examined in the context of virtual visitation. We integrate social exchange, anomie, and strain theories to argue that as communication is impeded between two actors, the less satisfied either will be with the…

Networking of Bibliographical Information: Lessons learned for the Virtual Observatory

NASA Astrophysics Data System (ADS)

Genova, Françoise; Egret, Daniel

Networking of bibliographic information is particularly remarkable in astronomy. On-line journals, the ADS bibliographic database, SIMBAD and NED are everyday tools for research, and provide easy navigation from one resource to another. Tables are published on line, in close collaboration with data centers. Recent new developments include the links between observatory archives and the ADS, as well as the large scale prototyping of object links between Astronomy and Astrophysics and SIMBAD, following those implemented a few years ago with New Astronomy and the International Bulletin of Variable stars . This networking has been made possible by close collaboration between the ADS, data centers such as the CDS and NED, and the journals, and this partnership being now extended to observatory archives. Simple, de facto exchange standards, like the bibcode to refer to a published paper, have been the key for building links and exchanging data. This partnership, in which practitioners from different disciplines agree to link their resources and to work together to define useful and usable standards, has produced a revolution in scientists' practice. It is an excellent model for the Virtual Observatory projects.

Social Media, Education and Data Sharing

NASA Astrophysics Data System (ADS)

King, T. A.; Walker, R. J.; Masters, A.

2011-12-01

Social media is a blending of technology and social interactions which allows for the creation and exchange of user-generated content. Social media started as conversations between groups of people, now companies are using social media to communicate with customers and politicians use it to communicate with their constituents. Social media is now finding uses in the science communities. This adoption is driven by the expectation of students that technology will be an integral part of their research and that it will match the technology they use in their social lifes. Students are using social media to keep informed and collaborate with others. They have also replaced notepads with smart mobile devices. We have been introducing social media components into Virtual Observatories as a way to quickly access and exchange information with a tap or a click. We discuss the use of Quick Response (QR) codes, Digital Object Identifiers (DOIs), unique identifiers, Twitter, Facebook and tiny URL redirects as ways to enable easier sharing of data and information. We also discuss what services and features are needed in a Virtual Observatory to make data sharing with social media possible.

Deeply virtual and exclusive electroproduction of ω-mesons

NASA Astrophysics Data System (ADS)

Morand, L.; Doré, D.; Garçon, M.; Guidal, M.; Laget, J.-M.; Morrow, S.; Sabatié, F.; Smith, E.; Adams, G.; Ambrozewicz, P.; Anghinolfi, M.; Asryan, G.; Audit, G.; Avakian, H.; Bagdasaryan, H.; Ball, J.; Ball, J. P.; Baltzell, N. A.; Barrow, S.; Batourine, V.; Battaglieri, M.; Bektasoglu, M.; Bellis, M.; Benmouna, N.; Berman, B. L.; Biselli, A. S.; Boiarinov, S.; Bonner, B. E.; Bouchigny, S.; Bradford, R.; Branford, D.; Briscoe, W. J.; Brooks, W. K.; Bültmann, S.; Burkert, V. D.; Butuceanu, C.; Calarco, J. R.; Careccia, S. L.; Carman, D. S.; Cazes, A.; Chen, S.; Cole, P. L.; Cords, D.; Corvisiero, P.; Crabb, D.; Cummings, J. P.; de Sanctis, E.; Devita, R.; Degtyarenko, P. V.; Denizli, H.; Dennis, L.; Deur, A.; Dharmawardane, K. V.; Dhuga, K. S.; Djalali, C.; Dodge, G. E.; Donnelly, J.; Doughty, D.; Dugger, M.; Dytman, S.; Dzyubak, O. P.; Egiyan, H.; Egiyan, K. S.; Elouadrhiri, L.; Eugenio, P.; Fatemi, R.; Feldman, G.; Fersch, R. G.; Feuerbach, R. J.; Funsten, H.; Gavalian, G.; Gilfoyle, G. P.; Giovanetti, K. L.; Girod, F.-X.; Goetz, J. T.; Gordon, C. I. O.; Gothe, R. W.; Griffioen, K. A.; Guillo, M.; Guler, N.; Guo, L.; Gyurjyan, V.; Hadjidakis, C.; Hakobyan, R. S.; Hardie, J.; Heddle, D.; Hersman, F. W.; Hicks, K.; Hleiqawi, I.; Holtrop, M.; Hyde-Wright, C. E.; Ilieva, Y.; Ireland, D. G.; Ito, M. M.; Jenkins, D.; Jo, H.-S.; Joo, K.; Juengst, H. G.; Kellie, J. D.; Khandaker, M.; Kim, W.; Klein, A.; Klein, F. J.; Klimenko, A. V.; Kossov, M.; Kubarovski, V.; Kramer, L. H.; Kuhn, S. E.; Kuhn, J.; Lachniet, J.; Langheinrich, J.; Lawrence, D.; Lee, T.; Li, Ji; Livingston, K.; Marchand, C.; Maximon, L. C.; McAleer, S.; McKinnon, B.; McNabb, J. W. C.; Mecking, B. A.; Mehrabyan, S.; Melone, J. J.; Mestayer, M. D.; Meyer, C. A.; Mikhailov, K.; Minehart, R.; Mirazita, M.; Miskimen, R.; Mokeev, V.; Mueller, J.; Mutchler, G. S.; Napolitano, J.; Nasseripour, R.; Niccolai, S.; Niculescu, G.; Niculescu, I.; Niczyporuk, B. B.; Niyazov, R. A.; Nozar, M.; O'Rielly, G. V.; Osipenko, M.; Ostrovidov, A. I.; Park, K.; Pasyuk, E.; Philips, S. A.; Pivnyuk, N.; Pocanic, D.; Pogorelko, O.; Polli, E.; Popa, I.; Pozdniakov, S.; Preedom, B. M.; Price, J. W.; Prok, Y.; Protopopescu, D.; Raue, B. A.; Riccardi, G.; Ricco, G.; Ripani, M.; Ritchie, B. G.; Ronchetti, F.; Rosner, G.; Rossi, P.; Rubin, P. D.; Salgado, C.; Santoro, J. P.; Sapunenko, V.; Schumacher, R. A.; Serov, V. S.; Sharabian, Y. G.; Shaw, J.; Skabelin, A. V.; Smith, L. C.; Sober, D. I.; Stavinsky, A.; Stepanyan, S.; Stepanyan, S. S.; Stokes, B. E.; Stoler, P.; Strakovsky, I. I.; Strauch, S.; Taiuti, M.; Tedeschi, D. J.; Thoma, U.; Tkabladze, A.; Todor, L.; Tur, C.; Ungaro, M.; Vineyard, M. F.; Vlassov, A. V.; Weinstein, L. B.; Weygand, D. P.; Williams, M.; Wolin, E.; Wood, M. H.; Yegneswaran, A.; Zana, L.

2005-06-01

The exclusive ω electroproduction off the proton was studied in a large kinematical domain above the nucleon resonance region and for the highest possible photon virtuality (Q2) with the 5.75 GeV beam at CEBAF and the CLAS spectrometer. Cross-sections were measured up to large values of the four-momentum transfer (- t < 2.7 GeV2) to the proton. The contributions of the interference terms σ{TT} and σ{TL} to the cross-sections, as well as an analysis of the ω spin density matrix, indicate that helicity is not conserved in this process. The t-channel π0 exchange, or more generally the exchange of the associated Regge trajectory, seems to dominate the reaction γ*p↦ωp, even for Q2 as large as 5 GeV2. Contributions of handbag diagrams, related to Generalized Parton Distributions in the nucleon, are therefore difficult to extract for this process. Remarkably, the high-t behaviour of the cross-sections is nearly Q2-independent, which may be interpreted as a coupling of the photon to a point-like object in this kinematical limit.

Center-defined unacceptable HLA antigens facilitate transplants for sensitized patients in a multi-center kidney exchange program.

PubMed

Baxter-Lowe, L A; Cecka, M; Kamoun, M; Sinacore, J; Melcher, M L

2014-07-01

Multi-center kidney paired donation (KPD) is an exciting new transplant option that has not yet approached its full potential. One barrier to progress is accurate virtual crossmatching for KPD waitlists with many highly sensitized patients. Virtual crossmatch results from a large multi-center consortium, the National Kidney Registry (NKR), were analyzed to determine the effectiveness of flexible center-specific criteria for virtual crossmatching. Approximately two-thirds of the patients on the NKR waitlist are highly sensitized (>80% CPRA). These patients have antibodies against HLA-A (63%), HLA-B (66%), HLA-C (41%), HLA-DRB1 (60%), HLA-DRB3/4/5 (18-22%), HLA-DQB1 (54%) and HLA-DPB1 (26%). With donors typed for these loci before activation, 91% of virtual crossmatches accurately predicted an acceptable cell-based donor crossmatch. Failed virtual crossmatches were attributed to equivocal virtual crossmatches (46%), changes in HLA antibodies (21%), antibodies against HLA-DQA (6%), transcription errors (6%), suspected non-HLA antibodies (5%), allele-specific antibodies (1%) and unknown causes (15%). Some failed crossmatches could be prevented by modifiable factors such as more frequent assessment of HLA antibodies, DQA1 typing of donors and auditing data entry. Importantly, when transplant centers have flexibility to define crossmatch criteria, it is currently feasible to use virtual crossmatching for highly sensitized patients to reliably predict acceptable cell-based crossmatches. © Copyright 2014 The American Society of Transplantation and the American Society of Transplant Surgeons.

Tree-level gluon amplitudes on the celestial sphere

NASA Astrophysics Data System (ADS)

Schreiber, Anders Ø.; Volovich, Anastasia; Zlotnikov, Michael

2018-06-01

Pasterski, Shao and Strominger have recently proposed that massless scattering amplitudes can be mapped to correlators on the celestial sphere at infinity via a Mellin transform. We apply this prescription to arbitrary n-point tree-level gluon amplitudes. The Mellin transforms of MHV amplitudes are given by generalized hypergeometric functions on the Grassmannian Gr (4 , n), while generic non-MHV amplitudes are given by more complicated Gelfand A-hypergeometric functions.

How large is the gluon polarization in the statistical parton distributions approach?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soffer, Jacques; Bourrely, Claude; Buccella, Franco

2015-04-10

We review the theoretical foundations of the quantum statistical approach to parton distributions and we show that by using some recent experimental results from Deep Inelastic Scattering, we are able to improve the description of the data by means of a new determination of the parton distributions. We will see that a large gluon polarization emerges, giving a significant contribution to the proton spin.

From quarks and gluons to baryon form factors.

PubMed

Eichmann, Gernot

2012-04-01

I briefly summarize recent results for nucleon and [Formula: see text] electromagnetic, axial and transition form factors in the Dyson-Schwinger approach. The calculation of the current diagrams from the quark-gluon level enables a transparent discussion of common features such as: the implications of dynamical chiral symmetry breaking and quark orbital angular momentum, the timelike structure of the form factors, and their interpretation in terms of missing pion-cloud effects.

Search for the top quark at CDF in events with two charged leptons, neutrinos and hadronic jets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leone, Sandra

1994-02-01

In this thesis we have investigated the direct production of top-anti top pairs through the gluon-gluon fusion and the quark-antiquark annihilation: gg→tt¯gg→tt¯ and qq¯→tt¯qq¯→tt¯. In the Standard Model each top quark decays to an intermediate vector boson W and a b quark ( t→Wbt→Wb )

Using blackmail, bribery, and guilt to address the tragedy of the virtual intellectual commons

NASA Astrophysics Data System (ADS)

Griffith, P. C.; Cook, R. B.; Wilson, B. E.; Gentry, M. J.; Horta, L. M.; McGroddy, M.; Morrell, A. L.; Wilcox, L. E.

2008-12-01

One goal of the NSF's vision for 21st Century Cyberinfrastructure is to create a virtual intellectual commons for the scientific community where advanced technologies perpetuate transformation of this community's productivity and capabilities. The metadata describing scientific observations, like the first paragraph of a news story, should answer the questions who? what? why? where? when? and how?, making them discoverable, comprehensible, contextualized, exchangeable, and machine-readable. Investigators who create good scientific metadata increase the scientific value of their observations within such a virtual intellectual commons. But the tragedy of this commons arises when investigators wish to receive without giving in return. The authors of this talk will describe how they have used combinations of blackmail, bribery, and guilt to motivate good behavior by investigators participating in two major scientific programs (NASA's component of the Large-scale Biosphere-Atmosphere Experiment in Amazonia; and the US Climate Change Science Program's North American Carbon Program).

Social Interaction Behavior in ADHD in Adults in a Virtual Trust Game.

PubMed

Lis, Stefanie; Baer, Nina; Franzen, Nele; Hagenhoff, Meike; Gerlach, Maika; Koppe, Georgia; Sammer, Gebhard; Gallhofer, Bernd; Kirsch, Peter

2016-04-01

Social cognitive functions in adults with ADHD were investigated in a virtual social exchange game. The sample consisted of 40 participants (20 adult ADHD participants, 20 healthy controls). Participants played a multiround trust game with virtual trustees who differed in regard to fairness and presence of emotional facial cues. Investments were higher in ADHD participants than in healthy participants except for partners who played fair with constant neutral expressions. ADHD patients did not adapt their behavior to the fairness of the trustee. In the presence of emotional facial cues, ADHD and healthy participants transferred more monetary units to happy rather than angry-looking trustees. Differences in investment behavior were not linked to deficits in emotion-recognition abilities or cognitive dysfunctions. Alterations in interaction behavior and in the formation of a general attitude toward social partners could be shown in adults with ADHD. © The Author(s) 2013.

MICA: The Meta-Institute for Computational Astrophysics

NASA Astrophysics Data System (ADS)

McMillan, Stephen L. W.; Djorgovski, S. G.; Hut, P.; Vesperini, E.; Knop, R.; Portegies Zwart, S.

2009-05-01

We describe MICA, the Meta Institute for Computational Astrophysics, the first professional scientific and educational, non-profit organization based in virtual worlds [VWs]. Most MICA activities are currently conducted in Second Life, arguably the most popular and best developed VW; we plan to expand our presence into other VWs as those venues evolve. The goals of MICA include (1) exploration, development and promotion of VWs and virtual reality [VR] technologies for professional research in astronomy and related fields; (2) development of novel networking venues and mechanisms for virtual scientific communication and interaction, including professional meetings, visualization, and telecollaboration; (3) use of VWs and VR technologies for education and public outreach; and (4) exchange of ideas and joint efforts with other scientific disciplines in promoting these goals for science and scholarship in general. We present representative example of MICA activities and achievements, and outline plans for expansion of the organization. For more information on MICA, please visit http://mica-vw.org .

Do Gluons Carry Proton Spin? - Toward Resolving the Spin Crisis (445th Brookhaven Lecture)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bazilevsky, Alexander

2009-01-21

Just as Earth and other planets spin within the solar system, subatomic quark and gluon particles spin within the protons and neutrons that spin within the nucleus of an atom. Quantum Chromodynamics (QCD) is a theory that describes interactions between subatomic particles and it has played a defining role in understanding the spin of protons and neutrons, which make up most of the visible mass in the universe. Experiments first completed at CERN and furthered at several other laboratories around the world revealed that surprisingly, quarks and their partnering anti-quarks are responsible for only 20 to 30 percent of protonmore » spin. These findings pointed to what would become known as "spin crisis." More recent experiments at BNL's Relativistic Heavy Ion Collider (RHIC), the first collider to smash protons that are "polarized," or made to spin in the same orientation, have helped to isolate the role of the gluon's spin within the spinning proton in hopes of resolving this crisis. In his lecture, Bazilevsky will explain how data from RHIC's PHENIX and STAR detectors help to reveal the role of gluons in the proton's spin. Bazilevsky will also discuss long- and short-term plans to attain a deeper look into the proton spin structure, utilizing RHIC and its future upgrades« less

Gluon dynamics, center symmetry, and the deconfinement phase transition in SU(3) pure Yang-Mills theory

NASA Astrophysics Data System (ADS)

Silva, P. J.; Oliveira, O.

2016-06-01

The correlations between the modulus of the Polyakov loop, its phase θ , and the Landau gauge gluon propagator at finite temperature are investigated in connection with the center symmetry for pure Yang-Mills SU(3) theory. In the deconfined phase, where the center symmetry is spontaneously broken, the phase of the Polyakov loop per configuration is close to θ =0 , ±2 π /3 . We find that the gluon propagator form factors associated with θ ≈0 differ quantitatively and qualitatively from those associated to θ ≈±2 π /3 . This difference between the form factors is a property of the deconfined phase and a sign of the spontaneous breaking of the center symmetry. Furthermore, given that this difference vanishes in the confined phase, it can be used as an order parameter associated to the deconfinement transition. For simulations near the critical temperature Tc, the difference between the propagators associated to θ ≈0 and θ ≈±2 π /3 allows one to classify the configurations as belonging to the confined or deconfined phase. This establishes a selection procedure which has a measurable impact on the gluon form factors. Our results also show that the absence of the selection procedure can be erroneously interpreted as lattice artifacts.

The time-delay signature of quark-gluon plasma formation in relativistic nuclear collisions

NASA Astrophysics Data System (ADS)

Rischke, Dirk H.; Gyulassy, Miklos

1996-02-01

The hydrodynamic expansion of quark-gluon plasmas with spherical and longitudinally boost-invariant geometries is studied as a function of the initial energy density. The sensitivity of the collective flow pattern to uncertainties in the nuclear matter equation of state is explored. We concentrate on the effect of a possible finite width, ΔT ˜ 0.1 Tc, of the transition region between quark-gluon plasma and hadronic phase. Although slow deflagration solutions that act to stall the expansion do not exist for ΔT > 0.08 Tc, we find, nevertheless, that the equation of state remains sufficiently soft in the transition region to delay the propagation of ordinary rarefaction waves for a considerable time. We compute the dependence of the pion-interferometry correlation function on ΔT, since this is the most promising observable for time-delayed expansion. The signature of time delay, proposed by Pratt and Bertsch, is an enhancement of the ratio of the inverse width of the pion correlation function in out-direction to that in side-direction. One of our main results is that this generic signature of quark-gluon plasma formation is rather robust to the uncertainties in the width of the transition region. Furthermore, for longitudinal boost-invariant geometries, the signal is likely to be maximized around RHIC energies

Casimir meets Poisson: improved quark/gluon discrimination with counting observables

DOE PAGES

Frye, Christopher; Larkoski, Andrew J.; Thaler, Jesse; ...

2017-09-19

Charged track multiplicity is among the most powerful observables for discriminating quark- from gluon-initiated jets. Despite its utility, it is not infrared and collinear (IRC) safe, so perturbative calculations are limited to studying the energy evolution of multiplicity moments. While IRC-safe observables, like jet mass, are perturbatively calculable, their distributions often exhibit Casimir scaling, such that their quark/gluon discrimination power is limited by the ratio of quark to gluon color factors. In this paper, we introduce new IRC-safe counting observables whose discrimination performance exceeds that of jet mass and approaches that of track multiplicity. The key observation is that trackmore » multiplicity is approximately Poisson distributed, with more suppressed tails than the Sudakov peak structure from jet mass. By using an iterated version of the soft drop jet grooming algorithm, we can define a “soft drop multiplicity” which is Poisson distributed at leading-logarithmic accuracy. In addition, we calculate the next-to-leading-logarithmic corrections to this Poisson structure. If we allow the soft drop groomer to proceed to the end of the jet branching history, we can define a collinear-unsafe (but still infrared-safe) counting observable. Exploiting the universality of the collinear limit, we define generalized fragmentation functions to study the perturbative energy evolution of collinear-unsafe multiplicity.« less

Casimir meets Poisson: improved quark/gluon discrimination with counting observables

DOE Office of Scientific and Technical Information (OSTI.GOV)

Frye, Christopher; Larkoski, Andrew J.; Thaler, Jesse

Charged track multiplicity is among the most powerful observables for discriminating quark- from gluon-initiated jets. Despite its utility, it is not infrared and collinear (IRC) safe, so perturbative calculations are limited to studying the energy evolution of multiplicity moments. While IRC-safe observables, like jet mass, are perturbatively calculable, their distributions often exhibit Casimir scaling, such that their quark/gluon discrimination power is limited by the ratio of quark to gluon color factors. In this paper, we introduce new IRC-safe counting observables whose discrimination performance exceeds that of jet mass and approaches that of track multiplicity. The key observation is that trackmore » multiplicity is approximately Poisson distributed, with more suppressed tails than the Sudakov peak structure from jet mass. By using an iterated version of the soft drop jet grooming algorithm, we can define a “soft drop multiplicity” which is Poisson distributed at leading-logarithmic accuracy. In addition, we calculate the next-to-leading-logarithmic corrections to this Poisson structure. If we allow the soft drop groomer to proceed to the end of the jet branching history, we can define a collinear-unsafe (but still infrared-safe) counting observable. Exploiting the universality of the collinear limit, we define generalized fragmentation functions to study the perturbative energy evolution of collinear-unsafe multiplicity.« less

Symmetry energy in cold dense matter

NASA Astrophysics Data System (ADS)

Jeong, Kie Sang; Lee, Su Houng

2016-01-01

We calculate the symmetry energy in cold dense matter both in the normal quark phase and in the 2-color superconductor (2SC) phase. For the normal phase, the thermodynamic potential is calculated by using hard dense loop (HDL) resummation to leading order, where the dominant contribution comes from the longitudinal gluon rest mass. The effect of gluonic interaction on the symmetry energy, obtained from the thermodynamic potential, was found to be small. In the 2SC phase, the non-perturbative BCS paring gives enhanced symmetry energy as the gapped states are forced to be in the common Fermi sea reducing the number of available quarks that can contribute to the asymmetry. We used high density effective field theory to estimate the contribution of gluon interaction to the symmetry energy. Among the gluon rest masses in 2SC phase, only the Meissner mass has iso-spin dependence although the magnitude is much smaller than the Debye mass. As the iso-spin dependence of gluon rest masses is even smaller than the case in the normal phase, we expect that the contribution of gluonic interaction to the symmetry energy in the 2SC phase will be minimal. The different value of symmetry energy in each phase will lead to different prediction for the particle yields in heavy ion collision experiment.

SU(2) lattice gluon propagator: Continuum limit, finite-volume effects, and infrared mass scale m{sub IR}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bornyakov, V. G.; Mitrjushkin, V. K.; Mueller-Preussker, M.

2010-03-01

We study the scaling behavior and finite (physical) volume effects as well as the Gribov copy dependence of the SU(2) Landau gauge gluon propagator on the lattice. Our physical lattice sizes range from (3.0 fm){sup 4} to (7.3 fm){sup 4}. Considering lattices with decreasing lattice spacing but fixed physical volume we confirm (nonperturbative) multiplicative renormalizability and the approach to the continuum limit for the renormalized gluon propagator D{sub ren}(p) at momenta |p| > or approx. 0.6 GeV. The finite-volume effects and Gribov copy influence turn out small in this region. On the contrary, in the deeper infrared we found themore » Gribov copy influence strong and finite-volume effects, which still require special attention. The gluon propagator does not seem to be consistent with a simple polelike behavior {approx}(p{sup 2}+m{sub g}{sup 2}){sup -1} for momenta |p| < or approx. 0.6 GeV. Instead, a Gaussian-type fit works very well in this region. From its width - for a physical volume (5.0 fm){sup 4} - we estimate a corresponding infrared (mass) scale to be m{sub IR{approx}}0.7 GeV.« less

Measuring the contribution of low Bjorken-x gluons to the proton spin with polarized proton-proton collisions

NASA Astrophysics Data System (ADS)

Wolin, Scott Justin

The PHENIX experiment is one of two detectors located at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory in Upton, NY. Understanding the spin structure of the proton is a central goal at RHIC, the only polarized proton-on-proton collider in existence. The PHENIX spin program has two primary objectives. The first is to improve the constraints on the polarized parton distributions of the anti-u and anti-d quarks within the proton. The second objective is to improve the constraint on the gluon spin contribution to the proton spin, DeltaG. The focus of this thesis is the second objective. PHENIX experiment has been successful at providing the first meaningful constraints on DeltaG, along with STAR, the other detector located at RHIC. These constraints have, in fact, eliminated the extreme scenarios for gluon polarization through measurements of the double spin asymmetry, ALL, between the cross section of like and unlike sign helicity pp interactions. ALL measurements can be performed with a variety of final states at PHENIX. Until 2009, these final states were only measured for pseudo-rapidities of |eta| < 0.35. This range of eta is referred to as mid-rapidity. These mid-rapidity measurements, like the polarized DIS measurements, suffer from a limited kinematic reach. Final states containing a measured particle with pT [special character omitted] 1 GeV/c are considered to have occurred in the hard scattering domain where the pp interaction is well approximated as an interaction of a quark or gluon in one proton and a quark or gluon in the second proton. Each of these interacting particles has a momentum fraction, x, of its parent proton's momentum. The gluon polarization is dependent on the momentum fraction and the net gluon polarization can be written as the integral of the momentum fraction dependent polarization: DeltaG = f(1,0)Delta g(x)dx. The momentum fractions of the two interacting particles give information about the final state jets. This provides the motivation to build a new calorimeter for PHENIX that is able to measure final states of pp interactions in which a low- x gluon was a participant. Like a fast moving car crashing into a slow moving car and the debris ending up mostly along the line of motion of the fast moving car, the debris of a high-x quark interacting with a low-x gluon will result in debris at forward rapidity at small angles to the initial quark momentum. The Muon Piston Calorimeter (MPC) was installed in 2006 and 2007 at forward rapidity, 3.1 < |eta| < 3.9, with the intention of giving PHENIX the ability to constrain Delta g(x) for x < 0.05. Following this, an electronics upgrade to the MPC will be described which enables the selection of events with two hadrons detected in the MPC. This requirement favors gluons at even lower x than the single hadron event selection. The di-hadron measurement that this upgrade makes possible will allow PHENIX to produce an ALL measurement that constrains Deltag(x) in the range of 5 x 10-4 < x < 0.01. Finally, we discuss the most important systematic uncertainty common to all ALL measurements which arises from the determination of the relative luminosity. A precision ALLL measurement requires measuring the final state yield from the portions of the proton beams that collide like and unlike sign helicity protons separately. It also requires understanding the ratio of the collision rates of these two portions of the beam exquisitely well. This is a long standing problem and, until recently, had threatened to severely restrict the ability of PHENIX to utilize the large data sets that have been acquired in the last two years to improve the constraints on DeltaG. We will conclude this thesis with a comprehensive overview of the relative luminosity systematic uncertainty and present a new framework within which this uncertainty can be determined. The measurement of the gluon contribution to the proton spin at the PHENIX experiment is a multi- faceted problem which requires a multi-faceted solution. This thesis describes several aspects of the solution as the single- and di-hadron measurements from MPC data are likely to provide the best constraints to Delta G at low-x for the next decade. Eventually, an Electron-Ion Collider (EIC) will be designed and commissioned that will further extend the kinematic reach of the polarized DIS experiments that motivated the spin program at RHIC. In the meantime, the goal of PHENIX in general, and the MPC in particular, is to glean as much information about the gluon polarization as possible before the EIC era arrives. (Abstract shortened by UMI.)

Type 2 Diabetes Education and Support in a Virtual Environment: A Secondary Analysis of Synchronously Exchanged Social Interaction and Support.

PubMed

Lewinski, Allison A; Anderson, Ruth A; Vorderstrasse, Allison A; Fisher, Edwin B; Pan, Wei; Johnson, Constance M

2018-02-21

Virtual environments (VEs) facilitate interaction and support among individuals with chronic illness, yet the characteristics of these VE interactions remain unknown. The objective of this study was to describe social interaction and support among individuals with type 2 diabetes (T2D) who interacted in a VE. Data included VE-mediated synchronous conversations and text-chat and asynchronous emails and discussion board posts from a study that facilitated interaction among individuals with T2D and diabetes educators (N=24) in 2 types of sessions: education and support. VE interactions consisted of communication techniques (how individuals interact in the VE), expressions of self-management (T2D-related topics), depth (personalization of topics), and breadth (number of topics discussed). Individuals exchanged support more often in the education (723/1170, 61.79%) than in the support (406/1170, 34.70%) sessions or outside session time (41/1170, 3.50%). Of all support exchanges, 535/1170 (45.73%) were informational, 377/1170 (32.22%) were emotional, 217/1170 (18.55%) were appraisal, and 41/1170 (3.50%) were instrumental. When comparing session types, education sessions predominately provided informational support (357/723, 49.4%), and the support sessions predominately provided emotional (159/406, 39.2%) and informational (159/406, 39.2%) support. VE-mediated interactions resemble those in face-to-face environments, as individuals in VEs engage in bidirectional exchanges with others to obtain self-management education and support. Similar to face-to-face environments, individuals in the VE revealed personal information, sought information, and exchanged support during the moderated education sessions and unstructured support sessions. With this versatility, VEs are able to contribute substantially to support for those with diabetes and, very likely, other chronic diseases. ©Allison A Lewinski, Ruth A Anderson, Allison A Vorderstrasse, Edwin B Fisher, Wei Pan, Constance M Johnson. Originally published in the Journal of Medical Internet Research (http://www.jmir.org), 21.02.2018.

Simulated Tempering Distributed Replica Sampling, Virtual Replica Exchange, and Other Generalized-Ensemble Methods for Conformational Sampling.

PubMed

Rauscher, Sarah; Neale, Chris; Pomès, Régis

2009-10-13

Generalized-ensemble algorithms in temperature space have become popular tools to enhance conformational sampling in biomolecular simulations. A random walk in temperature leads to a corresponding random walk in potential energy, which can be used to cross over energetic barriers and overcome the problem of quasi-nonergodicity. In this paper, we introduce two novel methods: simulated tempering distributed replica sampling (STDR) and virtual replica exchange (VREX). These methods are designed to address the practical issues inherent in the replica exchange (RE), simulated tempering (ST), and serial replica exchange (SREM) algorithms. RE requires a large, dedicated, and homogeneous cluster of CPUs to function efficiently when applied to complex systems. ST and SREM both have the drawback of requiring extensive initial simulations, possibly adaptive, for the calculation of weight factors or potential energy distribution functions. STDR and VREX alleviate the need for lengthy initial simulations, and for synchronization and extensive communication between replicas. Both methods are therefore suitable for distributed or heterogeneous computing platforms. We perform an objective comparison of all five algorithms in terms of both implementation issues and sampling efficiency. We use disordered peptides in explicit water as test systems, for a total simulation time of over 42 μs. Efficiency is defined in terms of both structural convergence and temperature diffusion, and we show that these definitions of efficiency are in fact correlated. Importantly, we find that ST-based methods exhibit faster temperature diffusion and correspondingly faster convergence of structural properties compared to RE-based methods. Within the RE-based methods, VREX is superior to both SREM and RE. On the basis of our observations, we conclude that ST is ideal for simple systems, while STDR is well-suited for complex systems.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brünner, F.; Parganlija, D.; Rebhan, A.

We present new results on the decay patterns of scalar and tensor glueballs in the top-down holographic Witten-Sakai-Sugimoto model. This model, which has only one free dimensionless parameter, gives semi-quantitative predictions for the vector meson spectrum, their decay widths, and also a gluon condensate in agreement with SVZ sum rules. The holographic predictions for scalar glueball decay rates are compared with experimental data for the widely discussed gluon candidates f{sub 0}(1500) and f{sub 0}(1710)

Relativistic Shock Waves in Viscous Gluon Matter

NASA Astrophysics Data System (ADS)

Bouras, I.; Molnár, E.; Niemi, H.; Xu, Z.; El, A.; Fochler, O.; Greiner, C.; Rischke, D. H.

2009-07-01

We solve the relativistic Riemann problem in viscous gluon matter employing a microscopic parton cascade. We demonstrate the transition from ideal to viscous shock waves by varying the shear viscosity to entropy density ratio η/s from zero to infinity. We show that an η/s ratio larger than 0.2 prevents the development of well-defined shock waves on time scales typical for ultrarelativistic heavy-ion collisions. Comparisons with viscous hydrodynamic calculations confirm our findings.

3D glasma initial state for relativistic heavy ion collisions

DOE PAGES

Schenke, Björn; Schlichting, Sören

2016-10-13

We extend the impact-parameter-dependent Glasma model to three dimensions using explicit small-x evolution of the two incoming nuclear gluon distributions. We compute rapidity distributions of produced gluons and the early-time energy momentum tensor as a function of space-time rapidity and transverse coordinates. Finally, we study rapidity correlations and fluctuations of the initial geometry and multiplicity distributions and make comparisons to existing models for the three-dimensional initial state.

From quarks and gluons to baryon form factors

PubMed Central

Eichmann, Gernot

2012-01-01

I briefly summarize recent results for nucleon and Δ(1232) electromagnetic, axial and transition form factors in the Dyson–Schwinger approach. The calculation of the current diagrams from the quark–gluon level enables a transparent discussion of common features such as: the implications of dynamical chiral symmetry breaking and quark orbital angular momentum, the timelike structure of the form factors, and their interpretation in terms of missing pion-cloud effects. PMID:26766879

Search for the Top Quark at CDF in Events with Two Charged Leptons, Neutrinos and Hadronic Jets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leone, Sandra

1994-06-01

In this thesis we have investigated the direct production of top-anti top pairs through the gluon-gluon fusion and the quark-antiquark annihilation:more » $$gg \\to t\\bar{t}$$ and $$q\\bar{q} \\to t\\bar{t}$$. In the Standard Model each top quark decays to an intermediate vector boson W and a b quark ( $$t \\to Wb$$ )....« less

Uncertainty of Polarized Parton Distributions

NASA Astrophysics Data System (ADS)

Hirai, M.; Goto, Y.; Horaguchi, T.; Kobayashi, H.; Kumano, S.; Miyama, M.; Saito, N.; Shibata, T.-A.

Polarized parton distribution functions are determined by a χ2 analysis of polarized deep inelastic experimental data. In this paper, uncertainty of obtained distribution functions is investigated by a Hessian method. We find that the uncertainty of the polarized gluon distribution is fairly large. Then, we estimate the gluon uncertainty by including the fake data which are generated from prompt photon process at RHIC. We observed that the uncertainty could be reduced with these data.

Deep learning in color: towards automated quark/gluon jet discrimination

DOE PAGES

Komiske, Patrick T.; Metodiev, Eric M.; Schwartz, Matthew D.

2017-01-25

Artificial intelligence offers the potential to automate challenging data-processing tasks in collider physics. Here, to establish its prospects, we explore to what extent deep learning with convolutional neural networks can discriminate quark and gluon jets better than observables designed by physicists. Our approach builds upon the paradigm that a jet can be treated as an image, with intensity given by the local calorimeter deposits. We supplement this construction by adding color to the images, with red, green and blue intensities given by the transverse momentum in charged particles, transverse momentum in neutral particles, and pixel-level charged particle counts. Overall, themore » deep networks match or outperform traditional jet variables. We also find that, while various simulations produce different quark and gluon jets, the neural networks are surprisingly insensitive to these differences, similar to traditional observables. This suggests that the networks can extract robust physical information from imperfect simulations.« less

Search for pair-produced massive coloured scalars in four-jet final states with the ATLAS detector in proton–proton collisions at $$\\sqrt{s} = 7\\ \\mbox{TeV}$$

DOE PAGES

Aad, G.; Abajyan, T.; Abbott, B.; ...

2013-01-15

A search for pair-produced massive coloured scalar particles decaying to a four-jet final state is performed by the ATLAS experiment at the LHC in proton–proton collisions at √s = 7 TeV. The analysed data sample corresponds to an integrated luminosity of 4.6 fb -1. No deviation from the Standard Model is observed in the invariant mass spectrum of the two-jet pairs. A limit on the scalar gluon pair production cross section of 70 pb (10 pb) is obtained at the 95 % confidence level for a scalar gluon mass of 150 GeV (350 GeV). Lastly, interpreting these results as massmore » limits on scalar gluons, masses ranging from 150 GeV to 287 GeV are excluded at the 95 % confidence level.« less

Deep learning in color: towards automated quark/gluon jet discrimination

NASA Astrophysics Data System (ADS)

Komiske, Patrick T.; Metodiev, Eric M.; Schwartz, Matthew D.

2017-01-01

Artificial intelligence offers the potential to automate challenging data-processing tasks in collider physics. To establish its prospects, we explore to what extent deep learning with convolutional neural networks can discriminate quark and gluon jets better than observables designed by physicists. Our approach builds upon the paradigm that a jet can be treated as an image, with intensity given by the local calorimeter deposits. We supplement this construction by adding color to the images, with red, green and blue intensities given by the transverse momentum in charged particles, transverse momentum in neutral particles, and pixel-level charged particle counts. Overall, the deep networks match or outperform traditional jet variables. We also find that, while various simulations produce different quark and gluon jets, the neural networks are surprisingly insensitive to these differences, similar to traditional observables. This suggests that the networks can extract robust physical information from imperfect simulations.

Wilson loop from a Dyson equation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pak, M.; Reinhardt, H.

2009-12-15

The Dyson equation proposed for planar temporal Wilson loops in the context of supersymmetric gauge theories is critically analyzed thereby exhibiting its ingredients and approximations involved. We reveal its limitations and identify its range of applicability in nonsupersymmetric gauge theories. In particular, we show that this equation is applicable only to strongly asymmetric planar Wilson loops (consisting of a long and a short pair of loop segments) and as a consequence the Wilsonian potential can be extracted only up to intermediate distances. By this equation the Wilson loop is exclusively determined by the gluon propagator. We solve the Dyson equationmore » in Coulomb gauge for the temporal Wilson loop with the instantaneous part of the gluon propagator and for the spatial Wilson loop with the static gluon propagator obtained in the Hamiltonian approach to continuum Yang-Mills theory and on the lattice. In both cases we find a linearly rising color potential.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dumitru, Adrian; Skokov, Vladimir

The conventional and linearly polarized Weizsäcker-Williams gluon distributions at small x are defined from the two-point function of the gluon field in light-cone gauge. They appear in the cross section for dijet production in deep inelastic scattering at high energy. We determine these functions in the small-x limit from solutions of the JIMWLK evolution equations and show that they exhibit approximate geometric scaling. Also, we discuss the functional distributions of these WW gluon distributions over the JIMWLK ensemble at rapidity Y ~ 1/αs. These are determined by a 2d Liouville action for the logarithm of the covariant gauge function g2trmore » A+(q)A+(-q). For transverse momenta on the order of the saturation scale we observe large variations across configurations (evolution trajectories) of the linearly polarized distribution up to several times its average, and even to negative values.« less

Top-pair production at hadron colliders with next-to-next-to-leading logarithmic soft-gluon resummation

NASA Astrophysics Data System (ADS)

Cacciari, Matteo; Czakon, Michał; Mangano, Michelangelo; Mitov, Alexander; Nason, Paolo

2012-04-01

Incorporating all recent theoretical advances, we resum soft-gluon corrections to the total ttbar cross-section at hadron colliders at the next-to-next-to-leading logarithmic (NNLL) order. We perform the resummation in the well established framework of Mellin N-space resummation. We exhaustively study the sources of systematic uncertainty like renormalization and factorization scale variation, power suppressed effects and missing two- and higher-loop corrections. The inclusion of soft-gluon resummation at NNLL brings only a minor decrease in the perturbative uncertainty with respect to the NLL approximation, and a small shift in the central value, consistent with the quoted uncertainties. These numerical predictions agree with the currently available measurements from the Tevatron and LHC and have uncertainty of similar size. We conclude that significant improvements in the ttbar cross-sections can potentially be expected only upon inclusion of the complete NNLO corrections.

Deep learning in color: towards automated quark/gluon jet discrimination

DOE Office of Scientific and Technical Information (OSTI.GOV)

Komiske, Patrick T.; Metodiev, Eric M.; Schwartz, Matthew D.

Artificial intelligence offers the potential to automate challenging data-processing tasks in collider physics. Here, to establish its prospects, we explore to what extent deep learning with convolutional neural networks can discriminate quark and gluon jets better than observables designed by physicists. Our approach builds upon the paradigm that a jet can be treated as an image, with intensity given by the local calorimeter deposits. We supplement this construction by adding color to the images, with red, green and blue intensities given by the transverse momentum in charged particles, transverse momentum in neutral particles, and pixel-level charged particle counts. Overall, themore » deep networks match or outperform traditional jet variables. We also find that, while various simulations produce different quark and gluon jets, the neural networks are surprisingly insensitive to these differences, similar to traditional observables. This suggests that the networks can extract robust physical information from imperfect simulations.« less

Transport coefficients of Quark-Gluon plasma with full QCD potential

NASA Astrophysics Data System (ADS)

J. P., Prasanth; Bannur, Vishnu M.

2018-05-01

The shear viscosity η, bulk viscosity ζ and their ratio with the entropy density, η / s, ζ / s have been studied in a quark-gluon plasma (QGP) within the cluster expansion method. The cluster expansion method allows us to include the interaction between the partons in the deconfined phase and to calculate the equation of state of quark-gluon plasma. It has been argued that the interactions present in the equation of state, the modified Cornell potential significantly contributes to the viscosity. The results obtained within our approaches agree with lattice quantum chromodynamics (LQCD) equation of state. We obtained η / s ≈ 0 . 128 within the temperature range T /Tc ∈ [ 0 . 9 , 1 . 5 ] which is very close to the theoretical lower bound η / s ≥ 1 /(4 π) in Yang-Mills theory. We also demonstrate that the effects of ζ / s at freezeout are possibly large.

An Exploratory Study of γp -> ϕ (K+K-) ω (π+π-π0) p in the GlueX Experiment at Jefferson Lab

NASA Astrophysics Data System (ADS)

Banks, Christopher; Salgado, Carlos; GlueX Collaboration

Mesons are subatomic particles that have intermediate masses between electrons and protons and manifest as quark-antiquark pairs kept together by the strong force (gluons). Quantum Chromodynamics (QCD) states the possibility for mesons manifested only as gluons (glueballs) or as quarks and gluons (hybrids). Some of those hybrid mesons could have quantum numbers that are inaccessible to conventional mesons (exotics). The GlueX detector at Jefferson Lab was built to search for exotic mesons at intermediate energies (2-3 GeV masses). The reaction γp -> ϕ (K+K-) ω (π+π-π0) p is of interest for this study. By simulating the detector and the reconstruction acceptance and efficiency, and by using expected signals and backgrounds through a detailed Monte Carlo, we have studied the possibilities of observing this reaction with the present GlueX configuration. Department of Energy (DOE).

Azimuthal Dependence of Intrinsic Top in Photon-Quark Scattering and Higgs Production in Boson-Gluon Fusion DIS

NASA Astrophysics Data System (ADS)

Boroun, G. R.; Khanehzar, A.; Boustanchi Kashan, M.

2017-11-01

In this paper, we study the top content of nucleon by analyzing azimuthal asymmetries in lepton-nucleon deep inelastic scattering (DIS), also we search for the Higgs boson associated production channel, t\\bar{t}H, at the large hadron-electron collider (LHeC) caused by boson-gluon fusion (BGF) contribution. We use azimuthal asymmetries in {γ }* Q cross sections in terms of helicity contributions to semi-inclusive deep inelastic scattering to investigate numerical properties of the \\cos 2φ distribution. We conclude that measuring azimuthal distributions caused by intrinsic heavy quark production can directly probe heavy quarks inside nucleon. Moreover, in order to estimate the probability of producing the Higgs boson, we suggest another approach in the framework of calculating t\\bar{t} cross section in boson-gluon fusion mechanism. Finally, we can confirm that this observed massive particle is referred to Higgs boson produced by fermion loop.

Mass Ordering of Spectra from Fragmentation of Saturated Gluon States in High-Multiplicity Proton-Proton Collisions

DOE PAGES

Schenke, Björn; Schlichting, Sören; Tribedy, Prithwish; ...

2016-10-14

The mass ordering of mean transverse momentummore » $$\\langle$$p T$$\\rangle$$ and of the Fourier harmonic coefficient v 2 (p T) of azimuthally anisotropic particle distributions in high energy hadron collisions is often interpreted as evidence for the hydrodynamic flow of the matter produced. We investigate an alternative initial state interpretation of this pattern in high-multiplicity proton-proton collisions at the LHC. The QCD Yang-Mills equations describing the dynamics of saturated gluons are solved numerically with initial conditions obtained from the color-glass-condensate-based impact-parameter-dependent glasma model. The gluons are subsequently fragmented into various hadron species employing the well established Lund string fragmentation algorithm of the pythia event generator. Lastly, we find that this initial state approach reproduces characteristic features of bulk spectra, in particular, the particle mass dependence of $$\\langle$$p T$$\\rangle$$ and v 2 (p T).« less

Integration of the virtual 3D model of a control system with the virtual controller

NASA Astrophysics Data System (ADS)

Herbuś, K.; Ociepka, P.

2015-11-01

Nowadays the design process includes simulation analysis of different components of a constructed object. It involves the need for integration of different virtual object to simulate the whole investigated technical system. The paper presents the issues related to the integration of a virtual 3D model of a chosen control system of with a virtual controller. The goal of integration is to verify the operation of an adopted object of in accordance with the established control program. The object of the simulation work is the drive system of a tunneling machine for trenchless work. In the first stage of work was created an interactive visualization of functioning of the 3D virtual model of a tunneling machine. For this purpose, the software of the VR (Virtual Reality) class was applied. In the elaborated interactive application were created adequate procedures allowing controlling the drive system of a translatory motion, a rotary motion and the drive system of a manipulator. Additionally was created the procedure of turning on and off the output crushing head, mounted on the last element of the manipulator. In the elaborated interactive application have been established procedures for receiving input data from external software, on the basis of the dynamic data exchange (DDE), which allow controlling actuators of particular control systems of the considered machine. In the next stage of work, the program on a virtual driver, in the ladder diagram (LD) language, was created. The control program was developed on the basis of the adopted work cycle of the tunneling machine. The element integrating the virtual model of the tunneling machine for trenchless work with the virtual controller is the application written in a high level language (Visual Basic). In the developed application was created procedures responsible for collecting data from the running, in a simulation mode, virtual controller and transferring them to the interactive application, in which is verified the operation of the adopted research object. The carried out work allowed foot the integration of the virtual model of the control system of the tunneling machine with the virtual controller, enabling the verification of its operation.

The value of virtual conferencing for ecology and conservation.

PubMed

Fraser, Hannah; Soanes, Kylie; Jones, Stuart A; Jones, Chris S; Malishev, Matthew

2017-06-01

The objectives of conservation science and dissemination of its research create a paradox: Conservation is about preserving the environment, yet scientists spread this message at conferences with heavy carbon footprints. Ecology and conservation science depend on global knowledge exchange-getting the best science to the places it is most needed. However, conference attendance from developed countries typically outweighs that from developing countries that are biodiversity and conservation hotspots. If any branch of science should be trying to maximize participation while minimizing carbon emissions, it is conservation. Virtual conferencing is common in other disciplines, such as education and humanities, but it is surprisingly underused in ecology and conservation. Adopting virtual conferencing entails a number of challenges, including logistics and unified acceptance, which we argue can be overcome through planning and technology. We examined 4 conference models: a pure-virtual model and 3 hybrid hub-and-node models, where hubs stream content to local nodes. These models collectively aim to mitigate the logistical and administrative challenges of global knowledge transfer. Embracing virtual conferencing addresses 2 essential prerequisites of modern conferences: lowering carbon emissions and increasing accessibility for remote, time- and resource-poor researchers, particularly those from developing countries. © 2017 The Authors. Conservation Biology published by Wiley Periodicals, Inc. on behalf of Society for Conservation Biology.

Implementing International Virtual Elementary Classroom Activities for Public School Students in the U.S. and Korea

ERIC Educational Resources Information Center

O'Neill, Eunhee Jung

2007-01-01

In today's global society, individuals with an understanding of different cultures that have the ability to apply this understanding to real world problem solving are more likely to become leaders. Preparing students for a global society is becoming a significant part of education. While many international online exchange projects have been…

Coherent exchange of healthcare knowledge in open systems.

PubMed

Buchan, I; Hanka, R

1997-01-01

This paper outlines design philosophies and methods for healthcare knowledge systems. Clinical priorities for knowledge are discussed in terms of temporal and individual needs. Book centred organisation of healthcare knowledge, which has proven effective in clinical practice, is proposed as the basis of virtual libraries available at the point of care for target groups of healthcare professionals.

Are We Ready for Another Change? Digital Signatures Can Change How We Handle the Academic Record

ERIC Educational Resources Information Center

Black, Thomas C.; Mohr, John

2004-01-01

In this electronic age, where information is digital and service is virtual, the registrar profession is changing rapidly to keep up with increasing standards and expectations. EDI and now XML standards enable system-to-system exchanges of academic records information. While many of the registrar's profession display student academic records under…

A Canonical Correlation Analysis of Social Capital and Knowledge Exchange for Virtual Members of IT Teams

ERIC Educational Resources Information Center

Dutton Feliu, Genevieve

2018-01-01

Social capital theory conceptualized social capital as key to connecting team members into the flow of valued resources and activities, with knowledge deemed one of the most valuable of these resources. Yet, the literature found teams struggle to effectively share knowledge. This quantitative survey-based study assessed the interrelationship…

Making Culture and Language Real in a Rural Setting: The Technology Connection.

ERIC Educational Resources Information Center

Smith, Elizabeth A.

2000-01-01

Asserts that with the growth of the Internet, e-mail, synchronous chat, and videoconferencing, students in rural (and urban) areas have virtually endless access to culture and language from their school or home. Describes the utilization of technology as a means of cultural exchange between Southwest Virginia Community College and the University…

"Are You a Computer?" Opening Exchanges in Virtual Reference Shape the Potential for Teaching

ERIC Educational Resources Information Center

Dempsey, Paula R.

2016-01-01

Academic reference librarians frequently work with students who are not aware of their professional roles. In online interactions, a student might not even realize that the librarian is a person. The ways students initiate conversations reveal their understanding of the mutual roles involved in reference encounters. Conversation analysis of live…

"CityVille": Collaborative Game Play, Communication and Skill Development in Social Networks

ERIC Educational Resources Information Center

Del-Moral, María-Esther; Guzmán-Duque, Alba-Patricia

2014-01-01

This paper has as its aim to analyze how CityVille, a videogame hosted on Facebook and oriented to the construction of a virtual city, can favor collaboration between gamers along with the exchange of strategies, equally contributing to learning transfer and skill acquisition. The first step consists in identifying the opportunities which the said…

Comparing Student Reflectiveness in Online Discussion Forums across Modes of Instruction and Levels of Courses

ERIC Educational Resources Information Center

Chadha, Anita

2017-01-01

Fostering reflective deliberation in the online classroom ensures that students reach a high level of achievement in virtual courses. Student peer exchanges were evaluated on a collaborative web site structured around interactive weekly discussions offered across an online, face-to-face, and upper- and lower-division political science courses.…

Technically Speaking: Transforming Language Learning through Virtual Learning Environments (MOOs).

ERIC Educational Resources Information Center

von der Emde, Silke; Schneider, Jeffrey; Kotter, Markus

2001-01-01

Draws on experiences from a 7-week exchange between students learning German at an American college and advanced students of English at a German university. Maps out the benefits to using a MOO (multiple user domains object-oriented) for language learning: a student-centered learning environment structured by such objectives as peer teaching,…

Maximum Mass of Hybrid Stars in the Quark Bag Model

NASA Astrophysics Data System (ADS)

Alaverdyan, G. B.; Vartanyan, Yu. L.

2017-12-01

The effect of model parameters in the equation of state for quark matter on the magnitude of the maximum mass of hybrid stars is examined. Quark matter is described in terms of the extended MIT bag model including corrections for one-gluon exchange. For nucleon matter in the range of densities corresponding to the phase transition, a relativistic equation of state is used that is calculated with two-particle correlations taken into account based on using the Bonn meson-exchange potential. The Maxwell construction is used to calculate the characteristics of the first order phase transition and it is shown that for a fixed value of the strong interaction constant αs, the baryon concentrations of the coexisting phases grow monotonically as the bag constant B increases. It is shown that for a fixed value of the strong interaction constant αs, the maximum mass of a hybrid star increases as the bag constant B decreases. For a given value of the bag parameter B, the maximum mass rises as the strong interaction constant αs increases. It is shown that the configurations of hybrid stars with maximum masses equal to or exceeding the mass of the currently known most massive pulsar are possible for values of the strong interaction constant αs > 0.6 and sufficiently low values of the bag constant.

Higgs constraints from vector boson fusion and scattering

DOE PAGES

Campbell, John M.; Ellis, R. Keith

2015-04-07

We present results on 4-lepton + 2-jet production, the partonic processes most commonly described as vector boson pair production in the Vector Boson Fusion (VBF) mode. That final state contains diagrams that are mediated by Higgs boson exchange. We focus particularly on the high-mass behaviour of the Higgs boson mediated diagrams, which unlike on-shell production, gives information about the Higgs couplings without assumptions on the Higgs boson total width. We assess the sensitivity of the high-mass region to Higgs coupling strengths, considering all vector boson pair channels, W - W +, W ± W ±, W ± Z and ZZ.more » Because of the small background, the most promising mode is W + W + which has sensitivity to Higgs couplings because of Higgs boson exchange in the t-channel. Furthermore, using the Caola-Melnikov (CM) method, the off-shell couplings can be interpreted as bounds on the Higgs boson total width. We estimate the bound that can be obtained with current data, as well as the bounds that could be obtained at √s=13 TeV in the VBF channel for data samples of 100 and 300 fb -1. The CM method has already been successfully applied in the gluon fusion (GGF) production channel. The VBF production channel gives important complementary information, because both production and decay of the Higgs boson occur already at tree graph level.« less

Approach to calculation of mass spectra and two-photon decays of c c¯ mesons in the framework of Bethe-Salpeter equation

NASA Astrophysics Data System (ADS)

Bhatnagar, Shashank; Alemu, Lmenew

2018-02-01

In this work we calculate the mass spectra of charmonium for 1 P ,…,4 P states of 0++ and 1++, for 1 S ,…,5 S states of 0-+, and for 1 S ,…,4 D states of 1- along with the two-photon decay widths of the ground and first excited states of 0++ quarkonia for the process O++→γ γ in the framework of a QCD-motivated Bethe-Salpeter equation (BSE). In this 4 ×4 BSE framework, the coupled Salpeter equations are first shown to decouple for the confining part of the interaction (under the heavy-quark approximation) and are analytically solved, and later the one-gluon-exchange interaction is perturbatively incorporated, leading to mass spectral equations for various quarkonia. The analytic forms of wave functions obtained are used for the calculation of the two-photon decay widths of χc 0. Our results are in reasonable agreement with data (where available) and other models.

Effects of the nucleon radius on neutron stars in a quark mean field model

NASA Astrophysics Data System (ADS)

Zhu, Zhen-Yu; Li, Ang

2018-03-01

We study the effects of free space nucleon radius on nuclear matter and neutron stars within the framework of the quark mean field model. The nucleon radius is treated self-consistently with this model, where quark confinement is adjusted to fit different values of nucleon radius. Corrections due to center-of-mass motion, quark-pion coupling, and one gluon exchange are included to obtain the nucleon mass in vacuum. The meson coupling constants that describe the behavior of the many-body nucleonic system are constructed by reproducing the empirical saturation properties of nuclear matter, including the recent determinations of symmetry energy parameters. Our results show that the nucleon radius in free space has negligible effects on the nuclear matter equation of state and neutron star mass-radius relations, which is different from the conclusion drawn in previous studies. We further explore that the sensitivity of star radius on the nucleon radius found in earlier publications is actually from the symmetry energy and its slope.

The Information Loss for QCD Matter in Cylindrical Black Holes at LHC

NASA Astrophysics Data System (ADS)

Ghaffary, Tooraj; Pincak, Richard

2018-03-01

In this paper, the information loss was found for QCD matter in cylindrical black holes at LHC by developing the Gottesman and Preskill approach to cylindrical black holes and determine the information transformation from the collapsing matter to the outgoing Hawking radiation state for gluons and quarks. It is found that for all gluon and quark with finite values of energies, all information from all emission processes experiences some degree of loss.

RHIC AND THE PURSUIT OF THE QUARK-GLUON PLASMA.

DOE Office of Scientific and Technical Information (OSTI.GOV)

MITCHELL,J.T.

2001-07-25

There is a fugitive on the loose. Its name is Quark-Gluon Plasma, alias the QGP. The QGP is a known informant with knowledge about the fundamental building blocks of nature that we wish to extract. This briefing will outline the status of the pursuit of the elusive QGP. We will cover what makes the QGP tick, its modus operandi, details on how we plan to hunt the fugitive down, and our level of success thus far.

The Information Loss for QCD Matter in Cylindrical Black Holes at LHC

NASA Astrophysics Data System (ADS)

Ghaffary, Tooraj; Pincak, Richard

2017-12-01

In this paper, the information loss was found for QCD matter in cylindrical black holes at LHC by developing the Gottesman and Preskill approach to cylindrical black holes and determine the information transformation from the collapsing matter to the outgoing Hawking radiation state for gluons and quarks. It is found that for all gluon and quark with finite values of energies, all information from all emission processes experiences some degree of loss.

THE COLOUR GLASS CONDENSATE: AN INTRODUCTION

DOE Office of Scientific and Technical Information (OSTI.GOV)

IANCU,E.; LEONIDOV,A.; MCLERRAN,L.

2001-08-06

In these lectures, the authors develop the theory of the Colour Glass Condensate. This is the matter made of gluons in the high density environment characteristic of deep inelastic scattering or hadron-hadron collisions at very high energy. The lectures are self contained and comprehensive. They start with a phenomenological introduction, develop the theory of classical gluon fields appropriate for the Colour Glass, and end with a derivation and discussion of the renormalization group equations which determine this effective theory.

OPE for super loops

NASA Astrophysics Data System (ADS)

Sever, Amit; Vieira, Pedro; Wang, Tianheng

2011-11-01

We extend the Operator Product Expansion for Null Polygon Wilson loops to the Mason-Skinner-Caron-Huot super loop dual to non MHV gluon amplitudes. We explain how the known tree level amplitudes can be promoted into an infinite amount of data at any loop order in the OPE picture. As an application, we re-derive all one loop NMHV six gluon amplitudes by promoting their tree level expressions. We also present some new all loops predictions for these amplitudes.

An integrand reconstruction method for three-loop amplitudes

NASA Astrophysics Data System (ADS)

Badger, Simon; Frellesvig, Hjalte; Zhang, Yang

2012-08-01

We consider the maximal cut of a three-loop four point function with massless kinematics. By applying Gröbner bases and primary decomposition we develop a method which extracts all ten propagator master integral coefficients for an arbitrary triple-box configuration via generalized unitarity cuts. As an example we present analytic results for the three loop triple-box contribution to gluon-gluon scattering in Yang-Mills with adjoint fermions and scalars in terms of three master integrals.

Understanding the proton's spin structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fred Myhrer; Thomas, Anthony W.

2010-02-01

We discuss the tremendous progress that has been towards an understanding of how the spin of the proton is distributed on its quark and gluon constituents. This is a problem that began in earnest twenty years ago with the discovery of the proton "spin crisis" by the European Muon Collaboration. The discoveries prompted by that original work have given us unprecedented insight into the amount of spin carried by polarized gluons and the orbital angular momentum of the quarks.

Symmetry preserving truncations of the gap and Bethe-Salpeter equations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Binosi, Daniele; Chang, Lei; Papavassiliou, Joannis

2016-05-01

Ward-Green-Takahashi (WGT) identities play a crucial role in hadron physics, e.g. imposing stringent relationships between the kernels of the one-and two-body problems, which must be preserved in any veracious treatment of mesons as bound states. In this connection, one may view the dressed gluon-quark vertex, Gamma(alpha)(mu), as fundamental. We use a novel representation of Gamma(alpha)(mu), in terms of the gluon-quark scattering matrix, to develop a method capable of elucidating the unique quark-antiquark Bethe-Salpeter kernel, K, that is symmetry consistent with a given quark gap equation. A strength of the scheme is its ability to expose and capitalize on graphic symmetriesmore » within the kernels. This is displayed in an analysis that reveals the origin of H-diagrams in K, which are two-particle-irreducible contributions, generated as two-loop diagrams involving the three-gluon vertex, that cannot be absorbed as a dressing of Gamma(alpha)(mu) in a Bethe-Salpeter kernel nor expressed as a member of the class of crossed-box diagrams. Thus, there are no general circumstances under which the WGT identities essential for a valid description of mesons can be preserved by a Bethe-Salpeter kernel obtained simply by dressing both gluon-quark vertices in a ladderlike truncation; and, moreover, adding any number of similarly dressed crossed-box diagrams cannot improve the situation.« less

Two-gluon and trigluon glueballs from dynamical holography QCD

NASA Astrophysics Data System (ADS)

Chen, Yi-dian; Huang, Mei

2016-12-01

We study the scalar, vector and tensor two-gluon and trigluon glueball spectra in the framework of the 5-dimension dynamical holographic QCD model, where the metric structure is deformed self-consistently by the dilaton field. For comparison, the glueball spectra are also calculated in the hard-wall and soft-wall holographic QCD models. In order to distinguish glueballs with even and odd parities, we introduce a positive and negative coupling between the dilaton field and glueballs, and for higher spin glueballs, we introduce a deformed 5-dimension mass. With this set-up, there is only one free parameter from the quadratic dilaton profile in the dynamical holographic QCD model, which is fixed by the scalar glueball spectra. It is found that the two-gluon glueball spectra produced in the dynamical holographic QCD model are in good agreement with lattice data. Among six trigluon glueballs, the produced masses for 1±- and 2-- are in good agreement with lattice data, and the produced masses for 0--, 0+- and 2+- are around 1.5 GeV lighter than lattice results. This result might indicate that the three trigluon glueballs of 0--, 0+- and 2+- are dominated by the three-gluon condensate contribution. Supported by the NSFC (11175251, 11621131001), DFG and NSFC (CRC 110), CAS Key Project KJCX2-EW-N01, K.C.Wong Education Foundation, and Youth Innovation Promotion Association of CAS

Strangeness Production in the ALICE Experiment at the LHC

NASA Astrophysics Data System (ADS)

Johnson, Harold; Fenner, Kiara; Harton, Austin; Garcia-Solis, Edmundo; Soltz, Ron

2015-04-01

The study of strange particle production is an important tool in understanding the properties of a hot and dense medium, the quark-gluon plasma, created in heavy-ion collisions at ultra-relativistic energies. This quark-gluon plasma (QGP) is believed to have been present just after the big bang. The standard model of physics contains six types of quarks. Strange quarks are not among the valence quarks found in protons and neutrons. Strange quark production is sensitive to the extremely high temperatures of the QGP. CERN's Large Hadron Collider accelerates particles to nearly the speed of light before colliding them to create this QGP state. In the results of high-energy particle collisions, hadrons are formed out of quarks and gluons when cooling from extremely high temperatures. Jets are a highly collimated cone of particles coming from the hadronization of a single quark or gluon. Understanding jet interactions may give us clues about the QGP. Using FastJet (a popular jet finder algorithm), we extracted strangeness, or strange particle characteristics of jets contained within proton-proton collisions during our research at CERN. We have identified jets with and without strange particles in proton-proton collisions and we will present a comparison of pT spectra in both cases. This material is based upon work supported by the National Science Foundation under grants PHY-1305280 and PHY-1407051.

Assessments of the Veteran Medication Allergy Knowledge Gap and Potential Safety Improvements with the Veteran Health Information Exchange (VHIE).

PubMed

Pan, Eric; Botts, Nathan; Jordan, Harmon; Olinger, Lois; Donahue, Margaret; Hsing, Nelson

2016-01-01

The U.S. Department of Veterans Affairs (VA) Veteran Health Information Exchange (VHIE, formerly Virtual Lifetime Electronic Record, or VLER) had been deployed at all VA sites and used to exchange clinical information with private sector healthcare partners nationally. This paper examined VHIE's effect on allergy documentation. Review of all inbound VHIE transactions in FY14 showed that VHIE use was associated with a nearly eight-fold increase in allergy documentation rate. Preliminary manual document review further showed that VA and partners had shared knowledge of only 38% ofpatient allergies, while VA had exclusive knowledge of another 58% ofpatient allergies, and partners had exclusive knowledge of the last 5% of patient allergies. To our knowledge, this is the first study that examined the effect of HIE on allergy documentation.

Assessments of the Veteran Medication Allergy Knowledge Gap and Potential Safety Improvements with the Veteran Health Information Exchange (VHIE)

PubMed Central

Pan, Eric; Botts, Nathan; Jordan, Harmon; Olinger, Lois; Donahue, Margaret; Hsing, Nelson

2016-01-01

The U.S. Department of Veterans Affairs (VA) Veteran Health Information Exchange (VHIE, formerly Virtual Lifetime Electronic Record, or VLER) had been deployed at all VA sites and used to exchange clinical information with private sector healthcare partners nationally. This paper examined VHIE’s effect on allergy documentation. Review of all inbound VHIE transactions in FY14 showed that VHIE use was associated with a nearly eight-fold increase in allergy documentation rate. Preliminary manual document review further showed that VA and partners had shared knowledge of only 38% ofpatient allergies, while VA had exclusive knowledge of another 58% ofpatient allergies, and partners had exclusive knowledge of the last 5% of patient allergies. To our knowledge, this is the first study that examined the effect of HIE on allergy documentation. PMID:28269897

Sharing Service Resource Information for Application Integration in a Virtual Enterprise - Modeling the Communication Protocol for Exchanging Service Resource Information

NASA Astrophysics Data System (ADS)

Yamada, Hiroshi; Kawaguchi, Akira

Grid computing and web service technologies enable us to use networked resources in a coordinated manner. An integrated service is made of individual services running on coordinated resources. In order to achieve such coordinated services autonomously, the initiator of a coordinated service needs to know detailed service resource information. This information ranges from static attributes like the IP address of the application server to highly dynamic ones like the CPU load. The most famous wide-area service discovery mechanism based on names is DNS. Its hierarchical tree organization and caching methods take advantage of the static information managed. However, in order to integrate business applications in a virtual enterprise, we need a discovery mechanism to search for the optimal resources based on the given a set of criteria (search keys). In this paper, we propose a communication protocol for exchanging service resource information among wide-area systems. We introduce the concept of the service domain that consists of service providers managed under the same management policy. This concept of the service domain is similar to that for autonomous systems (ASs). In each service domain, the service information provider manages the service resource information of service providers that exist in this service domain. The service resource information provider exchanges this information with other service resource information providers that belong to the different service domains. We also verified the protocol's behavior and effectiveness using a simulation model developed for proposed protocol.

Seeking virtual social support through blogging: A content analysis of published blog posts written by people with chronic pain

PubMed Central

Strong, Jenny

2018-01-01

Objective People with chronic pain often have limited avenues for social support. Social isolation often develops as their abilities to engage in daily social and vocational activities decrease. With recent advancements in technology and increasing use of social media, virtual platforms such as blogging may provide opportunities for social support. This study analyzed published blog posts of people with chronic pain to investigate how social support occurs through blogging for chronic pain blog users and the nature of such online interactions. Methods A total of 810 blog posts published from January 2014 to December 2015 on 44 publicly accessible chronic pain blogs were collected and analyzed through qualitative phenomenological thematic analysis. Results The Virtual Online Support Sequence (VOSS) was identified through the exchange of online comments; this sequence defines the process by which virtual social support can be established through the process of chronic pain blogging. Three subthemes were also identified in relation to social support in the online blogging environment: (a) the virtual community of pain blogging; (b) establishing social support through the VOSS; and (c) recounting everyday experiences related to pain. Conclusions These findings suggest that blogging can be useful in seeking, receiving and providing social support for people with chronic pain. Understanding this mechanism behind establishing virtual social support may potentially encourage people with chronic pain to pursue additional support online if they have limited face-to-face opportunities.

Development of relativistic shock waves in viscous gluon matter

NASA Astrophysics Data System (ADS)

Bouras, I.; Molnár, E.; Niemi, H.; Xu, Z.; El, A.; Fochler, O.; Greiner, C.; Rischke, D. H.

2009-11-01

To investigate the formation and the propagation of relativistic shock waves in viscous gluon matter we solve the relativistic Riemann problem using a microscopic parton cascade. We demonstrate the transition from ideal to viscous shock waves by varying the shear viscosity to entropy density ratio η/s. We show that an η/s ratio larger than 0.2 prevents the development of well-defined shock waves on time scales typical for ultrarelativistic heavy-ion collisions. These findings are confirmed by viscous hydrodynamic calculations.

Distribution of Linearly Polarized Gluons and Elliptic Azimuthal Anisotropy in Deep Inelastic Scattering Dijet Production at High Energy

DOE PAGES

Dumitru, Adrian; Lappi, Tuomas; Skokov, Vladimir

2015-12-17

In this study, we determine the distribution of linearly polarized gluons of a dense target at small x by solving the Balitsky–Jalilian-Marian–Iancu–McLerran–Weigert–Leonidov–Kovner rapidity evolution equations. From these solutions, we estimate the amplitude of cos2Φ azimuthal asymmetries in deep inelastic scattering dijet production at high energies. We find sizable long-range in rapidity azimuthal asymmetries with a magnitude in the range of v 2=~10%.

Evidence for simultaneous production of $$J/\\psi$$ and $$\\Upsilon$$ mesons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abazov, Victor Mukhamedovich

We report evidence for the simultaneous production of J/ψ and Υ mesons in 8.1 fb -1 of data collected at √s =1.96 TeV by the D0 experiment at the Fermilab pp - Tevatron Collider. Events with these characteristics are expected to be produced predominantly by gluon-gluon interactions. In our analysis, we extract the effective cross section characterizing the initial parton spatial distribution, σ eff = 2.2 ± 0.7 (stat) ± 0.9 (syst) mb.

Evidence for simultaneous production of $$J/\\psi$$ and $$\\Upsilon$$ mesons

DOE PAGES

Abazov, Victor Mukhamedovich

2016-02-25

We report evidence for the simultaneous production of J/ψ and Υ mesons in 8.1 fb -1 of data collected at √s =1.96 TeV by the D0 experiment at the Fermilab pp - Tevatron Collider. Events with these characteristics are expected to be produced predominantly by gluon-gluon interactions. In our analysis, we extract the effective cross section characterizing the initial parton spatial distribution, σ eff = 2.2 ± 0.7 (stat) ± 0.9 (syst) mb.

Gluon scattering amplitudes from gauge/string duality and integrability

NASA Astrophysics Data System (ADS)

Satoh, Yuji

2014-06-01

We discuss the gluon scattering amplitudes of the four-dimensional maximally supersymmetric Yang-Mills theory. By the gauge/string duality, the amplitudes at strong coupling are given by the area of the minimal surfaces in anti-de Sitter space, which can be analyzed by a set of integral equations of the thermodynamic Bethe ansatz (TBA) type. By using the two-dimensional integrable models and conformal field theories underlying the TBA system, we derive analytic expansions of the amplitudes around certain kinematic configurations.

Describing the strongly interacting quark-gluon plasma through the Friedberg-Lee model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shu Song; Li Jiarong; Institute of Particle Physics, Hua-Zhong Normal University, Wuhan 430079

2010-10-15

The Friedberg-Lee (FL) model is studied at finite temperature and density. The soliton solutions of the FL model in the deconfinement phase transition are solved and thoroughly discussed for certain boundary conditions. We indicate that the solitons before and after the deconfinement have different physical meanings: the soliton before deconfinement represents hadrons, while the soliton after the deconfinement represents the bound state of quarks which leads to a strongly interacting quark-gluon plasma phase. The corresponding phase diagram is given.

Effective actions for high energy scattering in QCD and in gravity

NASA Astrophysics Data System (ADS)

Lipatov, L. N.

2017-12-01

The scattering amplitudes in QCD and gravity at high energies are described in terms of reggeized gluons and gravitons, respectively. In particular, the BFKL Pomeron in N = 4 SUSY is dual to the reggeized graviton living in the 10-dimensional anti-de-Sitter space. The effective actions for the reggeized gluons and gravitons are local in their rapidities. The Euler-Lagrange equations for these effective theories are constructed and their solutions are used for calculations of corresponding Reggeon vertices and trajectories.

Color confinement from fluctuating topology

DOE PAGES

Kharzeev, Dmitri E.

2016-10-19

QCD possesses a compact gauge group, and this implies a non-trivial topological structure of the vacuum. In this contribution to the Gribov-85 Memorial volume, we first discuss the origin of Gribov copies and their interpretation in terms of fluctuating topology in the QCD vacuum. We then describe the recent work with E. Levin that links the confinement of gluons and color screening to the fluctuating topology, and discuss implications for spin physics, high energy scattering, and the physics of quark-gluon plasma.

Threshold resummation of soft gluons in hadronic reactions - an introduction.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berger, E. L.

The authors discuss the motivation for resummation of the effects of initial-state soft gluon radiation, to all orders in the strong coupling strength, for processes in which the near-threshold region in the partonic subenergy is important. The author summarizes the method of perturbative resummation and its application to the calculation of the total cross section for top quark production at hadron colliders. Comments are included on the differences between the treatment of subleading logarithmic terms in this method and in other approaches.

QCD dipole model and k T factorization

NASA Astrophysics Data System (ADS)

Bialas, A.; Navelet, H.; Peschanski, R.

2001-01-01

It is shown that the colour dipole approach to hard scattering at high energy is fully compatible with k T factorization at the leading logarithm approximation (in - logx Bj). The relations between the dipole amplitudes and unintegrated diagonal and non-diagonal gluon distributions are given. It is also shown that including the exact gluon kinematics in the k T factorization formula destroys the conservation of transverse position vectors and thus is incompatible with the dipole model for both elastic and diffractive amplitudes.

Fractal based observables to probe jet substructure of quarks and gluons

NASA Astrophysics Data System (ADS)

Davighi, Joe; Harris, Philip

2018-04-01

New jet observables are defined which characterize both fractal and scale-dependent contributions to the distribution of hadrons in a jet. These infrared safe observables, named Extended Fractal Observables (EFOs), have been applied to quark-gluon discrimination to demonstrate their potential utility. The EFOs are found to be individually discriminating and only weakly correlated to variables used in existing discriminators. Consequently, their inclusion improves discriminator performance, as here demonstrated with particle level simulation from the parton shower.

On the small-x behavior of the orbital angular momentum distributions in QCD

NASA Astrophysics Data System (ADS)

Hatta, Yoshitaka; Yang, Dong-Jing

2018-06-01

We present the numerical solution of the leading order QCD evolution equation for the orbital angular momentum distributions of quarks and gluons and discuss its implications for the nucleon spin sum rule. We observe that at small-x, the gluon helicity and orbital angular momentum distributions are roughly of the same magnitude but with opposite signs, indicating a significant cancellation between them. A similar cancellation occurs also in the quark sector. We explain analytically the reason for this cancellation.

12 CFR Appendix A to Part 235 - Official Board Commentary on Regulation II

Code of Federal Regulations, 2013 CFR

2013-01-01

.... Similarly, the term “debit card” includes a device with a chip or other embedded mechanism, such as a mobile... mobile phone) that stores several different payment codes or devices (“virtual cards”) that access... transactions, a cash withdrawal from an ATM is not a payment because there is no exchange of money for goods or...

12 CFR Appendix A to Part 235 - Official Board Commentary on Regulation II

Code of Federal Regulations, 2014 CFR

2014-01-01

.... Similarly, the term “debit card” includes a device with a chip or other embedded mechanism, such as a mobile... mobile phone) that stores several different payment codes or devices (“virtual cards”) that access... transactions, a cash withdrawal from an ATM is not a payment because there is no exchange of money for goods or...

12 CFR Appendix A to Part 235 - Official Board Commentary on Regulation II

Code of Federal Regulations, 2012 CFR

2012-01-01

.... Similarly, the term “debit card” includes a device with a chip or other embedded mechanism, such as a mobile... mobile phone) that stores several different payment codes or devices (“virtual cards”) that access... transactions, a cash withdrawal from an ATM is not a payment because there is no exchange of money for goods or...

The Gonzo Scientist. Slaying monsters for science.

PubMed

Bohannon, John

2008-06-20

Slaying Monsters for Science John Bohannon The first scientific conference held in Azeroth, the online universe of the role-playing game World of Warcraft, went off virtually without a hitch. Although the participants all died during the final day's social event - a massive raid on an enemy fort - they agree that this event is a glimpse at the future of scientific exchange.

Building Global Graduates and Developing Transnational Professional Skills through a Telecollaboration Project in Foreign Language Education

ERIC Educational Resources Information Center

Guadamillas Gómez, Ma Victoria

2017-01-01

The development of e-literacies and e-skills is of primary importance in gaining transferable aptitudes for the job market. Students in higher education need to take part in shared intercultural experiences which allow them to understand and cope with their peers in preparation for their futures. Furthermore, virtual exchange of information,…

A Mutation Affecting the Sodium/Proton Exchanger, "SLC9A6," Causes Mental Retardation with Tau Deposition

ERIC Educational Resources Information Center

Garbern, James Y.; Neumann, Manuela; Trojanowski, John Q.; Lee, Virginia M.-Y.; Feldman, Gerald; Norris, Joy W.; Friez, Michael J.; Schwartz, Charles E.; Stevenson, Roger; Sima, Anders A. F.

2010-01-01

We have studied a family with severe mental retardation characterized by the virtual absence of speech, autism spectrum disorder, epilepsy, late-onset ataxia, weakness and dystonia. Post-mortem examination of two males revealed widespread neuronal loss, with the most striking finding being neuronal and glial tau deposition in a pattern reminiscent…

Quantitative Predictions of Binding Free Energy Changes in Drug-Resistant Influenza Neuraminidase

DTIC Science & Technology

2012-08-30

drug resistance to two antiviral drugs, zanamivir and oseltamivir. We augmented molecular dynamics (MD) with Hamiltonian Replica Exchange and...conformations that are virtually identical to WT [10]. Molecular simulations that rigorously model the microscopic structure and thermodynamics PLOS...influenza neuraminidase (NA) that confer drug resistance to two antiviral drugs, zanamivir and oseltamivir. We augmented molecular dynamics (MD) with

A Cluster-Based Dual-Adaptive Topology Control Approach in Wireless Sensor Networks.

PubMed

Gui, Jinsong; Zhou, Kai; Xiong, Naixue

2016-09-25

Multi-Input Multi-Output (MIMO) can improve wireless network performance. Sensors are usually single-antenna devices due to the high hardware complexity and cost, so several sensors are used to form virtual MIMO array, which is a desirable approach to efficiently take advantage of MIMO gains. Also, in large Wireless Sensor Networks (WSNs), clustering can improve the network scalability, which is an effective topology control approach. The existing virtual MIMO-based clustering schemes do not either fully explore the benefits of MIMO or adaptively determine the clustering ranges. Also, clustering mechanism needs to be further improved to enhance the cluster structure life. In this paper, we propose an improved clustering scheme for virtual MIMO-based topology construction (ICV-MIMO), which can determine adaptively not only the inter-cluster transmission modes but also the clustering ranges. Through the rational division of cluster head function and the optimization of cluster head selection criteria and information exchange process, the ICV-MIMO scheme effectively reduces the network energy consumption and improves the lifetime of the cluster structure when compared with the existing typical virtual MIMO-based scheme. Moreover, the message overhead and time complexity are still in the same order of magnitude.

A Cluster-Based Dual-Adaptive Topology Control Approach in Wireless Sensor Networks

PubMed Central

Gui, Jinsong; Zhou, Kai; Xiong, Naixue

2016-01-01

Multi-Input Multi-Output (MIMO) can improve wireless network performance. Sensors are usually single-antenna devices due to the high hardware complexity and cost, so several sensors are used to form virtual MIMO array, which is a desirable approach to efficiently take advantage of MIMO gains. Also, in large Wireless Sensor Networks (WSNs), clustering can improve the network scalability, which is an effective topology control approach. The existing virtual MIMO-based clustering schemes do not either fully explore the benefits of MIMO or adaptively determine the clustering ranges. Also, clustering mechanism needs to be further improved to enhance the cluster structure life. In this paper, we propose an improved clustering scheme for virtual MIMO-based topology construction (ICV-MIMO), which can determine adaptively not only the inter-cluster transmission modes but also the clustering ranges. Through the rational division of cluster head function and the optimization of cluster head selection criteria and information exchange process, the ICV-MIMO scheme effectively reduces the network energy consumption and improves the lifetime of the cluster structure when compared with the existing typical virtual MIMO-based scheme. Moreover, the message overhead and time complexity are still in the same order of magnitude. PMID:27681731

Iris: Constructing and Analyzing Spectral Energy Distributions with the Virtual Observatory

NASA Astrophysics Data System (ADS)

Laurino, O.; Budynkiewicz, J.; Busko, I.; Cresitello-Dittmar, M.; D'Abrusco, R.; Doe, S.; Evans, J.; Pevunova, O.

2014-05-01

We present Iris 2.0, the latest release of the Virtual Astronomical Observatory application for building and analyzing Spectral Energy Distributions (SEDs). With Iris, users may read in and display SEDs inspect and edit any selection of SED data, fit models to SEDs in arbitrary spectral ranges, and calculate confidence limits on best-fit parameters. SED data may be loaded into the application from VOTable and FITS files compliant with the International Virtual Observatoy Alliance interoperable data models, or retrieved directly from NED or the Italian Space Agency Science Data Center; data in non-standard formats may also be converted within the application. Users may seamlessy exchange data between Iris and other Virtual Observatoy tools using the Simple Application Messaging Protocol. Iris 2.0 also provides a tool for redshifting, interpolating, and measuring integratd fluxes, and allows simple aperture corrections for individual points and SED segments. Custom Python functions, template models and template libraries may be imported into Iris for fitting SEDs. Iris may be extended through Java plugins; users can install third-party packages, or develop their own plugin using Iris' Software Development Kit. Iris 2.0 is available for Linux and Mac OS X systems.

Monitoring Contract Enforcement within Virtual Organizations

NASA Astrophysics Data System (ADS)

Squicciarini, Anna; Paci, Federica

Virtual Organizations (VOs) represent a new collaboration paradigm in which the participating entities pool resources, services, and information to achieve a common goal. VOs are often created on demand and dynamically evolve over time. An organization identifies a business opportunity and creates a VO to meet it. In this paper we develop a system for monitoring the sharing of resources in VO. Sharing rules are defined by a particular, common type of contract in which virtual organization members agree to make available some amount of specified resource over a given time period. The main component of the system is a monitoring tool for policy enforcement, called Security Controller (SC). VO members’ interactions are monitored in a decentralized manner in that each member has one associated SC which intercepts all the exchanged messages. We show that having SCs in VOs prevents from serious security breaches and guarantees VOs correct functioning without degrading the execution time of members’ interactions. We base our discussion on application scenarios and illustrate the SC prototype, along with some performance evaluation.

Virtual Communities for Diabetes Chronic Disease Healthcare

PubMed Central

Chorbev, Ivan; Sotirovska, Marija; Mihajlov, Dragan

2011-01-01

Diabetes is classified as the world's fastest-growing chronic illness that affects millions of people. It is a very serious disease, but the bright side is that it is treatable and can be managed. Proper education in this view is necessary to achieve essential control and prevent the aggregation of this chronic sickness. We have developed a healthcare social network that provides methods for distance learning; opportunities for creation of virtual self-help groups where patients can get information and establish interactions among each other in order to exchange important healthcare-related information; discussion forums; patient-to-healthcare specialist communication. The mission of our virtual community is to increase the independence of people with diabetes, self-management, empower them to take care of themselves, make their everyday activities easier, enrich their medical knowledge, and improve their health condition, make them more productive, and improve their communication with other patients with similar diagnoses. The ultimate goal is to enhance the quality of their life. PMID:22121358

Core-shell photoabsorption and photoelectron spectra of gas-phase pentacene: experiment and theory.

PubMed

Alagia, Michele; Baldacchini, Chiara; Betti, Maria Grazia; Bussolotti, Fabio; Carravetta, Vincenzo; Ekström, Ulf; Mariani, Carlo; Stranges, Stefano

2005-03-22

The C K-edge photoabsorption and 1s core-level photoemission of pentacene (C22H14) free molecules are experimentally measured, and calculated by self-consistent-field and static-exchange approximation ab initio methods. Six nonequivalent C atoms present in the molecule contribute to the C 1s photoemission spectrum. The complex near-edge structures of the carbon K-edge absorption spectrum present two main groups of discrete transitions between 283 and 288 eV photon energy, due to absorption to pi* virtual orbitals, and broader structures at higher energy, involving sigma* virtual orbitals. The sharp absorption structures to the pi* empty orbitals lay well below the thresholds for the C 1s ionizations, caused by strong excitonic and localization effects. We can definitely explain the C K-edge absorption spectrum as due to both final (virtual) and initial (core) orbital effects, mainly involving excitations to the two lowest-unoccupied molecular orbitals of pi* symmetry, from the six chemically shifted C 1s core orbitals.

Core-shell photoabsorption and photoelectron spectra of gas-phase pentacene: Experiment and theory

NASA Astrophysics Data System (ADS)

Alagia, Michele; Baldacchini, Chiara; Betti, Maria Grazia; Bussolotti, Fabio; Carravetta, Vincenzo; Ekström, Ulf; Mariani, Carlo; Stranges, Stefano

2005-03-01

The C K-edge photoabsorption and 1s core-level photoemission of pentacene (C22H14) free molecules are experimentally measured, and calculated by self-consistent-field and static-exchange approximation ab initio methods. Six nonequivalent C atoms present in the molecule contribute to the C 1s photoemission spectrum. The complex near-edge structures of the carbon K-edge absorption spectrum present two main groups of discrete transitions between 283 and 288eV photon energy, due to absorption to π* virtual orbitals, and broader structures at higher energy, involving σ* virtual orbitals. The sharp absorption structures to the π* empty orbitals lay well below the thresholds for the C 1s ionizations, caused by strong excitonic and localization effects. We can definitely explain the C K-edge absorption spectrum as due to both final (virtual) and initial (core) orbital effects, mainly involving excitations to the two lowest-unoccupied molecular orbitals of π* symmetry, from the six chemically shifted C 1s core orbitals.

Designing normative open virtual enterprises

NASA Astrophysics Data System (ADS)

Garcia, Emilia; Giret, Adriana; Botti, Vicente

2016-03-01

There is an increasing interest on developing virtual enterprises in order to deal with the globalisation of the economy, the rapid growth of information technologies and the increase of competitiveness. In this paper we deal with the development of normative open virtual enterprises (NOVEs). They are systems with a global objective that are composed of a set of heterogeneous entities and enterprises that exchange services following a specific normative context. In order to analyse and design systems of this kind the multi-agent paradigm seems suitable because it offers a specific solution for supporting the social and contractual relationships between enterprises and for formalising their business processes. This paper presents how the Regulated Open Multi-agent systems (ROMAS) methodology, an agent-oriented software methodology, can be used to analyse and design NOVEs. ROMAS offers a complete development process that allows identifying and formalising of the structure of NOVEs, their normative context and the interactions among their members. The use of ROMAS is exemplified by means of a case study that represents an automotive supply chain.

Measurement of the charged-particle multiplicity inside jets from $$\\sqrt{s}=8$$ $${\\mathrm{TeV}}$$ pp collisions with the ATLAS detector

DOE PAGES

Aad, G.; Abbott, B.; Abdallah, J.; ...

2016-06-13

The number of charged particles inside jets is a widely used discriminant for identifying the quark or gluon nature of the initiating parton and is sensitive to both the perturbative and non-perturbative components of fragmentation. This paper presents a measurement of the average number of charged particles with p T > 500 MeV inside high-momentum jets in dijet events using 20.3 fb -1 of data recorded with the ATLAS detector in pp collisions at √s=8 TeV collisions at the LHC. The jets considered have transverse momenta from 50 GeV up to and beyond 1.5 TeV . The reconstructed charged-particle trackmore » multiplicity distribution is unfolded to remove distortions from detector effects and the resulting charged-particle multiplicity is compared to several models. Lastly, quark and gluon jet fractions are used to extract the average charged-particle multiplicity for quark and gluon jets separately.« less

Critical point in the phase diagram of primordial quark-gluon matter from black hole physics

NASA Astrophysics Data System (ADS)

Critelli, Renato; Noronha, Jorge; Noronha-Hostler, Jacquelyn; Portillo, Israel; Ratti, Claudia; Rougemont, Romulo

2017-11-01

Strongly interacting matter undergoes a crossover phase transition at high temperatures T ˜1012 K and zero net-baryon density. A fundamental question in the theory of strong interactions, QCD, is whether a hot and dense system of quarks and gluons displays critical phenomena when doped with more quarks than antiquarks, where net-baryon number fluctuations diverge. Recent lattice QCD work indicates that such a critical point can only occur in the baryon dense regime of the theory, which defies a description from first principles calculations. Here we use the holographic gauge/gravity correspondence to map the fluctuations of baryon charge in the dense quark-gluon liquid onto a numerically tractable gravitational problem involving the charge fluctuations of holographic black holes. This approach quantitatively reproduces ab initio results for the lowest order moments of the baryon fluctuations and makes predictions for the higher-order baryon susceptibilities and also for the location of the critical point, which is found to be within the reach of heavy-ion collision experiments.

Constraints on the gluon PDF from top quark pair production at hadron colliders

NASA Astrophysics Data System (ADS)

Czakon, Michal; Mangano, Michelangelo L.; Mitov, Alexander; Rojo, Juan

2013-07-01

Using the recently derived NNLO cross sections [1], we provide NNLO+NNLL theoretical predictions for top quark pair production based on all the available NNLO PDF sets, and compare them with the most precise LHC and Tevatron data. In this comparison we study in detail the PDF uncertainty and the scale, m t and α s dependence of the theoretical predictions for each PDF set. Next, we observe that top quark pair production provides a powerful direct constraint on the gluon PDF at large x, and include Tevatron and LHC top pair data consistently into a global NNLO PDF fit. We then explore the phenomenological consequences of the reduced gluon PDF uncertainties, by showing how they can improve predictions for Beyond the Standard Model processes at the LHC. Finally, we update to full NNLO+NNLL the theoretical predictions for the ratio of top quark cross sections between different LHC center of mass energies, as well as the cross sections for hypothetical heavy fourth-generation quark production at the LHC.

Ghost-gluon vertex in the presence of the Gribov horizon

NASA Astrophysics Data System (ADS)

Mintz, B. W.; Palhares, L. F.; Sorella, S. P.; Pereira, A. D.

2018-02-01

We consider Yang-Mills theories quantized in the Landau gauge in the presence of the Gribov horizon via the refined Gribov-Zwanziger (RGZ) framework. As the restriction of the gauge path integral to the Gribov region is taken into account, the resulting gauge field propagators display a nontrivial infrared behavior, being very close to the ones observed in lattice gauge field theory simulations. In this work, we explore a higher correlation function in the refined Gribov-Zwanziger theory: the ghost-gluon interaction vertex, at one-loop level. We show explicit compatibility with kinematical constraints, as required by the Ward identities of the theory, and obtain analytical expressions in the limit of vanishing gluon momentum. We find that the RGZ results are nontrivial in the infrared regime, being compatible with lattice Yang-Mills simulations in both SU(2) and SU(3), as well as with solutions from Schwinger-Dyson equations in different truncation schemes, Functional Renormalization Group analysis, and the renormalization group-improved Curci-Ferrari model.

Early Time Dynamics of Gluon Fields in High Energy Nuclear Collisions

NASA Astrophysics Data System (ADS)

Kapusta, Joseph I.; Chen, Guangyao; Fries, Rainer J.; Li, Yang

2016-12-01

Nuclei colliding at very high energy create a strong, quasi-classical gluon field during the initial phase of their interaction. We present an analytic calculation of the initial space-time evolution of this field in the limit of very high energies using a formal recursive solution of the Yang-Mills equations. We provide analytic expressions for the initial chromo-electric and chromo-magnetic fields and for their energy-momentum tensor. In particular, we discuss event-averaged results for energy density and energy flow as well as for longitudinal and transverse pressure of this system. Our results are generally applicable if τ < 1 /Qs. The transverse energy flow of the gluon field exhibits hydrodynamic-like contributions that follow transverse gradients of the energy density. In addition, a rapidity-odd energy flow also emerges from the non-abelian analog of Gauss' Law and generates non-vanishing angular momentum of the field. We will discuss the space-time picture that emerges from our analysis and its implications for observables in heavy ion collisions.

QCD corrections to ZZ production in gluon fusion at the LHC

DOE PAGES

Caola, Fabrizio; Melnikov, Kirill; Rontsch, Raoul; ...

2015-11-23

We compute the next-to-leading-order QCD corrections to the production of two Z-bosons in the annihilation of two gluons at the LHC. Being enhanced by a large gluon flux, these corrections provide a distinct and, potentially, the dominant part of the N 3LO QCD contributions to Z-pair production in proton collisions. The gg → ZZ annihilation is a loop-induced process that receives the dominant contribution from loops of five light quarks, that are included in our computation in the massless approximation. We find that QCD corrections increase the gg → ZZ production cross section by O(50%–100%) depending on the values ofmore » the renormalization and factorization scales used in the leading-order computation and the collider energy. Furthermore, the large corrections to the gg → ZZ channel increase the pp → ZZ cross section by about 6% to 8%, exceeding the estimated theoretical uncertainty of the recent next-to-next-to-leading-order QCD calculation.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aidala, C.; Ajitanand, N. N.; Akiba, Y.

The cross section and transverse single-spin asymmetries of μ - and μ + from open heavy-flavor decays in polarized p+p collisions at √s = 200 GeV were measured in this paper by the PHENIX experiment during 2012 at the Relativistic Heavy Ion Collider. Because heavy-flavor production is dominated by gluon-gluon interactions at √s = 200 GeV, these measurements offer a unique opportunity to obtain information on the trigluon correlation functions. The measurements are performed at forward and backward rapidity (1.4 < |y| < 2.0) over the transverse momentum range of 1.25 < p T < 7 GeV/c for the crossmore » section and 1.25 < p T < 5 GeV/c for the asymmetry measurements. The obtained cross section is compared to a fixed-order-plus-next-to-leading-log perturbative-quantum-chromodynamics calculation. Finally, the asymmetry results are consistent with zero within uncertainties, and a model calculation based on twist-3 three-gluon correlations agrees with the data.« less

Unveiling the proton spin decomposition at a future electron-ion collider

DOE PAGES

Aschenauer, Elke C.; Sassot, Rodolfo; Stratmann, Marco

2015-11-24

We present a detailed assessment of how well a future electron-ion collider could constrain helicity parton distributions in the nucleon and, therefore, unveil the role of the intrinsic spin of quarks and gluons in the proton’s spin budget. Any remaining deficit in this decomposition will provide the best indirect constraint on the contribution due to the total orbital angular momenta of quarks and gluons. Specifically, all our studies are performed in the context of global QCD analyses based on realistic pseudodata and in the light of the most recent data obtained from polarized proton-proton collisions at BNL-RHIC that have providedmore » evidence for a significant gluon polarization in the accessible, albeit limited range of momentum fractions. We also present projections on what can be achieved on the gluon’s helicity distribution by the end of BNL-RHIC operations. As a result, all estimates of current and projected uncertainties are performed with the robust Lagrange multiplier technique.« less

\\psi (2S) enhancement in p-Pb collision as an indication of quark-gluon plasma formation at the Large Hadron Collider

NASA Astrophysics Data System (ADS)

Ganesh, S.; Singh, R., Captain; Mishra, M.

2018-03-01

Proton-nucleus collisions serve as an important baseline for the understanding and interpretation of the nucleus-nucleus collisions. These collisions have been employed to characterize the cold nuclear matter effects at SPS and Relativistic Heavy-Ion Collider energies for the past several years, as it was thought that quark-gluon plasma (QGP) is not formed in such collisions. However, at the Large Hadron Collider (LHC), there seems a possibility that QGP is formed during proton-lead (p-Pb) collisions. In this work, we have derived an expression for gluon induced excitation of J/\\psi to \\psi (2S), using pNRQCD, and show that the relative enhancement of \\psi (2S) vis-à-vis J/\\psi , especially at high p T , gives further indication that the QGP is indeed formed in p-Pb collisions at the most central collisions at LHC energy. J/\\psi and \\psi (2S) suppression effects seen at ALICE are also qualitatively explained.