Disconnected Diagrams in Lattice QCD

NASA Astrophysics Data System (ADS)

Gambhir, Arjun Singh

In this work, we present state-of-the-art numerical methods and their applications for computing a particular class of observables using lattice quantum chromodynamics (Lattice QCD), a discretized version of the fundamental theory of quarks and gluons. These observables require calculating so called "disconnected diagrams" and are important for understanding many aspects of hadron structure, such as the strange content of the proton. We begin by introducing the reader to the key concepts of Lattice QCD and rigorously define the meaning of disconnected diagrams through an example of the Wick contractions of the nucleon. Subsequently, the calculation of observables requiring disconnected diagrams is posed as the computationally challenging problem of finding the trace of the inverse of an incredibly large, sparse matrix. This is followed by a brief primer of numerical sparse matrix techniques that overviews broadly used methods in Lattice QCD and builds the background for the novel algorithm presented in this work. We then introduce singular value deflation as a method to improve convergence of trace estimation and analyze its effects on matrices from a variety of fields, including chemical transport modeling, magnetohydrodynamics, and QCD. Finally, we apply this method to compute observables such as the strange axial charge of the proton and strange sigma terms in light nuclei. The work in this thesis is innovative for four reasons. First, we analyze the effects of deflation with a model that makes qualitative predictions about its effectiveness, taking only the singular value spectrum as input, and compare deflated variance with different types of trace estimator noise. Second, the synergy between probing methods and deflation is investigated both experimentally and theoretically. Third, we use the synergistic combination of deflation and a graph coloring algorithm known as hierarchical probing to conduct a lattice calculation of light disconnected matrix elements

Local P violation effects and thermalization in QCD: Views from quantum field theory and holography

NASA Astrophysics Data System (ADS)

Zhitnitsky, Ariel R.

2012-07-01

We argue that the local violation of P and CP invariance in heavy ion collisions and the universal thermal aspects observed in high energy collisions are in fact two sides of the same coin, and both are related to quantum anomalies of QCD. We argue that the low energy relations representing the quantum anomalies of QCD are saturated by coherent low-dimensional vacuum configurations as observed in Monte Carlo lattice studies. The thermal spectrum and approximate universality of the temperature with no dependence on energy of colliding particles in this framework is due to the fact that the emission results from the distortion of these low-dimensional vacuum sheets rather than from the colliding particles themselves. The emergence of the long-range correlations of P odd domains (a feature which is apparently required for explanation of the asymmetry observed at RHIC and LHC) is also a result of the same distortion of the QCD vacuum configurations. We formulate the corresponding physics using the effective low energy effective Lagrangian. We also formulate the same physics in terms of the dual holographic picture when low-dimensional sheets of topological charge embedded in 4d space, as observed in Monte Carlo simulations, are identified with D2 branes. Finally, we argue that study of these long-range correlations in heavy ion collisions could serve as a perfect test of a proposal that the observed dark energy in present epoch is a result of a tiny deviation of the QCD vacuum energy in expanding universe from its conventional value in Minkowski space-time.

Novel topological effects in dense QCD in a magnetic field

NASA Astrophysics Data System (ADS)

Ferrer, E. J.; de la Incera, V.

2018-06-01

We study the electromagnetic properties of dense QCD in the so-called Magnetic Dual Chiral Density Wave phase. This inhomogeneous phase exhibits a nontrivial topology that comes from the fermion sector due to the asymmetry of the lowest Landau level modes. The nontrivial topology manifests in the electromagnetic effective action via a chiral anomaly term θFμνF˜μν, with a dynamic axion field θ given by the phase of the Dual Chiral Density Wave condensate. The coupling of the axion with the electromagnetic field leads to several macroscopic effects that include, among others, an anomalous, nondissipative Hall current, an anomalous electric charge, magnetoelectricity, and the formation of a hybridized propagating mode known as an axion polariton. Connection to topological insulators and Weyls semimetals, as well as possible implications for heavy-ion collisions and neutron stars are all highlighted.

Baryon number, strangeness, and electric charge fluctuations in QCD at high temperature

NASA Astrophysics Data System (ADS)

Cheng, M.; Hegde, P.; Jung, C.; Karsch, F.; Kaczmarek, O.; Laermann, E.; Mawhinney, R. D.; Miao, C.; Petreczky, P.; Schmidt, C.; Soeldner, W.

2009-04-01

We analyze baryon number, strangeness, and electric charge fluctuations as well as their correlations in QCD at high temperature. We present results obtained from lattice calculations performed with an improved staggered fermion action (p4 action) at two values of the lattice cutoff with almost physical up and down quark masses and a physical value for the strange quark mass. We compare these results, with an ideal quark gas at high temperature and a hadron resonance gas model at low temperature. We find that fluctuations and correlations are well described by the former already for temperatures about 1.5 times the transition temperature. At low temperature qualitative features of the lattice results are quite well described by a hadron resonance gas model. Higher order cumulants, which become increasingly sensitive to the light pions, however, show deviations from a resonance gas in the vicinity of the transition temperature.

Isovector and isoscalar tensor charges of the nucleon from lattice QCD

DOE PAGES

Bhattacharya, Tanmoy; Cirigliano, Vincenzo; Cohen, Saul D.; ...

2015-11-01

Here, we present results for the isovector and flavor diagonal tensor charges g u–d T, g u T, g d T, and g s T needed to probe novel tensor interactions at the TeV scale in neutron and nuclear β-decays and the contribution of the quark electric dipole moment (EDM) to the neutron EDM. The lattice QCD calculations were done using nine ensembles of gauge configurations generated by the MILC collaboration using the HISQ action with 2+1+1 dynamical flavors. These ensembles span three lattice spacings a ≈ 0.06, 0.09 and 0.12 fm and three quark masses corresponding to the pionmore » masses M π ≈ 130, 220 and 310 MeV. Using estimates from these ensembles, we quantify all systematic uncertainties and perform a simultaneous extrapolation in the lattice spacing, volume and light quark masses for the connected contributions. The final estimates of the connected nucleon (proton) tensor charge for the isovector combination is g u–d T = 1.020(76) in the MS¯ scheme at 2 GeV. The additional disconnected quark loop contributions needed for the flavor-diagonal matrix elements are calculated using a stochastic estimator employing the truncated solver method with the all-mode-averaging technique. We find that the size of the disconnected contribution is smaller than the statistical error in the connected contribution. This allows us to bound the disconnected contribution and include it as an additional uncertainty in the flavor-diagonal charges. After a continuum extrapolation, we find g u T = 0.774(66), g d T = –0.233(28) and g u+d T = 0.541(67). The strangeness tensor charge, that can make a significant contribution to the neutron EDM due to the large ratio m s/m u,d, is g s T = 0.008(9) in the continuum limit.« less

Topology (and axion's properties) from lattice QCD with a dynamical charm

NASA Astrophysics Data System (ADS)

Burger, Florian; Ilgenfritz, Ernst-Michael; Lombardo, Maria Paola; Müller-Preussker, Michael; Trunin, Anton

2017-11-01

We present results on QCD with four dynamical flavors in the temperature range 0.9 ≲ T /Tc ≲ 2. We have performed lattice simulations with Wilson fermions at maximal twist and measured the topological charge with gluonic and fermionic methods. The topological charge distribution is studied by means of its cumulants, which encode relevant properties of the QCD axion, a plausible Dark Matter candidate. The topological susceptibility measured with the fermionic method exhibits a power-law decay for T /Tc ≳ 2, with an exponent close to the one predicted by the Dilute Instanton Gas Approximation (DIGA). Close to Tc the temperature dependent effective exponent approaches the DIGA result from above, in agreement with recent analytic calculations. These results constrain the axion window, once an assumption on the fraction of axions contributing to Dark Matter is made.

Study of dark matter and QCD-charged mediators in the quasidegenerate regime

NASA Astrophysics Data System (ADS)

Davidson, Andrew; Kelso, Chris; Kumar, Jason; Sandick, Pearl; Stengel, Patrick

2017-12-01

We study a scenario in which the only light new particles are a Majorana fermion dark matter candidate and one or more QCD-charged scalars, which couple to light quarks. This scenario has several interesting phenomenological features if the new particles are nearly degenerate in mass. In particular, LHC searches for the light scalars have reduced sensitivity, since the visible and invisible products tend to be softer. Moreover, dark matter-scalar coannihilation can allow even relatively heavy dark matter candidates to be consistent thermal relics. Finally, the dark matter nucleon scattering cross section is enhanced in the quasidegenerate limit, allowing direct detection experiments to use both spin-independent and spin-dependent scattering to probe regions of parameter space beyond those probed by the LHC. Although this scenario has a broad application, we phrase this study in terms of the minimal supersymmetric standard model, in the limit where the only light sparticles are a binolike dark matter candidate and light-flavored squarks.

Disconnected Diagrams in Lattice QCD

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

Gambhir, Arjun

In this work, we present state-of-the-art numerical methods and their applications for computing a particular class of observables using lattice quantum chromodynamics (Lattice QCD), a discretized version of the fundamental theory of quarks and gluons. These observables require calculating so called \\disconnected diagrams" and are important for understanding many aspects of hadron structure, such as the strange content of the proton. We begin by introducing the reader to the key concepts of Lattice QCD and rigorously define the meaning of disconnected diagrams through an example of the Wick contractions of the nucleon. Subsequently, the calculation of observables requiring disconnected diagramsmore » is posed as the computationally challenging problem of finding the trace of the inverse of an incredibly large, sparse matrix. This is followed by a brief primer of numerical sparse matrix techniques that overviews broadly used methods in Lattice QCD and builds the background for the novel algorithm presented in this work. We then introduce singular value deflation as a method to improve convergence of trace estimation and analyze its effects on matrices from a variety of fields, including chemical transport modeling, magnetohydrodynamics, and QCD. Finally, we apply this method to compute observables such as the strange axial charge of the proton and strange sigma terms in light nuclei. The work in this thesis is innovative for four reasons. First, we analyze the effects of deflation with a model that makes qualitative predictions about its effectiveness, taking only the singular value spectrum as input, and compare deflated variance with different types of trace estimator noise. Second, the synergy between probing methods and deflation is investigated both experimentally and theoretically. Third, we use the synergistic combination of deflation and a graph coloring algorithm known as hierarchical probing to conduct a lattice calculation of light disconnected matrix

The generalized scheme-independent Crewther relation in QCD

NASA Astrophysics Data System (ADS)

Shen, Jian-Ming; Wu, Xing-Gang; Ma, Yang; Brodsky, Stanley J.

2017-07-01

The Principle of Maximal Conformality (PMC) provides a systematic way to set the renormalization scales order-by-order for any perturbative QCD calculable processes. The resulting predictions are independent of the choice of renormalization scheme, a requirement of renormalization group invariance. The Crewther relation, which was originally derived as a consequence of conformally invariant field theory, provides a remarkable connection between two observables when the β function vanishes: one can show that the product of the Bjorken sum rule for spin-dependent deep inelastic lepton-nucleon scattering times the Adler function, defined from the cross section for electron-positron annihilation into hadrons, has no pQCD radiative corrections. The ;Generalized Crewther Relation; relates these two observables for physical QCD with nonzero β function; specifically, it connects the non-singlet Adler function (Dns) to the Bjorken sum rule coefficient for polarized deep-inelastic electron scattering (CBjp) at leading twist. A scheme-dependent ΔCSB-term appears in the analysis in order to compensate for the conformal symmetry breaking (CSB) terms from perturbative QCD. In conventional analyses, this normally leads to unphysical dependence in both the choice of the renormalization scheme and the choice of the initial scale at any finite order. However, by applying PMC scale-setting, we can fix the scales of the QCD coupling unambiguously at every order of pQCD. The result is that both Dns and the inverse coefficient CBjp-1 have identical pQCD coefficients, which also exactly match the coefficients of the corresponding conformal theory. Thus one obtains a new generalized Crewther relation for QCD which connects two effective charges, αˆd (Q) =∑i≥1 αˆg1 i (Qi), at their respective physical scales. This identity is independent of the choice of the renormalization scheme at any finite order, and the dependence on the choice of the initial scale is negligible. Similar

Lattice QCD with strong external electric fields.

PubMed

Yamamoto, Arata

2013-03-15

We study particle generation by a strong electric field in lattice QCD. To avoid the sign problem of the Minkowskian electric field, we adopt the "isospin" electric charge. When a strong electric field is applied, the insulating vacuum is broken down and pairs of charged particles are produced by the Schwinger mechanism. The competition against the color confining force is also discussed.

FOREWORD: Extreme QCD 2012 (xQCD)

NASA Astrophysics Data System (ADS)

Alexandru, Andrei; Bazavov, Alexei; Liu, Keh-Fei

2013-04-01

The Extreme QCD 2012 conference, held at the George Washington University in August 2012, celebrated the 10th event in the series. It has been held annually since 2003 at different locations: San Carlos (2011), Bad Honnef (2010), Seoul (2009), Raleigh (2008), Rome (2007), Brookhaven (2006), Swansea (2005), Argonne (2004), and Nara (2003). As usual, it was a very productive and inspiring meeting that brought together experts in the field of finite-temperature QCD, both theoretical and experimental. On the experimental side, we heard about recent results from major experiments, such as PHENIX and STAR at Brookhaven National Laboratory, ALICE and CMS at CERN, and also about the constraints on the QCD phase diagram coming from astronomical observations of one of the largest laboratories one can imagine, neutron stars. The theoretical contributions covered a wide range of topics, including QCD thermodynamics at zero and finite chemical potential, new ideas to overcome the sign problem in the latter case, fluctuations of conserved charges and how they allow one to connect calculations in lattice QCD with experimentally measured quantities, finite-temperature behavior of theories with many flavors of fermions, properties and the fate of heavy quarkonium states in the quark-gluon plasma, and many others. The participants took the time to write up and revise their contributions and submit them for publication in these proceedings. Thanks to their efforts, we have now a good record of the ideas presented and discussed during the workshop. We hope that this will serve both as a reminder and as a reference for the participants and for other researchers interested in the physics of nuclear matter at high temperatures and density. To preserve the atmosphere of the event the contributions are ordered in the same way as the talks at the conference. We are honored to have helped organize the 10th meeting in this series, a milestone that reflects the lasting interest in this

Visualization Tools for Lattice QCD - Final Report

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

Massimo Di Pierro

2012-03-15

Our research project is about the development of visualization tools for Lattice QCD. We developed various tools by extending existing libraries, adding new algorithms, exposing new APIs, and creating web interfaces (including the new NERSC gauge connection web site). Our tools cover the full stack of operations from automating download of data, to generating VTK files (topological charge, plaquette, Polyakov lines, quark and meson propagators, currents), to turning the VTK files into images, movies, and web pages. Some of the tools have their own web interfaces. Some Lattice QCD visualization have been created in the past but, to our knowledge,more » our tools are the only ones of their kind since they are general purpose, customizable, and relatively easy to use. We believe they will be valuable to physicists working in the field. They can be used to better teach Lattice QCD concepts to new graduate students; they can be used to observe the changes in topological charge density and detect possible sources of bias in computations; they can be used to observe the convergence of the algorithms at a local level and determine possible problems; they can be used to probe heavy-light mesons with currents and determine their spatial distribution; they can be used to detect corrupted gauge configurations. There are some indirect results of this grant that will benefit a broader audience than Lattice QCD physicists.« less

Strangeness S =-1 hyperon-nucleon interactions: Chiral effective field theory versus lattice QCD

NASA Astrophysics Data System (ADS)

Song, Jing; Li, Kai-Wen; Geng, Li-Sheng

2018-06-01

Hyperon-nucleon interactions serve as basic inputs to studies of hypernuclear physics and dense (neutron) stars. Unfortunately, a precise understanding of these important quantities has lagged far behind that of the nucleon-nucleon interaction due to lack of high-precision experimental data. Historically, hyperon-nucleon interactions are either formulated in quark models or meson exchange models. In recent years, lattice QCD simulations and chiral effective field theory approaches start to offer new insights from first principles. In the present work, we contrast the state-of-the-art lattice QCD simulations with the latest chiral hyperon-nucleon forces and show that the leading order relativistic chiral results can already describe the lattice QCD data reasonably well. Given the fact that the lattice QCD simulations are performed with pion masses ranging from the (almost) physical point to 700 MeV, such studies provide a useful check on both the chiral effective field theory approaches as well as lattice QCD simulations. Nevertheless more precise lattice QCD simulations are eagerly needed to refine our understanding of hyperon-nucleon interactions.

Transport coefficients of a hot QCD medium and their relative significance in heavy-ion collisions

NASA Astrophysics Data System (ADS)

Mitra, Sukanya; Chandra, Vinod

2017-11-01

The main focus of this article is to obtain various transport coefficients for a hot QCD medium that is likely to be produced while colliding two heavy nuclei ultra-relativistically. The technical approach adopted here is the semiclassical transport theory. The away-from-equilibrium linearized transport equation has been set up by employing the Chapman-Enskog technique from the kinetic theory of a many-particle system with a collision term that includes the binary collisions of quarks/antiquarks and gluons. In order to include the effects of a strongly interacting, thermal medium, a quasi-particle description of a realistic hot QCD equation of state has been employed through the equilibrium modeling of the momentum distributions of gluons and quarks with nontrivial dispersion relations while extending the model for finite but small quark chemical potential. The effective coupling for strong interaction has been redefined following the charge renormalization under the scheme of the quasi-particle model. The consolidated effects on transport coefficients are seen to have a significant impact on their temperature dependence. Finally, the relative significances of momentum and heat transfer, as well as the charge diffusion processes in hot QCD, have been investigated by studying the ratios of the respective transport coefficients indicating different physical laws.

The generalized scheme-independent Crewther relation in QCD

DOE PAGES

Shen, Jian-Ming; Wu, Xing-Gang; Ma, Yang; ...

2017-05-10

The Principle of Maximal Conformality (PMC) provides a systematic way to set the renormalization scales order-by-order for any perturbative QCD calculable processes. The resulting predictions are independent of the choice of renormalization scheme, a requirement of renormalization group invariance. The Crewther relation, which was originally derived as a consequence of conformally invariant field theory, provides a remarkable connection between two observables when the β function vanishes: one can show that the product of the Bjorken sum rule for spin-dependent deep inelastic lepton–nucleon scattering times the Adler function, defined from the cross section for electron–positron annihilation into hadrons, has no pQCD radiative corrections. The “Generalized Crewther Relation” relates these two observables for physical QCD with nonzero β function; specifically, it connects the non-singlet Adler function (D ns) to the Bjorken sum rule coefficient for polarized deep-inelastic electron scattering (C Bjp) at leading twist. A scheme-dependent Δ CSB-term appears in the analysis in order to compensate for the conformal symmetry breaking (CSB) terms from perturbative QCD. In conventional analyses, this normally leads to unphysical dependence in both the choice of the renormalization scheme and the choice of the initial scale at any finite order. However, by applying PMC scale-setting, we can fix the scales of the QCD coupling unambiguously at every order of pQCD. The result is that both D ns and the inverse coefficient Cmore » $$-1\\atop{Bjp}$$ have identical pQCD coefficients, which also exactly match the coefficients of the corresponding conformal theory. Thus one obtains a new generalized Crewther relation for QCD which connects two effective charges, $$\\hat{α}$$ d(Q)=Σ i≥1$$\\hat{α}^i\\atop{g1}$$(Qi), at their respective physical scales. This identity is independent of the choice of the renormalization scheme at any finite order, and the dependence on

The generalized scheme-independent Crewther relation in QCD

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

Shen, Jian-Ming; Wu, Xing-Gang; Ma, Yang

The Principle of Maximal Conformality (PMC) provides a systematic way to set the renormalization scales order-by-order for any perturbative QCD calculable processes. The resulting predictions are independent of the choice of renormalization scheme, a requirement of renormalization group invariance. The Crewther relation, which was originally derived as a consequence of conformally invariant field theory, provides a remarkable connection between two observables when the β function vanishes: one can show that the product of the Bjorken sum rule for spin-dependent deep inelastic lepton–nucleon scattering times the Adler function, defined from the cross section for electron–positron annihilation into hadrons, has no pQCD radiative corrections. The “Generalized Crewther Relation” relates these two observables for physical QCD with nonzero β function; specifically, it connects the non-singlet Adler function (D ns) to the Bjorken sum rule coefficient for polarized deep-inelastic electron scattering (C Bjp) at leading twist. A scheme-dependent Δ CSB-term appears in the analysis in order to compensate for the conformal symmetry breaking (CSB) terms from perturbative QCD. In conventional analyses, this normally leads to unphysical dependence in both the choice of the renormalization scheme and the choice of the initial scale at any finite order. However, by applying PMC scale-setting, we can fix the scales of the QCD coupling unambiguously at every order of pQCD. The result is that both D ns and the inverse coefficient Cmore » $$-1\\atop{Bjp}$$ have identical pQCD coefficients, which also exactly match the coefficients of the corresponding conformal theory. Thus one obtains a new generalized Crewther relation for QCD which connects two effective charges, $$\\hat{α}$$ d(Q)=Σ i≥1$$\\hat{α}^i\\atop{g1}$$(Qi), at their respective physical scales. This identity is independent of the choice of the renormalization scheme at any finite order, and the dependence on

Effective holographic models for QCD: Glueball spectrum and trace anomaly

NASA Astrophysics Data System (ADS)

Ballon-Bayona, Alfonso; Boschi-Filho, Henrique; Mamani, Luis A. H.; Miranda, Alex S.; Zanchin, Vilson T.

2018-02-01

We investigate effective holographic models for QCD arising from five-dimensional dilaton gravity. The models are characterized by a dilaton with a mass term in the UV, dual to a CFT deformation by a relevant operator, and quadratic in the IR. The UV constraint leads to the explicit breaking of conformal symmetry, whereas the IR constraint guarantees linear confinement. We propose semianalytic interpolations between the UV and the IR and obtain a spectrum for scalar and tensor glueballs consistent with lattice QCD data. We use the glueball spectrum as a physical constraint to find the evolution of the model parameters as the mass term goes to 0. Finally, we reproduce the universal result for the trace anomaly of deformed CFTs and propose a dictionary between this result and the QCD trace anomaly. A nontrivial consequence of this dictionary is the emergence of a β function similar to the two-loop perturbative QCD result.

Longitudinal conductivity in strong magnetic field in perturbative QCD: Complete leading order

NASA Astrophysics Data System (ADS)

Hattori, Koichi; Li, Shiyong; Satow, Daisuke; Yee, Ho-Ung

2017-04-01

We compute the longitudinal electrical conductivity in the presence of a strong background magnetic field in complete leading order of perturbative QCD, based on the assumed hierarchy of scales αse B ≪(mq2,T2)≪e B . We formulate an effective kinetic theory of lowest Landau level quarks with the leading order QCD collision term arising from 1-to-2 processes that become possible due to 1 +1 dimensional Landau level kinematics. In the small mq/T ≪1 regime, the longitudinal conductivity behaves as σz z˜e2(e B )T /(αsmq2log (T /mq)) , where the quark mass dependence can be understood from the chiral anomaly with the axial charge relaxation provided by a finite quark mass mq. We also present parametric estimates for the longitudinal and transverse "color conductivities" in the presence of the strong magnetic field, by computing dominant damping rates for quarks and gluons that are responsible for color charge transportation. We observe that the longitudinal color conductivity is enhanced by the strong magnetic field, which implies that the sphaleron transition rate in perturbative QCD is suppressed by the strong magnetic field due to the enhanced Lenz's law in color field dynamics.

Regge spectra of excited mesons, harmonic confinement, and QCD vacuum structure

NASA Astrophysics Data System (ADS)

Nedelko, Sergei N.; Voronin, Vladimir E.

2016-05-01

An approach to QCD vacuum as a medium describable in terms of a statistical ensemble of almost everywhere homogeneous Abelian (anti-)self-dual gluon fields is briefly reviewed. These fields play the role of the confining medium for color charged fields as well as underline the mechanism of realization of chiral S UL(Nf)×S UR(Nf) and UA(1 ) symmetries. Hadronization formalism based on this ensemble leads to manifestly defined quantum effective meson action. Strong, electromagnetic, and weak interactions of mesons are represented in the action in terms of nonlocal n -point interaction vertices given by the quark-gluon loops averaged over the background ensemble. New systematic results for the mass spectrum and decay constants of radially excited light, heavy-light mesons, and heavy quarkonia are presented. The interrelation between the present approach, models based on ideas of soft-wall anti-de Sitter/QCD, light-front holographic QCD, and the picture of harmonic confinement is outlined.

Effective model approach to the dense state of QCD matter

NASA Astrophysics Data System (ADS)

Fukushima, Kenji

2011-12-01

The first-principle approach to the dense state of QCD matter, i.e. the lattice-QCD simulation at finite baryon density, is not under theoretical control for the moment. The effective model study based on QCD symmetries is a practical alternative. However the model parameters that are fixed by hadronic properties in the vacuum may have unknown dependence on the baryon chemical potential. We propose a new prescription to constrain the effective model parameters by the matching condition with the thermal Statistical Model. In the transitional region where thermal quantities blow up in the Statistical Model, deconfined quarks and gluons should smoothly take over the relevant degrees of freedom from hadrons and resonances. We use the Polyakov-loop coupled Nambu-Jona-Lasinio (PNJL) model as an effective description in the quark side and show how the matching condition is satisfied by a simple ansäatz on the Polyakov loop potential. Our results favor a phase diagram with the chiral phase transition located at slightly higher temperature than deconfinement which stays close to the chemical freeze-out points.

Isotensor Axial Polarizability and Lattice QCD Input for Nuclear Double-β Decay Phenomenology.

PubMed

Shanahan, Phiala E; Tiburzi, Brian C; Wagman, Michael L; Winter, Frank; Chang, Emmanuel; Davoudi, Zohreh; Detmold, William; Orginos, Kostas; Savage, Martin J

2017-08-11

The potential importance of short-distance nuclear effects in double-β decay is assessed using a lattice QCD calculation of the nn→pp transition and effective field theory methods. At the unphysical quark masses used in the numerical computation, these effects, encoded in the isotensor axial polarizability, are found to be of similar magnitude to the nuclear modification of the single axial current, which phenomenologically is the quenching of the axial charge used in nuclear many-body calculations. This finding suggests that nuclear models for neutrinoful and neutrinoless double-β decays should incorporate this previously neglected contribution if they are to provide reliable guidance for next-generation neutrinoless double-β decay searches. The prospects of constraining the isotensor axial polarizabilities of nuclei using lattice QCD input into nuclear many-body calculations are discussed.

Axial charges of N(1535) and N(1650) in lattice QCD with two flavors of dynamical quarks

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

Takahashi, Toru T.; Kunihiro, Teiji

2008-07-01

We show the first lattice QCD results on the axial charge g{sub A}{sup N}*{sup N}* of N*(1535) and N*(1650). The measurements are performed with two flavors of dynamical quarks employing the renormalization-group improved gauge action at {beta}=1.95 and the mean-field improved clover quark action with the hopping parameters, {kappa}=0.1375, 0.1390, and 0.1400. In order to properly separate signals of N*(1535) and N*(1650), we construct 2x2 correlation matrices and diagonalize them. Wraparound contributions in the correlator, which can be another source of signal contaminations, are eliminated by imposing the Dirichlet boundary condition in the temporal direction. We find that the axialmore » charge of N*(1535) takes small values such as g{sub A}{sup N}*{sup N}*{approx}O(0.1), whereas that of N*(1650) is about 0.5, which is found independent of quark masses and consistent with the predictions by the naive nonrelativistic quark model.« less

Lattice QCD at finite temperature and density from Taylor expansion

NASA Astrophysics Data System (ADS)

Steinbrecher, Patrick

2017-01-01

In the first part, I present an overview of recent Lattice QCD simulations at finite temperature and density. In particular, we discuss fluctuations of conserved charges: baryon number, electric charge and strangeness. These can be obtained from Taylor expanding the QCD pressure as a function of corresponding chemical potentials. Our simulations were performed using quark masses corresponding to physical pion mass of about 140 MeV and allow a direct comparison to experimental data from ultra-relativistic heavy ion beams at hadron colliders such as the Relativistic Heavy Ion Collider at Brookhaven National Laboratory and the Large Hadron Collider at CERN. In the second part, we discuss computational challenges for current and future exascale Lattice simulations with a focus on new silicon developments from Intel and NVIDIA.

Isotensor Axial Polarizability and Lattice QCD Input for Nuclear Double-β Decay Phenomenology

NASA Astrophysics Data System (ADS)

Shanahan, Phiala E.; Tiburzi, Brian C.; Wagman, Michael L.; Winter, Frank; Chang, Emmanuel; Davoudi, Zohreh; Detmold, William; Orginos, Kostas; Savage, Martin J.; Nplqcd Collaboration

2017-08-01

The potential importance of short-distance nuclear effects in double-β decay is assessed using a lattice QCD calculation of the n n →p p transition and effective field theory methods. At the unphysical quark masses used in the numerical computation, these effects, encoded in the isotensor axial polarizability, are found to be of similar magnitude to the nuclear modification of the single axial current, which phenomenologically is the quenching of the axial charge used in nuclear many-body calculations. This finding suggests that nuclear models for neutrinoful and neutrinoless double-β decays should incorporate this previously neglected contribution if they are to provide reliable guidance for next-generation neutrinoless double-β decay searches. The prospects of constraining the isotensor axial polarizabilities of nuclei using lattice QCD input into nuclear many-body calculations are discussed.

Isotensor Axial Polarizability and Lattice QCD Input for Nuclear Double- β Decay Phenomenology

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

Shanahan, Phiala E.; Tiburzi, Brian C.; Wagman, Michael L.

The potential importance of short-distance nuclear effects in double-more » $$\\beta$$ decay is assessed using a lattice QCD calculation of the $$nn\\rightarrow pp$$ transition and effective field theory methods. At the unphysical quark masses used in the numerical computation, these effects, encoded in the isotensor axial polarisability, are found to be of similar magnitude to the nuclear modification of the single axial current, which phenomenologically is the quenching of the axial charge used in nuclear many-body calculations. This finding suggests that nuclear models for neutrinoful and neutrinoless double-$$\\beta$$ decays should incorporate this previously neglected contribution if they are to provide reliable guidance for next-generation neutrinoless double-$$\\beta$$ decay searches. The prospects of constraining the isotensor axial polarisabilities of nuclei using lattice QCD input into nuclear many-body calculations are discussed.« less

Role of QCD monopoles in jet quenching

NASA Astrophysics Data System (ADS)

Ramamurti, Adith; Shuryak, Edward

2018-01-01

QCD monopoles are magnetically charged quasiparticles whose Bose-Einstein condensation (BEC) at T QCD proposes that scattering on the noncondensed component of the monopole ensemble at T >Tc is responsible for the unusual kinetic properties of quark-gluon plasma. In this paper, we study the contribution of the monopoles to jet quenching phenomenon, using the Baier-Dokshitzer-Mueller-Peigne-Schiff framework and hydrodynamic backgrounds. In the lowest order for cross sections, we calculate the nuclear modification factor, RAA, and azimuthal anisotropy, v2, of jets, as well as the dijet asymmetry, Aj, and compare those to the available data. We find relatively good agreement with experiment when using realistic hydrodynamic backgrounds. In addition, we find that event-by-event fluctuations are not necessary to reproduce RAA and v2 data, but play a role in Aj. Since the monopole-induced effects are maximal at T ≈Tc, we predict that their role should be significantly larger, relative to quarks and gluons, at lower RHIC energies.

First Monte Carlo Global Analysis of Nucleon Transversity with Lattice QCD Constraints

NASA Astrophysics Data System (ADS)

Lin, H.-W.; Melnitchouk, W.; Prokudin, A.; Sato, N.; Shows, H.; Jefferson Lab Angular Momentum JAM Collaboration

2018-04-01

We report on the first global QCD analysis of the quark transversity distributions in the nucleon from semi-inclusive deep-inelastic scattering (SIDIS), using a new Monte Carlo method based on nested sampling and constraints on the isovector tensor charge gT from lattice QCD. A simultaneous fit to the available SIDIS Collins asymmetry data is compatible with gT values extracted from a comprehensive reanalysis of existing lattice simulations, in contrast to previous analyses, which found significantly smaller gT values. The contributions to the nucleon tensor charge from u and d quarks are found to be δ u =0.3 (2 ) and δ d =-0.7 (2 ) at a scale Q2=2 GeV2.

Constraining the hadronic spectrum through QCD thermodynamics on the lattice

NASA Astrophysics Data System (ADS)

Alba, Paolo; Bellwied, Rene; Borsányi, Szabolcs; Fodor, Zoltan; Günther, Jana; Katz, Sandor D.; Mantovani Sarti, Valentina; Noronha-Hostler, Jacquelyn; Parotto, Paolo; Pasztor, Attila; Vazquez, Israel Portillo; Ratti, Claudia

2017-08-01

Fluctuations of conserved charges allow us to study the chemical composition of hadronic matter. A comparison between lattice simulations and the hadron resonance gas (HRG) model suggested the existence of missing strange resonances. To clarify this issue we calculate the partial pressures of mesons and baryons with different strangeness quantum numbers using lattice simulations in the confined phase of QCD. In order to make this calculation feasible, we perform simulations at imaginary strangeness chemical potentials. We systematically study the effect of different hadronic spectra on thermodynamic observables in the HRG model and compare to lattice QCD results. We show that, for each hadronic sector, the well-established states are not enough in order to have agreement with the lattice results. Additional states, either listed in the Particle Data Group booklet (PDG) but not well established, or predicted by the quark model (QM), are necessary in order to reproduce the lattice data. For mesons, it appears that the PDG and the quark model do not list enough strange mesons, or that, in this sector, interactions beyond those included in the HRG model are needed to reproduce the lattice QCD results.

Spontaneous CP breaking in QCD and the axion potential: an effective Lagrangian approach

NASA Astrophysics Data System (ADS)

Di Vecchia, Paolo; Rossi, Giancarlo; Veneziano, Gabriele; Yankielowicz, Shimon

2017-12-01

Using the well-known low-energy effective Lagrangian of QCD — valid for small (non-vanishing) quark masses and a large number of colors — we study in detail the regions of parameter space where CP is spontaneously broken/unbroken for a vacuum angle θ = π. In the CP broken region there are first order phase transitions as one crosses θ = π, while on the (hyper)surface separating the two regions, there are second order phase transitions signalled by the vanishing of the mass of a pseudo Nambu-Goldstone boson and by a divergent QCD topological susceptibility. The second order point sits at the end of a first order line associated with the CP spontaneous breaking, in the appropriate complex parameter plane. When the effective Lagrangian is extended by the inclusion of an axion these features of QCD imply that standard calculations of the axion potential have to be revised if the QCD parameters fall in the above mentioned CP broken region, in spite of the fact that the axion solves the strong- CP problem. These last results could be of interest for axionic dark matter calculations if the topological susceptibility of pure Yang-Mills theory falls off sufficiently fast when temperature is increased towards the QCD deconfining transition.

QCD Evolution 2016

NASA Astrophysics Data System (ADS)

The QCD Evolution 2016 workshop was held at the National Institute for Subatomic Physics (Nikhef) in Amsterdam, May 30 - June 3, 2016. The workshop is a continuation of a series of workshops held during five consecutive years, in 2011, 2012, 2013, 2015 at Jefferson Lab, and in 2014 in Santa Fe, NM. With the rapid developments in our understanding of the evolution of parton distributions including low-x, TMDs, GPDs, higher-twist correlation functions, and the associated progress in perturbative QCD, lattice QCD and effective field theory techniques, we look forward to yet another exciting meeting in 2016. The program of QCD Evolution 2016 will pay special attention to the topics of importance for ongoing experiments, in the full range from Jefferson Lab energies to LHC energies or future experiments such as a future Electron Ion Collider, recently recommended as a highest priority in U.S. Department of Energy's 2015 Long Range Plan for Nuclear Science.

Prompt atmospheric neutrino fluxes: perturbative QCD models and nuclear effects

DOE PAGES

Bhattacharya, Atri; Enberg, Rikard; Jeong, Yu Seon; ...

2016-11-28

We evaluate the prompt atmospheric neutrino flux at high energies using three different frameworks for calculating the heavy quark production cross section in QCD: NLO perturbative QCD, k T factorization including low-x resummation, and the dipole model including parton saturation. We use QCD parameters, the value for the charm quark mass and the range for the factorization and renormalization scales that provide the best description of the total charm cross section measured at fixed target experiments, at RHIC and at LHC. Using these parameters we calculate differential cross sections for charm and bottom production and compare with the latest datamore » on forward charm meson production from LHCb at 7 TeV and at 13 TeV, finding good agreement with the data. In addition, we investigate the role of nuclear shadowing by including nuclear parton distribution functions (PDF) for the target air nucleus using two different nuclear PDF schemes. Depending on the scheme used, we find the reduction of the flux due to nuclear effects varies from 10% to 50% at the highest energies. Finally, we compare our results with the IceCube limit on the prompt neutrino flux, which is already providing valuable information about some of the QCD models.« less

Quark–gluon plasma phenomenology from anisotropic lattice QCD

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

Skullerud, Jon-Ivar; Kelly, Aoife; Aarts, Gert

The FASTSUM collaboration has been carrying out simulations of N{sub f} = 2 + 1 QCD at nonzero temperature in the fixed-scale approach using anisotropic lattices. Here we present the status of these studies, including recent results for electrical conductivity and charge diffusion, and heavy quarkonium (charm and beauty) physics.

Hamiltonian Effective Field Theory Study of the N^{*}(1535) Resonance in Lattice QCD.

PubMed

Liu, Zhan-Wei; Kamleh, Waseem; Leinweber, Derek B; Stokes, Finn M; Thomas, Anthony W; Wu, Jia-Jun

2016-02-26

Drawing on experimental data for baryon resonances, Hamiltonian effective field theory (HEFT) is used to predict the positions of the finite-volume energy levels to be observed in lattice QCD simulations of the lowest-lying J^{P}=1/2^{-} nucleon excitation. In the initial analysis, the phenomenological parameters of the Hamiltonian model are constrained by experiment and the finite-volume eigenstate energies are a prediction of the model. The agreement between HEFT predictions and lattice QCD results obtained on volumes with spatial lengths of 2 and 3 fm is excellent. These lattice results also admit a more conventional analysis where the low-energy coefficients are constrained by lattice QCD results, enabling a determination of resonance properties from lattice QCD itself. Finally, the role and importance of various components of the Hamiltonian model are examined.

Nonperturbative QCD Coupling and its $$\\beta$$-function from Light-Front Holography

DOE PAGES

Brodskey, Stanley J.; de Teramond, Guy; Deur, Alexandre P.

2010-05-28

The light-front holographic mapping of classical gravity in AdS space, modified by a positive-sign dilaton background, leads to a non-perturbative effective couplingmore » $$\\alpha_s^{AdS}(Q^2)$$. It agrees with hadron physics data extracted from different observables, such as the effective charge defined by the Bjorken sum rule, as well as with the predictions of models with built-in confinement and lattice simulations. It also displays a transition from perturbative to nonperturbative conformal regimes at a momentum scale $$ \\sim 1$$ GeV. The resulting $$\\beta$$-function appears to capture the essential characteristics of the full $$\\beta$$-function of QCD, thus giving further support to the application of the gauge/gravity duality to the confining dynamics of strongly coupled QCD. Commensurate scale relations relate observables to each other without scheme or scale ambiguity. In this paper we extrapolate these relations to the nonperturbative domain, thus extending the range of predictions based on $$\\alpha_s^{AdS}(Q^2)$$.« less

Massive photons: An infrared regularization scheme for lattice QCD + QED

DOE PAGES

Endres, Michael G.; Shindler, Andrea; Tiburzi, Brian C.; ...

2016-08-10

The commonly adopted approach for including electromagnetic interactions in lattice QCD simulations relies on using finite volume as the infrared regularization for QED. The long-range nature of the electromagnetic interaction, however, implies that physical quantities are susceptible to power-law finite volume corrections, which must be removed by performing costly simulations at multiple lattice volumes, followed by an extrapolation to the infinite volume limit. In this work, we introduce a photon mass as an alternative means for gaining control over infrared effects associated with electromagnetic interactions. We present findings for hadron mass shifts due to electromagnetic interactions (i.e., for the proton,more » neutron, charged and neutral kaon) and corresponding mass splittings, and compare the results with those obtained from conventional QCD+QED calculations. Results are reported for numerical studies of three flavor electroquenched QCD using ensembles corresponding to 800 MeV pions, ensuring that the only appreciable volume corrections arise from QED effects. The calculations are performed with three lattice volumes with spatial extents ranging from 3.4 - 6.7 fm. As a result, we find that for equal computing time (not including the generation of the lattice configurations), the electromagnetic mass shifts can be extracted from computations on a single (our smallest) lattice volume with comparable or better precision than the conventional approach.« less

QCD as a Theory of Hadrons

NASA Astrophysics Data System (ADS)

Narison, Stephan

2004-05-01

About Stephan Narison; Outline of the book; Preface; Acknowledgements; Part I. General Introduction: 1. A short flash on particle physics; 2. The pre-QCD era; 3. The QCD story; 4. Field theory ingredients; Part II. QCD Gauge Theory: 5. Lagrangian and gauge invariance; 6. Quantization using path integral; 7. QCD and its global invariance; Part III. MS scheme for QCD and QED: Introduction; 8. Dimensional regularization; 9. The MS renormalization scheme; 10. Renormalization of operators using the background field method; 11. The renormalization group; 12. Other renormalization schemes; 13. MS scheme for QED; 14. High-precision low-energy QED tests; Part IV. Deep Inelastic Scattering at Hadron Colliders: 15. OPE for deep inelastic scattering; 16. Unpolarized lepton-hadron scattering; 17. The Altarelli-Parisi equation; 18. More on unpolarized deep inelastic scatterings; 19. Polarized deep-inelastic processes; 20. Drell-Yan process; 21. One 'prompt photon' inclusive production; Part V. Hard Processes in e+e- Collisions: Introduction; 22. One hadron inclusive production; 23. gg scatterings and the 'spin' of the photon; 24. QCD jets; 25. Total inclusive hadron productions; Part VI. Summary of QCD Tests and as Measurements; Part VII. Power Corrections in QCD: 26. Introduction; 27. The SVZ expansion; 28. Technologies for evaluating Wilson coefficients; 29. Renormalons; 30. Beyond the SVZ expansion; Part VIII. QCD Two-Point Functions: 31. References guide to original works; 32. (Pseudo)scalar correlators; 33. (Axial-)vector two-point functions; 34. Tensor-quark correlator; 35. Baryonic correlators; 36. Four-quark correlators; 37. Gluonia correlators; 38. Hybrid correlators; 39. Correlators in x-space; Part IX. QCD Non-Perturbative Methods: 40. Introduction; 41. Lattice gauge theory; 42. Chiral perturbation theory; 43. Models of the QCD effective action; 44. Heavy quark effective theory; 45. Potential approaches to quarkonia; 46. On monopole and confinement; Part X. QCD

QCD as a Theory of Hadrons

NASA Astrophysics Data System (ADS)

Narison, Stephan

2007-07-01

About Stephan Narison; Outline of the book; Preface; Acknowledgements; Part I. General Introduction: 1. A short flash on particle physics; 2. The pre-QCD era; 3. The QCD story; 4. Field theory ingredients; Part II. QCD Gauge Theory: 5. Lagrangian and gauge invariance; 6. Quantization using path integral; 7. QCD and its global invariance; Part III. MS scheme for QCD and QED: Introduction; 8. Dimensional regularization; 9. The MS renormalization scheme; 10. Renormalization of operators using the background field method; 11. The renormalization group; 12. Other renormalization schemes; 13. MS scheme for QED; 14. High-precision low-energy QED tests; Part IV. Deep Inelastic Scattering at Hadron Colliders: 15. OPE for deep inelastic scattering; 16. Unpolarized lepton-hadron scattering; 17. The Altarelli-Parisi equation; 18. More on unpolarized deep inelastic scatterings; 19. Polarized deep-inelastic processes; 20. Drell-Yan process; 21. One 'prompt photon' inclusive production; Part V. Hard Processes in e+e- Collisions: Introduction; 22. One hadron inclusive production; 23. gg scatterings and the 'spin' of the photon; 24. QCD jets; 25. Total inclusive hadron productions; Part VI. Summary of QCD Tests and as Measurements; Part VII. Power Corrections in QCD: 26. Introduction; 27. The SVZ expansion; 28. Technologies for evaluating Wilson coefficients; 29. Renormalons; 30. Beyond the SVZ expansion; Part VIII. QCD Two-Point Functions: 31. References guide to original works; 32. (Pseudo)scalar correlators; 33. (Axial-)vector two-point functions; 34. Tensor-quark correlator; 35. Baryonic correlators; 36. Four-quark correlators; 37. Gluonia correlators; 38. Hybrid correlators; 39. Correlators in x-space; Part IX. QCD Non-Perturbative Methods: 40. Introduction; 41. Lattice gauge theory; 42. Chiral perturbation theory; 43. Models of the QCD effective action; 44. Heavy quark effective theory; 45. Potential approaches to quarkonia; 46. On monopole and confinement; Part X. QCD

Study of transverse momenta of charged hadrons produced in ν p andbar vp charged current interactions

NASA Astrophysics Data System (ADS)

Jones, G. T.; Kennedy, B. W.; Middleton, R. P.; O'Neale, S. W.; Cooper, A. M.; Grant, A.; Klein, H.; Mittendorfer, J.; Morrison, D. R. O.; Parker, A.; Schmid, P.; Wachsmuth, H.; Hamisi, F.; Mobayyen, M. M.; Villalobos-Baillie, O.; Aderholz, M.; Deck, L.; Schmitz, N.; Wittek, W.; Corrigan, G.; Myatt, G.; Radojicic, D.; Retter, M.

1984-06-01

Data from a neutrino and antineutrino hydrogen experiment with BEBC are used to investigate transverse properties of the produced charged hadrons. Measurements are presented on average transverse momenta of charged pions as functions of Feynman- x and the hadronic mass, on the transverse momentum flow within an event and on jet-related quantities. The main features of the data are well described by the LUND model. The data favour a version of the model in which soft gluon effects are included and the primordial transverse momentum of the quarks in the proton is small. Effects from 1st order QCD (hard gluon emission) are negligible.

Chiral magnetic effect in lattice QCD with a chiral chemical potential.

PubMed

Yamamoto, Arata

2011-07-15

We perform a first lattice QCD simulation including a two-flavor dynamical fermion with a chiral chemical potential. Because the chiral chemical potential gives rise to no sign problem, we can exactly analyze a chirally imbalanced QCD matter by Monte Carlo simulation. By applying an external magnetic field to this system, we obtain a finite induced current along the magnetic field, which corresponds to the chiral magnetic effect. The obtained induced current is proportional to the magnetic field and to the chiral chemical potential, which is consistent with an analytical prediction.

First Monte Carlo Global Analysis of Nucleon Transversity with Lattice QCD Constraints.

PubMed

Lin, H-W; Melnitchouk, W; Prokudin, A; Sato, N; Shows, H

2018-04-13

We report on the first global QCD analysis of the quark transversity distributions in the nucleon from semi-inclusive deep-inelastic scattering (SIDIS), using a new Monte Carlo method based on nested sampling and constraints on the isovector tensor charge g_{T} from lattice QCD. A simultaneous fit to the available SIDIS Collins asymmetry data is compatible with g_{T} values extracted from a comprehensive reanalysis of existing lattice simulations, in contrast to previous analyses, which found significantly smaller g_{T} values. The contributions to the nucleon tensor charge from u and d quarks are found to be δu=0.3(2) and δd=-0.7(2) at a scale Q^{2}=2  GeV^{2}.

2017 QCD Evolution 2017

NASA Astrophysics Data System (ADS)

2017-05-01

The QCD Evolution 2017 workshop was held at Jefferson Lab, May 22-26, 2017. The workshop is a continuation of a series of workshops held during six consecutive years, in 2011, 2012, 2013, 2015 at Jefferson Lab, and in 2014 in Santa Fe, NM, and in 2016 at the National Institute for Subatomic Physics (Nikhef) in Amsterdam. With the rapid developments in our understanding of the evolution of parton distributions including TMDs, GPDs, low-x, higher-twist correlation functions, and the associated progress in perturbative QCD, lattice QCD and effective field theory techniques, we look forward to yet another exciting meeting in 2017. The program of QCD Evolution 2017 will pay special attention to the topics of importance for ongoing experiments, in the full range from Jefferson Lab energies to RHIC and LHC energies or future experiments such as a future Electron Ion Collider, recently recommended as a highest priority in U.S. Department of Energy's 2015 Long Range Plan for Nuclear Science.

The current matrix elements from HAL QCD method

NASA Astrophysics Data System (ADS)

Watanabe, Kai; Ishii, Noriyoshi

2018-03-01

HAL QCD method is a method to construct a potential (HAL QCD potential) that reproduces the NN scattering phase shift faithful to the QCD. The HAL QCD potential is obtained from QCD by eliminating the degrees of freedom of quarks and gluons and leaving only two particular hadrons. Therefor, in the effective quantum mechanics of two nucleons defined by HAL QCD potential, the conserved current consists not only of the nucleon current but also an extra current originating from the potential (two-body current). Though the form of the two-body current is closely related to the potential, it is not straight forward to extract the former from the latter. In this work, we derive the the current matrix element formula in the quantum mechanics defined by the HAL QCD potential. As a first step, we focus on the non-relativistic case. To give an explicit example, we consider a second quantized non-relativistic two-channel coupling model which we refer to as the original model. From the original model, the HAL QCD potential for the open channel is constructed by eliminating the closed channel in the elastic two-particle scattering region. The current matrix element formula is derived by demanding the effective quantum mechanics defined by the HAL QCD potential to respond to the external field in the same way as the original two-channel coupling model.

Virtual Compton scattering off a spinless target in AdS/QCD

NASA Astrophysics Data System (ADS)

Marquet, Cyrille; Roiesnel, Claude; Wallon, Samuel

2010-04-01

We study the doubly virtual Compton scattering off a spinless target γ* P → γ* P' within the Anti-de Sitter(AdS)/QCD formalism. We find that the general structure allowed by the Lorentz invariance and gauge invariance of the Compton amplitude is not easily reproduced with the standard recipes of the AdS/QCD correspondence. In the soft-photon regime, where the semi-classical approximation is supposed to apply best, we show that the measurements of the electric and magnetic polarizabilities of a target like the charged pion in real Compton scattering, can already serve as stringent tests.

Simulations of QCD and QED with C* boundary conditions

NASA Astrophysics Data System (ADS)

Hansen, Martin; Lucini, Biagio; Patella, Agostino; Tantalo, Nazario

2018-03-01

We present exploratory results from dynamical simulations of QCD in isolation, as well as QCD coupled to QED, with C* boundary conditions. In finite volume, the use of C* boundary conditions allows for a gauge invariant and local formulation of QED without zero modes. In particular we show that the simulations reproduce known results and that masses of charged mesons can be extracted in a completely gauge invariant way. For the simulations we use a modified version of the HiRep code. The primary features of the simulation code are presented and we discuss some details regarding the implementation of C* boundary conditions and the simulated lattice action. Preprint: CP3-Origins-2017-046 DNRF90, CERN-TH-2017-214

Topics in QCD at Nonzero Temperature and Density

NASA Astrophysics Data System (ADS)

Pangeni, Kamal

Understanding the behavior of matter at ultra-high density such as neutron stars require the knowledge of ground state properties of Quantum chromodynamics (QCD) at finite chemical potential. However, this task has turned out to be very difficult because of two main reasons: 1) QCD may still be strongly coupled at those regimes making perturbative calculations unreliable and 2) QCD at finite density suffers from the sign problem that makes the use of lattice simulation problematic and it even affects phenomenological models. In the first part of this thesis, we show that the sign problem in analytical calculations of finite density models can be solved by considering the CK-symmetric, where C is charge conjugation and K is complex conjugation, complex saddle points of the effective action. We then explore the properties and consequences of such complex saddle points at non-zero temperature and density. Due to CK symmetry, the mass matrix eigenvalues in these models are not always real but can be complex, which results in damped oscillation of the density-density correlation function, a new feature of finite density models. To address the generality of such behavior, we next consider a lattice model of QCD with static quarks at strong-coupling. Computation of the mass spectrum confirms the existence of complex eigenvalues in much of temperature-chemical potential plane. This provides an independent confirmation of our results obtained using phenomenological models of QCD. The existence of regions in parameter space where density-density correlation function exhibit damped oscillation is one of the hallmarks of typical liquid-gas system. The formalism developed to tackle the sign problem in QCD models actually gives a simple understanding for the existence of such behavior in liquid-gas system. To this end, we develop a generic field theoretic model for the treatment of liquid-gas phase transition. An effective field theory at finite density derived from a

QCD In Extreme Conditions

NASA Astrophysics Data System (ADS)

Wilczek, Frank

Introduction Symmetry and the Phenomena of QCD Apparent and Actual Symmetries Asymptotic Freedom Confinement Chiral Symmetry Breaking Chiral Anomalies and Instantons High Temperature QCD: Asymptotic Properties Significance of High Temperature QCD Numerical Indications for Quasi-Free Behavior Ideas About Quark-Gluon Plasma Screening Versus Confinement Models of Chiral Symmetry Breaking More Refined Numerical Experiments High-Temperature QCD: Phase Transitions Yoga of Phase Transitions and Order Parameters Application to Glue Theories Application to Chiral Transitions Close Up on Two Flavors A Genuine Critical Point! (?) High-Density QCD: Methods Hopes, Doubts, and Fruition Another Renormalization Group Pairing Theory Taming the Magnetic Singularity High-Density QCD: Color-Flavor Locking and Quark-Hadron Continuity Gauge Symmetry (Non)Breaking Symmetry Accounting Elementary Excitations A Modified Photon Quark-Hadron Continuity Remembrance of Things Past More Quarks Fewer Quarks and Reality

Baryon interactions in lattice QCD: the direct method vs. the HAL QCD potential method

NASA Astrophysics Data System (ADS)

Iritani, T.; HAL QCD Collaboration

We make a detailed comparison between the direct method and the HAL QCD potential method for the baryon-baryon interactions, taking the $\\Xi\\Xi$ system at $m_\\pi= 0.51$ GeV in 2+1 flavor QCD and using both smeared and wall quark sources. The energy shift $\\Delta E_\\mathrm{eff}(t)$ in the direct method shows the strong dependence on the choice of quark source operators, which means that the results with either (or both) source are false. The time-dependent HAL QCD method, on the other hand, gives the quark source independent $\\Xi\\Xi$ potential, thanks to the derivative expansion of the potential, which absorbs the source dependence to the next leading order correction. The HAL QCD potential predicts the absence of the bound state in the $\\Xi\\Xi$($^1$S$_0$) channel at $m_\\pi= 0.51$ GeV, which is also confirmed by the volume dependence of finite volume energy from the potential. We also demonstrate that the origin of the fake plateau in the effective energy shift $\\Delta E_\\mathrm{eff}(t)$ at $t \\sim 1$ fm can be clarified by a few low-lying eigenfunctions and eigenvalues on the finite volume derived from the HAL QCD potential, which implies that the ground state saturation of $\\Xi\\Xi$($^1$S$_0$) requires $t \\sim 10$ fm in the direct method for the smeared source on $(4.3 \\ \\mathrm{fm})^3$ lattice, while the HAL QCD method does not suffer from such a problem.

Lattice QCD with mismatched fermi surfaces.

PubMed

Yamamoto, Arata

2014-04-25

We study two flavor fermions with mismatched chemical potentials in quenched lattice QCD. We first consider a large isospin chemical potential, where a charged pion is condensed, and then introduce a small mismatch between the chemical potentials of the up quark and the down antiquark. We find that the homogeneous pion condensate is destroyed by the mismatch of the chemical potentials. We also find that the two-point correlation function shows spatial oscillation, which indicates an inhomogeneous ground state, although it is not massless but massive in the present simulation setup.

First Renormalized Parton Distribution Functions from Lattice QCD

NASA Astrophysics Data System (ADS)

Lin, Huey-Wen; LP3 Collaboration

2017-09-01

We present the first lattice-QCD results on the nonperturbatively renormalized parton distribution functions (PDFs). Using X.D. Ji's large-momentum effective theory (LaMET) framework, lattice-QCD hadron structure calculations are able to overcome the longstanding problem of determining the Bjorken- x dependence of PDFs. This has led to numerous additional theoretical works and exciting progress. In this talk, we will address a recent development that implements a step missing from prior lattice-QCD calculations: renormalization, its effects on the nucleon matrix elements, and the resultant changes to the calculated distributions.

Lattice QCD in rotating frames.

PubMed

Yamamoto, Arata; Hirono, Yuji

2013-08-23

We formulate lattice QCD in rotating frames to study the physics of QCD matter under rotation. We construct the lattice QCD action with the rotational metric and apply it to the Monte Carlo simulation. As the first application, we calculate the angular momenta of gluons and quarks in the rotating QCD vacuum. This new framework is useful to analyze various rotation-related phenomena in QCD.

Measuring the charged pion polarizability in the gamma gamma -> pi+pi- reaction

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

Lawrence, David W.; Miskimen, Rory A.; Mushkarenkov, Alexander Nikolaevich

2013-08-01

Development has begun of a new experiment to measure the charged pion polarizabilitymore » $$\\alpha_{\\pi}-\\beta_{\\pi}$$. The charged pion polarizability ranks among the most important tests of low-energy QCD presently unresolved by experiment. Analogous to precision measurements of $$\\pi^{\\circ}\\rightarrow\\gamma\\gamma$$ that test the intrinsic odd-parity (anomalous) sector of QCD, the pion polarizability tests the intrinsic even-parity sector of QCD. The measurement will be performed using the $$\\gamma\\gamma\\rightarrow\\pi^{+{}}\\pi^{-{}}$$ cross section accessed via the Primakoff mechanism on nuclear targets using the GlueX detector in Hall D at Jefferson Lab. The linearly polarized photon source in Hall-D will be utilized to separate the Primakoff cross-section from coherent $$\\rho^{\\circ}$$ production.« less

The Nc dependencies of baryon masses: Analysis with Lattice QCD and Effective Theory

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

Calle Cordon, Alvaro C.; DeGrand, Thomas A.; Goity, Jose L.

Baryon masses at varying values of Nc and light quark masses are studied with Lattice QCD and the results are analyzed in a low energy effective theory based on a combined framework of the 1/Nc and Heavy Baryon Chiral Perturbation Theory expansions. Lattice QCD results for Nc=3, 5 and 7 obtained in quenched calculations, as well as results for unquenched calculations for Nc=3, are used for the analysis. The results are consistent with a previous analysis of Nc=3 LQCD results, and in addition permit the determination of sub-leading in 1/Nc effects in the spin-flavor singlet component of the baryon massesmore » as well as in the hyperfine splittings.« less

Investigating the topological structure of quenched lattice QCD with overlap fermions using a multi-probing approximation

NASA Astrophysics Data System (ADS)

Zou, You-Hao; Zhang, Jian-Bo; Xiong, Guang-Yi; Chen, Ying; Liu, Chuan; Liu, Yu-Bin; Ma, Jian-Ping

2017-10-01

The topological charge density and topological susceptibility are determined by a multi-probing approximation using overlap fermions in quenched SU(3) gauge theory. Then we investigate the topological structure of the quenched QCD vacuum, and compare it with results from the all-scale topological density. The results are consistent. Random permuted topological charge density is used to check whether these structures represent underlying ordered properties. The pseudoscalar glueball mass is extracted from the two-point correlation function of the topological charge density. We study 3 ensembles of different lattice spacing a with the same lattice volume 163×32. The results are compatible with the results of all-scale topological charge density, and the topological structures revealed by multi-probing are much closer to all-scale topological charge density than those from eigenmode expansion. Supported by National Natural Science Foundation of China (NSFC) (11335001, 11275169, 11075167), It is also supported in part by the DFG and the NSFC (11261130311) through funds provided to the Sino-German CRC 110 "Symmetries and the Emergence of Structure in QCD". This work was also funded in part by National Basic Research Program of China (973 Program) (2015CB856700)

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

Chiral dynamics in the low-temperature phase of QCD

NASA Astrophysics Data System (ADS)

Brandt, Bastian B.; Francis, Anthony; Meyer, Harvey B.; Robaina, Daniel

2014-09-01

We investigate the low-temperature phase of QCD and the crossover region with two light flavors of quarks. The chiral expansion around the point (T,m=0) in the temperature vs quark-mass plane indicates that a sharp real-time excitation exists with the quantum numbers of the pion. An exact sum rule is derived for the thermal modification of the spectral function associated with the axial charge density; the (dominant) pion pole contribution obeys the sum rule. We determine the two parameters of the pion dispersion relation using lattice QCD simulations and test the applicability of the chiral expansion. The time-dependent correlators are also analyzed using the maximum entropy method, yielding consistent results. Finally, we test the predictions of the chiral expansion around the point (T=0,m=0) for the temperature dependence of static observables.

Neutral and charged scalar mesons, pseudoscalar mesons, and diquarks in magnetic fields

NASA Astrophysics Data System (ADS)

Liu, Hao; Wang, Xinyang; Yu, Lang; Huang, Mei

2018-04-01

We investigate both (pseudo)scalar mesons and diquarks in the presence of external magnetic field in the framework of the two-flavored Nambu-Jona-Lasinio (NJL) model, where mesons and diquarks are constructed by infinite sum of quark-loop chains by using random phase approximation. The polarization function of the quark-loop is calculated to the leading order of 1 /Nc expansion by taking the quark propagator in the Landau level representation. We systematically investigate the masses behaviors of scalar σ meson, neutral and charged pions as well as the scalar diquarks, with respect to the magnetic field strength at finite temperature and chemical potential. It is shown that the numerical results of both neutral and charged pions are consistent with the lattice QCD simulations. The mass of the charge neutral pion keeps almost a constant under the magnetic field, which is preserved by the remnant symmetry of QCD ×QED in the vacuum. The mass of the charge neutral scalar σ is around two times quark mass and increases with the magnetic field due to the magnetic catalysis effect, which is an typical example showing that the polarized internal quark structure cannot be neglected when we consider the meson properties under magnetic field. For the charged particles, the one quark-antiquark loop contribution to the charged π± increases essentially with the increase of magnetic fields due to the magnetic catalysis of the polarized quarks. However, the one quark-quark loop contribution to the scalar diquark mass is negative comparing with the point-particle result and the loop effect is small.

QCD for Postgraduates (1/5)

ScienceCinema

Zanderighi, Giulia

2018-04-26

Modern QCD - Lecture 1 Starting from the QCD Lagrangian we will revisit some basic QCD concepts and derive fundamental properties like gauge invariance and isospin symmetry and will discuss the Feynman rules of the theory. We will then focus on the gauge group of QCD and derive the Casimirs CF and CA and some useful color identities.

QCD and Light-Front Dynamics

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

Brodsky, Stanley J.; de Teramond, Guy F.; /SLAC /Southern Denmark U., CP3-Origins /Costa Rica U.

2011-01-10

AdS/QCD, the correspondence between theories in a dilaton-modified five-dimensional anti-de Sitter space and confining field theories in physical space-time, provides a remarkable semiclassical model for hadron physics. Light-front holography allows hadronic amplitudes in the AdS fifth dimension to be mapped to frame-independent light-front wavefunctions of hadrons in physical space-time. The result is a single-variable light-front Schroedinger equation which determines the eigenspectrum and the light-front wavefunctions of hadrons for general spin and orbital angular momentum. The coordinate z in AdS space is uniquely identified with a Lorentz-invariant coordinate {zeta} which measures the separation of the constituents within a hadron at equalmore » light-front time and determines the off-shell dynamics of the bound state wavefunctions as a function of the invariant mass of the constituents. The hadron eigenstates generally have components with different orbital angular momentum; e.g., the proton eigenstate in AdS/QCD with massless quarks has L = 0 and L = 1 light-front Fock components with equal probability. Higher Fock states with extra quark-anti quark pairs also arise. The soft-wall model also predicts the form of the nonperturbative effective coupling and its {beta}-function. The AdS/QCD model can be systematically improved by using its complete orthonormal solutions to diagonalize the full QCD light-front Hamiltonian or by applying the Lippmann-Schwinger method to systematically include QCD interaction terms. Some novel features of QCD are discussed, including the consequences of confinement for quark and gluon condensates. A method for computing the hadronization of quark and gluon jets at the amplitude level is outlined.« less

Energy flow and charged particle spectra in deep inelastic scattering at HERA

NASA Astrophysics Data System (ADS)

Abt, I.; Ahmed, T.; Andreev, V.; Aid, S.; Andrieu, B.; Appuhn, R.-D.; Arpagaus, M.; Babaev, A.; Bärwolff, H.; Bán, J.; Baranov, P.; Barrelet, E.; Bartel, W.; Bassler, U.; Beck, H. P.; Behrend, H.-J.; Belousov, A.; Berger, Ch.; Bergstein, H.; Bernardi, G.; Bernet, R.; Bertrand-Coremans, G.; Besançon, M.; Biddulph, P.; Binder, E.; Bizot, J. C.; Blobel, V.; Borras, K.; Bosetti, P. C.; Boudry, V.; Bourdarios, C.; Braemer, A.; Brasse, F.; Braun, U.; Braunschweig, W.; Brisson, V.; Bruncko, D.; Büngener, L.; Bürger, J.; Büsser, F. W.; Buniatian, A.; Burke, S.; Buschhorn, G.; Campbell, A. J.; Carli, T.; Charles, F.; Chyla, J.; Clarke, D.; Clegg, A. B.; Colombo, M.; Coughlan, J. A.; Courau, A.; Coutures, Ch.; Cozzika, G.; Criegee, L.; Cvach, J.; Dagoret, S.; Dainton, J. B.; Danilov, M.; Dann, A. W. E.; Dau, W. D.; David, M.; Deffur, E.; Delcourt, B.; Del Buono, L.; Devel, M.; de Roeck, A.; di Nezza, P.; Dingus, P.; Dollfus, C.; Dowell, J. D.; Dreis, H. B.; Drescher, A.; Duboc, J.; Düllmann, D.; Dünger, O.; Duhm, H.; Ebbinghaus, R.; Eberle, M.; Ebert, J.; Ebert, T. R.; Eckerlin, G.; Efremenko, V.; Egli, S.; Ehrlichmann, H.; Eichenberger, S.; Eichler, R.; Eisele, F.; Eisenhandler, E.; Ellis, N. N.; Ellison, R. J.; Elsen, E.; Erdmann, M.; Evrard, E.; Favart, L.; Fedotov, A.; Feeken, D.; Felst, R.; Feltesse, J.; Fensome, I. F.; Ferencei, J.; Ferrarotto, F.; Flamm, K.; Flauger, W.; Fleischer, M.; Flieser, M.; Flügge, G.; Fomenko, A.; Fominykh, B.; Forbush, M.; Formánek, J.; Foster, J. M.; Franke, G.; Fretwurst, E.; Fuhrmann, P.; Gabathuler, E.; Gamerdinger, K.; Garvey, J.; Gayler, J.; Gebauer, M.; Gellrich, A.; Gennis, M.; Genzel, H.; Gerhards, R.; Godfrey, L.; Goerlach, U.; Goerlich, L.; Gogitidze, N.; Goldberg, M.; Goldner, D.; Goodall, A. M.; Gorelov, I.; Goritchev, P.; Grab, C.; Grässler, H.; Grässler, R.; Greenshaw, T.; Greif, H.; Grindhammer, G.; Gruber, A.; Gruber, C.; Haack, J.; Haidt, D.; Hajduk, L.; Hamon, O.; Hampel, M.; Hanlon, E. M.; Hapke, M.; Harjes, J.; Haydar, R.; Haynes, W. J.; Heatherington, J.; Hedberg, V.; Heinzelmann, G.; Henderson, R. C. W.; Henschel, H.; Herma, R.; Herynek, I.; Hildesheim, W.; Hill, P.; Hilton, C. D.; Hladký, J.; Hoeger, K. C.; Höppner, M.; Huet, Ph.; Hufnagel, H.; Huot, N.; Ibbotson, M.; Itterbeck, H.; Jabiol, M.-A.; Jacholkowska, A.; Jacobsson, C.; Jaffre, M.; Jansen, T.; Jönsson, L.; Johannsen, K.; Johnson, D. P.; Johnson, L.; Jung, H.; Kalmus, P. I. P.; Kant, D.; Kazarian, S.; Kaschowitz, R.; Kasselmann, P.; Kathage, U.; Kaufmann, H. H.; Kenyon, I. R.; Kermiche, S.; Keuker, C.; Kiesling, C.; Klein, M.; Kleinwort, C.; Knies, G.; Ko, W.; Köhler, T.; Kolanoski, H.; Kole, F.; Kolya, S. D.; Korbel, V.; Korn, M.; Kostka, P.; Kotelnikov, S. K.; Krasny, M. W.; Krücker, D.; Krüger, 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.; Langkau, R.; Lanius, P.; Laporte, J. F.; Lebedev, A.; Leuschner, A.; Leverenz, C.; Levonian, S.; Lewin, D.; Ley, Ch.; Lindner, A.; Lindström, G.; Linsel, F.; Lipinski, J.; Loch, P.; Lohmander, H.; Lopez, G. C.; Lüers, D.; Lüke, D.; Magnussen, N.; Malinovski, E.; Mani, S.; Marage, P.; Marks, J.; Marshall, R.; Martens, J.; Martin, R.; Martyn, H.-U.; Martyniak, J.; Masson, S.; Mavroidis, A.; Maxfield, S. J.; McMahon, S. J.; Mehta, A.; Meier, K.; Mercer, D.; Merz, T.; Meyer, C. A.; Meyer, H.; Meyer, J.; Mikocki, S.; Monnier, E.; Moreau, F.; Moreels, J.; Morris, J. V.; Müller, K.; Murín, P.; Murray, S. A.; Nagovizin, V.; Naroska, B.; Naumann, Th.; Newman, P. R.; Newton, D.; Neyret, D.; Nguyen, H. K.; Niebergall, F.; Niebuhr, C.; Nisius, R.; Nowak, G.; Noyes, G. W.; Nyberg, M.; Oberlack, H.; Obrock, U.; Olsson, J. E.; Orenstein, S.; Ould-Saada, F.; Pascaud, C.; Patel, G. D.; Peppel, E.; Peters, S.; Phillips, H. T.; Phillips, J. P.; Pichler, Ch.; Pilgram, W.; Pitzl, D.; Prell, S.; Prosi, R.; Rädel, G.; Raupach, F.; Rauschnabel, K.; Reimer, P.; Reinshagen, S.; Ribarics, P.; Riech, V.; Riedlberger, J.; Riess, S.; Rietz, M.; Robertson, S. M.; Robmann, P.; Roosen, R.; Rosenbauer, K.; Rostovtsev, A.; Royon, C.; Rudowicz, M.; Ruffer, M.; Rusakov, S.; Rybicki, K.; Sahlmann, N.; Sanchez, E.; Sankey, D. P. C.; Savitsky, M.; Schacht, P.; Schleper, P.; von Schlippe, W.; Schmidt, C.; Schmidt, D.; Schmitz, W.; Schöning, A.; Schröder, V.; Schuhmann, E.; Schulz, M.; Schwab, B.; Schwind, A.; Scobel, W.; Seehausen, U.; 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.; Soloviev, Y.; Spitzer, H.; Steenbock, M.; Steffen, P.; Steinberg, R.; Stella, B.; Stephens, K.; Stier, J.; Stösslein, U.; Strachota, J.; Straumann, U.; Struczinski, W.; Sutton, J. P.; Taylor, R. E.; Tchernyshov, V.; Thiebaux, C.; Thompson, G.; Tichomirov, I.; Truöl, P.; Turnau, J.; Tutas, J.; Urban, L.; Usik, A.; Valkar, S.; Valkarova, A.; Vallée, C.; van Esch, P.; Vartapetian, A.; Vazdik, Y.; Vecko, M.; Verrecchia, P.; Vick, R.; Villet, G.; Vogel, E.; Wacker, K.; Walker, I. W.; Walther, A.; Weber, G.; Wegener, D.; Wegener, A.; Wellisch, H. P.; West, L. R.; Willard, S.; Winde, M.; Winter, G.-G.; Wolff, Th.; Womersley, L. A.; Wright, A. E.; Wulff, N.; Yiou, T. P.; Žáček, J.; Zeitnitz, C.; Ziaeepour, H.; Zimmer, M.; Zimmermann, W.; Zomer, F.

1994-09-01

Global properties of the hadronic final state in deep inelastic scattering events at HERA are investigated. The data are corrected for detector effects and are compared directly with QCD phenomenology. Energy flows in both the laboratory frame and the hadronic centre of mass system and energy-energy correlations in the laboratory frame are presented. Comparing various QCD models, the colour dipole model provides the only satisfactory description of the data. In the hadronic centre of mass system the momentum components of charged particles longitudinal and transverse to the virtual boson direction are measured and compared with lower energy lepton-nucleon scattering data as well as with e + e - dat from LEP.

NLO QCD effective field theory analysis of W+W- production at the LHC including fermionic operators

NASA Astrophysics Data System (ADS)

Baglio, Julien; Dawson, Sally; Lewis, Ian M.

2017-10-01

We study the impact of anomalous gauge boson and fermion couplings on the production of W+W- pairs at the LHC. Helicity amplitudes are presented separately to demonstrate the sources of new physics contributions and the impact of QCD and electroweak corrections. The QCD corrections have important effects on the fits to anomalous couplings, in particular when one W boson is longitudinally polarized and the other is transversely polarized. In effective field theory language, we demonstrate that the dimension-6 approximation to constraining new physics effects in W+W- pair production fails at pT˜500 - 1000 GeV .

θ and the η ' in large N supersymmetric QCD

DOE PAGES

Dine, Michael; Draper, Patrick; Stephenson-Haskins, Laurel; ...

2017-05-22

Here, we study the large N θ dependence and the η' potential in supersymmetric QCD with small soft SUSY-breaking terms. Known exact results in SUSY QCD are found to reflect a variety of expectations from large N perturbation theory, including the presence of branches and the behavior of theories with matter (both with N f << N and N f ~ N ). But, there are also striking departures from ordinary QCD and the conventional large N description: instanton effects, when under control, are not exponentially suppressed at large N , and branched structure in supersymmetric QCD is always associatedmore » with approximate discrete symmetries. We suggest that these differences motivate further study of large N QCD on the lattice.« less

Algorithms for Disconnected Diagrams in Lattice QCD

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

Gambhir, Arjun Singh; Stathopoulos, Andreas; Orginos, Konstantinos

2016-11-01

Computing disconnected diagrams in Lattice QCD (operator insertion in a quark loop) entails the computationally demanding problem of taking the trace of the all to all quark propagator. We first outline the basic algorithm used to compute a quark loop as well as improvements to this method. Then, we motivate and introduce an algorithm based on the synergy between hierarchical probing and singular value deflation. We present results for the chiral condensate using a 2+1-flavor clover ensemble and compare estimates of the nucleon charges with the basic algorithm.

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.

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

QCD equation of state to O (μB6) from lattice QCD

NASA Astrophysics Data System (ADS)

Bazavov, A.; Ding, H.-T.; Hegde, P.; Kaczmarek, O.; Karsch, F.; Laermann, E.; Maezawa, Y.; Mukherjee, Swagato; Ohno, H.; Petreczky, P.; Sandmeyer, H.; Steinbrecher, P.; Schmidt, C.; Sharma, S.; Soeldner, W.; Wagner, M.

2017-03-01

We calculated the QCD equation of state using Taylor expansions that include contributions from up to sixth order in the baryon, strangeness and electric charge chemical potentials. Calculations have been performed with the Highly Improved Staggered Quark action in the temperature range T ∈[135 MeV ,330 MeV ] using up to four different sets of lattice cutoffs corresponding to lattices of size Nσ3×Nτ with aspect ratio Nσ/Nτ=4 and Nτ=6 - 16 . The strange quark mass is tuned to its physical value, and we use two strange to light quark mass ratios ms/ml=20 and 27, which in the continuum limit correspond to a pion mass of about 160 and 140 MeV, respectively. Sixth-order results for Taylor expansion coefficients are used to estimate truncation errors of the fourth-order expansion. We show that truncation errors are small for baryon chemical potentials less then twice the temperature (μB≤2 T ). The fourth-order equation of state thus is suitable for the modeling of dense matter created in heavy ion collisions with center-of-mass energies down to √{sN N}˜12 GeV . We provide a parametrization of basic thermodynamic quantities that can be readily used in hydrodynamic simulation codes. The results on up to sixth-order expansion coefficients of bulk thermodynamics are used for the calculation of lines of constant pressure, energy and entropy densities in the T -μB plane and are compared with the crossover line for the QCD chiral transition as well as with experimental results on freeze-out parameters in heavy ion collisions. These coefficients also provide estimates for the location of a possible critical point. We argue that results on sixth-order expansion coefficients disfavor the existence of a critical point in the QCD phase diagram for μB/T ≤2 and T /Tc(μB=0 )>0.9 .

QCD equation of state to O ( μ B 6 ) from lattice QCD

DOE PAGES

Bazavov, A.; Ding, H. -T.; Hegde, P.; ...

2017-03-07

In this work, we calculated the QCD equation of state using Taylor expansions that include contributions from up to sixth order in the baryon, strangeness and electric charge chemical potentials. Calculations have been performed with the Highly Improved Staggered Quark action in the temperature range T ϵ [135 MeV, 330 MeV] using up to four different sets of lattice cut-offs corresponding to lattices of size Nmore » $$3\\atop{σ}$$ × N τ with aspect ratio N σ/N τ = 4 and N τ = 6-16. The strange quark mass is tuned to its physical value and we use two strange to light quark mass ratios m s/m l = 20 and 27, which in the continuum limit correspond to a pion mass of about 160 MeV and 140 MeV respectively. Sixth-order results for Taylor expansion coefficients are used to estimate truncation errors of the fourth-order expansion. We show that truncation errors are small for baryon chemical potentials less then twice the temperature (µ B ≤ 2T ). The fourth-order equation of state thus is suitable for √the modeling of dense matter created in heavy ion collisions with center-of-mass energies down to √sNN ~ 12 GeV. We provide a parametrization of basic thermodynamic quantities that can be readily used in hydrodynamic simulation codes. The results on up to sixth order expansion coefficients of bulk thermodynamics are used for the calculation of lines of constant pressure, energy and entropy densities in the T -µ B plane and are compared with the crossover line for the QCD chiral transition as well as with experimental results on freeze-out parameters in heavy ion collisions. These coefficients also provide estimates for the location of a possible critical point. Lastly, we argue that results on sixth order expansion coefficients disfavor the existence of a critical point in the QCD phase diagram for µ B/T ≤ 2 and T/T c(µ B = 0) > 0.9.« less

QCD topological susceptibility from the nonlocal chiral quark model

NASA Astrophysics Data System (ADS)

Nam, Seung-Il; Kao, Chung-Wen

2017-06-01

We investigate the quantum chromodynamics (QCD) topological susceptibility χ by using the semi-bosonized nonlocal chiral-quark model (SB-NLχQM) for the leading large- N c contributions. This model is based on the liquid-instanton QCD-vacuum configuration, in which SU(3) flavor symmetry is explicitly broken by the finite current-quark mass ( m u,d, m s) ≈ (5, 135) MeV. To compute χ, we derive the local topological charge-density operator Q t( x) from the effective action of SB-NLχQM. We verify that the derived expression for χ in our model satisfies the Witten- Veneziano (WV) and the Leutwyler-Smilga (LS) formulae, and the Crewther theorem in the chiral limit by construction. Once the average instanton size and the inter-instanton distance are fixed with ρ¯ = 1/3 fm and R¯ = 1 fm, respectively, all the other parameters are determined self-consistently within the model. We obtain χ = (167.67MeV)4, which is comparable with the empirical value χ = (175±5MeV)4 whereas it turns out that χ QL = (194.30MeV)4 in the quenched limit. Thus, we conclude that the value of χ will be reduced around 10 20% by the dynamical-quark contribution.

QCD at finite isospin chemical potential

NASA Astrophysics Data System (ADS)

Brandt, Bastian B.; Endrődi, Gergely; Schmalzbauer, Sebastian

2018-03-01

We investigate the properties of QCD at finite isospin chemical potential at zero and non-zero temperatures. This theory is not affected by the sign problem and can be simulated using Monte-Carlo techniques. With increasing isospin chemical potential and temperatures below the deconfinement transition the system changes into a phase where charged pions condense, accompanied by an accumulation of low modes of the Dirac operator. The simulations are enabled by the introduction of a pionic source into the action, acting as an infrared regulator for the theory, and physical results are obtained by removing the regulator via an extrapolation. We present an update of our study concerning the associated phase diagram using 2+1 flavours of staggered fermions with physical quark masses and the comparison to Taylor expansion. We also present first results for our determination of the equation of state at finite isospin chemical potential and give an example for a cosmological application. The results can also be used to gain information about QCD at small baryon chemical potentials using reweighting with respect to the pionic source parameter and the chemical potential and we present first steps in this direction.

Light meson gas in the QCD vacuum and oscillating universe

NASA Astrophysics Data System (ADS)

Prokhorov, George; Pasechnik, Roman

2018-01-01

We have developed a phenomenological effective quantum-field theoretical model describing the "hadron gas" of the lightest pseudoscalar mesons, scalar σ-meson and σ-vacuum, i.e. the expectation value of the σ-field, at finite temperatures. The corresponding thermodynamic approach was formulated in terms of the generating functional derived from the effective Lagrangian providing the basic thermodynamic information about the "meson plasma + QCD condensate" system. This formalism enables us to study the QCD transition from the hadron phase with direct implications for cosmological evolution. Using the hypothesis about a positively-definite QCD vacuum contribution stochastically produced in early universe, we show that the universe could undergo a series of oscillations during the QCD epoch before resuming unbounded expansion.

Fluctuations and correlations of conserved charges in QCD at finite temperature with effective models

NASA Astrophysics Data System (ADS)

Fu, Wei-Jie; Liu, Yu-Xin; Wu, Yue-Liang

2010-01-01

We study fluctuations of conserved charges including baryon number, electric charge, and strangeness as well as the correlations among these conserved charges in the 2+1 flavor Polyakov-Nambu-Jona-Lasinio model at finite temperature. The calculated results are compared with those obtained from recent lattice calculations performed with an improved staggered fermion action at two values of the lattice cutoff with almost physical up and down quark masses and a physical value for the strange quark mass. We find that our calculated results are well consistent with those obtained in lattice calculations except for some quantitative differences for fluctuations related with strange quarks. Our calculations indicate that there is a pronounced cusp in the ratio of the quartic to quadratic fluctuations of baryon number, i.e. χ4B/χ2B, at the critical temperature during the phase transition, which confirms that χ4B/χ2B is a useful probe of the deconfinement and chiral phase transition.

Hadron electric polarizability from lattice QCD

NASA Astrophysics Data System (ADS)

Alexandru, Andrei

2017-09-01

Electromagnetic polarizabilities are important parameters for hadron structure, describing the response of the charge and current distributions inside the hadron to an external electromagnetic field. For most hadrons these quantities are poorly constrained experimentally since they can only be measured indirectly. Lattice QCD can be used to compute these quantities directly in terms of quark and gluons degrees of freedom, using the background field method. We present results for the neutron electric polarizability for two different quark masses, light enough to connect to chiral perturbation theory. These are currently the lightest quark masses used in polarizability studies. For each pion mass we compute the polarizability at four different volumes and perform an infinite volume extrapolation. We also discuss the effect of turning on the coupling between the background field and the sea quarks. A.A. is supported in part by the National Science Foundation CAREER Grant PHY-1151648 and by U.S. DOE Grant No. DE-FG02-95ER40907.

Large Ice Crystal Charge Transfer Studies

DTIC Science & Technology

1988-10-28

electrification. However, the extra- polation using qcd 4 was completely unjustified. With corrected values of the separation probability of ice crystals...contact to leak away from the local area or become trapped in the crystal lattice . Obviously, larger initial charge transfers, with larger 6 crystals

NLO QCD effective field theory analysis of W +W - production at the LHC including fermionic operators

DOE PAGES

Baglio, Julien; Dawson, Sally; Lewis, Ian M.

2017-10-03

In this paper, we study the impact of anomalous gauge boson and fermion couplings on the production of W +W - pairs at the LHC. Helicity amplitudes are presented separately to demonstrate the sources of new physics contributions and the impact of QCD and electroweak corrections. The QCD corrections have important effects on the fits to anomalous couplings, in particular when one W boson is longitudinally polarized and the other is transversely polarized. In effective field theory language, we demonstrate that the dimension-6 approximation to constraining new physics effects in W +W - pair production fails at p T ~more » 500 - 1000 GeV.« less

NLO QCD effective field theory analysis of W +W - production at the LHC including fermionic operators

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

Baglio, Julien; Dawson, Sally; Lewis, Ian M.

In this paper, we study the impact of anomalous gauge boson and fermion couplings on the production of W +W - pairs at the LHC. Helicity amplitudes are presented separately to demonstrate the sources of new physics contributions and the impact of QCD and electroweak corrections. The QCD corrections have important effects on the fits to anomalous couplings, in particular when one W boson is longitudinally polarized and the other is transversely polarized. In effective field theory language, we demonstrate that the dimension-6 approximation to constraining new physics effects in W +W - pair production fails at p T ~more » 500 - 1000 GeV.« less

Nucleon structure from 2+1-flavor domain-wall QCD

NASA Astrophysics Data System (ADS)

Ohta, Shigemi

2018-03-01

Nucleon-structure calculations of isovector vector-and axialvector-current form factors, transversity and scalar charge, and quark momentum and helicity fractions are reported from two recent 2+1-flavor dynamical domain-wall fermions lattice-QCD ensembles generated jointly by the RIKEN-BNL-Columbia and UKQCD Collaborations with Iwasaki × dislocation-suppressing-determinatn-ratio gauge action at inverse lattice spacing of 1.378(7) GeV and pion mass values of 249.4(3) and 172.3(3) MeV.

Exclusive QCD processes, quark-hadron duality, and the transition to perturbative QCD

NASA Astrophysics Data System (ADS)

Corianò, Claudio; Li, Hsiang-nan; Savkli, Cetin

1998-07-01

Experiments at CEBAF will scan the intermediate-energy region of the QCD dynamics for the nucleon form factors and for Compton Scattering. These experiments will definitely clarify the role of resummed perturbation theory and of quark-hadron duality (QCD sum rules) in this regime. With this perspective in mind, we review the factorization theorem of perturbative QCD for exclusive processes at intermediate energy scales, which embodies the transverse degrees of freedom of a parton and the Sudakov resummation of the corresponding large logarithms. We concentrate on the pion and proton electromagnetic form factors and on pion Compton scattering. New ingredients, such as the evolution of the pion wave function and the complete two-loop expression of the Sudakov factor, are included. The sensitivity of our predictions to the infrared cutoff for the Sudakov evolution is discussed. We also elaborate on QCD sum rule methods for Compton Scattering, which provide an alternative description of this process. We show that, by comparing the local duality analysis to resummed perturbation theory, it is possible to describe the transition of exclusive processes to perturbative QCD.

First Monte Carlo Global Analysis of Nucleon Transversity with Lattice QCD Constraints

DOE PAGES

Lin, Huey-Wen; Melnitchouk, Wally; Prokudin, Alexei; ...

2018-04-11

We report on the first global QCD analysis of the quark transversity distributions in the nucleon from semi-inclusive deep-inelastic scattering (SIDIS), using a new Monte Carlo method based on nested sampling and constraints on the isovector tensor chargemore » $$g_T$$ from lattice QCD. A simultaneous fit to the available SIDIS Collins asymmetry data is compatible with $$g_T$$ values extracted from a comprehensive reanalysis of existing lattice simulations, in contrast to previous analyses, which found significantly smaller $$g_T$$ values. The contributions to the nucleon tensor charge from $u$ and $d$ quarks are found to be $$\\delta u = 0.3(2)$$ and $$\\delta d = -0.7(2)$$ at a scale $Q^2 = 2$ GeV$^2$.« less

First Monte Carlo Global Analysis of Nucleon Transversity with Lattice QCD Constraints

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

Lin, Huey-Wen; Melnitchouk, Wally; Prokudin, Alexei

We report on the first global QCD analysis of the quark transversity distributions in the nucleon from semi-inclusive deep-inelastic scattering (SIDIS), using a new Monte Carlo method based on nested sampling and constraints on the isovector tensor chargemore » $$g_T$$ from lattice QCD. A simultaneous fit to the available SIDIS Collins asymmetry data is compatible with $$g_T$$ values extracted from a comprehensive reanalysis of existing lattice simulations, in contrast to previous analyses, which found significantly smaller $$g_T$$ values. The contributions to the nucleon tensor charge from $u$ and $d$ quarks are found to be $$\\delta u = 0.3(2)$$ and $$\\delta d = -0.7(2)$$ at a scale $Q^2 = 2$ GeV$^2$.« less

Sivers and Boer-Mulders observables from lattice QCD

NASA Astrophysics Data System (ADS)

Musch, B. U.; Hägler, Ph.; Engelhardt, M.; Negele, J. W.; Schäfer, A.

2012-05-01

We present a first calculation of transverse momentum-dependent nucleon observables in dynamical lattice QCD employing nonlocal operators with staple-shaped, “process-dependent” Wilson lines. The use of staple-shaped Wilson lines allows us to link lattice simulations to TMD effects determined from experiment, and, in particular, to access nonuniversal, naively time-reversal odd TMD observables. We present and discuss results for the generalized Sivers and Boer-Mulders transverse momentum shifts for the SIDIS and DY cases. The effect of staple-shaped Wilson lines on T-even observables is studied for the generalized tensor charge and a generalized transverse shift related to the worm-gear function g1T. We emphasize the dependence of these observables on the staple extent and the Collins-Soper evolution parameter. Our numerical calculations use an nf=2+1 mixed action scheme with domain wall valence fermions on an Asqtad sea and pion masses 369 MeV as well as 518 MeV.

Continuous Advances in QCD 2008

NASA Astrophysics Data System (ADS)

Peloso, Marco M.

2008-12-01

-classical origin of non-abelian monopoles / K. Konishi. A generalized construction for lumps and non-abelian vortices / W. Vinci -- 6. Dynamics in supersymmetric theories. Cusp anomalous dimension in planar maximally supersymmetric Yang-Mills theory / B. Basso. SO(2M) and USp(2M) (hyper)Kähler quotients and lumps / S. B. Gudnason -- 7. Other developments. Gluinos condensing at the CCNI: 4096 CPUs weigh in / J. Giedt ... [et al.]. Baryon Regge trajectories and the 1/N[symbol] expansion / J. L. Goity, N. Matagne. Infrared behavior of the fermion propagator in unquenched QED[symbol] with finite threshold effects / Y. Hoshino. Gauge fields in accelerated frames / F. Lenz. QCD at complex coupling, large order in perturbation theory and the gluon condensate / Y. Meurice. 511 KeV line and other diffuse emissions as a trace of the dark matter / A. R. Zhitnitsky -- 8. Glimpses of the conference.

New Methods in Non-Perturbative QCD

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

Unsal, Mithat

2017-01-31

In this work, we investigate the properties of quantum chromodynamics (QCD), by using newly developing mathematics and physics formalisms. Almost all of the mass in the visible universe emerges from a quantum chromodynamics (QCD), which has a completely negligible microscopic mass content. An intimately related issue in QCD is the quark confinement problem. Answers to non-perturbative questions in QCD remained largely elusive despite much effort over the years. It is also believed that the usual perturbation theory is inadequate to address these kinds of problems. Perturbation theory gives a divergent asymptotic series (even when the theory is properly renormalized), andmore » there are non-perturbative phenomena which never appear at any order in perturbation theory. Recently, a fascinating bridge between perturbation theory and non-perturbative effects has been found: a formalism called resurgence theory in mathematics tells us that perturbative data and non-perturbative data are intimately related. Translating this to the language of quantum field theory, it turns out that non-perturbative information is present in a coded form in perturbation theory and it can be decoded. We take advantage of this feature, which is particularly useful to understand some unresolved mysteries of QCD from first principles. In particular, we use: a) Circle compactifications which provide a semi-classical window to study confinement and mass gap problems, and calculable prototypes of the deconfinement phase transition; b) Resurgence theory and transseries which provide a unified framework for perturbative and non-perturbative expansion; c) Analytic continuation of path integrals and Lefschetz thimbles which may be useful to address sign problem in QCD at finite density.« less

QCD for Postgraduates (2/5)

ScienceCinema

Zanderighi, Giulia

2018-05-21

Modern QCD - Lecture 2 We will start discussing the matter content of the theory and revisit the experimental measurements that led to the discovery of quarks. We will then consider a classic QCD observable, the R-ratio, and use it to illustrate the appearance of UV divergences and the need to renormalize the coupling constant of QCD. We will then discuss asymptotic freedom and confinement. Finally, we will examine a case where soft and collinear infrared divergences appear, will discuss the soft approximation in QCD and will introduce the concept of infrared safe jets.

Renormalization of Extended QCD2

NASA Astrophysics Data System (ADS)

Fukaya, Hidenori; Yamamura, Ryo

2015-10-01

Extended QCD (XQCD), proposed by Kaplan [D. B. Kaplan, arXiv:1306.5818], is an interesting reformulation of QCD with additional bosonic auxiliary fields. While its partition function is kept exactly the same as that of original QCD, XQCD naturally contains properties of low-energy hadronic models. We analyze the renormalization group flow of 2D (X)QCD, which is solvable in the limit of a large number of colors N_c, to understand what kind of roles the auxiliary degrees of freedom play and how the hadronic picture emerges in the low-energy region.

Pion quasiparticle in the low-temperature phase of QCD

NASA Astrophysics Data System (ADS)

Brandt, Bastian B.; Francis, Anthony; Meyer, Harvey B.; Robaina, Daniel

2015-11-01

We investigate the properties of the pion quasiparticle in the low-temperature phase of two-flavor QCD on the lattice with support from chiral effective theory. We find that the pion quasiparticle mass is significantly reduced compared to its value in the vacuum, in contrast with the static screening mass, which increases with temperature. By a simple argument, near the chiral limit the two masses are expected to determine the quasiparticle dispersion relation. Analyzing two-point functions of the axial charge density at nonvanishing spatial momentum, we find that the predicted dispersion relation and the residue of the pion pole are consistent with the lattice data at low momentum. This test, based on fits to the correlation functions, is confirmed by a second analysis using the Backus-Gilbert method.

Nuclear PDF for neutrino and charged lepton data

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

Kovarik, K.

2011-10-06

Neutrino Deep Inelastic Scattering (DIS) on nuclei is an essential process to constrain the strange quark parton distribution functions (PDF) in the proton. The critical component on the way to using the neutrino DIS data in a proton PDF analysis is understanding the nuclear effects in parton distribution functions. We parametrize these effects by nuclear parton distribution functions (NPDF). Here we compare results from two analysis of NPDF both done at next-to-leading order in QCD. The first uses neutral current charged-lepton (l{sup {+-}A}) Deeply Inelastic Scattering (DIS) and Drell-Yan data for several nuclear targets and the second uses neutrino-nucleon DISmore » data. We compare the nuclear corrections factors (F{sub 2}{sup Fe}/F{sub 2}{sup D}) for the charged-lepton data with other results from the literature. In particular, we compare and contrast fits based upon the charged-lepton DIS data with those using neutrino-nucleon DIS data.« less

Two-color QCD at high density

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

Boz, Tamer; Skullerud, Jon-Ivar; Centre for the Subatomic Structure of Matter, Adelaide University, Adelaide, SA 5005

2016-01-22

QCD at high chemical potential has interesting properties such as deconfinement of quarks. Two-color QCD, which enables numerical simulations on the lattice, constitutes a laboratory to study QCD at high chemical potential. Among the interesting properties of two-color QCD at high density is the diquark condensation, for which we present recent results obtained on a finer lattice compared to previous studies. The quark propagator in two-color QCD at non-zero chemical potential is referred to as the Gor’kov propagator. We express the Gor’kov propagator in terms of form factors and present recent lattice simulation results.

Effective Theories for QCD-like at TeV Scale

NASA Astrophysics Data System (ADS)

Lu, Jie; Bijnens, Johan

2016-04-01

We study the Effective Field Theory of three QCD-like theories, which can be classified by having quarks in a complex, real or pseudo-real representations of the gauge group. The Lagrangians are written in a very similar way so that the calculations can be done using techniques from Chiral Perturbation Theory (ChPT). We calculated the vacuum-expectation-value, the mass and the decay constant of pseudo-Goldstone Bosons up to next-to-next-to leading order (NNLO) [J. Bijnens and J. Lu, JHEP 0911 (2009) 116 [arxiv:arXiv:0910.5424 [hep-ph

QCD phase-transition and chemical freezeout in nonzero magnetic field at NICA

NASA Astrophysics Data System (ADS)

Tawfik, Abdel Nasser

2017-01-01

Because of relativistic off-center motion of the charged spectators and the local momentum-imbalance experienced by the participants, a huge magnetic field is likely generated in high-energy collisions. The influence of such short-lived magnetic field on the QCD phase-transition(s) is analysed. From Polyakov linear-sigma model, we study the chiral phase-transition and the magnetic response and susceptibility in dependence on temperature, density and magnetic field strength. The systematic measurements of the phase-transition characterizing signals, such as the fluctuations, the dynamical correlations and the in-medium modifications of rho-meson, for instance, in different interacting systems and collision centralities are conjectured to reveal an almost complete description for the QCD phase-structure and the chemical freezeout. We limit the discussion to NICA energies.

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.

Accurate determinations of alpha(s) from realistic lattice QCD.

PubMed

Mason, Q; Trottier, H D; Davies, C T H; Foley, K; Gray, A; Lepage, G P; Nobes, M; Shigemitsu, J

2005-07-29

We obtain a new value for the QCD coupling constant by combining lattice QCD simulations with experimental data for hadron masses. Our lattice analysis is the first to (1) include vacuum polarization effects from all three light-quark flavors (using MILC configurations), (2) include third-order terms in perturbation theory, (3) systematically estimate fourth and higher-order terms, (4) use an unambiguous lattice spacing, and (5) use an [symbol: see text](a2)-accurate QCD action. We use 28 different (but related) short-distance quantities to obtain alpha((5)/(MS))(M(Z)) = 0.1170(12).

Reliable semiclassical computations in QCD

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

Dine, Michael; Department of Physics, Stanford University Stanford, California 94305-4060; Festuccia, Guido

We revisit the question of whether or not one can perform reliable semiclassical QCD computations at zero temperature. We study correlation functions with no perturbative contributions, and organize the problem by means of the operator product expansion, establishing a precise criterion for the validity of a semiclassical calculation. For N{sub f}>N, a systematic computation is possible; for N{sub f}effects at large N. As an application, we describe a test of QCD lattice gauge theory computations in the chiral limit.

Conserved charge fluctuations at vanishing and non-vanishing chemical potential

NASA Astrophysics Data System (ADS)

Karsch, Frithjof

2017-11-01

Up to 6th order cumulants of fluctuations of net baryon-number, net electric charge and net strangeness as well as correlations among these conserved charge fluctuations are now being calculated in lattice QCD. These cumulants provide a wealth of information on the properties of strong-interaction matter in the transition region from the low temperature hadronic phase to the quark-gluon plasma phase. They can be used to quantify deviations from hadron resonance gas (HRG) model calculations which frequently are used to determine thermal conditions realized in heavy ion collision experiments. Already some second order cumulants like the correlations between net baryon-number and net strangeness or net electric charge differ significantly at temperatures above 155 MeV in QCD and HRG model calculations. We show that these differences increase at non-zero baryon chemical potential constraining the applicability range of HRG model calculations to even smaller values of the temperature.

Critical opalescence in baryonic QCD matter.

PubMed

Antoniou, N G; Diakonos, F K; Kapoyannis, A S; Kousouris, K S

2006-07-21

We show that critical opalescence, a clear signature of second-order phase transition in conventional matter, manifests itself as critical intermittency in QCD matter produced in experiments with nuclei. This behavior is revealed in transverse momentum spectra as a pattern of power laws in factorial moments, to all orders, associated with baryon production. This phenomenon together with a similar effect in the isoscalar sector of pions (sigma mode) provide us with a set of observables associated with the search for the QCD critical point in experiments with nuclei at high energies.

Identifying QCD Transition Using Deep Learning

NASA Astrophysics Data System (ADS)

Zhou, Kai; Pang, Long-gang; Su, Nan; Petersen, Hannah; Stoecker, Horst; Wang, Xin-Nian

2018-02-01

In this proceeding we review our recent work using supervised learning with a deep convolutional neural network (CNN) to identify the QCD equation of state (EoS) employed in hydrodynamic modeling of heavy-ion collisions given only final-state particle spectra ρ(pT, V). We showed that there is a traceable encoder of the dynamical information from phase structure (EoS) that survives the evolution and exists in the final snapshot, which enables the trained CNN to act as an effective "EoS-meter" in detecting the nature of the QCD transition.

Most Strange Dibaryon from Lattice QCD

NASA Astrophysics Data System (ADS)

Gongyo, Shinya; Sasaki, Kenji; Aoki, Sinya; Doi, Takumi; Hatsuda, Tetsuo; Ikeda, Yoichi; Inoue, Takashi; Iritani, Takumi; Ishii, Noriyoshi; Miyamoto, Takaya; Nemura, Hidekatsu; HAL QCD Collaboration

2018-05-01

The Ω Ω system in the 1S0 channel (the most strange dibaryon) is studied on the basis of the (2 +1 )-flavor lattice QCD simulations with a large volume (8.1 fm )3 and nearly physical pion mass mπ≃146 MeV at a lattice spacing of a ≃0.0846 fm . We show that lattice QCD data analysis by the HAL QCD method leads to the scattering length a0=4.6 (6 )(-0.5+1.2) fm , the effective range reff=1.27 (3 )(-0.03+0.06) fm , and the binding energy BΩ Ω=1.6 (6 )(-0.6+0.7) MeV . These results indicate that the Ω Ω system has an overall attraction and is located near the unitary regime. Such a system can be best searched experimentally by the pair-momentum correlation in relativistic heavy-ion collisions.

Measurement of jet charge in dijet events from $$\\sqrt{s}$$ = 8 TeV $pp$ collisions with the ATLAS detector

DOE PAGES

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

2016-03-02

In this study, the momentum-weighted sum of the charges of tracks associated to a jet is sensitive to the charge of the initiating quark or gluon. This paper presents a measurement of the distribution of momentum-weighted sums, called jet charge, in dijet events using 20.3 fb -1 of data recorded with the ATLAS detector at √s = 8 TeV in pp collisions at the LHC. The jet charge distribution is unfolded to remove distortions from detector effects and the resulting particle-level distribution is compared with several models. The p T dependence of the jet charge distribution average and standard deviationmore » are compared to predictions obtained with several leading-order and next-to-leading-order parton distribution functions. The data are also compared to different Monte Carlo simulations of QCD dijet production using various settings of the free parameters within these models. The chosen value of the strong coupling constant used to calculate gluon radiation is found to have a significant impact on the predicted jet charge. There is evidence for a p T dependence of the jet charge distribution for a given jet flavor. In agreement with perturbative QCD predictions, the data show that the average jet charge of quark-initiated jets decreases in magnitude as the energy of the jet increases.« less

Most Strange Dibaryon from Lattice QCD.

PubMed

Gongyo, Shinya; Sasaki, Kenji; Aoki, Sinya; Doi, Takumi; Hatsuda, Tetsuo; Ikeda, Yoichi; Inoue, Takashi; Iritani, Takumi; Ishii, Noriyoshi; Miyamoto, Takaya; Nemura, Hidekatsu

2018-05-25

The ΩΩ system in the ^{1}S_{0} channel (the most strange dibaryon) is studied on the basis of the (2+1)-flavor lattice QCD simulations with a large volume (8.1  fm)^{3} and nearly physical pion mass m_{π}≃146  MeV at a lattice spacing of a≃0.0846  fm. We show that lattice QCD data analysis by the HAL QCD method leads to the scattering length a_{0}=4.6(6)(_{-0.5}^{+1.2})  fm, the effective range r_{eff}=1.27(3)(_{-0.03}^{+0.06})  fm, and the binding energy B_{ΩΩ}=1.6(6)(_{-0.6}^{+0.7})  MeV. These results indicate that the ΩΩ system has an overall attraction and is located near the unitary regime. Such a system can be best searched experimentally by the pair-momentum correlation in relativistic heavy-ion collisions.

Phenomenological consequences of enhanced bulk viscosity near the QCD critical point

DOE PAGES

Monnai, Akihiko; Mukherjee, Swagato; Yin, Yi

2017-03-06

In the proximity of the QCD critical point the bulk viscosity of quark-gluon matter is expected to be proportional to nearly the third power of the critical correlation length, and become significantly enhanced. Here, this work is the first attempt to study the phenomenological consequences of enhanced bulk viscosity near the QCD critical point. For this purpose, we implement the expected critical behavior of the bulk viscosity within a non-boost-invariant, longitudinally expanding 1 + 1 dimensional causal relativistic hydrodynamical evolution at nonzero baryon density. We demonstrate that the critically enhanced bulk viscosity induces a substantial nonequilibrium pressure, effectively softening themore » equation of state, and leads to sizable effects in the flow velocity and single-particle distributions at the freeze-out. In conclusion, the observable effects that may arise due to the enhanced bulk viscosity in the vicinity of the QCD critical point can be used as complementary information to facilitate searches for the QCD critical point.« less

Nucleon-nucleon interactions via Lattice QCD: Methodology. HAL QCD approach to extract hadronic interactions in lattice QCD

NASA Astrophysics Data System (ADS)

Aoki, Sinya

2013-07-01

We review the potential method in lattice QCD, which has recently been proposed to extract nucleon-nucleon interactions via numerical simulations. We focus on the methodology of this approach by emphasizing the strategy of the potential method, the theoretical foundation behind it, and special numerical techniques. We compare the potential method with the standard finite volume method in lattice QCD, in order to make pros and cons of the approach clear. We also present several numerical results for nucleon-nucleon potentials.

Susceptibility of the QCD vacuum to CP-odd electromagnetic background fields.

PubMed

D'Elia, Massimo; Mariti, Marco; Negro, Francesco

2013-02-22

We investigate two flavor quantum chromodynamics (QCD) in the presence of CP-odd electromagnetic background fields and determine, by means of lattice QCD simulations, the induced effective θ term to first order in E[over →] · B[over →]. We employ a rooted staggered discretization and study lattice spacings down to 0.1 fm and Goldstone pion masses around 480 MeV. In order to deal with a positive measure, we consider purely imaginary electric fields and real magnetic fields, and then exploit the analytic continuation. Our results are relevant to a description of the effective pseudoscalar quantum electrodynamics-QCD interactions.

Sivers and Boer-Mulders observables from lattice QCD.

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

B.U. Musch, Ph. Hagler, M. Engelhardt, J.W. Negele, A. Schafer

We present a first calculation of transverse momentum dependent nucleon observables in dynamical lattice QCD employing non-local operators with staple-shaped, 'process-dependent' Wilson lines. The use of staple-shaped Wilson lines allows us to link lattice simulations to TMD effects determined from experiment, and in particular to access non-universal, naively time-reversal odd TMD observables. We present and discuss results for the generalized Sivers and Boer-Mulders transverse momentum shifts for the SIDIS and DY cases. The effect of staple-shaped Wilson lines on T-even observables is studied for the generalized tensor charge and a generalized transverse shift related to the worm gear function g{submore » 1}T. We emphasize the dependence of these observables on the staple extent and the Collins-Soper evolution parameter. Our numerical calculations use an n{sub f} = 2+1 mixed action scheme with domain wall valence fermions on an Asqtad sea and pion masses 369 MeV as well as 518 MeV.« less

Extension of the HAL QCD approach to inelastic and multi-particle scatterings in lattice QCD

NASA Astrophysics Data System (ADS)

Aoki, S.

We extend the HAL QCD approach, with which potentials between two hadrons can be obtained in QCD at energy below inelastic thresholds, to inelastic and multi-particle scatterings. We first derive asymptotic behaviors of the Nambu-Bethe-Salpeter (NBS) wave function at large space separations for systems with more than 2 particles, in terms of the one-shell $T$-matrix consrainted by the unitarity of quantum field theories. We show that its asymptotic behavior contains phase shifts and mixing angles of $n$ particle scatterings. This property is one of the essential ingredients of the HAL QCD scheme to define "potential" from the NBS wave function in quantum field theories such as QCD. We next construct energy independent but non-local potentials above inelastic thresholds, in terms of these NBS wave functions. We demonstrate an existence of energy-independent coupled channel potentials with a non-relativistic approximation, where momenta of all particles are small compared with their own masses. Combining these two results, we can employ the HAL QCD approach also to investigate inelastic and multi-particle scatterings.

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.

Second-order QCD effects in Higgs boson production through vector boson fusion

NASA Astrophysics Data System (ADS)

Cruz-Martinez, J.; Gehrmann, T.; Glover, E. W. N.; Huss, A.

2018-06-01

We compute the factorising second-order QCD corrections to the electroweak production of a Higgs boson through vector boson fusion. Our calculation is fully differential in the kinematics of the Higgs boson and of the final state jets, and uses the antenna subtraction method to handle infrared singular configurations in the different parton-level contributions. Our results allow us to reassess the impact of the next-to-leading order (NLO) QCD corrections to electroweak Higgs-plus-three-jet production and of the next-to-next-to-leading order (NNLO) QCD corrections to electroweak Higgs-plus-two-jet production. The NNLO corrections are found to be limited in magnitude to around ± 5% and are uniform in several of the kinematical variables, displaying a kinematical dependence only in the transverse momenta and rapidity separation of the two tagging jets.

Aspects of Chiral Symmetry Breaking in Lattice QCD

NASA Astrophysics Data System (ADS)

Horkel, Derek P.

In this thesis we describe two studies concerting lattice quantum chromodynamics (LQCD): first, an analysis of the phase structure of Wilson and twisted-mass fermions with isospin breaking effects, second a computational study measuring non-perturbative Greens functions. We open with a brief overview of the formalism of QCD and LQCD, focusing on the aspects necessary for understanding how a lattice computation is performed and how discretization effects can be understood. Our work in Wilson and twisted-mass fermions investigates an increasingly relevant regime where lattice simulations are performed with quarks at or near their physical masses and both the mass difference of the up and down quarks and their differing electric charges are included. Our computation of a non-perturbative Greens functions on the lattice serves as a first attempt to validate recent work by Dine et. al. [24] in which they calculate Greens functions which vanish in perturbation theory, yet have a contribution from the one instanton background. In chapter 2, we determine the phase diagram and pion spectrum for Wilson and twisted-mass fermions in the presence of non-degeneracy between the up and down quark and discretization errors, using Wilson and twisted-mass chiral perturbation theory. We find that the CP-violating phase of the continuum theory (which occurs for sufficiently large non-degeneracy) is continuously connected to the Aoki phase of the lattice theory with degenerate quarks. We show that discretization effects can, in some cases, push simulations with physical masses closer to either the CP-violating phase or another phase not present in the continuum, so that at sufficiently large lattice spacings physical-point simulations could lie in one of these phases. In chapter 3, we extend the work in chapter 2 to include the effects of electromagnetism, so that it is applicable to recent simulations incorporating all sources of isospin breaking. For Wilson fermions, we find that the

Higgs boson couplings to bottom quarks: two-loop supersymmetry-QCD corrections.

PubMed

Noth, David; Spira, Michael

2008-10-31

We present two-loop supersymmetry (SUSY) QCD corrections to the effective bottom Yukawa couplings within the minimal supersymmetric extension of the standard model (MSSM). The effective Yukawa couplings include the resummation of the nondecoupling corrections Deltam_{b} for large values of tanbeta. We have derived the two-loop SUSY-QCD corrections to the leading SUSY-QCD and top-quark-induced SUSY-electroweak contributions to Deltam_{b}. The scale dependence of the resummed Yukawa couplings is reduced from O(10%) to the percent level. These results reduce the theoretical uncertainties of the MSSM Higgs branching ratios to the accuracy which can be achieved at a future linear e;{+}e;{-} collider.

Current matrix element in HAL QCD's wavefunction-equivalent potential method

NASA Astrophysics Data System (ADS)

Watanabe, Kai; Ishii, Noriyoshi

2018-04-01

We give a formula to calculate a matrix element of a conserved current in the effective quantum mechanics defined by the wavefunction-equivalent potentials proposed by the HAL QCD collaboration. As a first step, a non-relativistic field theory with two-channel coupling is considered as the original theory, with which a wavefunction-equivalent HAL QCD potential is obtained in a closed analytic form. The external field method is used to derive the formula by demanding that the result should agree with the original theory. With this formula, the matrix element is obtained by sandwiching the effective current operator between the left and right eigenfunctions of the effective Hamiltonian associated with the HAL QCD potential. In addition to the naive one-body current, the effective current operator contains an additional two-body term emerging from the degrees of freedom which has been integrated out.

The Chiral Separation Effect in quenched finite-density QCD

NASA Astrophysics Data System (ADS)

Puhr, Matthias; Buividovich, Pavel

2018-03-01

We present results of a study of the Chiral Separation Effect (CSE) in quenched finite-density QCD. Using a recently developed numerical method we calculate the conserved axial current for exactly chiral overlap fermions at finite density for the first time. We compute the anomalous transport coeffcient for the CSE in the confining and deconfining phase and investigate possible deviations from the universal value. In both phases we find that non-perturbative corrections to the CSE are absent and we reproduce the universal value for the transport coeffcient within small statistical errors. Our results suggest that the CSE can be used to determine the renormalisation factor of the axial current.

Dark-matter QCD-axion searches.

PubMed

Rosenberg, Leslie J

2015-10-06

In the late 20th century, cosmology became a precision science. Now, at the beginning of the next century, the parameters describing how our universe evolved from the Big Bang are generally known to a few percent. One key parameter is the total mass density of the universe. Normal matter constitutes only a small fraction of the total mass density. Observations suggest this additional mass, the dark matter, is cold (that is, moving nonrelativistically in the early universe) and interacts feebly if at all with normal matter and radiation. There's no known such elementary particle, so the strong presumption is the dark matter consists of particle relics of a new kind left over from the Big Bang. One of the most important questions in science is the nature of this dark matter. One attractive particle dark-matter candidate is the axion. The axion is a hypothetical elementary particle arising in a simple and elegant extension to the standard model of particle physics that nulls otherwise observable CP-violating effects (where CP is the product of charge reversal C and parity inversion P) in quantum chromo dynamics (QCD). A light axion of mass 10(-(6-3)) eV (the invisible axion) would couple extraordinarily weakly to normal matter and radiation and would therefore be extremely difficult to detect in the laboratory. However, such an axion is a compelling dark-matter candidate and is therefore a target of a number of searches. Compared with other particle dark-matter candidates, the plausible range of axion dark-matter couplings and masses is narrowly constrained. This focused search range allows for definitive searches, where a nonobservation would seriously impugn the dark-matter QCD-axion hypothesis. Axion searches use a wide range of technologies, and the experiment sensitivities are now reaching likely dark-matter axion couplings and masses. This article is a selective overview of the current generation of sensitive axion searches. Not all techniques and experiments

Axial current generation by P-odd domains in QCD matter

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

Iatrakis, Ioannis; Yin, Yi; Lin, Shu

2015-06-23

The dynamics of topological domains which break parity (P) and charge-parity (CP) symmetry of QCD are studied. We derive in a general setting that those local domains will generate an axial current and quantify the strength of the induced axial current. Thus, our findings are verified in a top-down holographic model. The relation between the real time dynamics of those local domains and the chiral magnetic field is also elucidated. We finally argue that such an induced axial current would be phenomenologically important in a heavy-ion collisions experiment.

Charged-pion cross sections and double-helicity asymmetries in polarized p +p collisions at √{s }=200 GeV

NASA Astrophysics Data System (ADS)

Adare, A.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Akimoto, R.; Al-Ta'Ani, H.; Alexander, J.; Andrews, K. R.; Angerami, A.; Aoki, K.; Apadula, N.; Appelt, E.; Aramaki, Y.; Armendariz, R.; Aschenauer, E. C.; Atomssa, E. T.; Awes, T. C.; Azmoun, B.; Babintsev, V.; Bai, M.; Bannier, B.; Barish, K. N.; Bassalleck, B.; Basye, A. T.; Bathe, S.; Baublis, V.; Baumann, C.; Bazilevsky, A.; Belmont, R.; Ben-Benjamin, J.; Bennett, R.; Blau, D. S.; Bok, J. S.; Boyle, K.; Brooks, M. L.; Broxmeyer, D.; Buesching, H.; Bumazhnov, V.; Bunce, G.; Butsyk, S.; Campbell, S.; Castera, P.; Chen, C.-H.; Chi, C. Y.; Chiu, M.; Choi, I. J.; Choi, J. B.; Choudhury, R. K.; Christiansen, P.; Chujo, T.; Chvala, O.; Cianciolo, V.; Citron, Z.; Cole, B. A.; Conesa Del Valle, Z.; Connors, M.; Csanád, M.; Csörgő, T.; Dairaku, S.; Datta, A.; David, G.; Dayananda, M. K.; Denisov, A.; Deshpande, A.; Desmond, E. J.; Dharmawardane, K. V.; Dietzsch, O.; Dion, A.; Donadelli, M.; Drapier, O.; Drees, A.; Drees, K. A.; Durham, J. M.; Durum, A.; D'Orazio, L.; Efremenko, Y. V.; Engelmore, T.; Enokizono, A.; En'yo, H.; Esumi, S.; Fadem, B.; Fields, D. E.; Finger, M.; Finger, M.; Fleuret, F.; Fokin, S. L.; Frantz, J. E.; Franz, A.; Frawley, A. D.; Fukao, Y.; Fusayasu, T.; Gal, C.; Garishvili, I.; Giordano, F.; Glenn, A.; Gong, X.; Gonin, M.; Goto, Y.; Granier de Cassagnac, R.; Grau, N.; Greene, S. V.; Grosse Perdekamp, M.; Gunji, T.; Guo, L.; Gustafsson, H.-Å.; Haggerty, J. S.; Hahn, K. I.; Hamagaki, H.; Hamblen, J.; Han, R.; Hanks, J.; Harper, C.; Hashimoto, K.; Haslum, E.; Hayano, R.; He, X.; Hemmick, T. K.; Hester, T.; Hill, J. C.; Hollis, R. S.; Holzmann, W.; Homma, K.; Hong, B.; Horaguchi, T.; Hori, Y.; Hornback, D.; Huang, S.; Ichihara, T.; Ichimiya, R.; Iinuma, H.; Ikeda, Y.; Imai, K.; Inaba, M.; Iordanova, A.; Isenhower, D.; Ishihara, M.; Issah, M.; Ivanischev, D.; Iwanaga, Y.; Jacak, B. V.; Jia, J.; Jiang, X.; John, D.; Johnson, B. M.; Jones, T.; Joo, K. S.; Jouan, D.; Kamin, J.; Kaneti, S.; Kang, B. H.; Kang, J. H.; Kang, J. S.; Kapustinsky, J.; Karatsu, K.; Kasai, M.; Kawall, D.; Kazantsev, A. V.; Kempel, T.; Khanzadeev, A.; Kijima, K. M.; Kim, B. I.; Kim, D. J.; Kim, E.-J.; Kim, Y.-J.; Kim, Y. K.; Kinney, E.; Kiss, Á.; Kistenev, E.; Kleinjan, D.; Kline, P.; Kochenda, L.; Komkov, B.; Konno, M.; Koster, J.; Kotov, D.; Král, A.; Kunde, G. J.; Kurita, K.; Kurosawa, M.; Kwon, Y.; Kyle, G. S.; Lacey, R.; Lai, Y. S.; Lajoie, J. G.; Lebedev, A.; Lee, D. M.; Lee, J.; Lee, K. B.; Lee, K. S.; Lee, S. H.; Lee, S. R.; Leitch, M. J.; Leite, M. A. L.; Li, X.; Lim, S. H.; Linden Levy, L. A.; Liu, H.; Liu, M. X.; Love, B.; Lynch, D.; Maguire, C. F.; Makdisi, Y. I.; Manion, A.; Manko, V. I.; Mannel, E.; Mao, Y.; Masui, H.; McCumber, M.; McGaughey, P. L.; McGlinchey, D.; McKinney, C.; Means, N.; Mendoza, M.; Meredith, B.; Miake, Y.; Mibe, T.; Mignerey, A. C.; Miki, K.; Milov, A.; Mitchell, J. T.; Miyachi, Y.; Mohanty, A. K.; Moon, H. J.; Morino, Y.; Morreale, A.; Morrison, D. P.; Motschwiller, S.; Moukhanova, T. V.; Murakami, T.; Murata, J.; Nagamiya, S.; Nagle, J. L.; Naglis, M.; Nagy, M. I.; Nakagawa, I.; Nakamiya, Y.; Nakamura, K. R.; Nakamura, T.; Nakano, K.; Newby, J.; Nguyen, M.; Nihashi, M.; Nouicer, R.; Nyanin, A. S.; Oakley, C.; O'Brien, E.; Ogilvie, C. A.; Oka, M.; Okada, K.; Oskarsson, A.; Ouchida, M.; Ozawa, K.; Pak, R.; Pantuev, V.; Papavassiliou, V.; Park, B. H.; Park, I. H.; Park, S. K.; Pate, S. F.; Patel, L.; Pei, H.; Peng, J.-C.; Pereira, H.; Peressounko, D. Yu.; Petti, R.; Pinkenburg, C.; Pisani, R. P.; Proissl, M.; Purschke, M. L.; Qu, H.; Rak, J.; Ravinovich, I.; Read, K. F.; Reygers, K.; Riabov, V.; Riabov, Y.; Richardson, E.; Roach, D.; Roche, G.; Rolnick, S. D.; Rosati, M.; Rosendahl, S. S. E.; Rubin, J. G.; Sahlmueller, B.; Saito, N.; Sakaguchi, T.; Samsonov, V.; Sano, S.; Sarsour, M.; Sato, T.; Savastio, M.; Sawada, S.; Sedgwick, K.; Seidl, R.; Seto, R.; Sharma, D.; Shein, I.; Shibata, T.-A.; Shigaki, K.; Shim, H. H.; Shimomura, M.; Shoji, K.; Shukla, P.; Sickles, A.; Silva, C. L.; Silvermyr, D.; Silvestre, C.; Sim, K. S.; Singh, B. K.; Singh, C. P.; Singh, V.; Slunečka, M.; Sodre, T.; Soltz, R. A.; Sondheim, W. E.; Sorensen, S. P.; Sourikova, I. V.; Stankus, P. W.; Stenlund, E.; Stoll, S. P.; Sugitate, T.; Sukhanov, A.; Sun, J.; Sziklai, J.; Takagui, E. M.; Takahara, A.; Taketani, A.; Tanabe, R.; Tanaka, Y.; Taneja, S.; Tanida, K.; Tannenbaum, M. J.; Tarafdar, S.; Taranenko, A.; Tennant, E.; Themann, H.; Thomas, D.; Togawa, M.; Tomášek, L.; Tomášek, M.; Torii, H.; Towell, R. S.; Tserruya, I.; Tsuchimoto, Y.; Utsunomiya, K.; Vale, C.; van Hecke, H. W.; Vazquez-Zambrano, E.; Veicht, A.; Velkovska, J.; Vértesi, R.; Virius, M.; Vossen, A.; Vrba, V.; Vznuzdaev, E.; Wang, X. R.; Watanabe, D.; Watanabe, K.; Watanabe, Y.; Watanabe, Y. S.; Wei, F.; Wei, R.; Wessels, J.; White, S. N.; Winter, D.; Woody, C. L.; Wright, R. M.; Wysocki, M.; Yamaguchi, Y. L.; Yang, R.; Yanovich, A.; Ying, J.; Yokkaichi, S.; Yoo, J. S.; You, Z.; Young, G. R.; Younus, I.; Yushmanov, I. E.; Zajc, W. A.; Zelenski, A.; Zhou, S.; Phenix Collaboration

2015-02-01

We present midrapidity charged-pion invariant cross sections, the ratio of the π- to π+ cross sections and the charge-separated double-spin asymmetries in polarized p +p collisions at √{s }=200 GeV . While the cross section measurements are consistent within the errors of next-to-leading-order (NLO) perturbative quantum chromodynamics predictions (pQCD), the same calculations overestimate the ratio of the charged-pion cross sections. This discrepancy arises from the cancellation of the substantial systematic errors associated with the NLO-pQCD predictions in the ratio and highlights the constraints these data will place on flavor-dependent pion fragmentation functions. The charge-separated pion asymmetries presented here sample an x range of ˜0.03 - 0.16 and provide unique information on the sign of the gluon-helicity distribution.

Improving Charging-Breeding Simulations with Space-Charge Effects

NASA Astrophysics Data System (ADS)

Bilek, Ryan; Kwiatkowski, Ania; Steinbrügge, René

2016-09-01

Rare-isotope-beam facilities use Highly Charged Ions (HCI) for accelerators accelerating heavy ions and to improve measurement precision and resolving power of certain experiments. An Electron Beam Ion Trap (EBIT) is able to create HCI through successive electron impact, charge breeding trapped ions into higher charge states. CBSIM was created to calculate successive charge breeding with an EBIT. It was augmented by transferring it into an object-oriented programming language, including additional elements, improving ion-ion collision factors, and exploring the overlap of the electron beam with the ions. The calculation is enhanced with the effects of residual background gas by computing the space charge due to charge breeding. The program assimilates background species, ionizes and charge breeds them alongside the element being studied, and allows them to interact with the desired species through charge exchange, giving fairer overview of realistic charge breeding. Calculations of charge breeding will be shown for realistic experimental conditions. We reexamined the implementation of ionization energies, cross sections, and ion-ion interactions when charge breeding.

Some New/Old Approaches to QCD

DOE R&D Accomplishments Database

Gross, D. J.

1992-11-01

In this lecture I shall discuss some recent attempts to revive some old ideas to address the problem of solving QCD. I believe that it is timely to return to this problem which has been woefully neglected for the last decade. QCD is a permanent part of the theoretical landscape and eventually we will have to develop analytic tools for dealing with the theory in the infra-red. Lattice techniques are useful but they have not yet lived up to their promise. Even if one manages to derive the hadronic spectrum numerically, to an accuracy of 10% or even 1%, we will not be truly satisfied unless we have some analytic understanding of the results. Also, lattice Monte-Carlo methods can only be used to answer a small set of questions. Many issues of great conceptual and practical interest-in particular the calculation of scattering amplitudes, are thus far beyond lattice control. Any progress in controlling QCD in an explicit analytic, fashion would be of great conceptual value. It would also be of great practical aid to experimentalists, who must use rather ad-hoc and primitive models of QCD scattering amplitudes to estimate the backgrounds to interesting new physics. I will discuss an attempt to derive a string representation of QCD and a revival of the large N approach to QCD. Both of these ideas have a long history, many theorist-years have been devoted to their pursuit-so far with little success. I believe that it is time to try again. In part this is because of the progress in the last few years in string theory. Our increased understanding of string theory should make the attempt to discover a stringy representation of QCD easier, and the methods explored in matrix models might be employed to study the large N limit of QCD.

Kenneth Wilson and Lattice QCD

NASA Astrophysics Data System (ADS)

Ukawa, Akira

2015-09-01

We discuss the physics and computation of lattice QCD, a space-time lattice formulation of quantum chromodynamics, and Kenneth Wilson's seminal role in its development. We start with the fundamental issue of confinement of quarks in the theory of the strong interactions, and discuss how lattice QCD provides a framework for understanding this phenomenon. A conceptual issue with lattice QCD is a conflict of space-time lattice with chiral symmetry of quarks. We discuss how this problem is resolved. Since lattice QCD is a non-linear quantum dynamical system with infinite degrees of freedom, quantities which are analytically calculable are limited. On the other hand, it provides an ideal case of massively parallel numerical computations. We review the long and distinguished history of parallel-architecture supercomputers designed and built for lattice QCD. We discuss algorithmic developments, in particular the difficulties posed by the fermionic nature of quarks, and their resolution. The triad of efforts toward better understanding of physics, better algorithms, and more powerful supercomputers have produced major breakthroughs in our understanding of the strong interactions. We review the salient results of this effort in understanding the hadron spectrum, the Cabibbo-Kobayashi-Maskawa matrix elements and CP violation, and quark-gluon plasma at high temperatures. We conclude with a brief summary and a future perspective.

The QCD mass gap and quark deconfinement scales as mass bounds in strong gravity

NASA Astrophysics Data System (ADS)

Burikham, Piyabut; Harko, Tiberiu; Lake, Matthew J.

2017-11-01

Though not a part of mainstream physics, Salam's theory of strong gravity remains a viable effective model for the description of strong interactions in the gauge singlet sector of QCD, capable of producing particle confinement and asymptotic freedom, but not of reproducing interactions involving SU(3) color charge. It may therefore be used to explore the stability and confinement of gauge singlet hadrons, though not to describe scattering processes that require color interactions. It is a two-tensor theory of both strong interactions and gravity, in which the strong tensor field is governed by equations formally identical to the Einstein equations, apart from the coupling parameter, which is of order 1 {GeV}^{-1}. We revisit the strong gravity theory and investigate the strong gravity field equations in the presence of a mixing term which induces an effective strong cosmological constant, Λ f. This introduces a strong de Sitter radius for strongly interacting fermions, producing a confining bubble, which allows us to identify Λ f with the `bag constant' of the MIT bag model, B ˜eq 2 × 10^{14} {g} {cm}^{-3}. Assuming a static, spherically symmetric geometry, we derive the strong gravity TOV equation, which describes the equilibrium properties of compact hadronic objects. From this, we determine the generalized Buchdahl inequalities for a strong gravity `particle', giving rise to upper and lower bounds on the mass/radius ratio of stable, compact, strongly interacting objects. We show, explicitly, that the existence of the lower mass bound is induced by the presence of Λ _f, producing a mass gap, and that the upper bound corresponds to a deconfinement phase transition. The physical implications of our results for holographic duality in the context of the AdS/QCD and dS/QCD correspondences are also discussed.

Discretization effects in the topological susceptibility in lattice QCD

NASA Astrophysics Data System (ADS)

Hart, A.

2004-04-01

We study the topological susceptibility χ in QCD with two quark flavors using lattice field configurations that have been produced with an O(a)-improved clover quark action. We find clear evidence for the expected suppression at a small quark mass mq and examine the variation of χ with this mass and the lattice spacing a. A joint continuum and chiral extrapolation yields good agreement with theoretical expectations as a,mq→0. A moderate increase in autocorrelation is observed on the more chiral ensembles, but within large statistical errors. Finite volume effects are negligible for the Leutwyler-Smilga parameter xLS≳10, and no evidence for a nearby phase transition is observed.

Experimenting with Langevin lattice QCD

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

Gavai, R.V.; Potvin, J.; Sanielevici, S.

1987-05-01

We report on the status of our investigations of the effects of systematic errors upon the practical merits of Langevin updating in full lattice QCD. We formulate some rules for the safe use of this updating procedure and some observations on problems which may be common to all approximate fermion algorithms.

Scheme variations of the QCD coupling

NASA Astrophysics Data System (ADS)

Boito, Diogo; Jamin, Matthias; Miravitllas, Ramon

2017-03-01

The Quantum Chromodynamics (QCD) coupling αs is a central parameter in the Standard Model of particle physics. However, it depends on theoretical conventions related to renormalisation and hence is not an observable quantity. In order to capture this dependence in a transparent way, a novel definition of the QCD coupling, denoted by â, is introduced, whose running is explicitly renormalisation scheme invariant. The remaining renormalisation scheme dependence is related to transformations of the QCD scale Λ, and can be parametrised by a single parameter C. Hence, we call â the C-scheme coupling. The dependence on C can be exploited to study and improve perturbative predictions of physical observables. This is demonstrated for the QCD Adler function and hadronic decays of the τ lepton.

Resonant conversions of QCD axions into hidden axions and suppressed isocurvature perturbations

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

Kitajima, Naoya; Takahashi, Fuminobu, E-mail: kitajima@tuhep.phys.tohoku.ac.jp, E-mail: fumi@tuhep.phys.tohoku.ac.jp

2015-01-01

We study in detail MSW-like resonant conversions of QCD axions into hidden axions, including cases where the adiabaticity condition is only marginally satisfied, and where anharmonic effects are non-negligible. When the resonant conversion is efficient, the QCD axion abundance is suppressed by the hidden and QCD axion mass ratio. We find that, when the resonant conversion is incomplete due to a weak violation of the adiabaticity, the CDM isocurvature perturbations can be significantly suppressed, while non-Gaussianity of the isocurvature perturbations generically remain unsuppressed. The isocurvature bounds on the inflation scale can therefore be relaxed by the partial resonant conversion ofmore » the QCD axions into hidden axions.« less

Refining new-physics searches in B→Dτν with lattice QCD.

PubMed

Bailey, Jon A; Bazavov, A; Bernard, C; Bouchard, C M; Detar, C; Du, Daping; El-Khadra, A X; Foley, J; Freeland, E D; Gámiz, E; Gottlieb, Steven; Heller, U M; Kim, Jongjeong; Kronfeld, A S; Laiho, J; Levkova, L; Mackenzie, P B; Meurice, Y; Neil, E T; Oktay, M B; Qiu, Si-Wei; Simone, J N; Sugar, R; Toussaint, D; Van de Water, R S; Zhou, Ran

2012-08-17

The semileptonic decay channel B→Dτν is sensitive to the presence of a scalar current, such as that mediated by a charged-Higgs boson. Recently, the BABAR experiment reported the first observation of the exclusive semileptonic decay B→Dτ(-)ν, finding an approximately 2σ disagreement with the standard-model prediction for the ratio R(D)=BR(B→Dτν)/BR(B→Dℓν), where ℓ = e,μ. We compute this ratio of branching fractions using hadronic form factors computed in unquenched lattice QCD and obtain R(D)=0.316(12)(7), where the errors are statistical and total systematic, respectively. This result is the first standard-model calculation of R(D) from ab initio full QCD. Its error is smaller than that of previous estimates, primarily due to the reduced uncertainty in the scalar form factor f(0)(q(2)). Our determination of R(D) is approximately 1σ higher than previous estimates and, thus, reduces the tension with experiment. We also compute R(D) in models with electrically charged scalar exchange, such as the type-II two-Higgs-doublet model. Once again, our result is consistent with, but approximately 1σ higher than, previous estimates for phenomenologically relevant values of the scalar coupling in the type-II model. As a by-product of our calculation, we also present the standard-model prediction for the longitudinal-polarization ratio P(L)(D)=0.325(4)(3).

Charged-pion cross sections and double-helicity asymmetries in polarized p + p collisions at √s = 200 GeV

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

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

2015-02-02

We present midrapidity charged-pion invariant cross sections, the ratio of the π⁻ to π⁺ cross sections and the charge-separated double-spin asymmetries in polarized p+p collisions at √s = 200 GeV. While the cross section measurements are consistent within the errors of next-to-leadingorder (NLO) perturbative quantum chromodynamics predictions (pQCD), the same calculations over estimate the ratio of the charged-pion cross sections. This discrepancy arises from the cancellation of the substantial systematic errors associated with the NLO-pQCD predictions in the ratio and highlights the constraints these data will place on flavor dependent pion fragmentation functions. Thus, the charge-separated pion asymmetries presented heremore » sample an x range of ~0.03–0.16 and provide unique information on the sign of the gluon-helicity distribution.« less

Domain wall network as QCD vacuum: confinement, chiral symmetry, hadronization

NASA Astrophysics Data System (ADS)

Nedelko, Sergei N.; Voronin, Vladimir V.

2017-03-01

An approach to QCD vacuum as a medium describable in terms of statistical ensemble of almost everywhere homogeneous Abelian (anti-)self-dual gluon fields is reviewed. These fields play the role of the confining medium for color charged fields as well as underline the mechanism of realization of chiral SUL(Nf) × SUR(Nf) and UA(1) symmetries. Hadronization formalism based on this ensemble leads to manifestly defined quantum effective meson action. Strong, electromagnetic and weak interactions of mesons are represented in the action in terms of nonlocal n-point interaction vertices given by the quark-gluon loops averaged over the background ensemble. Systematic results for the mass spectrum and decay constants of radially excited light, heavy-light mesons and heavy quarkonia are presented. Relationship of this approach to the results of functional renormalization group and Dyson-Schwinger equations, and the picture of harmonic confinement is briefly outlined.

Scattering processes and resonances from lattice QCD

NASA Astrophysics Data System (ADS)

Briceño, Raúl A.; Dudek, Jozef J.; Young, Ross D.

2018-04-01

The vast majority of hadrons observed in nature are not stable under the strong interaction; rather they are resonances whose existence is deduced from enhancements in the energy dependence of scattering amplitudes. The study of hadron resonances offers a window into the workings of quantum chromodynamics (QCD) in the low-energy nonperturbative region, and in addition many probes of the limits of the electroweak sector of the standard model consider processes which feature hadron resonances. From a theoretical standpoint, this is a challenging field: the same dynamics that binds quarks and gluons into hadron resonances also controls their decay into lighter hadrons, so a complete approach to QCD is required. Presently, lattice QCD is the only available tool that provides the required nonperturbative evaluation of hadron observables. This article reviews progress in the study of few-hadron reactions in which resonances and bound states appear using lattice QCD techniques. The leading approach is described that takes advantage of the periodic finite spatial volume used in lattice QCD calculations to extract scattering amplitudes from the discrete spectrum of QCD eigenstates in a box. An explanation is given of how from explicit lattice QCD calculations one can rigorously garner information about a variety of resonance properties, including their masses, widths, decay couplings, and form factors. The challenges which currently limit the field are discussed along with the steps being taken to resolve them.

Dissociation of heavy quarkonium in hot QCD medium in a quasiparticle model

NASA Astrophysics Data System (ADS)

Agotiya, Vineet Kumar; Chandra, Vinod; Jamal, M. Yousuf; Nilima, Indrani

2016-11-01

Following a recent work on the effective description of the equations of state for hot QCD obtained from a hard thermal loop expression for the gluon self-energy, in terms of the quasigluons and quasiquarks and antiquarks with respective effective fugacities, the dissociation process of heavy quarkonium in hot QCD medium has been investigated. This has been done by investigating the medium modification to a heavy quark potential. The medium-modified potential has a quite different form (a long-range Coulomb tail in addition to the usual Yukawa term) in contrast to the usual picture of Debye screening. The flavor dependence binding energies of the heavy quarkonia states and the dissociation temperature have been obtained by employing the Debye mass for pure gluonic and full QCD case computed employing the quasiparticle picture. Thus, estimated dissociation patterns of the charmonium and bottomonium states, considering Debye mass from different approaches in the pure gluonic case and full QCD, have shown good agreement with the other potential model studies.

η and η' mesons from lattice QCD.

PubMed

Christ, N H; Dawson, C; Izubuchi, T; Jung, C; Liu, Q; Mawhinney, R D; Sachrajda, C T; Soni, A; Zhou, R

2010-12-10

The large mass of the ninth pseudoscalar meson, the η', is believed to arise from the combined effects of the axial anomaly and the gauge field topology present in QCD. We report a realistic, 2+1-flavor, lattice QCD calculation of the η and η' masses and mixing which confirms this picture. The physical eigenstates show small octet-singlet mixing with a mixing angle of θ=-14.1(2.8)°. Extrapolation to the physical light quark mass gives, with statistical errors only, mη=573(6) MeV and mη'=947(142) MeV, consistent with the experimental values of 548 and 958 MeV.

Scaling functions for the Inverse Compressibility near the QCD critical point

NASA Astrophysics Data System (ADS)

Lacey, Roy

2017-09-01

The QCD phase diagram can be mapped out by studying fluctuations and their response to changes in the temperature and baryon chemical potential. Theoretical studies indicate that the cumulant ratios Cn /Cm used to characterize the fluctuation of conserved charges, provide a valuable probe of deconfinement and chiral dynamics, as well as for identifying the position of the critical endpoint (CEP) in the QCD phase diagram. The ratio C1 /C2 , which is linked to the inverse compressibility, vanishes at the CEP due to the divergence of the net quark number fluctuations at the critical point belonging to the Z(2) universality class. Therefore, it's associated scaling function can give insight on the location of the critical end point, as well as the critical exponents required to assign its static universality class. Scaling functions for the ratio C1 /C2 , obtained from net-proton multiplicity distributions for a broad range of collision centralities in Au+Au (√{sNN} = 7.7 - 200 GeV) collisions will be presented and discussed.

Strange and Charge Symmetry Violating Electromagnetic Form Factors of the Nucleon

NASA Astrophysics Data System (ADS)

Shanahan, P. E.

We summarise recent work based on lattice QCD simulations of the electromagnetic form factors of the octet baryons from the CSSM/QCDSF/UKQCD collaborations. After an analysis of the simulation results using techniques to approach the infinite volume limit and the physical pseudoscalar masses at non-zero momentum transfer, the extrapolated proton and neutron form factors are found to be in excellent agreement with those extracted from experiment. Given the success of these calculations, we describe how the strange electromagnetic form factors may be estimated from these results under the same assumption of charge symmetry used in experimental determinations of those quantities. Motivated by the necessity of that assumption, we explore a method for determining the size of charge symmetry breaking effects using the same lattice results.

Nuclear reactions from lattice QCD

DOE PAGES

Briceño, Raúl A.; Davoudi, Zohreh; Luu, Thomas C.

2015-01-13

In this study, one of the overarching goals of nuclear physics is to rigorously compute properties of hadronic systems directly from the fundamental theory of strong interactions, Quantum Chromodynamics (QCD). In particular, the hope is to perform reliable calculations of nuclear reactions which will impact our understanding of environments that occur during big bang nucleosynthesis, the evolution of stars and supernovae, and within nuclear reactors and high energy/density facilities. Such calculations, being truly ab initio, would include all two-nucleon and three- nucleon (and higher) interactions in a consistent manner. Currently, lattice QCD provides the only reliable option for performing calculationsmore » of some of the low-energy hadronic observables. With the aim of bridging the gap between lattice QCD and nuclear many-body physics, the Institute for Nuclear Theory held a workshop on Nuclear Reactions from Lattice QCD on March 2013. In this review article, we report on the topics discussed in this workshop and the path planned to move forward in the upcoming years.« less

Sea quarks contribution to the nucleon magnetic moment and charge radius at the physical point

NASA Astrophysics Data System (ADS)

Sufian, Raza Sabbir; Yang, Yi-Bo; Liang, Jian; Draper, Terrence; Liu, Keh-Fei; χ QCD Collaboration

2017-12-01

We report a comprehensive analysis of the light and strange disconnected-sea quarks contribution to the nucleon magnetic moment, charge radius, and the electric and magnetic form factors. The lattice QCD calculation includes ensembles across several lattice volumes and lattice spacings with one of the ensembles at the physical pion mass. We adopt a model-independent extrapolation of the nucleon magnetic moment and the charge radius. We have performed a simultaneous chiral, infinite volume, and continuum extrapolation in a global fit to calculate results in the continuum limit. We find that the combined light and strange disconnected-sea quarks contribution to the nucleon magnetic moment is μM(DI )=-0.022 (11 )(09 ) μN and to the nucleon mean square charge radius is ⟨r2⟩E(DI ) =-0.019 (05 )(05 ) fm2 which is about 1 /3 of the difference between the ⟨rp2⟩E of electron-proton scattering and that of a muonic atom and so cannot be ignored in obtaining the proton charge radius in the lattice QCD calculation. The most important outcome of this lattice QCD calculation is that while the combined light-sea and strange quarks contribution to the nucleon magnetic moment is small at about 1%, a negative 2.5(9)% contribution to the proton mean square charge radius and a relatively larger positive 16.3(6.1)% contribution to the neutron mean square charge radius come from the sea quarks in the nucleon. For the first time, by performing global fits, we also give predictions of the light and strange disconnected-sea quarks contributions to the nucleon electric and magnetic form factors at the physical point and in the continuum and infinite volume limits in the momentum transfer range of 0 ≤Q2≤0.5 GeV2 .

Search for the chiral magnetic effect in relativistic heavy-ion collisions

NASA Astrophysics Data System (ADS)

Zhao, Jie

2018-05-01

Relativistic heavy-ion collisions provide an ideal environment to study the emergent phenomena in quantum chromodynamics (QCD). The chiral magnetic effect (CME) is one of the most interesting, arising from the topological charge fluctuations of QCD vacua, immersed in a strong magnetic field. Since the first measurement nearly a decade ago of the possibly CME-induced charge correlation, extensive studies have been devoted to background contributions to those measurements. Many new ideas and techniques have been developed to reduce or eliminate the backgrounds. This paper reviews these developments and the overall progress in the search for the CME.

Importance of the Bulk Viscosity of QCD in Ultrarelativistic Heavy-Ion Collisions

DOE PAGES

Ryu, S.; Paquet, J. -F.; Shen, C.; ...

2015-09-22

In this study, we investigate the consequences of a nonzero bulk viscosity coefficient on the transverse momentum spectra, azimuthal momentum anisotropy, and multiplicity of charged hadrons produced in heavy ion collisions at LHC energies. The agreement between a realistic 3D hybrid simulation and the experimentally measured data considerably improves with the addition of a bulk viscosity coefficient for strongly interacting matter. Lastly, this paves the way for an eventual quantitative determination of several QCD transport coefficients from the experimental heavy ion and hadron-nucleus collision programs.

Polyakov loop modeling for hot QCD

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

Fukushima, Kenji; Skokov, Vladimir

Here, we review theoretical aspects of quantum chromodynamics (QCD) at finite temperature. The most important physical variable to characterize hot QCD is the Polyakov loop, which is an approximate order parameter for quark deconfinement in a hot gluonic medium. Additionally to its role as an order parameter, the Polyakov loop has rich physical contents in both perturbative and non-perturbative sectors. This review covers a wide range of subjects associated with the Polyakov loop from topological defects in hot QCD to model building with coupling to the Polyakov loop.

Polyakov loop modeling for hot QCD

DOE PAGES

Fukushima, Kenji; Skokov, Vladimir

2017-06-19

Here, we review theoretical aspects of quantum chromodynamics (QCD) at finite temperature. The most important physical variable to characterize hot QCD is the Polyakov loop, which is an approximate order parameter for quark deconfinement in a hot gluonic medium. Additionally to its role as an order parameter, the Polyakov loop has rich physical contents in both perturbative and non-perturbative sectors. This review covers a wide range of subjects associated with the Polyakov loop from topological defects in hot QCD to model building with coupling to the Polyakov loop.

Scattering processes and resonances from lattice QCD

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

Briceno, Raul A.; Dudek, Jozef J.; Young, Ross D.

The vast majority of hadrons observed in nature are not stable under the strong interaction; rather they are resonances whose existence is deduced from enhancements in the energy dependence of scattering amplitudes. The study of hadron resonances offers a window into the workings of quantum chromodynamics (QCD) in the low-energy nonperturbative region, and in addition many probes of the limits of the electroweak sector of the standard model consider processes which feature hadron resonances. From a theoretical standpoint, this is a challenging field: the same dynamics that binds quarks and gluons into hadron resonances also controls their decay into lightermore » hadrons, so a complete approach to QCD is required. Presently, lattice QCD is the only available tool that provides the required nonperturbative evaluation of hadron observables. This paper reviews progress in the study of few-hadron reactions in which resonances and bound states appear using lattice QCD techniques. The leading approach is described that takes advantage of the periodic finite spatial volume used in lattice QCD calculations to extract scattering amplitudes from the discrete spectrum of QCD eigenstates in a box. An explanation is given of how from explicit lattice QCD calculations one can rigorously garner information about a variety of resonance properties, including their masses, widths, decay couplings, and form factors. Finally, the challenges which currently limit the field are discussed along with the steps being taken to resolve them.« less

Scattering processes and resonances from lattice QCD

DOE PAGES

Briceno, Raul A.; Dudek, Jozef J.; Young, Ross D.

2018-04-18

The vast majority of hadrons observed in nature are not stable under the strong interaction; rather they are resonances whose existence is deduced from enhancements in the energy dependence of scattering amplitudes. The study of hadron resonances offers a window into the workings of quantum chromodynamics (QCD) in the low-energy nonperturbative region, and in addition many probes of the limits of the electroweak sector of the standard model consider processes which feature hadron resonances. From a theoretical standpoint, this is a challenging field: the same dynamics that binds quarks and gluons into hadron resonances also controls their decay into lightermore » hadrons, so a complete approach to QCD is required. Presently, lattice QCD is the only available tool that provides the required nonperturbative evaluation of hadron observables. This paper reviews progress in the study of few-hadron reactions in which resonances and bound states appear using lattice QCD techniques. The leading approach is described that takes advantage of the periodic finite spatial volume used in lattice QCD calculations to extract scattering amplitudes from the discrete spectrum of QCD eigenstates in a box. An explanation is given of how from explicit lattice QCD calculations one can rigorously garner information about a variety of resonance properties, including their masses, widths, decay couplings, and form factors. Finally, the challenges which currently limit the field are discussed along with the steps being taken to resolve them.« less

Basics of QCD perturbation theory

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

Soper, D.E.

1997-06-01

This is an introduction to the use of QCD perturbation theory, emphasizing generic features of the theory that enable one to separate short-time and long-time effects. The author also covers some important classes of applications: electron-positron annihilation to hadrons, deeply inelastic scattering, and hard processes in hadron-hadron collisions. 31 refs., 38 figs.

Charge renormalization and inversion of a highly charged lipid bilayer: effects of dielectric discontinuities and charge correlations.

PubMed

Taheri-Araghi, Sattar; Ha, Bae-Yeun

2005-08-01

We reexamine the problem of charge renormalization and inversion of a highly charged surface of a low dielectric constant immersed in ionic solutions. To be specific, we consider an asymmetrically charged lipid bilayer, in which only one layer is negatively charged. In particular, we study how dielectric discontinuities and charge correlations (among lipid charges and condensed counterions) influence the effective charge of the surface. When counterions are monovalent (e.g., Na+), our mean-field approach implies that dielectric discontinuities can enhance counterion condensation. A simple scaling picture shows how the effects of dielectric discontinuities and surface-charge distributions are intertwined: Dielectric discontinuities diminish condensation if the backbone charge is uniformly smeared out while counterions are localized in space; they can, however, enhance condensation when the backbone charge is discrete. In the presence of asymmetric salts such as CaCl2 , we find that the correlation effect, treated at the Gaussian level, is more pronounced when the surface has a lower dielectric constant, inverting the sign of the charge at a smaller value of Ca2+ concentration.

K - bar K mixing in a low energy effective QCD

NASA Astrophysics Data System (ADS)

Bergan, A. E.; Eeg, J. O.

1994-09-01

We consider the contribution from the siamese penguin diagram toK - bar K mixing. Combining some previous results, this contribution could be numerically significant, which is the motivation for the present calculation. For the siamese penguin, the effective lagrangian obtained from the perturbative region above ≈1 GeV is highly non-local. We account for such non-local effects by using an effective low-energy QCD, advocated by many authors, where the quarks are coupled to the pseudoscalar mesons π, K, η. Taking into account the momentum variation of the effective penguin interaction, it is found that the matrix element of the siamese penguin is finite in the limitΛ _χ to infty , the CP-conserving part being about 50% of the well known box contribution. However, taking into account the finiteness of the cut-off, a numerical integration shows that the siamese penguin contribution is drastically reduced, and is only 0.2 0.3% of the box result.

Dark-matter QCD-axion searches

DOE PAGES

Rosenberg, Leslie J.

2015-01-12

In the late 20th century, cosmology became a precision science. At the beginning of the next century, the parameters describing how our universe evolved from the Big Bang are generally known to a few percent. One key parameter is the total mass density of the universe. Normal matter constitutes only a small fraction of the total mass density. Observations suggest this additional mass, the dark matter, is cold (that is, moving nonrelativistically in the early universe) and interacts feebly if at all with normal matter and radiation. There’s no known such elementary particle, so the strong presumption is the darkmore » matter consists of particle relics of a new kind left over from the Big Bang. One of the most important questions in science is the nature of this dark matter. One attractive particle dark-matter candidate is the axion. The axion is a hypothetical elementary particle arising in a simple and elegant extension to the standard model of particle physics that nulls otherwise observable CP-violating effects (where CP is the product of charge reversal C and parity inversion P) in quantum chromo dynamics (QCD). A light axion of mass 10 -(6–3) eV (the invisible axion) would couple extraordinarily weakly to normal matter and radiation and would therefore be extremely difficult to detect in the laboratory. But, such an axion is a compelling dark-matter candidate and is therefore a target of a number of searches. Compared with other particle dark-matter candidates, the plausible range of axion dark-matter couplings and masses is narrowly constrained. This focused search range allows for definitive searches, where a nonobservation would seriously impugn the dark-matter QCD-axion hypothesis. Axion searches use a wide range of technologies, and the experiment sensitivities are now reaching likely dark-matter axion couplings and masses. Our paper is a selective overview of the current generation of sensitive axion searches. Finally, not all techniques and

Dark-matter QCD-axion searches

PubMed Central

Rosenberg, Leslie J

2015-01-01

In the late 20th century, cosmology became a precision science. Now, at the beginning of the next century, the parameters describing how our universe evolved from the Big Bang are generally known to a few percent. One key parameter is the total mass density of the universe. Normal matter constitutes only a small fraction of the total mass density. Observations suggest this additional mass, the dark matter, is cold (that is, moving nonrelativistically in the early universe) and interacts feebly if at all with normal matter and radiation. There’s no known such elementary particle, so the strong presumption is the dark matter consists of particle relics of a new kind left over from the Big Bang. One of the most important questions in science is the nature of this dark matter. One attractive particle dark-matter candidate is the axion. The axion is a hypothetical elementary particle arising in a simple and elegant extension to the standard model of particle physics that nulls otherwise observable CP-violating effects (where CP is the product of charge reversal C and parity inversion P) in quantum chromo dynamics (QCD). A light axion of mass 10−(6–3) eV (the invisible axion) would couple extraordinarily weakly to normal matter and radiation and would therefore be extremely difficult to detect in the laboratory. However, such an axion is a compelling dark-matter candidate and is therefore a target of a number of searches. Compared with other particle dark-matter candidates, the plausible range of axion dark-matter couplings and masses is narrowly constrained. This focused search range allows for definitive searches, where a nonobservation would seriously impugn the dark-matter QCD-axion hypothesis. Axion searches use a wide range of technologies, and the experiment sensitivities are now reaching likely dark-matter axion couplings and masses. This article is a selective overview of the current generation of sensitive axion searches. Not all techniques and

Mass-improvement of the vector current in three-flavor QCD

NASA Astrophysics Data System (ADS)

Fritzsch, P.

2018-06-01

We determine two improvement coefficients which are relevant to cancel mass-dependent cutoff effects in correlation functions with operator insertions of the non-singlet local QCD vector current. This determination is based on degenerate three-flavor QCD simulations of non-perturbatively O( a) improved Wilson fermions with tree-level improved gauge action. Employing a very robust strategy that has been pioneered in the quenched approximation leads to an accurate estimate of a counterterm cancelling dynamical quark cutoff effects linear in the trace of the quark mass matrix. To our knowledge this is the first time that such an effect has been determined systematically with large significance.

Nucleon QCD sum rules in the instanton medium

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

Ryskin, M. G.; Drukarev, E. G., E-mail: drukarev@pnpi.spb.ru; Sadovnikova, V. A.

2015-09-15

We try to find grounds for the standard nucleon QCD sum rules, based on a more detailed description of the QCD vacuum. We calculate the polarization operator of the nucleon current in the instanton medium. The medium (QCD vacuum) is assumed to be a composition of the small-size instantons and some long-wave gluon fluctuations. We solve the corresponding QCD sum rule equations and demonstrate that there is a solution with the value of the nucleon mass close to the physical one if the fraction of the small-size instantons contribution is w{sub s} ≈ 2/3.

QCD analysis of $W$- and $Z$-boson production at Tevatron

DOE PAGES

Camarda, S.; Belov, P.; Cooper-Sarkar, A. M.; ...

2015-09-28

Recent measurements of the W-boson charge asymmetry and of the Z-boson production cross sections, performed at the Tevatron collider in Run II by the D0 and CDF collaborations, are studied using the HERAFitter framework to assess their impact on the proton parton distribution functions (PDFs). Thus, the Tevatron measurements, together with deep-inelastic scattering data from HERA, are included in a QCD analysis performed at next-to-leading order, and compared to the predictions obtained using other PDF sets from different groups. Good agreement between measurements and theoretical predictions is observed. The Tevatron data provide significant constraints on the d-valence quark distribution.

QCD analysis of $W$- and $Z$-boson production at Tevatron

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

Camarda, S.; Belov, P.; Cooper-Sarkar, A. M.

Recent measurements of the W-boson charge asymmetry and of the Z-boson production cross sections, performed at the Tevatron collider in Run II by the D0 and CDF collaborations, are studied using the HERAFitter framework to assess their impact on the proton parton distribution functions (PDFs). Thus, the Tevatron measurements, together with deep-inelastic scattering data from HERA, are included in a QCD analysis performed at next-to-leading order, and compared to the predictions obtained using other PDF sets from different groups. Good agreement between measurements and theoretical predictions is observed. The Tevatron data provide significant constraints on the d-valence quark distribution.

Analysis of nucleon electromagnetic form factors from light-front holographic QCD: The spacelike region

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

Sufian, Raza Sabbir; de Teramond, Guy F.; Brodsky, Stanley J.

We present a comprehensive analysis of the space-like nucleon electromagnetic form factors and their flavor decomposition within the framework of light-front holographic QCD. We show that the inclusion of the higher Fock componentsmore » $$|{qqqq\\bar{q}}$$ has a significant effect on the spin-flip elastic Pauli form factor and almost zero effect on the spin-conserving Dirac form factor. We present light-front holographic QCD results for the proton and neutron form factors at any momentum transfer range, including asymptotic predictions, and show that our results agree with the available experimental data with high accuracy. In order to correctly describe the Pauli form factor we need an admixture of a five quark state of about 30$$\\%$$ in the proton and about 40$$\\%$$ in the neutron. We also extract the nucleon charge and magnetic radii and perform a flavor decomposition of the nucleon electromagnetic form factors. The free parameters needed to describe the experimental nucleon form factors are very few: two parameters for the probabilities of higher Fock states for the spin-flip form factor and a phenomenological parameter $r$, required to account for possible SU(6) spin-flavor symmetry breaking effects in the neutron, whereas the Pauli form factors are normalized to the experimental values of the anomalous magnetic moments. As a result, the covariant spin structure for the Dirac and Pauli nucleon form factors prescribed by AdS$$_5$$ semiclassical gravity incorporates the correct twist scaling behavior from hard scattering and also leads to vector dominance at low energy.« less

Analysis of nucleon electromagnetic form factors from light-front holographic QCD: The spacelike region

DOE PAGES

Sufian, Raza Sabbir; de Teramond, Guy F.; Brodsky, Stanley J.; ...

2017-01-10

We present a comprehensive analysis of the space-like nucleon electromagnetic form factors and their flavor decomposition within the framework of light-front holographic QCD. We show that the inclusion of the higher Fock componentsmore » $$|{qqqq\\bar{q}}$$ has a significant effect on the spin-flip elastic Pauli form factor and almost zero effect on the spin-conserving Dirac form factor. We present light-front holographic QCD results for the proton and neutron form factors at any momentum transfer range, including asymptotic predictions, and show that our results agree with the available experimental data with high accuracy. In order to correctly describe the Pauli form factor we need an admixture of a five quark state of about 30$$\\%$$ in the proton and about 40$$\\%$$ in the neutron. We also extract the nucleon charge and magnetic radii and perform a flavor decomposition of the nucleon electromagnetic form factors. The free parameters needed to describe the experimental nucleon form factors are very few: two parameters for the probabilities of higher Fock states for the spin-flip form factor and a phenomenological parameter $r$, required to account for possible SU(6) spin-flavor symmetry breaking effects in the neutron, whereas the Pauli form factors are normalized to the experimental values of the anomalous magnetic moments. As a result, the covariant spin structure for the Dirac and Pauli nucleon form factors prescribed by AdS$$_5$$ semiclassical gravity incorporates the correct twist scaling behavior from hard scattering and also leads to vector dominance at low energy.« less

Energy dependence of the transverse momentum distributions of charged particles in pp collisions measured by ALICE.

PubMed

Abelev, B; Adam, J; Adamová, D; Adare, A M; Aggarwal, M M; Aglieri Rinella, G; Agnello, M; Agocs, A G; Agostinelli, A; Ahammed, Z; Ahmad, N; Ahmad Masoodi, A; Ahmed, I; Ahn, S A; Ahn, S U; Aimo, I; Aiola, S; Ajaz, M; Akindinov, A; Aleksandrov, D; Alessandro, B; Alexandre, D; Alici, A; Alkin, A; Alme, J; Alt, T; Altini, V; Altinpinar, S; Altsybeev, I; Alves Garcia Prado, C; Andrei, C; Andronic, A; Anguelov, V; Anielski, J; Antičić, T; Antinori, F; Antonioli, P; Aphecetche, L; Appelshäuser, H; Arbor, N; Arcelli, S; Armesto, N; Arnaldi, R; Aronsson, T; Arsene, I C; Arslandok, M; Augustinus, A; Averbeck, R; Awes, T C; Äystö, J; Azmi, M D; Bach, M; Badalà, A; Baek, Y W; Bailhache, R; Bala, R; Baldisseri, A; Baltasar Dos Santos Pedrosa, F; Bán, J; Baral, R C; Barbera, R; Barile, F; Barnaföldi, G G; Barnby, L S; Barret, V; Bartke, J; Basile, M; Bastid, N; Basu, S; Bathen, B; Batigne, G; Batyunya, B; Batzing, P C; Baumann, C; Bearden, I G; Beck, H; Bedda, C; Behera, N K; Belikov, I; Bellini, F; 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Chattopadhyay, S; Cherney, M; Cheshkov, C; Cheynis, B; Chibante Barroso, V; Chinellato, D D; Chochula, P; Chojnacki, M; Choudhury, S; Christakoglou, P; Christensen, C H; Christiansen, P; Chujo, T; Chung, S U; Cicalo, C; Cifarelli, L; Cindolo, F; Cleymans, J; Colamaria, F; Colella, D; Collu, A; Colocci, M; Conesa Balbastre, G; Conesa Del Valle, Z; Connors, M E; Contin, G; Contreras, J G; Cormier, T M; Corrales Morales, Y; Cortese, P; Cortés Maldonado, I; Cosentino, M R; Costa, F; Crochet, P; Cruz Albino, R; Cuautle, E; Cunqueiro, L; Dainese, A; Dang, R; Danu, A; Das, K; Das, D; Das, I; Dash, A; Dash, S; De, S; Delagrange, H; Deloff, A; Dénes, E; Deppman, A; de Barros, G O V; De Caro, A; de Cataldo, G; de Cuveland, J; De Falco, A; De Gruttola, D; De Marco, N; De Pasquale, S; de Rooij, R; Diaz Corchero, M A; Dietel, T; Divià, R; Di Bari, D; Di Giglio, C; Di Liberto, S; Di Mauro, A; Di Nezza, P; Djuvsland, Ø; Dobrin, A; Dobrowolski, T; Dönigus, B; Dordic, O; Dubey, A K; Dubla, A; Ducroux, L; 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Mitu, C; Mlynarz, J; Mohanty, B; Molnar, L; Montaño Zetina, L; Monteno, M; Montes, E; Moon, T; Morando, M; Moreira De Godoy, D A; Moretto, S; Morreale, A; Morsch, A; Muccifora, V; Mudnic, E; Muhuri, S; Mukherjee, M; Müller, H; Munhoz, M G; Murray, S; Musa, L; Nandi, B K; Nania, R; Nappi, E; Nattrass, C; Nayak, T K; Nazarenko, S; Nedosekin, A; Nicassio, M; Niculescu, M; Nielsen, B S; Nikolaev, S; Nikulin, S; Nikulin, V; Nilsen, B S; Nilsson, M S; Noferini, F; Nomokonov, P; Nooren, G; Nyanin, A; Nyatha, A; Nystrand, J; Oeschler, H; Oh, S K; Oh, S; Olah, L; Oleniacz, J; Oliveira Da Silva, A C; Onderwaater, J; Oppedisano, C; Ortiz Velasquez, A; Oskarsson, A; Otwinowski, J; Oyama, K; Pachmayer, Y; Pachr, M; Pagano, P; Paić, G; Painke, F; Pajares, C; Pal, S K; Palaha, A; Palmeri, A; Papikyan, V; Pappalardo, G S; Park, W J; Passfeld, A; Patalakha, D I; Paticchio, V; Paul, B; Pawlak, T; Peitzmann, T; Pereira Da Costa, H; Pereira De Oliveira Filho, E; Peresunko, D; Pérez Lara, C E; Perrino, D; Peryt, W; Pesci, A; Pestov, Y; Petráček, V; Petran, M; Petris, M; Petrov, P; Petrovici, M; Petta, C; Piano, S; Pikna, M; Pillot, P; Pinazza, O; Pinsky, L; Pitz, N; Piyarathna, D B; Planinic, M; Płoskoń, M; Pluta, J; Pochybova, S; Podesta-Lerma, P L M; Poghosyan, M G; Polichtchouk, B; Poljak, N; Pop, A; Porteboeuf-Houssais, S; Pospíšil, V; Potukuchi, B; Prasad, S K; Preghenella, R; Prino, F; Pruneau, C A; Pshenichnov, I; Puddu, G; Punin, V; Putschke, J; Qvigstad, H; Rachevski, A; Rademakers, A; Rak, J; Rakotozafindrabe, A; Ramello, L; Raniwala, S; Raniwala, R; Räsänen, S S; Rascanu, B T; Rathee, D; Rauch, W; Rauf, A W; Razazi, V; Read, K F; Real, J S; Redlich, K; Reed, R J; Rehman, A; Reichelt, P; Reicher, M; Reidt, F; Renfordt, R; Reolon, A R; Reshetin, A; Rettig, F; Revol, J-P; Reygers, K; Riccati, L; Ricci, R A; Richert, T; Richter, M; Riedler, P; Riegler, W; Riggi, F; Rivetti, A; Rodríguez Cahuantzi, M; Rodriguez Manso, A; Røed, K; Rogochaya, E; Rohni, S; Rohr, D; Röhrich, D; Romita, R; Ronchetti, F; Rosnet, P; Rossegger, S; Rossi, A; Roy, P; Roy, C; Rubio Montero, A J; Rui, R; Russo, R; Ryabinkin, E; Rybicki, A; Sadovsky, S; Šafařík, K; Sahoo, R; Sahu, P K; Saini, J; Sakaguchi, H; Sakai, S; Sakata, D; Salgado, C A; Salzwedel, J; Sambyal, S; Samsonov, V; Sanchez Castro, X; Šándor, L; Sandoval, A; Sano, M; Santagati, G; Santoro, R; Sarkar, D; Scapparone, E; Scarlassara, F; Scharenberg, R P; Schiaua, C; Schicker, R; Schmidt, C; Schmidt, H R; Schuchmann, S; Schukraft, J; Schulc, M; Schuster, T; Schutz, Y; Schwarz, K; Schweda, K; Scioli, G; Scomparin, E; Scott, R; Scott, P A; Segato, G; Selyuzhenkov, I; Seo, J; Serci, S; Serradilla, E; Sevcenco, A; Shabetai, A; Shabratova, G; Shahoyan, R; Sharma, S; Sharma, N; Shigaki, K; Shtejer, K; Sibiriak, Y; Siddhanta, S; Siemiarczuk, T; Silvermyr, D; Silvestre, C; Simatovic, G; Singaraju, R; Singh, R; Singha, S; Singhal, V; Sinha, B C; Sinha, T; Sitar, B; Sitta, M; Skaali, T B; Skjerdal, K; Smakal, R; Smirnov, N; Snellings, R J M; Søgaard, C; Soltz, R; Song, M; Song, J; Soos, C; Soramel, F; Spacek, M; Sputowska, I; Spyropoulou-Stassinaki, M; Srivastava, B K; Stachel, J; Stan, I; Stefanek, G; Steinpreis, M; Stenlund, E; Steyn, G; Stiller, J H; Stocco, D; Stolpovskiy, M; Strmen, P; Suaide, A A P; Subieta Vásquez, M A; Sugitate, T; Suire, C; Suleymanov, M; Sultanov, R; Šumbera, M; Susa, T; Symons, T J M; Szanto de Toledo, A; Szarka, I; Szczepankiewicz, A; Szymański, M; Takahashi, J; Tangaro, M A; Tapia Takaki, J D; Tarantola Peloni, A; Tarazona Martinez, A; Tauro, A; Tejeda Muñoz, G; Telesca, A; Terrevoli, C; Ter Minasyan, A; Thäder, J; Thomas, D; Tieulent, R; Timmins, A R; Toia, A; Torii, H; Trubnikov, V; Trzaska, W H; Tsuji, T; Tumkin, A; Turrisi, R; Tveter, T S; Ulery, J; Ullaland, K; Ulrich, J; Uras, A; Urciuoli, G M; Usai, G L; Vajzer, M; Vala, M; Valencia Palomo, L; Vande Vyvre, P; Vannucci, L; Van Hoorne, J W; van Leeuwen, M; Vargas, A; Varma, R; Vasileiou, M; Vasiliev, A; Vechernin, V; Veldhoen, M; Venaruzzo, M; Vercellin, E; Vergara, S; Vernet, R; Verweij, M; Vickovic, L; Viesti, G; Viinikainen, J; Vilakazi, Z; Villalobos Baillie, O; Vinogradov, A; Vinogradov, L; Vinogradov, Y; Virgili, T; Viyogi, Y P; Vodopyanov, A; Völkl, M A; Voloshin, S; Voloshin, K; Volpe, G; von Haller, B; Vorobyev, I; Vranic, D; Vrláková, J; Vulpescu, B; Vyushin, A; Wagner, B; Wagner, V; Wagner, J; Wang, Y; Wang, Y; Wang, M; Watanabe, D; Watanabe, K; Weber, M; Wessels, J P; Westerhoff, U; Wiechula, J; Wikne, J; Wilde, M; Wilk, G; Wilkinson, J; Williams, M C S; Windelband, B; Winn, M; Xiang, C; Yaldo, C G; Yamaguchi, Y; Yang, H; Yang, P; Yang, S; Yano, S; Yasnopolskiy, S; Yi, J; Yin, Z; Yoo, I-K; Yushmanov, I; Zaccolo, V; Zach, C; Zampolli, C; Zaporozhets, S; Zarochentsev, A; Závada, P; Zaviyalov, N; Zbroszczyk, H; Zelnicek, P; Zgura, I S; Zhalov, M; Zhang, F; Zhang, Y; Zhang, H; Zhang, X; Zhou, D; Zhou, Y; Zhou, F; Zhu, X; Zhu, J; Zhu, J; Zhu, H; Zichichi, A; Zimmermann, M B; Zimmermann, A; Zinovjev, G; Zoccarato, Y; Zynovyev, M; Zyzak, M

Differential cross sections of charged particles in inelastic pp collisions as a function of p T have been measured at [Formula: see text] at the LHC. The p T spectra are compared to NLO-pQCD calculations. Though the differential cross section for an individual [Formula: see text] cannot be described by NLO-pQCD, the relative increase of cross section with [Formula: see text] is in agreement with NLO-pQCD. Based on these measurements and observations, procedures are discussed to construct pp reference spectra at [Formula: see text] up to p T =50 GeV/ c as required for the calculation of the nuclear modification factor in nucleus-nucleus and proton-nucleus collisions.

QCD with Chiral Imbalance: models vs. lattice

NASA Astrophysics Data System (ADS)

Andrianov, Alexander; Andrianov, Vladimir; Espriu, Domenec

2017-03-01

In heavy ion collisions (HIC) at high energies there may appear new phases of matter which must be described by QCD. These phases may have different color and flavour symmetries associated with the constituents involved in collisions as well as various space-time symmetries of hadron matter. Properties of the QCD medium in such a matter can be approximately described, in particular, by a number of right-handed (RH) and left-handed (LH) light quarks. The chiral imbalance (ChI) is characterized by the difference between the numbers of RH and LH quarks and supposedly occurs in the fireball after HIC. Accordingly we have to introduce a quark chiral (axial) chemical potential which simulates a ChI emerging in such a phase. In this report we discuss the possibility of a phase with Local spatial Parity Breaking (LPB) in such an environment and outline conceivable signatures for the registration of LPB as well as the appearance of new states in the spectra of scalar, pseudoscalar and vector particles as a consequence of local ChI. The comparison of the results obtained in the effective QCD- motivated models with lattice data is also performed.

Remarks on the Phase Transition in QCD

NASA Astrophysics Data System (ADS)

Wilczek, Frank

The significance of the question of the order of the phase transition in QCD, and recent evidence that real-world QCD is probably close to having a single second order transition as a function of temperature, is reviewed. Although this circumstance seems to remove the possibility that the QCD transition during the big bang might have had spectacular cosmological consequences, there is some good news: it allows highly non-trivial yet reliable quantitative predictions to be made for the behavior near the transition. These predictions can be tested in numerical simulations and perhaps even eventually in heavy ion collisions. The present paper is a very elementary discussion of the relevant concepts, meant to be an accessible introduction for those innocent of the renormalization group approach to critical phenomena and/or the details of QCD.

Towards understanding Regge trajectories in holographic QCD

NASA Astrophysics Data System (ADS)

Catà, Oscar

2007-05-01

We reassess a work done by Migdal on the spectrum of low-energy vector mesons in QCD in the light of the anti-de Sitter (AdS)-QCD correspondence. Recently, a tantalizing parallelism was suggested between Migdal’s work and a family of holographic duals of QCD. Despite the intriguing similarities, both approaches face a major drawback: the spectrum is in conflict with well-tested Regge scaling. However, it has recently been shown that holographic duals can be modified to accommodate Regge behavior. Therefore, it is interesting to understand whether Regge behavior can also be achieved in Migdal’s approach. In this paper we investigate this issue. We find that Migdal’s approach, which is based on a modified Padé approximant, is closely related to the issue of quark-hadron duality breakdown in QCD.

QCD tests in $$p\\bar{p}$$ collisions

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

Huth, John E.; Mangano, Michelangelo L.

1993-02-01

We review the status of QCD tests in high energy p-pbar collisions. Contents: i) Introduction ii) QCD in Hadronic Collisions iii) Jet Production iv) Heavy Flavour Production v) W and Z Production vi) Direct Photons.

Azimuthal angle dependence of the charge imbalance from charge conservation effects

NASA Astrophysics Data System (ADS)

BoŻek, Piotr

2018-03-01

The experimental search for the chiral magnetic effect in heavy-ion collisions is based on charge-dependent correlations between emitted particles. Recently, a sensitive observable comparing event-by-event distributions of the charge splitting projected on the directions along and perpendicular to the direction of the elliptic flow has been proposed. The results of a (3 + 1)-dimensional hydrodynamic model show that the preliminary experimental data of the STAR Collaboration can be explained as due to background effects, such as resonance decays and local charge conservation in the particle production. A related observable based on the third-order harmonic flow is proposed to further investigate such background effects in charge-dependent correlations.

Vortical susceptibility of finite-density QCD matter

DOE PAGES

Aristova, A.; Frenklakh, D.; Gorsky, A.; ...

2016-10-07

Here, the susceptibility of finite-density QCD matter to vorticity is introduced, as an analog of magnetic susceptibility. It describes the spin polarization of quarks and antiquarks in finite-density QCD matter induced by rotation. We estimate this quantity in the chirally broken phase using the mixed gauge-gravity anomaly at finite baryon density. It is proposed that the vortical susceptibility of QCD matter is responsible for the polarization of Λ and Λ¯ hyperons observed recently in heavy ion collisions at RHIC by the STAR collaboration.

AdS/QCD and Light Front Holography: A New Approximation to QCD

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

Brodsky, Stanley J.; de Teramond, Guy

2010-02-15

The combination of Anti-de Sitter space (AdS) methods with light-front holography leads to a semi-classical first approximation to the spectrum and wavefunctions of meson and baryon light-quark bound states. Starting from the bound-state Hamiltonian equation of motion in QCD, we derive relativistic light-front wave equations in terms of an invariant impact variable {zeta} which measures the separation of the quark and gluonic constituents within the hadron at equal light-front time. These equations of motion in physical space-time are equivalent to the equations of motion which describe the propagation of spin-J modes in anti-de Sitter (AdS) space. Its eigenvalues give themore » hadronic spectrum, and its eigenmodes represent the probability distribution of the hadronic constituents at a given scale. Applications to the light meson and baryon spectra are presented. The predicted meson spectrum has a string-theory Regge form M{sup 2} = 4{kappa}{sup 2}(n+L+S/2); i.e., the square of the eigenmass is linear in both L and n, where n counts the number of nodes of the wavefunction in the radial variable {zeta}. The space-like pion form factor is also well reproduced. One thus obtains a remarkable connection between the description of hadronic modes in AdS space and the Hamiltonian formulation of QCD in physical space-time quantized on the light-front at fixed light-front time {tau}. The model can be systematically improved by using its complete orthonormal solutions to diagonalize the full QCD light-front Hamiltonian or by applying the Lippmann-Schwinger method in order to systematically include the QCD interaction terms.« less

Lattice analysis for the energy scale of QCD phenomena.

PubMed

Yamamoto, Arata; Suganuma, Hideo

2008-12-12

We formulate a new framework in lattice QCD to study the relevant energy scale of QCD phenomena. By considering the Fourier transformation of link variable, we can investigate the intrinsic energy scale of a physical quantity nonperturbatively. This framework is broadly available for all lattice QCD calculations. We apply this framework for the quark-antiquark potential and meson masses in quenched lattice QCD. The gluonic energy scale relevant for the confinement is found to be less than 1 GeV in the Landau or Coulomb gauge.

Tetraquarks in holographic QCD

NASA Astrophysics Data System (ADS)

Gutsche, Thomas; Lyubovitskij, Valery E.; Schmidt, Ivan

2017-08-01

Using a soft-wall AdS/QCD approach we derive the Schrödinger-type equation of motion for the tetraquark wave function, which is dual to the dimension-4 AdS bulk profile. The latter coincides with the number of constituents in the leading Fock state of the tetraquark. The obtained equation of motion is solved analytically, providing predictions for both the tetraquark wave function and its mass. A low mass limit for possible tetraquark states is given by M ≥2 κ =1 GeV , where κ =0.5 GeV is the typical value of the scale parameter in soft-wall AdS/QCD. We confirm results of the COMPASS Collaboration recently reported on the discovery of the a1(1414 ) state, interpreted as a tetraquark state composed of light quarks and having JP C=1++. Our prediction for the mass of this state, Ma1=√{2 } GeV ≃1.414 GeV , is in good agreement with the COMPASS result Ma1=1.41 4-0.013+0.015 GeV . Next we included finite quark mass effects, which are essential for the tetraquark states involving heavy quarks.

The decay of Λ _b→ p~K^- in QCD factorization approach

NASA Astrophysics Data System (ADS)

Zhu, Jie; Ke, Hong-Wei; Wei, Zheng-Tao

2016-05-01

With only the tree-level operator, the decay of Λ _b→ pK is predicted to be one order smaller than the experimental data. The QCD penguin effects should be taken into account. In this paper, we explore the one-loop QCD corrections to the decay of Λ _b→ pK within the framework of QCD factorization approach. For the baryon system, the diquark approximation is adopted. The transition hadronic matrix elements between Λ _b and p are calculated in the light-front quark model. The branching ratio of Λ _b→ pK is predicted to be about 4.85× 10^{-6}, which is consistent with experimental data (4.9± 0.9)× 10^{-6}. The CP violation is about 5 % in theory.

Effects of Discrete Charge Clustering in Simulations of Charged Interfaces.

PubMed

Grime, John M A; Khan, Malek O

2010-10-12

A system of counterions between charged surfaces is investigated, with the surfaces represented by uniform charged planes and three different arrangements of discrete surface charges - an equispaced grid and two different clustered arrangements. The behaviors of a series of systems with identical net surface charge density are examined, with particular emphasis placed on the long ranged corrections via the method of "charged slabs" and the effects of the simulation cell size. Marked differences are observed in counterion distributions and the osmotic pressure dependent on the particular representation of the charged surfaces; the uniformly charged surfaces and equispaced grids of discrete charge behave in a broadly similar manner, but the clustered systems display a pronounced decrease in osmotic pressure as the simulation size is increased. The influence of the long ranged correction is shown to be minimal for all but the very smallest of system sizes.

Update on ɛK with lattice QCD inputs

NASA Astrophysics Data System (ADS)

Jang, Yong-Chull; Lee, Weonjong; Lee, Sunkyu; Leem, Jaehoon

2018-03-01

We report updated results for ɛK, the indirect CP violation parameter in neutral kaons, which is evaluated directly from the standard model with lattice QCD inputs. We use lattice QCD inputs to fix B\\hatk,|Vcb|,ξ0,ξ2,|Vus|, and mc(mc). Since Lattice 2016, the UTfit group has updated the Wolfenstein parameters in the angle-only-fit method, and the HFLAV group has also updated |Vcb|. Our results show that the evaluation of ɛK with exclusive |Vcb| (lattice QCD inputs) has 4.0σ tension with the experimental value, while that with inclusive |Vcb| (heavy quark expansion based on OPE and QCD sum rules) shows no tension.

Superconformal Baryon-Meson Symmetry and Light-Front Holographic QCD

DOE PAGES

Dosch, Hans Guenter; de Teramond, Guy F.; Brodsky, Stanley J.

2015-04-10

We construct an effective QCD light-front Hamiltonian for both mesons and baryons in the chiral limit based on the generalized supercharges of a superconformal graded algebra. The superconformal construction is shown to be equivalent to a semi-classical approximation to light-front QCD and its embedding in AdS space. The specific breaking of conformal invariance inside the graded algebra uniquely determines the effective confinement potential. The generalized supercharges connect the baryon and meson spectra to each other in a remarkable manner. In particular, the π/b 1 Regge trajectory is identified as the superpartner of the nucleon trajectory. However, the lowest-lying state onmore » this trajectory, the π-meson is massless in the chiral limit and has no supersymmetric partner.« less

Recent development in lattice QCD studies for three-nucleon forces

NASA Astrophysics Data System (ADS)

Doi, Takumi; HAL QCD Collaboration

2014-09-01

The direct determination of nuclear forces from QCD has been one of the most desirable challenges in nuclear physics. Recently, a first-principles lattice QCD determination is becoming possible by a novel theoretical method, HAL QCD method, in which Nambu-Bethe-Salpeter (NBS) wave functions are utilized. In this talk, I will focus on the study of three-nucleon forces in HAL QCD method by presenting the recent theoretical/numerical development.

Spontaneous breaking of discrete symmetries in QCD on a small volume

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

Lucini, B.; Patella, A.; Pica, C.

2007-11-20

In a compact space with non-trivial cycles, for sufficiently small values of the compact dimensions, charge conjugation (C), spatial reflection (P) and time reversal (J) are spontaneously broken in QCD. The order parameter for the symmetry breaking is the trace of the Wilson line wrapping around the compact dimension, which acquires an imaginary part in the broken phase. We show that a physical signature for the symmetry breaking is a persistent baryonic current wrapping in the compact directions. The existence of such a current is derived analytically at first order in perturbation theory and confirmed in the non-perturbative regime bymore » lattice simulations.« less

QCD in heavy quark production and decay

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

Wiss, J.

1997-06-01

The author discusses how QCD is used to understand the physics of heavy quark production and decay dynamics. His discussion of production dynamics primarily concentrates on charm photoproduction data which are compared to perturbative QCD calculations which incorporate fragmentation effects. He begins his discussion of heavy quark decay by reviewing data on charm and beauty lifetimes. Present data on fully leptonic and semileptonic charm decay are then reviewed. Measurements of the hadronic weak current form factors are compared to the nonperturbative QCD-based predictions of Lattice Gauge Theories. He next discusses polarization phenomena present in charmed baryon decay. Heavy Quark Effectivemore » Theory predicts that the daughter baryon will recoil from the charmed parent with nearly 100% left-handed polarization, which is in excellent agreement with present data. He concludes by discussing nonleptonic charm decay which is traditionally analyzed in a factorization framework applicable to two-body and quasi-two-body nonleptonic decays. This discussion emphasizes the important role of final state interactions in influencing both the observed decay width of various two-body final states as well as modifying the interference between interfering resonance channels which contribute to specific multibody decays. 50 refs., 77 figs.« less

QCD on the BlueGene/L Supercomputer

NASA Astrophysics Data System (ADS)

Bhanot, G.; Chen, D.; Gara, A.; Sexton, J.; Vranas, P.

2005-03-01

In June 2004 QCD was simulated for the first time at sustained speed exceeding 1 TeraFlops in the BlueGene/L supercomputer at the IBM T.J. Watson Research Lab. The implementation and performance of QCD in the BlueGene/L is presented.

Production of leading charged particles and leading charged-particle jets at small transverse momenta in pp collisions at $$\\sqrt{s}$$ = 8 TeV

DOE PAGES

Khachatryan, Vardan

2015-12-01

The per-event yield of the highest transverse momentum charged particle and charged-particle jet, integrated above a given p min T threshold starting at p min T=0.8 and 1 GeV, respectively, is studied in pp collisions at s√=8 TeV. Furthermore, the particles and the jets are measured in the pseudorapidity ranges |η|<2.4 and 1.9, respectively. Our data are sensitive to the momentum scale at which parton densities saturate in the proton, to multiple partonic interactions, and to other key aspects of the transition between the soft and hard QCD regimes in hadronic collisions.

Hard QCD rescattering in few nucleon systems

NASA Astrophysics Data System (ADS)

Maheswari, Dhiraj; Sargsian, Misak

2017-01-01

The theoretical framework of hard QCD rescattering mechanism (HRM) is extended to calculate the high energy γ3 He -> pd reaction at 900 center of mass angle. In HRM model , the incoming high energy photon strikes a quark from one of the nucleons in the target which subsequently undergoes hard rescattering with the quarks from the other nucleons generating hard two-body baryonic system in the final state of the reaction. Based on the HRM, a parameter free expression for the differential cross section for the reaction is derived, expressed through the 3 He -> pd transition spectral function, hard pd -> pd elastic scattering cross section and the effective charge of the quarks being interchanged in the hard rescattering process. The numerical estimates obtained from this expression for the differential cross section are in a good agreement with the data recently obtained at the Jefferson Lab experiment, showing the energy scaling of cross section with an exponent of s-17, also consistent with the quark counting rule. The angular and energy dependences of the cross section are also predicted within HRM which are in good agreement with the preliminary data of these distributions. Research is supported by the US Department of Energy.

Bs and Ds decay constants in three-flavor lattice QCD.

PubMed

Wingate, Matthew; Davies, Christine T H; Gray, Alan; Lepage, G Peter; Shigemitsu, Junko

2004-04-23

Capitalizing on recent advances in lattice QCD, we present a calculation of the leptonic decay constants f(B(s)) and f(D(s)) that includes effects of one strange sea quark and two light sea quarks via an improved staggered action. By shedding the quenched approximation and the associated lattice scale uncertainty, lattice QCD greatly increases its predictive power. Nonrelativistic QCD is used to simulate heavy quarks with masses between 1.5m(c) and m(b). We arrive at the following results: f(B(s))=260+/-7+/-26+/-8+/-5 and f(D(s))=290+/-20+/-29+/-29+/-6 MeV. The first quoted error is the statistical uncertainty, and the rest estimate the sizes of higher order terms neglected in this calculation. All of these uncertainties are systematically improvable by including another order in the weak coupling expansion, the nonrelativistic expansion, or the Symanzik improvement program.

Going Beyond QCD in Lattice Gauge Theory

NASA Astrophysics Data System (ADS)

Fleming, G. T.

2011-01-01

Strongly coupled gauge theories (SCGT's) have been studied theoretically for many decades using numerous techniques. The obvious motivation for these efforts stemmed from a desire to understand the source of the strong nuclear force: Quantum Chromo-dynamics (QCD). Guided by experimental results, theorists generally consider QCD to be a well-understood SCGT. Unfortunately, it is not clear how to extend the lessons learned from QCD to other SCGT's. Particularly urgent motivators for new studies of other SCGT's are the ongoing searches for physics beyond the standard model (BSM) at the Large Hadron Collider (LHC) and the Tevatron. Lattice gauge theory (LGT) is a technique for systematically-improvable calculations in many SCGT's. It has become the standard for non-perturbative calculations in QCD and it is widely believed that it may be useful for study of other SCGT's in the realm of BSM physics. We will discuss the prospects and potential pitfalls for these LGT studies, focusing primarily on the flavor dependence of SU(3) gauge theory.

The Top Quark, QCD, And New Physics.

DOE R&D Accomplishments Database

Dawson, S.

2002-06-01

The role of the top quark in completing the Standard Model quark sector is reviewed, along with a discussion of production, decay, and theoretical restrictions on the top quark properties. Particular attention is paid to the top quark as a laboratory for perturbative QCD. As examples of the relevance of QCD corrections in the top quark sector, the calculation of e{sup+}e{sup -}+ t{bar t} at next-to-leading-order QCD using the phase space slicing algorithm and the implications of a precision measurement of the top quark mass are discussed in detail. The associated production of a t{bar t} pair and a Higgs boson in either e{sup+}e{sup -} or hadronic collisions is presented at next-to-leading-order QCD and its importance for a measurement of the top quark Yulrawa coupling emphasized. Implications of the heavy top quark mass for model builders are briefly examined, with the minimal supersymmetric Standard Model and topcolor discussed as specific examples.

The Symmetries of QCD

ScienceCinema

Chivukula, Sekhar

2017-12-22

The symmetries of a quantum field theory can be realized in a variety of ways. Symmetries can be realized explicitly, approximately, through spontaneous symmetry breaking or, via an anomaly, quantum effects can dynamically eliminate a symmetry of the theory that was present at the classical level.  Quantum Chromodynamics (QCD), the modern theory of the strong interactions, exemplify each of these possibilities. The interplay of these effects determine the spectrum of particles that we observe and, ultimately, account for 99% of the mass of ordinary matter. 

Recent QCD Studies at the Tevatron

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

Group, Robert Craig

2008-04-01

Since the beginning of Run II at the Fermilab Tevatron the QCD physics groups of the CDF and D0 experiments have worked to reach unprecedented levels of precision for many QCD observables. Thanks to the large dataset--over 3 fb{sup -1} of integrated luminosity recorded by each experiment--important new measurements have recently been made public and will be summarized in this paper.

Scalar production and decay to top quarks including interference effects at NLO in QCD in an EFT approach

DOE PAGES

Franzosi, Diogo Buarque; Vryonidou, Eleni; Zhang, Cen

2017-10-13

Scalar and pseudo-scalar resonances decaying to top quarks are common predictions in several scenarios beyond the standard model (SM) and are extensively searched for by LHC experiments. Challenges on the experimental side require optimising the strategy based on accurate predictions. Firstly, QCD corrections are known to be large both for the SM QCD background and for the pure signal scalar production. Secondly, leading order and approximate next-to-leading order (NLO) calculations indicate that the interference between signal and background is large and drastically changes the lineshape of the signal, from a simple peak to a peak-dip structure. Therefore, a robust predictionmore » of this interference at NLO accuracy in QCD is necessary to ensure that higher-order corrections do not alter the lineshapes. We compute the exact NLO corrections, assuming a point-like coupling between the scalar and the gluons and consistently embedding the calculation in an effective field theory within an automated framework, and present results for a representative set of beyond the SM benchmarks. The results can be further matched to parton shower simulation, providing more realistic predictions. We find that NLO corrections are important and lead to a significant reduction of the uncertainties. We also discuss how our computation can be used to improve the predictions for physics scenarios where the gluon-scalar loop is resolved and the effective approach is less applicable.« less

Scalar production and decay to top quarks including interference effects at NLO in QCD in an EFT approach

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

Franzosi, Diogo Buarque; Vryonidou, Eleni; Zhang, Cen

Scalar and pseudo-scalar resonances decaying to top quarks are common predictions in several scenarios beyond the standard model (SM) and are extensively searched for by LHC experiments. Challenges on the experimental side require optimising the strategy based on accurate predictions. Firstly, QCD corrections are known to be large both for the SM QCD background and for the pure signal scalar production. Secondly, leading order and approximate next-to-leading order (NLO) calculations indicate that the interference between signal and background is large and drastically changes the lineshape of the signal, from a simple peak to a peak-dip structure. Therefore, a robust predictionmore » of this interference at NLO accuracy in QCD is necessary to ensure that higher-order corrections do not alter the lineshapes. We compute the exact NLO corrections, assuming a point-like coupling between the scalar and the gluons and consistently embedding the calculation in an effective field theory within an automated framework, and present results for a representative set of beyond the SM benchmarks. The results can be further matched to parton shower simulation, providing more realistic predictions. We find that NLO corrections are important and lead to a significant reduction of the uncertainties. We also discuss how our computation can be used to improve the predictions for physics scenarios where the gluon-scalar loop is resolved and the effective approach is less applicable.« less

Archeology and evolution of QCD

NASA Astrophysics Data System (ADS)

De Rújula, A.

2017-03-01

These are excerpts from the closing talk at the "XIIth Conference on Quark Confinement and the Hadron Spectrum", which took place last Summer in Thessaloniki -an excellent place to enjoy an interest in archeology. A more complete personal view of the early days of QCD and the rest of the Standard Model is given in [1]. Here I discuss a few of the points which -to my judgement- illustrate well the QCD evolution (in time), both from a scientific and a sociological point of view.

Kaon-Nucleon potential from lattice QCD

NASA Astrophysics Data System (ADS)

Ikeda, Y.; Aoki, S.; Doi, T.; Hatsuda, T.; Inoue, T.; Ishii, N.; Murano, K.; Nemura, H.; Sasaki, K.

2010-04-01

We study the K N interactions in the I(Jπ) = 0(1/2-) and 1(1/2-) channels and associated exotic state Θ+ from 2+1 flavor full lattice QCD simulation for relatively heavy quark mass corresponding to mπ = 871 MeV. The s-wave K N potentials are obtained from the Bethe-Salpeter wave function by using the method recently developed by HAL QCD (Hadrons to Atomic nuclei from Lattice QCD) Collaboration. Potentials in both channels reveal short range repulsions: Strength of the repulsion is stronger in the I = 1 potential, which is consistent with the prediction of the Tomozawa-Weinberg term. The I = 0 potential is found to have attractive well at mid range. From these potentials, the K N scattering phase shifts are calculated and compared with the experimental data.

Present constraints on the H-dibaryon at the physical point from Lattice QCD

DOE PAGES

Beane, S. R.; Chang, E.; Detmold, W.; ...

2011-11-10

The current constraints from Lattice QCD on the existence of the H-dibaryon are discussed. With only two significant Lattice QCD calculations of the H-dibaryon binding energy at approximately the same lattice spacing, the form of the chiral and continuum extrapolations to the physical point are not determined. In this brief report, an extrapolation that is quadratic in the pion mass, motivated by low-energy effective field theory, is considered. An extrapolation that is linear in the pion mass is also considered, a form that has no basis in the effective field theory, but is found to describe the light-quark mass dependencemore » observed in Lattice QCD calculations of the octet baryon masses. In both cases, the extrapolation to the physical pion mass allows for a bound H-dibaryon or a near-threshold scattering state.« less

QCD PHASE TRANSITIONS-VOLUME 15.

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

SCHAFER,T.

1998-11-04

The title of the workshop, ''The QCD Phase Transitions'', in fact happened to be too narrow for its real contents. It would be more accurate to say that it was devoted to different phases of QCD and QCD-related gauge theories, with strong emphasis on discussion of the underlying non-perturbative mechanisms which manifest themselves as all those phases. Before we go to specifics, let us emphasize one important aspect of the present status of non-perturbative Quantum Field Theory in general. It remains true that its studies do not get attention proportional to the intellectual challenge they deserve, and that the theoristsmore » working on it remain very fragmented. The efforts to create Theory of Everything including Quantum Gravity have attracted the lion share of attention and young talent. Nevertheless, in the last few years there was also a tremendous progress and even some shift of attention toward emphasis on the unity of non-perturbative phenomena. For example, we have seen some. efforts to connect the lessons from recent progress in Supersymmetric theories with that in QCD, as derived from phenomenology and lattice. Another example is Maldacena conjecture and related development, which connect three things together, string theory, super-gravity and the (N=4) supersymmetric gauge theory. Although the progress mentioned is remarkable by itself, if we would listen to each other more we may have chance to strengthen the field and reach better understanding of the spectacular non-perturbative physics.« less

QCD Phase Transitions, Volume 15

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

Schaefer, T.; Shuryak, E.

1999-03-20

The title of the workshop, ''The QCD Phase Transitions'', in fact happened to be too narrow for its real contents. It would be more accurate to say that it was devoted to different phases of QCD and QCD-related gauge theories, with strong emphasis on discussion of the underlying non-perturbative mechanisms which manifest themselves as all those phases. Before we go to specifics, let us emphasize one important aspect of the present status of non-perturbative Quantum Field Theory in general. It remains true that its studies do not get attention proportional to the intellectual challenge they deserve, and that the theoristsmore » working on it remain very fragmented. The efforts to create Theory of Everything including Quantum Gravity have attracted the lion share of attention and young talent. Nevertheless, in the last few years there was also a tremendous progress and even some shift of attention toward emphasis on the unity of non-perturbative phenomena. For example, we have seen some efforts to connect the lessons from recent progress in Supersymmetric theories with that in QCD, as derived from phenomenology and lattice. Another example is Maldacena conjecture and related development, which connect three things together, string theory, super-gravity and the (N=4) supersymmetric gauge theory. Although the progress mentioned is remarkable by itself, if we would listen to each other more we may have chance to strengthen the field and reach better understanding of the spectacular non-perturbative physics.« less

Improved perturbative QCD formalism for Bc meson decays

NASA Astrophysics Data System (ADS)

Liu, Xin; Li, Hsiang-nan; Xiao, Zhen-Jun

2018-06-01

We derive the kT resummation for doubly heavy-flavored Bc meson decays by including the charm quark mass effect into the known formula for a heavy-light system. The resultant Sudakov factor is employed in the perutrbative QCD study of the "golden channel" Bc+→J /ψ π+. With a reasonable model for the Bc meson distribution amplitude, which maintains approximate on-shell conditions of both the partonic bottom and charm quarks, it is observed that the imaginary piece of the Bc→J /ψ transition form factor appears to be power suppressed, and the Bc+→J /ψ π+ branching ratio is not lower than 10-3. The above improved perturbative QCD formalism is applicable to Bc meson decays to other charmonia and charmed mesons.

Testing the Standard Model and Fundamental Symmetries in Nuclear Physics with Lattice QCD and Effective Field Theory

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

Walker-Loud, Andre

The research supported by this grant is aimed at probing the limits of the Standard Model through precision low-energy nuclear physics. The work of the PI (AWL) and additional personnel is to provide theory input needed for a number of potentially high-impact experiments, notably, hadronic parity violation, Dark Matter direct detection and searches for permanent electric dipole moments (EDMs) in nucleons and nuclei. In all these examples, a quantitative understanding of low-energy nuclear physics from the fundamental theory of strong interactions, Quantum Chromo-Dynamics (QCD), is necessary to interpret the experimental results. The main theoretical tools used and developed in thismore » work are the numerical solution to QCD known as lattice QCD (LQCD) and Effective Field Theory (EFT). This grant is supporting a new research program for the PI, and as such, needed to be developed from the ground up. Therefore, the first fiscal year of this grant, 08/01/2014-07/31/2015, has been spent predominantly establishing this new research effort. Very good progress has been made, although, at this time, there are not many publications to show for the effort. After one year, the PI accepted a job at Lawrence Berkeley National Laboratory, so this final report covers just a single year of five years of the grant.« less

Causal Diffusion and the Survival of Charge Fluctuations

NASA Astrophysics Data System (ADS)

Abdel-Aziz, Mohamed; Gavin, Sean

2004-10-01

Diffusion may obliterate fluctuation signals of the QCD phase transition in nuclear collisions at SPS and RHIC energies. We propose a hyperbolic diffusion equation to study the dissipation of net charge fluctuations [1]. This equation is needed in a relativistic context, because the classic parabolic diffusion equation violates causality. We find that causality substantially limits the extent to which diffusion can dissipate these fluctuations. [1] M. Abdel-Aziz and S. Gavin, nucl-th/0404058

QCD inequalities for hadron interactions.

PubMed

Detmold, William

2015-06-05

We derive generalizations of the Weingarten-Witten QCD mass inequalities for particular multihadron systems. For systems of any number of identical pseudoscalar mesons of maximal isospin, these inequalities prove that near threshold interactions between the constituent mesons must be repulsive and that no bound states can form in these channels. Similar constraints in less symmetric systems are also extracted. These results are compatible with experimental results (where known) and recent lattice QCD calculations, and also lead to a more stringent bound on the nucleon mass than previously derived, m_{N}≥3/2m_{π}.

Hadron scattering, resonances, and QCD

NASA Astrophysics Data System (ADS)

Briceño, R. A.

2016-11-01

The non-perturbative nature of quantum chromodynamics (QCD) has historically left a gap in our understanding of the connection between the fundamental theory of the strong interactions and the rich structure of experimentally observed phenomena. For the simplest properties of stable hadrons, this is now circumvented with the use of lattice QCD (LQCD). In this talk I discuss a path towards a rigorous determination of few-hadron observables from LQCD. I illustrate the power of the methodology by presenting recently determined scattering amplitudes in the light-meson sector and their resonance content.

Better than $l/Mflops sustained: a scalable PC-based parallel computer for lattice QCD

NASA Astrophysics Data System (ADS)

Fodor, Zoltán; Katz, Sándor D.; Papp, Gábor

2003-05-01

We study the feasibility of a PC-based parallel computer for medium to large scale lattice QCD simulations. The Eötvös Univ., Inst. Theor. Phys. cluster consists of 137 Intel P4-1.7GHz nodes with 512 MB RDRAM. The 32-bit, single precision sustained performance for dynamical QCD without communication is 1510 Mflops/node with Wilson and 970 Mflops/node with staggered fermions. This gives a total performance of 208 Gflops for Wilson and 133 Gflops for staggered QCD, respectively (for 64-bit applications the performance is approximately halved). The novel feature of our system is its communication architecture. In order to have a scalable, cost-effective machine we use Gigabit Ethernet cards for nearest-neighbor communications in a two-dimensional mesh. This type of communication is cost effective (only 30% of the hardware costs is spent on the communication). According to our benchmark measurements this type of communication results in around 40% communication time fraction for lattices upto 48 3·96 in full QCD simulations. The price/sustained-performance ratio for full QCD is better than l/Mflops for Wilson (and around 1.5/Mflops for staggered) quarks for practically any lattice size, which can fit in our parallel computer. The communication software is freely available upon request for non-profit organizations.

Effects of nonequilibrated topological charge distributions on pseudoscalar meson masses and decay constants

NASA Astrophysics Data System (ADS)

Bernard, C.; Toussaint, D.

2018-04-01

We study the effects of failure to equilibrate the squared topological charge Q2 on lattice calculations of pseudoscalar masses and decay constants. The analysis is based on chiral perturbation theory calculations of the dependence of these quantities on the QCD vacuum angle θ . For the light-light partially quenched case, we rederive the known chiral perturbation theory results of Aoki and Fukaya, but using the nonperturbatively valid chiral theory worked out by Golterman, Sharpe and Singleton, and by Sharpe and Shoresh. We then extend these calculations to heavy-light mesons. Results when staggered taste violations are important are also presented. The derived Q2 dependence is compared to that of simulations using the MILC Collaboration's ensembles of lattices with four flavors of dynamical highly improved staggered quarks. We find agreement, albeit with large statistical errors. These results can be used to correct for the leading effects of unequilibrated Q2, or to make estimates of the systematic error coming from the failure to equilibrate Q2. In an appendix, we show that the partially quenched chiral theory may be extended beyond a lower bound on valence masses discovered by Sharpe and Shoresh. Subtleties occurring when a sea-quark mass vanishes are discussed in another appendix.

Gravitation waves from QCD and electroweak phase transitions

NASA Astrophysics Data System (ADS)

Chen, Yidian; Huang, Mei; Yan, Qi-Shu

2018-05-01

We investigate the gravitation waves produced from QCD and electroweak phase transitions in the early universe by using a 5-dimension holographic QCD model and a holographic technicolor model. The dynamical holographic QCD model is to describe the pure gluon system, where a first order confinement-deconfinement phase transition can happen at the critical temperature around 250 MeV. The minimal holographic technicolor model is introduced to model the strong dynamics of electroweak, it can give a first order electroweak phase transition at the critical temperature around 100-360 GeV. We find that for both GW signals produced from QCD and EW phase transitions, in the peak frequency region, the dominant contribution comes from the sound waves, while away from the peak frequency region the contribution from the bubble collision is dominant. The peak frequency of gravitation wave determined by the QCD phase transition is located around 10-7 Hz which is within the detectability of FAST and SKA, and the peak frequency of gravitational wave predicted by EW phase transition is located at 0.002 - 0.007 Hz, which might be detectable by BBO, DECIGO, LISA and ELISA.

Spin polarized photons from an axially charged plasma at weak coupling: Complete leading order

DOE PAGES

Mamo, Kiminad A.; Yee, Ho-Ung

2016-03-24

In the presence of (approximately conserved) axial charge in the QCD plasma at finite temperature, the emitted photons are spin aligned, which is a unique P- and CP-odd signature of axial charge in the photon emission observables. We compute this “P-odd photon emission rate” in a weak coupling regime at a high temperature limit to complete leading order in the QCD coupling constant: the leading log as well as the constant under the log. As in the P-even total emission rate in the literature, the computation of the P-odd emission rate at leading order consists of three parts: (1) Comptonmore » and pair annihilation processes with hard momentum exchange, (2) soft t- and u-channel contributions with hard thermal loop resummation, (3) Landau-Pomeranchuk-Migdal resummation of collinear bremsstrahlung and pair annihilation. In conclusion, we present analytical and numerical evaluations of these contributions to our P-odd photon emission rate observable.« less

Precision probes of QCD at high energies

DOE PAGES

Alioli, Simone; Farina, Marco; Pappadopulo, Duccio; ...

2017-07-20

New physics, that is too heavy to be produced directly, can leave measurable imprints on the tails of kinematic distributions at the LHC.We use energetic QCD processes to perform novel measurements of the Standard Model (SM) Effective Field Theory. We show that the dijet invariant mass spectrum, and the inclusive jet transverse momentum spectrum, are sensitive to a dimension 6 operator that modifies the gluon propagator at high energies. The dominant effect is constructive or destructive interference with SM jet production. Here, we compare differential next-to-leading order predictions from POWHEG to public 7TeV jet data, including scale, PDF, and experimentalmore » uncertainties and their respective correlations. Furthermore, we constrain a New Physics (NP) scale of 3.5TeV with current data. We project the reach of future 13 and 100TeV measurements, which we estimate to be sensitive to NP scales of 8 and 60TeV, respectively. As an application, we apply our bounds to constrain heavy vector octet colorons that couple to the QCD current. We conclude that effective operators will surpass bump hunts, in terms of coloron mass reach, even for sequential couplings.« less

Precision probes of QCD at high energies

NASA Astrophysics Data System (ADS)

Alioli, Simone; Farina, Marco; Pappadopulo, Duccio; Ruderman, Joshua T.

2017-07-01

New physics, that is too heavy to be produced directly, can leave measurable imprints on the tails of kinematic distributions at the LHC. We use energetic QCD processes to perform novel measurements of the Standard Model (SM) Effective Field Theory. We show that the dijet invariant mass spectrum, and the inclusive jet transverse momentum spectrum, are sensitive to a dimension 6 operator that modifies the gluon propagator at high energies. The dominant effect is constructive or destructive interference with SM jet production. We compare differential next-to-leading order predictions from POWHEG to public 7 TeV jet data, including scale, PDF, and experimental uncertainties and their respective correlations. We constrain a New Physics (NP) scale of 3.5 TeV with current data. We project the reach of future 13 and 100 TeV measurements, which we estimate to be sensitive to NP scales of 8 and 60 TeV, respectively. As an application, we apply our bounds to constrain heavy vector octet colorons that couple to the QCD current. We project that effective operators will surpass bump hunts, in terms of coloron mass reach, even for sequential couplings.

The CP-PACS Project and Lattice QCD Results

NASA Astrophysics Data System (ADS)

Iwasaki, Y.

The aim of the CP-PACS project was to develop a massively parallel computer for performing numerical research in computational physics with primary emphasis on lattice QCD. The CP-PACS computer with a peak speed of 614 GFLOPS with 2048 processors was completed in September 1996, and has been in full operation since October 1996. We present an overview of the CP-PACS project and describe characteristics of the CP-PACS computer. The CP-PACS has been mainly used for hadron spectroscopy studies in lattice QCD. Main results in lattice QCD simulations are given.

Testing the QCD string at large Nc from the thermodynamics of the hadronic phase

NASA Astrophysics Data System (ADS)

Cohen, Thomas D.

2007-02-01

It is generally believed that in the limit of a large number of colors (Nc) the description of confinement via flux tubes becomes valid and QCD can be modeled accurately via a hadronic string theory—at least for highly excited states. QCD at large Nc also has a well-defined deconfinement transition at a temperature Tc. In this talk it is shown how the thermodyanmics of the metastable hadronic phase of QCD (above Tc) at large NC can be related directly to properties of the effective QCD string. The key points in the derivation is the weakly interacting nature of hadrons at large Nc and the existence of a Hagedorn temperature TH for the effective string theory. From this it can be seen at large Nc and near TH, the energy density and pressure of the hadronic phase scale as E ˜ (TH - T)-(D⊥-6)/2 (for D⊥ < 6) and P ˜ (TH - T)-(D⊥-4)/2 (for D⊥ < 4) where D⊥ is the effective number of transverse dimensions of the string theory. This behavior for D⊥ < 6 is qualitatively different from typical models in statistical mechanics and if observed on the lattice would provide a direct test of the stringy nature of large Nc QCD. However since it can be seen that TH > Tc this behavior is of relevance only to the metastable phase. The prospect of using this result to extract D⊥ via lattice simulations of the metastable hadronic phase at moderately large Nc is discussed.

Moriond QCD 2013 Experimental Summary

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

Denisov, Dmitri

2013-06-28

The article presents experimental highlights of Moriond 2013 QCD conference. This was fantastic conference and the first Moriond QCD since the discovery of the Higgs boson. Many new results about its properties have been presented at the conference with Higgs-like particle becoming a Higgs as it properties match expected for the Higgs boson pretty well. There were many new results presented in all experimental areas including QCD, elecroweak, studies of the top, bottom and charm quarks, searches for physics beyond Standard Model as well as studies of the heavy ion collisions. 56 experimental talks have been presented at the conferencemore » and it is impossible to cover each result in the summary, so highlights are limited to what I was able to present in my summary talk presented on March 16 2013. The proceedings of the conference cover in depth all talks presented and I urge you to get familiar with all of them. Theoretical Summary of the conference was given by Michelangelo Mangano, so theory talks are not covered in the article.« less

QCD tests with SLD and polarized beams

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

Strauss, M.G.

1994-12-01

The author presents a measurement of the strong coupling {alpha}{sub s} derived from multijet rates using data collected by the SLD experiment at SLAC and find that {alpha}{sub s}(M{sub Z}{sup 2}) = 0.118 {+-} 0.002(stat.) {+-} 0.003(syst.) {+-} 0.010(theory). He presents tests of the flavor independence of strong interactions via preliminary measurements of the ratios {alpha}{sub s}(b)/{alpha}{sub s}(udsc) and {alpha}{sub s}(uds)/{alpha}{sub s}(bc). In addition, the group has measured the difference in charged particle multiplicity between Z{sup 0} {yields} b{bar b} and Z{sup 0} {yields} u{bar u}, d{bar d}, s{bar s} events, and find that it supports the prediction of perturbativemore » QCD that the multiplicity difference be independent of center-of-mass energy. Finally, the group has made a preliminary study of jet polarization using the jet handedness technique.« less

Parton distributions and lattice QCD calculations: A community white paper

NASA Astrophysics Data System (ADS)

Lin, Huey-Wen; Nocera, Emanuele R.; Olness, Fred; Orginos, Kostas; Rojo, Juan; Accardi, Alberto; Alexandrou, Constantia; Bacchetta, Alessandro; Bozzi, Giuseppe; Chen, Jiunn-Wei; Collins, Sara; Cooper-Sarkar, Amanda; Constantinou, Martha; Del Debbio, Luigi; Engelhardt, Michael; Green, Jeremy; Gupta, Rajan; Harland-Lang, Lucian A.; Ishikawa, Tomomi; Kusina, Aleksander; Liu, Keh-Fei; Liuti, Simonetta; Monahan, Christopher; Nadolsky, Pavel; Qiu, Jian-Wei; Schienbein, Ingo; Schierholz, Gerrit; Thorne, Robert S.; Vogelsang, Werner; Wittig, Hartmut; Yuan, C.-P.; Zanotti, James

2018-05-01

In the framework of quantum chromodynamics (QCD), parton distribution functions (PDFs) quantify how the momentum and spin of a hadron are divided among its quark and gluon constituents. Two main approaches exist to determine PDFs. The first approach, based on QCD factorization theorems, realizes a QCD analysis of a suitable set of hard-scattering measurements, often using a variety of hadronic observables. The second approach, based on first-principle operator definitions of PDFs, uses lattice QCD to compute directly some PDF-related quantities, such as their moments. Motivated by recent progress in both approaches, in this document we present an overview of lattice-QCD and global-analysis techniques used to determine unpolarized and polarized proton PDFs and their moments. We provide benchmark numbers to validate present and future lattice-QCD calculations and we illustrate how they could be used to reduce the PDF uncertainties in current unpolarized and polarized global analyses. This document represents a first step towards establishing a common language between the two communities, to foster dialogue and to further improve our knowledge of PDFs.

Study of QCD-dynamics in η and η' production and decays

NASA Astrophysics Data System (ADS)

Beck, Reinhard; Wiedner, Ulrich

2017-01-01

One aim of this project lies in studying QCD dynamics using photoproduction of η and η' mesons with the CBELSA/TAPS experiment at the accelerator facility ELSA. Hadronic decay modes of η and η' are analyzed that allow the study of symmetry breaking effects in QCD. Furthermore, excited η-states produced with a photon beam are studied within the scope of this project. Of special interest is hereby the nature of the η(1405). The high data samples for η- and η'-photoproduction off the proton allow in addition the determination of polarization observables.

Exploring Partonic Structure of Hadrons Using ab initio Lattice QCD Calculations.

PubMed

Ma, Yan-Qing; Qiu, Jian-Wei

2018-01-12

Following our previous proposal, we construct a class of good "lattice cross sections" (LCSs), from which we can study the partonic structure of hadrons from ab initio lattice QCD calculations. These good LCSs, on the one hand, can be calculated directly in lattice QCD, and on the other hand, can be factorized into parton distribution functions (PDFs) with calculable coefficients, in the same way as QCD factorization for factorizable hadronic cross sections. PDFs could be extracted from QCD global analysis of the lattice QCD generated data of LCSs. We also show that the proposed functions for lattice QCD calculation of PDFs in the literature are special cases of these good LCSs.

Moving heavy quarkonium entropy, effective string tension, and the QCD phase diagram

NASA Astrophysics Data System (ADS)

Chen, Xun; Feng, Sheng-Qin; Shi, Ya-Fei; Zhong, Yang

2018-03-01

The entropy and effective string tension of the moving heavy quark-antiquark pair in the strongly coupled plasmas are calculated by using a deformed an anti-de Sitter/Reissner-Nordström black hole metric. A sharp peak of the heavy-quarkonium entropy around the deconfinement transition can be realized in our model, which is consistent with the lattice QCD result. The effective string tension of the heavy quark-antiquark pair is related to the deconfinement phase transition. Thus, we investigate the deconfinement phase transition by analyzing the characteristics of the effective string tension with different temperatures, chemical potentials, and rapidities. It is found that the results of phase diagram calculated through effective string tension are in agreement with results calculated through a Polyakov loop. We argue that a moving system will reach the phase transition point at a lower temperature and chemical potential than a stationary system. It means that the lifetime of the moving quark-gluon plasma become longer than the static one.

Photoinduced ultrafast charge-order melting: Charge-order inversion and nonthermal effects

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

van Veenendaal, Michel

2016-09-01

The effect of photoexcitation is studied for a system with checkerboard charge order induced by displacements of ligands around a metal site. The motion of the ligands is treated classically and the electronic charges are simplified to two-level molecular bond charges. The calculations are done for a checkerboard charge-ordered system with about 100 000 ligand oscillators coupled to a fixed-temperature bath. The initial photoexcitation is followed by a rapid decrease in the charge-order parameter within 50–100 femtoseconds while leaving the correlation length almost unchanged. Depending on the fluence, a complete melting of the charge order occurs in less than amore » picosecond. While for low fluences, the system returns to its original state, for full melting, it recovers to its broken-symmetry state leading to an inversion of the charge order. For small long-range interactions, recovery can be slow due to domain formation.« less

Photoinduced ultrafast charge-order melting: Charge-order inversion and nonthermal effects

DOE PAGES

van Veenendaal, Michel

2016-09-01

The effect of photoexcitation is studied for a system with checkerboard charge order induced by displacements of ligands around a metal site. The motion of the ligands is treated classically and the electronic charges are simplified to two-level molecular bond charges. The calculations are done for a checkerboard charge-ordered system with about 100 000 ligand oscillators coupled to a fixed-temperature bath. The initial photoexcitation is followed by a rapid decrease in the charge-order parameter within 50–100 femtoseconds while leaving the correlation length almost unchanged. Depending on the fluence, a complete melting of the charge order occurs in less than amore » picosecond. While for low fluences, the system returns to its original state, for full melting, it recovers to its broken-symmetry state leading to an inversion of the charge order. Finally, for small long-range interactions, recovery can be slow due to domain formation.« less

Further Comments on a Vanishing Singlet Axial Vector Charge

NASA Astrophysics Data System (ADS)

Cheng, T. P.; Kochelev, N. I.; Vento, Vicente

The recent suggestion of a vanishing flavor-singlet axial-charge of nucleon due to a nontrivial vacuum structure is further amplified. A perturbative QCD discussion, applicable for the heavy quark contributions, relates it to the physics of the decoupling theorem. It is also shown that gA0˜= 0 leads to a negative η‧-meson-quark coupling, which has been found to be compatible with the chiral quark model phenomenology.

Hadron electric polarizability from lattice QCD

NASA Astrophysics Data System (ADS)

Alexandru, Andrei; Lujan, Michael; Freeman, Walter; Lee, Frank

2015-04-01

Electric polarizability measures the ability of the electric field to deform a particle. Experimentally, electric and magnetic polarizabilities can be measured in Compton scattering experiments. To compute these quantities theoretically we need to understand the internal structure of the scatterer and the dynamics of its constituents. For hadrons - bound stated of quarks and gluons - this is a very difficult problem. Lattice QCD can be used to compute the polarizabilities directly in terms of quark and gluons degrees of freedom. In this talk we focus on the neutron. We present results for the electric polarizability for two different quark masses, light enough to connect to chiral perturbation theory. These are currently the lightest quark masses used in lattice QCD polarizability studies. For each pion mass we compute the polarizability at four different volumes and perform an infinite volume extrapolation. For one ensemble, we also discuss the effect of turning on the coupling between the background field and the sea quarks. We compare our results to chiral perturbation theory expectations.

Symmetric and anti-symmetric LS hyperon potentials from lattice QCD

NASA Astrophysics Data System (ADS)

Ishii, Noriyoshi; Murano, Keiko; Nemura, Hidekatsu; Sasaki, Kenji; Inoue, Takashi; HAL QCD Collaboration

2014-09-01

We present recent results of odd-parity hyperon-hyperon potentials from lattice QCD. By using HAL QCD method, we generate hyperon-hyperon potentials from Nambu-Bethe-Salpeter (NBS) wave functions generated by lattice QCD simulation in the flavor SU(3) limit. Potentials in the irreducible flavor SU(3) representations are combined to make a Lambda-N potential which has a strong symmetric LS potential and a weak anti-symmetric LS potential. We discuss a possible cancellation between symmetric and anti-symmetric LS (Lambda-N) potentials after the coupled Sigma-N sector is integrated out. We present recent results of odd-parity hyperon-hyperon potentials from lattice QCD. By using HAL QCD method, we generate hyperon-hyperon potentials from Nambu-Bethe-Salpeter (NBS) wave functions generated by lattice QCD simulation in the flavor SU(3) limit. Potentials in the irreducible flavor SU(3) representations are combined to make a Lambda-N potential which has a strong symmetric LS potential and a weak anti-symmetric LS potential. We discuss a possible cancellation between symmetric and anti-symmetric LS (Lambda-N) potentials after the coupled Sigma-N sector is integrated out. This work is supported by JSPS KAKENHI Grant Number 25400244.

Fluctuations in the quark-meson model for QCD with isospin chemical potential

NASA Astrophysics Data System (ADS)

Kamikado, Kazuhiko; Strodthoff, Nils; von Smekal, Lorenz; Wambach, Jochen

2013-01-01

We study the two-flavor quark-meson (QM) model with the functional renormalization group (FRG) to describe the effects of collective mesonic fluctuations on the phase diagram of QCD at finite baryon and isospin chemical potentials, μB and μI. With only isospin chemical potential there is a precise equivalence between the competing dynamics of chiral versus pion condensation and that of collective mesonic and baryonic fluctuations in the quark-meson-diquark model for two-color QCD at finite baryon chemical potential. Here, finite μB = 3 μ introduces an additional dimension to the phase diagram as compared to two-color QCD, however. At zero temperature, the (μI, μ) plane of this phase diagram is strongly constrained by the "Silver Blaze problem." In particular, the onset of pion condensation must occur at μI =mπ / 2, independent of μ as long as μ +μI stays below the constituent quark mass of the QM model or the liquid-gas transition line of nuclear matter in QCD. In order to maintain this relation beyond mean field it is crucial to compute the pion mass from its timelike correlator with the FRG in a consistent way.

On microscopic structure of the QCD vacuum

NASA Astrophysics Data System (ADS)

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

2018-05-01

We propose a new class of regular stationary axially symmetric solutions in a pure QCD which correspond to monopole-antimonopole pairs at macroscopic scale. The solutions represent vacuum field configurations which are locally stable against quantum gluon fluctuations in any small space-time vicinity. This implies that the monopole-antimonopole pair can serve as a structural element in microscopic description of QCD vacuum formation.

K-->pipi amplitudes from lattice QCD with a light charm quark.

PubMed

Giusti, L; Hernández, P; Laine, M; Pena, C; Wennekers, J; Wittig, H

2007-02-23

We compute the leading-order low-energy constants of the DeltaS=1 effective weak Hamiltonian in the quenched approximation of QCD with up, down, strange, and charm quarks degenerate and light. They are extracted by comparing the predictions of finite-volume chiral perturbation theory with lattice QCD computations of suitable correlation functions carried out with quark masses ranging from a few MeV up to half of the physical strange mass. We observe a DeltaI=1/2 enhancement in this corner of the parameter space of the theory. Although matching with the experimental result is not observed for the DeltaI=1/2 amplitude, our computation suggests large QCD contributions to the physical DeltaI=1/2 rule in the GIM limit, and represents the first step to quantify the role of the charm-quark mass in K-->pipi amplitudes. The use of fermions with an exact chiral symmetry is an essential ingredient in our computation.

Structure of the Roper resonance from lattice QCD constraints

NASA Astrophysics Data System (ADS)

Wu, Jia-jun; Leinweber, Derek B.; Liu, Zhan-wei; Thomas, Anthony W.

2018-05-01

Two different effective field theory descriptions of the pion-nucleon scattering data are constructed to describe the region of the Roper resonance. In one, the resonance is the result of strong rescattering between coupled meson-baryon channels, while in the other the resonance has a large bare-baryon (or quark-model-like) component. The predictions of these two scenarios are compared with the latest lattice QCD simulation results in this channel. We find that the second scenario is not consistent with lattice QCD results, whereas the first agrees with those constraints. In that preferred scenario, the mass of the quark-model-like state is approximately 2 GeV, with the infinite-volume Roper resonance best described as a resonance generated dynamically through strongly coupled meson-baryon channels.

Connecting physical resonant amplitudes and lattice QCD

DOE PAGES

Bolton, Daniel R.; Briceno, Raul A.; Wilson, David J.

2016-03-18

Here, we present a determination of the isovector,more » $P$-wave $$\\pi\\pi$$ scattering phase shift obtained by extrapolating recent lattice QCD results from the Hadron Spectrum Collaboration using $$m_\\pi =236$$ MeV. The finite volume spectra are described using extensions of L\\"uscher's method to determine the infinite volume Unitarized Chiral Perturbation Theory scattering amplitude. We exploit the pion mass dependence of this effective theory to obtain the scattering amplitude at $$m_\\pi= 140$$ MeV. The scattering phase shift is found to be in good agreement with experiment up to center of mass energies of 1.2 GeV. The analytic continuation of the scattering amplitude to the complex plane yields a $$\\rho$$-resonance pole at $$E_\\rho= \\left[755(2)(1)(^{20}_{02})-\\frac{i}{2}\\,129(3)(1)(^{7}_{1})\\right]~{\\rm MeV}$$. The techniques presented illustrate a possible pathway towards connecting lattice QCD observables of few-body, strongly interacting systems to experimentally accessible quantities.« less

Charmed bottom baryon spectroscopy from lattice QCD

DOE PAGES

Brown, Zachary S.; Detmold, William; Meinel, Stefan; ...

2014-11-19

In this study, we calculate the masses of baryons containing one, two, or three heavy quarks using lattice QCD. We consider all possible combinations of charm and bottom quarks, and compute a total of 36 different states with J P = 1/2 + and J P = 3/2 +. We use domain-wall fermions for the up, down, and strange quarks, a relativistic heavy-quark action for the charm quarks, and nonrelativistic QCD for the bottom quarks. Our analysis includes results from two different lattice spacings and seven different pion masses. We perform extrapolations of the baryon masses to the continuum limitmore » and to the physical pion mass using SU(4|2) heavy-hadron chiral perturbation theory including 1/m Q and finite-volume effects. For the 14 singly heavy baryons that have already been observed, our results agree with the experimental values within the uncertainties. We compare our predictions for the hitherto unobserved states with other lattice calculations and quark-model studies.« less

A proposal of a local modified QCD

NASA Astrophysics Data System (ADS)

Cabo Montes de Oca, A.

2012-06-01

A local and renormalizable version of a modified PQCD introduced in previous works is presented. The construction indicates that it could be equivalent to massless QCD. The case in which only quark condensate effects are retained is discussed in more detail. Then, the appearing auxiliary fermion fields can be integrated, leading to a theory with the action of massless QCD, to which one local and gauge invariant Lagrangian term for each quark flavour is added. Those action terms are defined by two gluon and two quark fields, in a form curiously not harming power counting renormalizability. The gluon self-energy is evaluated in second order in the gauge coupling and all orders in the new quark couplings, and the result became transversal as required by the gauge invariance. The vacuum energy was also calculated in the two-loop approximation and became gauge parameter independent. The possibilities that higher-loop contributions to the vacuum energy allow the generation of a quark mass hierarchy as a flavour symmetry-breaking effect are commented. The decision on this issue needs a further evaluation of more than two-loop contributions, in which more than one type of quark loops start appearing, possibly leading to interference effects in the vacuum energy.

The effective hyper-Kähler potential in the N = 2 supersymmetric QCD

NASA Astrophysics Data System (ADS)

Ketov, Sergei V.

1997-02-01

The effective low-energy hyper-Kähler potential for a massive N = 2 matter in N = 2 super-QCD is investigated. TheN = 2 extended supersymmetry severely restricts the N = 2 matter self-couplings so that their exact form can be fixed by a few parameters, which is apparent in the N = 2 harmonic superspace. In the N = 2 QED with a single matter hypermultiplet, the one-loop perturbative calculations lead to the Taub-NUT hyper-Kähler metric in the massive case, and a free metric in the massless case. It is remarkable that the naive non-renormalization `theorem' does not apply. There exists a manifestly N = 2 supersymmetric duality transformation converting the low-energy effective action for the N = 2 QED hypermultiplet into a sum of the quadratic and the improved (non-polynomial) actions for an N = 2 tensor multiplet. The duality transformation also gives a simple connection between the low-energy effective action in the N = 2 harmonic superspace and the component results.

Scheme Variations of the QCD Coupling and Hadronic τ Decays

NASA Astrophysics Data System (ADS)

Boito, Diogo; Jamin, Matthias; Miravitllas, Ramon

2016-10-01

The quantum chromodynamics (QCD) coupling αs is not a physical observable of the theory, since it depends on conventions related to the renormalization procedure. We introduce a definition of the QCD coupling, denoted by α^s, whose running is explicitly renormalization scheme invariant. The scheme dependence of the new coupling α^s is parametrized by a single parameter C , related to transformations of the QCD scale Λ . It is demonstrated that appropriate choices of C can lead to substantial improvements in the perturbative prediction of physical observables. As phenomenological applications, we study e+e- scattering and decays of the τ lepton into hadrons, both being governed by the QCD Adler function.

Isovector charges of the nucleon from 2 + 1 -flavor QCD with clover fermions

DOE PAGES

Yoon, Boram; Jang, Yong -Chull; Gupta, Rajan; ...

2017-04-13

We present high-statistics estimates of the isovector charges of the nucleon from four 2+1-flavor ensembles generated using Wilson-clover fermions with stout smearing and tree-level tadpole improved Symanzik gauge action at lattice spacingsmore » $a=0.114$ and $0.080$ fm and with $$M_\\pi \\approx 315$$ and 200 MeV. The truncated solver method with bias correction and the coherent source sequential propagator construction are used to cost-effectively achieve $O(10^5)$ measurements on each ensemble. Using these data, the analysis of two-point correlation functions is extended to include four states in the fits and of three-point functions to three states. Control over excited-state contamination in the calculation of the nucleon mass, the mass gaps between excited states, and in the matrix elements is demonstrated by the consistency of estimates using this multistate analysis of the spectral decomposition of the correlation functions and from simulations of the three-point functions at multiple values of the source-sink separation. Lastly, the results for all three charges, $$g_A$$, $$g_S$$ and $$g_T$$, are in good agreement with calculations done using the clover-on-HISQ lattice formulation with similar values of the lattice parameters.« less

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.

Light-Front Holography, Light-Front Wavefunctions, and Novel QCD Phenomena

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

Brodsky, Stanley J.; /SLAC /Southern Denmark U., CP3-Origins; de Teramond, Guy F.

2012-02-16

Light-Front Holography is one of the most remarkable features of the AdS/CFT correspondence. In spite of its present limitations it provides important physical insights into the nonperturbative regime of QCD and its transition to the perturbative domain. This novel framework allows hadronic amplitudes in a higher dimensional anti-de Sitter (AdS) space to be mapped to frame-independent light-front wavefunctions of hadrons in physical space-time. The model leads to an effective confining light-front QCD Hamiltonian and a single-variable light-front Schroedinger equation which determines the eigenspectrum and the light-front wavefunctions of hadrons for general spin and orbital angular momentum. The coordinate z inmore » AdS space is uniquely identified with a Lorentz-invariant coordinate {zeta} which measures the separation of the constituents within a hadron at equal light-front time and determines the off-shell dynamics of the bound-state wavefunctions, and thus the fall-off as a function of the invariant mass of the constituents. The soft-wall holographic model modified by a positive-sign dilaton metric, leads to a remarkable one-parameter description of nonperturbative hadron dynamics - a semi-classical frame-independent first approximation to the spectra and light-front wavefunctions of meson and baryons. The model predicts a Regge spectrum of linear trajectories with the same slope in the leading orbital angular momentum L of hadrons and the radial quantum number n. The hadron eigensolutions projected on the free Fock basis provides the complete set of valence and non-valence light-front Fock state wavefunctions {Psi}{sub n/H} (x{sub i}, k{sub {perpendicular}i}, {lambda}{sub i}) which describe the hadron's momentum and spin distributions needed to compute the direct measures of hadron structure at the quark and gluon level, such as elastic and transition form factors, distribution amplitudes, structure functions, generalized parton distributions and

Two-photon decay of the neutral pion in lattice QCD.

PubMed

Feng, Xu; Aoki, Sinya; Fukaya, Hidenori; Hashimoto, Shoji; Kaneko, Takashi; Noaki, Jun-Ichi; Shintani, Eigo

2012-11-02

We perform a nonperturbative calculation of the π(0) → γγ transition form factor and the associated decay width using lattice QCD. The amplitude for a two-photon final state, which is not an eigenstate of QCD, is extracted through a Euclidean time integral of the relevant three-point function. We utilize the all-to-all quark propagator technique to carry out this integration as well as to include the disconnected quark diagram contributions. The overlap fermion formulation is employed on the lattice to ensure exact chiral symmetry on the lattice. After examining various sources of systematic effects, except for a possible discretization effect, we obtain Γπ(0) → γγ = 7.83(31)(49) eV for the pion decay width, where the first error is statistical and the second is our estimate of the systematic error.

Bose-Fermi degeneracies in large N adjoint QCD

DOE PAGES

Basar, Gokce; Cherman, Aleksey; McGady, David

2015-07-06

Here, we analyze the large N limit of adjoint QCD, an SU( N) gauge theory with N f flavors of massless adjoint Majorana fermions, compactified on S 3 × S 1. We focus on the weakly-coupled confining small- S 3 regime. If the fermions are given periodic boundary conditions on S 1, we show that there are large cancellations between bosonic and fermionic contributions to the twisted partition function. These cancellations follow a pattern previously seen in the context of misaligned supersymmetry, and lead to the absence of Hagedorn instabilities for any S 1 size L, even though the bosonicmore » and fermionic densities of states both have Hagedorn growth. Adjoint QCD stays in the confining phase for any L ~ N 0, explaining how it is able to enjoy large N volume independence for any L. The large N boson-fermion cancellations take place in a setting where adjoint QCD is manifestly non-supersymmetric at any finite N, and are consistent with the recent conjecture that adjoint QCD has emergent fermionic symmetries in the large N limit.« less

STATIC QUARK ANTI-QUARK FREE AND INTERNAL ENERGY IN 2-FLAVOR QCD AND BOUND STATES IN THE QGP.

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

ZANTOW, F.; KACZMAREK, O.

2005-07-25

We present results on heavy quark free energies in 2-flavour QCD. The temperature dependence of the interaction between static quark anti-quark pairs will be analyzed in terms of temperature dependent screening radii, which give a first estimate on the medium modification of (heavy quark) bound states in the quark gluon plasma. Comparing those radii to the (zero temperature) mean squared charge radii of chasmonium states indicates that the J/{Psi} may survive the phase transition as a bound state, while {chi}{sub c} and {Psi}{prime} are expected to show significant thermal modifications at temperatures close to the transition. Furthermore we will analyzemore » the relation between heavy quark free energies, entropy contributions and internal energy and discuss their relation to potential models used to analyze the melting of heavy quark bound states above the deconfinement temperature. Results of different groups and various potential models for bound states in the deconfined phase of QCD are compared.« less

Nucleon transverse momentum-dependent parton distributions in lattice QCD: Renormalization patterns and discretization effects

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

Yoon, Boram; Engelhardt, Michael; Gupta, Rajan

Lattice QCD calculations of transverse momentum-dependent parton distribution functions (TMDs) in nucleons are presented in this paper, based on the evaluation of nucleon matrix elements of quark bilocal operators with a staple-shaped gauge connection. Both time-reversal odd effects, namely, the generalized Sivers and Boer-Mulders transverse momentum shifts, as well as time-reversal even effects, namely, the generalized transversity and one of the generalized worm-gear shifts, are studied. Results are obtained on two different n f = 2 + 1 flavor ensembles with approximately matching pion masses but very different discretization schemes: domain-wall fermions (DWF) with lattice spacing a = 0.084 fmmore » and pion mass 297 MeV, and Wilson-clover fermions with a = 0.114 fm and pion mass 317 MeV. Comparison of the results on the two ensembles yields insight into the length scales at which lattice discretization errors are small, and into the extent to which the renormalization pattern obeyed by the continuum QCD TMD operator continues to apply in the lattice formulation. For the studied TMD observables, the results are found to be consistent between the two ensembles at sufficiently large separation of the quark fields within the operator, whereas deviations are observed in the local limit and in the case of a straight link gauge connection, which is relevant to the studies of parton distribution functions. Finally and furthermore, the lattice estimates of the generalized Sivers shift obtained here are confronted with, and are seen to tend towards, a phenomenological estimate extracted from experimental data.« less

Nucleon transverse momentum-dependent parton distributions in lattice QCD: Renormalization patterns and discretization effects

DOE PAGES

Yoon, Boram; Engelhardt, Michael; Gupta, Rajan; ...

2017-11-21

Lattice QCD calculations of transverse momentum-dependent parton distribution functions (TMDs) in nucleons are presented in this paper, based on the evaluation of nucleon matrix elements of quark bilocal operators with a staple-shaped gauge connection. Both time-reversal odd effects, namely, the generalized Sivers and Boer-Mulders transverse momentum shifts, as well as time-reversal even effects, namely, the generalized transversity and one of the generalized worm-gear shifts, are studied. Results are obtained on two different n f = 2 + 1 flavor ensembles with approximately matching pion masses but very different discretization schemes: domain-wall fermions (DWF) with lattice spacing a = 0.084 fmmore » and pion mass 297 MeV, and Wilson-clover fermions with a = 0.114 fm and pion mass 317 MeV. Comparison of the results on the two ensembles yields insight into the length scales at which lattice discretization errors are small, and into the extent to which the renormalization pattern obeyed by the continuum QCD TMD operator continues to apply in the lattice formulation. For the studied TMD observables, the results are found to be consistent between the two ensembles at sufficiently large separation of the quark fields within the operator, whereas deviations are observed in the local limit and in the case of a straight link gauge connection, which is relevant to the studies of parton distribution functions. Finally and furthermore, the lattice estimates of the generalized Sivers shift obtained here are confronted with, and are seen to tend towards, a phenomenological estimate extracted from experimental data.« less

Top-quark decay at next-to-next-to-leading order in QCD.

PubMed

Gao, Jun; Li, Chong Sheng; Zhu, Hua Xing

2013-01-25

We present the complete calculation of the top-quark decay width at next-to-next-to-leading order in QCD, including next-to-leading electroweak corrections as well as finite bottom quark mass and W boson width effects. In particular, we also show the first results of the fully differential decay rates for the top-quark semileptonic decay t → W(+)(l(+)ν)b at next-to-next-to-leading order in QCD. Our method is based on the understanding of the invariant mass distribution of the final-state jet in the singular limit from effective field theory. Our result can be used to study arbitrary infrared-safe observables of top-quark decay with the highest perturbative accuracy.

Neutrinoless double beta decay and QCD running at low energy scales

NASA Astrophysics Data System (ADS)

González, M.; Hirsch, M.; Kovalenko, S. G.

2018-06-01

There is a common belief that the main uncertainties in the theoretical analysis of neutrinoless double beta (0 ν β β ) decay originate from the nuclear matrix elements. Here, we uncover another previously overlooked source of potentially large uncertainties stemming from nonperturbative QCD effects. Recently perturbative QCD corrections have been calculated for all dimension 6 and 9 effective operators describing 0 ν β β -decay and their importance for a reliable treatment of 0 ν β β -decay has been demonstrated. However, these perturbative results are valid at energy scales above ˜1 GeV , while the typical 0 ν β β scale is about ˜100 MeV . In view of this fact we examine the possibility of extrapolating the perturbative results towards sub-GeV nonperturbative scales on the basis of the QCD coupling constant "freezing" behavior using background perturbation theory. Our analysis suggests that such an infrared extrapolation does modify the perturbative results for both short-range and long-range mechanisms of 0 ν β β -decay in general only moderately. We also discuss that the tensor⊗tensor effective operator cannot appear alone in the low energy limit of any renormalizable high-scale model and then demonstrate that all five linearly independent combinations of the scalar and tensor operators, which can appear in renormalizable models, are infrared stable.

Large N{sub c}, constituent quarks, and N, {Delta} charge radii

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

Buchmann, Alfons J.; Lebed, Richard F.

2000-11-01

We show how one may define baryon constituent quarks in a rigorous manner, given physical assumptions that hold in the large-N{sub c} limit of QCD. This constituent picture gives rise to an operator expansion that has been used to study large-N{sub c} baryon observables; here we apply it to the case of charge radii of the N and {Delta} states, using minimal dynamical assumptions. For example, one finds the relation r{sub p}{sup 2}-r{sub {Delta}{sup +}}{sup 2}=r{sub n}{sup 2}-r{sub {Delta}{sup 0}}{sup 2} to be broken only by three-body, O(1/N{sub c}{sup 2}) effects for any N{sub c}.

QCD dirac operator at nonzero chemical potential: lattice data and matrix model.

PubMed

Akemann, Gernot; Wettig, Tilo

2004-03-12

Recently, a non-Hermitian chiral random matrix model was proposed to describe the eigenvalues of the QCD Dirac operator at nonzero chemical potential. This matrix model can be constructed from QCD by mapping it to an equivalent matrix model which has the same symmetries as QCD with chemical potential. Its microscopic spectral correlations are conjectured to be identical to those of the QCD Dirac operator. We investigate this conjecture by comparing large ensembles of Dirac eigenvalues in quenched SU(3) lattice QCD at a nonzero chemical potential to the analytical predictions of the matrix model. Excellent agreement is found in the two regimes of weak and strong non-Hermiticity, for several different lattice volumes.

Matrix theory for baryons: an overview of holographic QCD for nuclear physics.

PubMed

Aoki, Sinya; Hashimoto, Koji; Iizuka, Norihiro

2013-10-01

We provide, for non-experts, a brief overview of holographic QCD (quantum chromodynamics) and a review of the recent proposal (Hashimoto et al 2010 (arXiv:1003.4988[hep-th])) of a matrix-like description of multi-baryon systems in holographic QCD. Based on the matrix model, we derive the baryon interaction at short distances in multi-flavor holographic QCD. We show that there is a very universal repulsive core of inter-baryon forces for a generic number of flavors. This is consistent with a recent lattice QCD analysis for Nf = 2, 3 where the repulsive core looks universal. We also provide a comparison of our results with the lattice QCD and the operator product expansion analysis.

Exploring Partonic Structure of Hadrons Using ab initio Lattice QCD Calculations

DOE PAGES

Ma, Yan-Qing; Qiu, Jian-Wei

2018-01-10

Following our previous proposal, we construct a class of good "lattice cross sections" (LCSs), from which we can study the partonic structure of hadrons from ab initio lattice QCD calculations. These good LCSs, on the one hand, can be calculated directly in lattice QCD, and on the other hand, can be factorized into parton distribution functions (PDFs) with calculable coefficients, in the same way as QCD factorization for factorizable hadronic cross sections. PDFs could be extracted from QCD global analysis of the lattice QCD generated data of LCSs. In conclusion, we also show that the proposed functions for lattice QCDmore » calculation of PDFs in the literature are special cases of these good LCSs.« less

Chiral effective theory methods and their application to the structure of hadrons from lattice QCD

NASA Astrophysics Data System (ADS)

Shanahan, P. E.

2016-12-01

For many years chiral effective theory (ChEFT) has enabled and supported lattice QCD calculations of hadron observables by allowing systematic effects from unphysical lattice parameters to be controlled. In the modern era of precision lattice simulations approaching the physical point, ChEFT techniques remain valuable tools. In this review we discuss the modern uses of ChEFT applied to lattice studies of hadron structure in the context of recent determinations of important and topical quantities. We consider muon g-2, strangeness in the nucleon, the proton radius, nucleon polarizabilities, and sigma terms relevant to the prediction of dark-matter-hadron interaction cross-sections, among others.

Effects of Charged Particles on Human Tumor Cells

PubMed Central

Held, Kathryn D.; Kawamura, Hidemasa; Kaminuma, Takuya; Paz, Athena Evalour S.; Yoshida, Yukari; Liu, Qi; Willers, Henning; Takahashi, Akihisa

2016-01-01

The use of charged particle therapy in cancer treatment is growing rapidly, in large part because the exquisite dose localization of charged particles allows for higher radiation doses to be given to tumor tissue while normal tissues are exposed to lower doses and decreased volumes of normal tissues are irradiated. In addition, charged particles heavier than protons have substantial potential clinical advantages because of their additional biological effects, including greater cell killing effectiveness, decreased radiation resistance of hypoxic cells in tumors, and reduced cell cycle dependence of radiation response. These biological advantages depend on many factors, such as endpoint, cell or tissue type, dose, dose rate or fractionation, charged particle type and energy, and oxygen concentration. This review summarizes the unique biological advantages of charged particle therapy and highlights recent research and areas of particular research needs, such as quantification of relative biological effectiveness (RBE) for various tumor types and radiation qualities, role of genetic background of tumor cells in determining response to charged particles, sensitivity of cancer stem-like cells to charged particles, role of charged particles in tumors with hypoxic fractions, and importance of fractionation, including use of hypofractionation, with charged particles. PMID:26904502

Parton distributions and lattice QCD calculations: A community white paper

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

Lin, Huey-Wen; Nocera, Emanuele R.; Olness, Fred

In the framework of quantum chromodynamics (QCD), parton distribution functions (PDFs) quantify how the momentum and spin of a hadron are divided among its quark and gluon constituents. Two main approaches exist to determine PDFs. The first approach, based on QCD factorization theorems, realizes a QCD analysis of a suitable set of hard-scattering measurements, often using a variety of hadronic observables. The second approach, based on first-principle operator definitions of PDFs, uses lattice QCD to compute directly some PDF-related quantities, such as their moments. Motivated by recent progress in both approaches, in this paper we present an overview of lattice-QCDmore » and global-analysis techniques used to determine unpolarized and polarized proton PDFs and their moments. We provide benchmark numbers to validate present and future lattice-QCD calculations and we illustrate how they could be used to reduce the PDF uncertainties in current unpolarized and polarized global analyses. Finally, this document represents a first step towards establishing a common language between the two communities, to foster dialogue and to further improve our knowledge of PDFs.« less

Parton distributions and lattice QCD calculations: A community white paper

DOE PAGES

Lin, Huey-Wen; Nocera, Emanuele R.; Olness, Fred; ...

2018-01-31

In the framework of quantum chromodynamics (QCD), parton distribution functions (PDFs) quantify how the momentum and spin of a hadron are divided among its quark and gluon constituents. Two main approaches exist to determine PDFs. The first approach, based on QCD factorization theorems, realizes a QCD analysis of a suitable set of hard-scattering measurements, often using a variety of hadronic observables. The second approach, based on first-principle operator definitions of PDFs, uses lattice QCD to compute directly some PDF-related quantities, such as their moments. Motivated by recent progress in both approaches, in this paper we present an overview of lattice-QCDmore » and global-analysis techniques used to determine unpolarized and polarized proton PDFs and their moments. We provide benchmark numbers to validate present and future lattice-QCD calculations and we illustrate how they could be used to reduce the PDF uncertainties in current unpolarized and polarized global analyses. Finally, this document represents a first step towards establishing a common language between the two communities, to foster dialogue and to further improve our knowledge of PDFs.« less

Importance of proper renormalization scale-setting for QCD testing at colliders

DOE PAGES

Wu, Xing -Gang; Wang, Sheng -Quan; Brodsky, Stanley J.

2015-12-22

A primary problem affecting perturbative quantum chromodynamic (pQCD) analyses is the lack of a method for setting the QCD running-coupling renormalization scale such that maximally precise fixed-order predictions for physical observables are obtained. The Principle of Maximum Conformality (PMC) eliminates the ambiguities associated with the conventional renormalization scale-setting procedure, yielding predictions that are independent of the choice of renormalization scheme. The QCD coupling scales and the effective number of quark flavors are set order-by-order in the pQCD series. The PMC has a solid theoretical foundation, satisfying the standard renormalization group invariance condition and all of the self-consistency conditions derived frommore » the renormalization group. The PMC scales at each order are obtained by shifting the arguments of the strong force coupling constant αs to eliminate all non-conformal {βi} terms in the pQCD series. The {βi} terms are determined from renormalization group equations without ambiguity. The correct behavior of the running coupling at each order and at each phase-space point can then be obtained. The PMC reduces in the N C → 0 Abelian limit to the Gell-Mann-Low method. In this brief report, we summarize the results of our recent application of the PMC to a number of collider processes, emphasizing the generality and applicability of this approach. A discussion of hadronic Z decays shows that, by applying the PMC, one can achieve accurate predictions for the total and separate decay widths at each order without scale ambiguities. We also show that, if one employs the PMC to determine the top-quark pair forward-backward asymmetry at the next-to-next-to-leading order level, one obtains a comprehensive, self-consistent pQCD explanation for the Tevatron measurements of the asymmetry. This accounts for the “increasing-decreasing” behavior observed by the D0 collaboration for increasing tt¯ invariant mass. At lower

QCD and Asymptotic Freedom:. Perspectives and Prospects

NASA Astrophysics Data System (ADS)

Wilczek, Frank

QCD is now a mature theory, and it is possible to begin to view its place in the conceptual universe of physics with an appropriate perspective. There is a certain irony in the achievements of QCD. For the problems which initially drove its development — specifically, the desire to understand in detail the force that holds atomic nuclei together, and later the desire to calculate the spectrum of hadrons and their interactions — only limited insight has been achieved. However, I shall argue that QCD is actually more special and important a theory than one had any right to anticipate. In many ways, the importance of the solution transcends that of the original motivating problems. After elaborating on these quasiphilosophical remarks, I discuss two current frontiers of physics that illustrate the continuing vitality of the ideas. The recent wealth of beautiful precision experiments measuring the parameters of the standard model have made it possible to consider the unification of couplings in unprecedented quantitative detail. One central result emerging from these developments is a tantalizing hint of virtual supersymmetry. The possibility of phase transitions in matter at temperatures of order ~102 MeV, governed by QCD dynamics, is of interest from several points of view. Besides having a certain intrinsic grandeur, the question “Does the nature of matter change qualitatively, as it is radically heated?” is important for cosmology, relevant to planned high-energy heavy-ion collision experiments, and provides a promising arena for numerical simulations of QCD. Recent numerical work seems to be consistent with expectations suggested by renormalization group analysis of the potential universality classes of the QCD chiral phase transition; specifically, that the transition is second-order for two species of massless quarks but first order otherwise. There is an interesting possibility of long-range correlations in heavy ion collisions due to the creation of

QCD: Quantum Chromodynamics

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

Lincoln, Don

The strongest force in the universe is the strong nuclear force and it governs the behavior of quarks and gluons inside protons and neutrons. The name of the theory that governs this force is quantum chromodynamics, or QCD. In this video, Fermilab’s Dr. Don Lincoln explains the intricacies of this dominant component of the Standard Model.

Lepton-rich cold QCD matter in protoneutron stars

NASA Astrophysics Data System (ADS)

Jiménez, J. C.; Fraga, E. S.

2018-05-01

We investigate protoneutron star matter using the state-of-the-art perturbative equation of state for cold and dense QCD in the presence of a fixed lepton fraction in which both electrons and neutrinos are included. Besides computing the modifications in the equation of state due to the presence of trapped neutrinos, we show that stable strange quark matter has a more restricted parameter space. We also study the possibility of nucleation of unpaired quark matter in the core of protoneutron stars by matching the lepton-rich QCD pressure onto a hadronic equation of state, namely TM1 with trapped neutrinos. Using the inherent dependence of perturbative QCD on the renormalization scale parameter, we provide a measure of the uncertainty in the observables we compute.

Implications of the principle of maximum conformality for the QCD strong coupling

DOE PAGES

Deur, Alexandre; Shen, Jian -Ming; Wu, Xing -Gang; ...

2017-08-14

The Principle of Maximum Conformality (PMC) provides scale-fixed perturbative QCD predictions which are independent of the choice of the renormalization scheme, as well as the choice of the initial renormalization scale. In this article, we will test the PMC by comparing its predictions for the strong couplingmore » $$\\alpha^s_{g_1}(Q)$$, defined from the Bjorken sum rule, with predictions using conventional pQCD scale-setting. The two results are found to be compatible with each other and with the available experimental data. However, the PMC provides a significantly more precise determination, although its domain of applicability ($$Q \\gtrsim 1.5$$ GeV) does not extend to as small values of momentum transfer as that of a conventional pQCD analysis ($$Q \\gtrsim 1$$ GeV). In conclusion, we suggest that the PMC range of applicability could be improved by a modified intermediate scheme choice or using a single effective PMC scale.« less

Massive QCD Amplitudes at Higher Orders

NASA Astrophysics Data System (ADS)

Moch, S.; Mitov, A.

2007-11-01

We consider the factorisation properties of on-shell QCD amplitudes with massive partons in the limit when all kinematical invariants are large compared to the parton mass and discuss the structure of their infrared singularities. The dimensionally regulated soft poles and the large collinear logarithms of the parton masses exponentiate to all orders. Based on this factorisation a simple relation between massless and massive scattering amplitudes in gauge theories can be established. We present recent applications of this relation for the calculation of the two-loop virtual QCD corrections to the hadro-production of heavy quarks.

QCD Physics with the CMS Experiment

NASA Astrophysics Data System (ADS)

Cerci, S.

2017-12-01

Jets which are the signatures of quarks and gluons in the detector can be described by Quantum Chromodynamics (QCD) in terms of parton-parton scattering. Jets are abundantly produced at the LHC's high energy scales. Measurements of inclusive jets, dijets and multijets can be used to test perturbative QCD predictions and to constrain parton distribution functions (PDF), as well as to measure the strong coupling constant αS . The measurements use the samples of proton-proton collisions collected with the CMS detector at the LHC at various center-of-mass energies of 7, 8 and 13 TeV.

Hadron mass spectrum from lattice QCD.

PubMed

Majumder, Abhijit; Müller, Berndt

2010-12-17

Finite temperature lattice simulations of quantum chromodynamics (QCD) are sensitive to the hadronic mass spectrum for temperatures below the "critical" temperature T(c) ≈ 160 MeV. We show that a recent precision determination of the QCD trace anomaly shows evidence for the existence of a large number of hadron states beyond those known from experiment. The lattice results are well represented by an exponentially growing mass spectrum up to a temperature T=155 MeV. Using simple parametrizations of the hadron mass spectrum we show how one may estimate the total spectral weight in these yet undermined states.

Nucleon matrix elements from lattice QCD with all-mode-averaging and a domain-decomposed solver: An exploratory study

NASA Astrophysics Data System (ADS)

von Hippel, Georg; Rae, Thomas D.; Shintani, Eigo; Wittig, Hartmut

2017-01-01

We study the performance of all-mode-averaging (AMA) when used in conjunction with a locally deflated SAP-preconditioned solver, determining how to optimize the local block sizes and number of deflation fields in order to minimize the computational cost for a given level of overall statistical accuracy. We find that AMA enables a reduction of the statistical error on nucleon charges by a factor of around two at the same cost when compared to the standard method. As a demonstration, we compute the axial, scalar and tensor charges of the nucleon in Nf = 2 lattice QCD with non-perturbatively O(a)-improved Wilson quarks, using O(10,000) measurements to pursue the signal out to source-sink separations of ts ∼ 1.5 fm. Our results suggest that the axial charge is suffering from a significant amount (5-10%) of excited-state contamination at source-sink separations of up to ts ∼ 1.2 fm, whereas the excited-state contamination in the scalar and tensor charges seems to be small.

The cosmic QCD phase transition with dense matter and its gravitational waves from holography

NASA Astrophysics Data System (ADS)

Ahmadvand, M.; Bitaghsir Fadafan, K.

2018-04-01

Consistent with cosmological constraints, there are scenarios with the large lepton asymmetry which can lead to the finite baryochemical potential at the cosmic QCD phase transition scale. In this paper, we investigate this possibility in the holographic models. Using the holographic renormalization method, we find the first order Hawking-Page phase transition, between the Reissner-Nordström AdS black hole and thermal charged AdS space, corresponding to the de/confinement phase transition. We obtain the gravitational wave spectra generated during the evolution of bubbles for a range of the bubble wall velocity and examine the reliability of the scenarios and consequent calculations by gravitational wave experiments.

Lattice QCD results for the HVP contribution to the anomalous magnetic moments of leptons

NASA Astrophysics Data System (ADS)

2018-03-01

We present lattice QCD results by the Budapest-Marseille-Wuppertal (BMW) Collaboration for the leading-order contribution of the hadron vacuum polarization (LOHVP) to the anomalous magnetic moments of all charged leptons. Calculations are performed with u, d, s and c quarks at their physical masses, in volumes of linear extent larger than 6 fm, and at six values of the lattice spacing, allowing for controlled continuum extrapolations. All connected and disconnected contributions are calculated for not only the muon but also the electron and tau anomalous magnetic moments. Systematic uncertainties are thoroughly discussed and comparisons with other calculations and phenomenological estimates are made.

The Erice Centre, Gell-Mann QCD, the Effective Energy and Complexity

NASA Astrophysics Data System (ADS)

Zichichi, A.

2014-06-01

On the occasion of the 80th Anniversary of Murray Gell-Mann I recalled the role played by Murray in those experimental and technological activities I had been directly involved during many years, which started in 1955 up to the time of the LHC supercollider, where we propose to study the Quark-Gluon-Coloured-World (QGCW), which is totally different from our world made of QCD colourless baryons and mesons...

D-Wave Heavy Baryons from QCD Sum Rules

NASA Astrophysics Data System (ADS)

Mao, Qiang; Chen, Hua-Xing; Hosaka, Atsushi; Liu, Xiang; Zhu, Shi-Lin

We study the D-wave heavy baryons using the method of QCD sum rules in the framework of heavy quark effective theory. Our results suggest that the Λc(2860), Λc(2880), Ξc(3055) and Ξc(3080) complete two D-wave SU(3) flavor 3¯F charmed baryon doublets of JP = 3/2+ and 5/2+.

Local-duality QCD sum rules for strong isospin breaking in the decay constants of heavy-light mesons.

PubMed

Lucha, Wolfgang; Melikhov, Dmitri; Simula, Silvano

2018-01-01

We discuss the leptonic decay constants of heavy-light mesons by means of Borel QCD sum rules in the local-duality (LD) limit of infinitely large Borel mass parameter. In this limit, for an appropriate choice of the invariant structures in the QCD correlation functions, all vacuum-condensate contributions vanish and all nonperturbative effects are contained in only one quantity, the effective threshold. We study properties of the LD effective thresholds in the limits of large heavy-quark mass [Formula: see text] and small light-quark mass [Formula: see text]. In the heavy-quark limit, we clarify the role played by the radiative corrections in the effective threshold for reproducing the pQCD expansion of the decay constants of pseudoscalar and vector mesons. We show that the dependence of the meson decay constants on [Formula: see text] arises predominantly (at the level of 70-80%) from the calculable [Formula: see text]-dependence of the perturbative spectral densities. Making use of the lattice QCD results for the decay constants of nonstrange and strange pseudoscalar and vector heavy mesons, we obtain solid predictions for the decay constants of heavy-light mesons as functions of [Formula: see text] in the range from a few to 100 MeV and evaluate the corresponding strong isospin-breaking effects: [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text].

Methods to characterize charging effects

NASA Astrophysics Data System (ADS)

Slots, H.

1984-08-01

Methods to characterize charging in insulating material under high voltage dc stress, leading to electrical breakdown, are reviewed. The behavior of the charges can be studied by ac loss angle measurements after application or removal of dc bias. Measurements were performed on oil-paper and oil-Mylar systems. The poor reproducibility of the measurements makes it impossible to draw more than qualitative conclusions about the charging effects. With an ultrasound pressure wave the electric field distribution in a material can be determined. An alternative derivation for the transient response of a system which elucidates the influence of several parameters in a simple way is given.

Observables of QCD diffraction

NASA Astrophysics Data System (ADS)

Mieskolainen, Mikael; Orava, Risto

2017-03-01

A new combinatorial vector space measurement model is introduced for soft QCD diffraction. The model independent mathematical construction resolves experimental complications; the theoretical framework of the approach includes the Good-Walker view of diffraction, Regge phenomenology together with AGK cutting rules and random fluctuations.

Renormalization scheme dependence of high-order perturbative QCD predictions

NASA Astrophysics Data System (ADS)

Ma, Yang; Wu, Xing-Gang

2018-02-01

Conventionally, one adopts typical momentum flow of a physical observable as the renormalization scale for its perturbative QCD (pQCD) approximant. This simple treatment leads to renormalization scheme-and-scale ambiguities due to the renormalization scheme and scale dependence of the strong coupling and the perturbative coefficients do not exactly cancel at any fixed order. It is believed that those ambiguities will be softened by including more higher-order terms. In the paper, to show how the renormalization scheme dependence changes when more loop terms have been included, we discuss the sensitivity of pQCD prediction on the scheme parameters by using the scheme-dependent {βm ≥2}-terms. We adopt two four-loop examples, e+e-→hadrons and τ decays into hadrons, for detailed analysis. Our results show that under the conventional scale setting, by including more-and-more loop terms, the scheme dependence of the pQCD prediction cannot be reduced as efficiently as that of the scale dependence. Thus a proper scale-setting approach should be important to reduce the scheme dependence. We observe that the principle of minimum sensitivity could be such a scale-setting approach, which provides a practical way to achieve optimal scheme and scale by requiring the pQCD approximate be independent to the "unphysical" theoretical conventions.

QCD: Quantum Chromodynamics

ScienceCinema

Lincoln, Don

2018-01-16

The strongest force in the universe is the strong nuclear force and it governs the behavior of quarks and gluons inside protons and neutrons. The name of the theory that governs this force is quantum chromodynamics, or QCD. In this video, Fermilab’s Dr. Don Lincoln explains the intricacies of this dominant component of the Standard Model.

Hadron interactions and exotic hadrons from lattice QCD

NASA Astrophysics Data System (ADS)

Ikeda, Yoichi

2014-09-01

One of the interesting subjects in hadron physics is to look for the multiquark configurations. One of candidates is the H-dibaryon (udsuds), and the possibility of the bound H-dibaryon has been recently studied from lattice QCD. We also extend the HAL QCD method to define potentials on the lattice between baryons to meson-meson systems including charm quarks to search for the bound tetraquark Tcc (ud c c) and Tcs (ud c s). In the presentation, after reviewing the HAL QCD method, we report the results on the H-dibaryon, the tetraquark Tcc (ud c c) and Tcs (ud c s), where we have employed the relativistic heavy quark action to treat the charm quark dynamics with pion masses, mπ = 410, 570, 700 MeV.

Progress in vacuum susceptibilities and their applications to the chiral phase transition of QCD

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

Cui, Zhu-Fang, E-mail: phycui@nju.edu.cn; State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, CAS, Beijing, 100190; Hou, Feng-Yao

2015-07-15

The QCD vacuum condensates and various vacuum susceptibilities are all important parameters which characterize the nonperturbative properties of the QCD vacuum. In the QCD sum rules external field formula, various QCD vacuum susceptibilities play important roles in determining the properties of hadrons. In this paper, we review the recent progress in studies of vacuum susceptibilities together with their applications to the chiral phase transition of QCD. The results of the tensor, the vector, the axial–vector, the scalar, and the pseudo-scalar vacuum susceptibilities are shown in detail in the framework of Dyson–Schwinger equations.

QCD unitarity constraints on Reggeon Field Theory

NASA Astrophysics Data System (ADS)

Kovner, Alex; Levin, Eugene; Lublinsky, Michael

2016-08-01

We point out that the s-channel unitarity of QCD imposes meaningful constraints on a possible form of the QCD Reggeon Field Theory. We show that neither the BFKL nor JIMWLK nor Braun's Hamiltonian satisfy the said constraints. In a toy, zero transverse dimensional case we construct a model that satisfies the analogous constraint and show that at infinite energy it indeed tends to a "black disk limit" as opposed to the model with triple Pomeron vertex only, routinely used as a toy model in the literature.

Solvation effects on like-charge attraction.

PubMed

Ghanbarian, Shahzad; Rottler, Jörg

2013-02-28

We present results of molecular dynamics simulations of the electrostatic interaction between two parallel charged rods in the presence of divalent counterions. Such polyelectrolytes have been considered as a simple model for understanding electrostatic interactions in highly charged biomolecules such as DNA. Since there are correlations between the free charge carriers, the phenomenon of like charge attraction appears for specific parameters. We explore the role of solvation effects and the resulting deviations from Coulomb's law on the nanoscale on this peculiar phenomenon. The behavior of the force between the charged rods in a simulation with atomistic representation of water molecules is completely different from a model in which water is modeled as a continuum dielectric. By calculating counterion-rodion pair correlation functions, we find that the presence of water molecules changes the structure of the counterion cloud and results in both qualitative and quantitative changes of the force between highly charged polyelectrolytes.

Hybrid baryons in QCD

DOE PAGES

Dudek, Jozef J.; Edwards, Robert G.

2012-03-21

In this study, we present the first comprehensive study of hybrid baryons using lattice QCD methods. Using a large basis of composite QCD interpolating fields we extract an extensive spectrum of baryon states and isolate those of hybrid character using their relatively large overlap onto operators which sample gluonic excitations. We consider the spectrum of Nucleon and Delta states at several quark masses finding a set of positive parity hybrid baryons with quantum numbersmore » $$N_{1/2^+},\\,N_{1/2^+},\\,N_{3/2^+},\\, N_{3/2^+},\\,N_{5/2^+},\\,$$ and $$\\Delta_{1/2^+},\\, \\Delta_{3/2^+}$$ at an energy scale above the first band of `conventional' excited positive parity baryons. This pattern of states is compatible with a color octet gluonic excitation having $$J^{P}=1^{+}$$ as previously reported in the hybrid meson sector and with a comparable energy scale for the excitation, suggesting a common bound-state construction for hybrid mesons and baryons.« less

Process-independent strong running coupling

DOE PAGES

Binosi, Daniele; Mezrag, Cedric; Papavassiliou, Joannis; ...

2017-09-25

Here, we unify two widely different approaches to understanding the infrared behavior of quantum chromodynamics (QCD), one essentially phenomenological, based on data, and the other computational, realized via quantum field equations in the continuum theory. Using the latter, we explain and calculate a process-independent running-coupling for QCD, a new type of effective charge that is an analogue of the Gell-Mann–Low effective coupling in quantum electrodynamics. The result is almost identical to the process-dependent effective charge defined via the Bjorken sum rule, which provides one of the most basic constraints on our knowledge of nucleon spin structure. As a result, thismore » reveals the Bjorken sum to be a near direct means by which to gain empirical insight into QCD's Gell-Mann–Low effective charge.« less

Process-independent strong running coupling

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

Binosi, Daniele; Mezrag, Cedric; Papavassiliou, Joannis

Here, we unify two widely different approaches to understanding the infrared behavior of quantum chromodynamics (QCD), one essentially phenomenological, based on data, and the other computational, realized via quantum field equations in the continuum theory. Using the latter, we explain and calculate a process-independent running-coupling for QCD, a new type of effective charge that is an analogue of the Gell-Mann–Low effective coupling in quantum electrodynamics. The result is almost identical to the process-dependent effective charge defined via the Bjorken sum rule, which provides one of the most basic constraints on our knowledge of nucleon spin structure. As a result, thismore » reveals the Bjorken sum to be a near direct means by which to gain empirical insight into QCD's Gell-Mann–Low effective charge.« less

Instanton liquid properties from lattice QCD

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

Athenodorou, A.; Boucaud, Philippe; De Soto, F.

Here, we examined the instanton contribution to the QCD configurations generated from lattice QCD for N F = 0, N F = 2 + 1 and N F = 2 + 1 + 1 dynamical quark flavors from two different and complementary approaches. First via the use of Gradient flow, we computed instanton liquid properties using an algorithm to localize instantons in the gauge field configurations and studied their evolution with flow time. Then, the analysis of the running at low momenta of gluon Green's functions serves as an independent confirmation of the instanton density which can also be derivedmore » without the use of the Gradient flow.« less

Instanton liquid properties from lattice QCD

DOE PAGES

Athenodorou, A.; Boucaud, Philippe; De Soto, F.; ...

2018-02-22

Here, we examined the instanton contribution to the QCD configurations generated from lattice QCD for N F = 0, N F = 2 + 1 and N F = 2 + 1 + 1 dynamical quark flavors from two different and complementary approaches. First via the use of Gradient flow, we computed instanton liquid properties using an algorithm to localize instantons in the gauge field configurations and studied their evolution with flow time. Then, the analysis of the running at low momenta of gluon Green's functions serves as an independent confirmation of the instanton density which can also be derivedmore » without the use of the Gradient flow.« less

Flux tubes in the QCD vacuum

NASA Astrophysics Data System (ADS)

Cea, Paolo; Cosmai, Leonardo; Cuteri, Francesca; Papa, Alessandro

2017-06-01

The hypothesis that the QCD vacuum can be modeled as a dual superconductor is a powerful tool to describe the distribution of the color field generated by a quark-antiquark static pair and, as such, can provide useful clues for the understanding of confinement. In this work we investigate, by lattice Monte Carlo simulations of the S U (3 ) pure gauge theory and of (2 +1 )-flavor QCD with physical mass settings, some properties of the chromoelectric flux tube at zero temperature and their dependence on the physical distance between the static sources. We draw some conclusions about the validity domain of the dual superconductor picture.

A consumer`s guide to lattice QCD results

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

DeGrand, T.

1994-12-01

The author presents an overview of recent lattice QCD results on hadron spectroscopy and matrix elements. Case studies include light quark spectroscopy, the determination of {alpha}{sub s} from heavy quark spectroscopy, the D-meson decay constant, a calculation of the Isgur-Wise function, and some examples of the (lack of) effect of sea quarks on matrix elements. The review is intended for the nonexpert.

Lattice QCD and nucleon resonances

NASA Astrophysics Data System (ADS)

Edwards, R. G.; Fiebig, H. R.; Fleming, G.; Richards, D. G.; LHP Collaboration

2004-06-01

Lattice calculations provide an ab initio means for the study of QCD. Recent progress at understanding the spectrum and structure of nucleons from lattice QCD studies is reviewed. Measurements of the masses of the lightest particles for the lowest spin values are described and related to predictions of the quark model. Measurements of the mass of the first radial excitation of the nucleon, the so-called Roper resonance, obtained using Bayesian statistical analyses, are detailed. The need to perform calculations at realistically light values of the pion mass is emphasised, and the exciting progress at attaining such masses is outlined. The talk concludes with future prospects, emphasising the importance of constructing a basis of interpolating operators that is sensitive to three-quark states, to multi-quark states, and to excited glue.

Symmetry Transition Preserving Chirality in QCD: A Versatile Random Matrix Model

NASA Astrophysics Data System (ADS)

Kanazawa, Takuya; Kieburg, Mario

2018-06-01

We consider a random matrix model which interpolates between the chiral Gaussian unitary ensemble and the Gaussian unitary ensemble while preserving chiral symmetry. This ensemble describes flavor symmetry breaking for staggered fermions in 3D QCD as well as in 4D QCD at high temperature or in 3D QCD at a finite isospin chemical potential. Our model is an Osborn-type two-matrix model which is equivalent to the elliptic ensemble but we consider the singular value statistics rather than the complex eigenvalue statistics. We report on exact results for the partition function and the microscopic level density of the Dirac operator in the ɛ regime of QCD. We compare these analytical results with Monte Carlo simulations of the matrix model.

Top Quark Pair Production in Association with a Jet with Next-to-Leading-Order QCD Off-Shell Effects at the Large Hadron Collider.

PubMed

Bevilacqua, G; Hartanto, H B; Kraus, M; Worek, M

2016-02-05

We present a complete description of top quark pair production in association with a jet in the dilepton channel. Our calculation is accurate to next-to-leading order (NLO) in QCD and includes all nonresonant diagrams, interferences, and off-shell effects of the top quark. Moreover, nonresonant and off-shell effects due to the finite W gauge boson width are taken into account. This calculation constitutes the first fully realistic NLO computation for top quark pair production with a final state jet in hadronic collisions. Numerical results for differential distributions as well as total cross sections are presented for the Large Hadron Collider at 8 TeV. With our inclusive cuts, NLO predictions reduce the unphysical scale dependence by more than a factor of 3 and lower the total rate by about 13% compared to leading-order QCD predictions. In addition, the size of the top quark off-shell effects is estimated to be below 2%.

Aspects of QCD current algebra on a null plane

NASA Astrophysics Data System (ADS)

Beane, S. R.; Hobbs, T. J.

2016-09-01

Consequences of QCD current algebra formulated on a light-like hyperplane are derived for the forward scattering of vector and axial-vector currents on an arbitrary hadronic target. It is shown that current algebra gives rise to a special class of sum rules that are direct consequences of the independent chiral symmetry that exists at every point on the two-dimensional transverse plane orthogonal to the lightlike direction. These sum rules are obtained by exploiting the closed, infinite-dimensional algebra satisfied by the transverse moments of null-plane axial-vector and vector charge distributions. In the special case of a nucleon target, this procedure leads to the Adler-Weisberger, Gerasimov-Drell-Hearn, Cabibbo-Radicati and Fubini-Furlan-Rossetti sum rules. Matching to the dispersion-theoretic language which is usually invoked in deriving these sum rules, the moment sum rules are shown to be equivalent to algebraic constraints on forward S-matrix elements in the Regge limit.

QCD for Postgraduates (4/5)

ScienceCinema

Zanderighi, Giulia

2018-05-23

Modern QCD - Lecture 4. We will consider some processes of interest at the LHC and will discuss the main elements of their cross-section calculations. We will also summarize the current status of higher order calculations.

Quark–hadron phase structure, thermodynamics, and magnetization of QCD matter

NASA Astrophysics Data System (ADS)

Nasser Tawfik, Abdel; Magied Diab, Abdel; Hussein, M. T.

2018-05-01

The SU(3) Polyakov linear-sigma model (PLSM) is systematically implemented to characterize the quark-hadron phase structure and to determine various thermodynamic quantities and the magnetization of quantum chromodynamic (QCD) matter. Using mean-field approximation, the dependence of the chiral order parameter on a finite magnetic field is also calculated. Under a wide range of temperatures and magnetic field strengths, various thermodynamic quantities including trace anomaly, speed of sound squared, entropy density, and specific heat are presented, and some magnetic properties are described as well. Where available these results are compared to recent lattice QCD calculations. The temperature dependence of these quantities confirms our previous finding that the transition temperature is reduced with the increase in the magnetic field strength, i.e. QCD matter is characterized by an inverse magnetic catalysis. Furthermore, the temperature dependence of the magnetization showing that QCD matter has paramagnetic properties slightly below and far above the pseudo-critical temperature is confirmed as well. The excellent agreement with recent lattice calculations proves that our QCD-like approach (PLSM) seems to possess the correct degrees of freedom in both the hadronic and partonic phases and describes well the dynamics deriving confined hadrons to deconfined quark-gluon plasma.

Magnetic charge and photon mass: Physical string singularities, Dirac condition, and magnetic confinement

NASA Astrophysics Data System (ADS)

Evans, Timothy J.; Singleton, Douglas

2018-04-01

We find exact, simple solutions to the Proca version of Maxwell’s equations with magnetic sources. Several properties of these solutions differ from the usual case of magnetic charge with a massless photon: (i) the string singularities of the usual 3-vector potentials become real singularities in the magnetic fields; (ii) the different 3-vector potentials become gauge inequivalent and physically distinct solutions; (iii) the magnetic field depends on r and 𝜃 and thus is no longer rotationally symmetric; (iv) a combined system of electric and magnetic charge carries a field angular momentum even when the electric and magnetic charges are located at the same place (i.e. for dyons); (v) for these dyons, one recovers the standard Dirac condition despite the photon being massive. We discuss the reason for this. We conclude by proposing that the string singularity in the magnetic field of an isolated magnetic charge suggests a confinement mechanism for magnetic charge, similar to the flux tube confinement of quarks in QCD.

Edge charge asymmetry in top pair production at the LHC

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

Xiao Bo; Wang Youkai; Zhou Zhongqiu

2011-03-01

In this brief report, we propose a new definition of charge asymmetry in top pair production at the LHC, namely, the edge charge asymmetry (ECA). ECA utilizes the information of drifting direction only for single top (or antitop) with hadronic decay. Therefore, ECA can be free from the uncertainty arising from the missing neutrino in the tt event reconstruction. Moreover, rapidity Y of top (or antitop) is required to be greater than a critical value Y{sub C} in order to suppress the symmetric tt events mainly due to the gluon-gluon fusion process. In this paper, ECA is calculated up tomore » next-to-leading order QCD in the standard model and the choice of the optimal Y{sub C} is investigated.« less

Effects of image charges, interfacial charge discreteness, and surface roughness on the zeta potential of spherical electric double layers.

PubMed

Gan, Zecheng; Xing, Xiangjun; Xu, Zhenli

2012-07-21

We investigate the effects of image charges, interfacial charge discreteness, and surface roughness on spherical electric double layer structures in electrolyte solutions with divalent counterions in the setting of the primitive model. By using Monte Carlo simulations and the image charge method, the zeta potential profile and the integrated charge distribution function are computed for varying surface charge strengths and salt concentrations. Systematic comparisons were carried out between three distinct models for interfacial charges: (1) SURF1 with uniform surface charges, (2) SURF2 with discrete point charges on the interface, and (3) SURF3 with discrete interfacial charges and finite excluded volume. By comparing the integrated charge distribution function and the zeta potential profile, we argue that the potential at the distance of one ion diameter from the macroion surface is a suitable location to define the zeta potential. In SURF2 model, we find that image charge effects strongly enhance charge inversion for monovalent interfacial charges, and strongly suppress charge inversion for multivalent interfacial charges. For SURF3, the image charge effect becomes much smaller. Finally, with image charges in action, we find that excluded volumes (in SURF3) suppress charge inversion for monovalent interfacial charges and enhance charge inversion for multivalent interfacial charges. Overall, our results demonstrate that all these aspects, i.e., image charges, interfacial charge discreteness, their excluding volumes, have significant impacts on zeta potentials of electric double layers.

One-loop QCD thermodynamics in a strong homogeneous and static magnetic field

NASA Astrophysics Data System (ADS)

Rath, Shubhalaxmi; Patra, Binoy Krishna

2017-12-01

We have studied how the equation of state of thermal QCD with two light flavors is modified in a strong magnetic field. We calculate the thermodynamic observables of hot QCD matter up to one-loop, where the magnetic field affects mainly the quark contribution and the gluon part is largely unaffected except for the softening of the screening mass. We have first calculated the pressure of a thermal QCD medium in a strong magnetic field, where the pressure at fixed temperature increases with the magnetic field faster than the increase with the temperature at constant magnetic field. This can be understood from the dominant scale of thermal medium in the strong magnetic field, being the magnetic field, in the same way that the temperature dominates in a thermal medium in the absence of magnetic field. Thus although the presence of a strong magnetic field makes the pressure of hot QCD medium larger, the dependence of pressure on the temperature becomes less steep. Consistent with the above observations, the entropy density is found to decrease with the temperature in the presence of a strong magnetic field which is again consistent with the fact that the strong magnetic field restricts the dynamics of quarks to two dimensions, hence the phase space becomes squeezed resulting in the reduction of number of microstates. Moreover the energy density is seen to decrease and the speed of sound of thermal QCD medium increases in the presence of a strong magnetic field. These findings could have phenomenological implications in heavy ion collisions because the expansion dynamics of the medium produced in non-central ultra-relativistic heavy ion collisions is effectively controlled by both the energy density and the speed of sound.

Nuclear physics from Lattice QCD

NASA Astrophysics Data System (ADS)

Shanahan, Phiala

2017-09-01

I will discuss the current state and future scope of numerical Lattice Quantum Chromodynamics (LQCD) calculations of nuclear matrix elements. The goal of the program is to provide direct QCD calculations of nuclear observables relevant to experimental programs, including double-beta decay matrix elements, nuclear corrections to axial matrix elements relevant to long-baseline neutrino experiments and nuclear sigma terms needed for theory predictions of dark matter cross-sections at underground detectors. I will discuss the progress and challenges on these fronts, and also address recent work constraining a gluonic analogue of the EMC effect, which will be measurable at a future electron-ion collider.

Wilson loops and QCD/string scattering amplitudes

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

Makeenko, Yuri; Olesen, Poul; Niels Bohr International Academy, Niels Bohr Institute, Blegdamsvej 17, 2100 Copenhagen O

2009-07-15

We generalize modern ideas about the duality between Wilson loops and scattering amplitudes in N=4 super Yang-Mills theory to large N QCD by deriving a general relation between QCD meson scattering amplitudes and Wilson loops. We then investigate properties of the open-string disk amplitude integrated over reparametrizations. When the Wilson-loop is approximated by the area behavior, we find that the QCD scattering amplitude is a convolution of the standard Koba-Nielsen integrand and a kernel. As usual poles originate from the first factor, whereas no (momentum-dependent) poles can arise from the kernel. We show that the kernel becomes a constant whenmore » the number of external particles becomes large. The usual Veneziano amplitude then emerges in the kinematical regime, where the Wilson loop can be reliably approximated by the area behavior. In this case, we obtain a direct duality between Wilson loops and scattering amplitudes when spatial variables and momenta are interchanged, in analogy with the N=4 super Yang-Mills theory case.« less

Electroweak Higgs production with HiggsPO at NLO QCD

NASA Astrophysics Data System (ADS)

Greljo, Admir; Isidori, Gino; Lindert, Jonas M.; Marzocca, David; Zhang, Hantian

2017-12-01

We present the HiggsPO UFO model for Monte Carlo event generation of electroweak VH and VBF Higgs production processes at NLO in QCD in the formalism of Higgs pseudo-observables (PO). We illustrate the use of this tool by studying the QCD corrections, matched to a parton shower, for several benchmark points in the Higgs PO parameter space. We find that, while being sizable and thus important to be considered in realistic experimental analyses, the QCD higher-order corrections largely factorize. As an additional finding, based on the NLO results, we advocate to consider 2D distributions of the two-jet azimuthal-angle difference and the leading jet p_T for new physics searches in VBF Higgs production. The HiggsPO UFO model is publicly available.

Domain walls and the C P anomaly in softly broken supersymmetric QCD

NASA Astrophysics Data System (ADS)

Draper, Patrick

2018-04-01

In ordinary QCD with light, degenerate, fundamental flavors, C P symmetry is spontaneously broken at θ =π , and domain wall solutions connecting the vacua can be constructed in chiral perturbation theory. In some cases the breaking of C P saturates a 't Hooft anomaly, and anomaly inflow requires nontrivial massless excitations on the domain walls. Analogously, C P can be spontaneously broken in supersymmetric QCD (SQCD) with light flavors and small soft breaking parameters. We study C P breaking and domain walls in softly broken SQCD with NfQCD, the supersymmetric case contains an extra light field, the η', which has interesting effects on the structure of the walls. Vanishing of the C P anomaly is associated with the existence of multiple domain wall trajectories through field space, including walls which support no nontrivial massless excitations. In cases with an anomaly such walls are forbidden, and their absence in the relevant SQCD theories can be seen directly from the geometry of the low energy field space. In the case Nf=N -1 , multiple approximately Bogomol'nyi-Prasad-Sommerfield walls connect the vacua. Corrections to their tensions can be computed at leading order in the soft breaking parameters, producing a phase diagram for the stable wall trajectory. We also comment on domain walls in the similar case of QCD with an adjoint and fundamental flavors, and on the impact of adding an axion in this theory.

Neutron and proton electric dipole moments from N f=2+1 domain-wall fermion lattice QCD

DOE PAGES

Shintani, Eigo; Blum, Thomas; Izubuchi, Taku; ...

2016-05-05

We present a lattice calculation of the neutron and proton electric dipole moments (EDM’s) with N f = 2 + 1 flavors of domain-wall fermions. The neutron and proton EDM form factors are extracted from three-point functions at the next-to-leading order in the θ vacuum of QCD. In this computation, we use pion masses 330 and 420 MeV and 2.7 fm 3 lattices with Iwasaki gauge action and a 170 MeV pion and 4.6 fm 3 lattice with I-DSDR gauge action, all generated by the RBC and UKQCD collaborations. The all-mode-averaging technique enables an efficient, high statistics calculation; however themore » statistical errors on our results are still relatively large, so we investigate a new direction to reduce them, reweighting with the local topological charge density which appears promising. Furthermore, we discuss the chiral behavior and finite size effects of the EDM’s in the context of baryon chiral perturbation theory.« less

Effects of granular charge on flow and mixing

NASA Astrophysics Data System (ADS)

Shinbrot, T.; Herrmann, H. J.

2008-12-01

Sandstorms in the desert have long been reported to produce sparks and other electrical disturbances - indeed as long ago as 1850, Faraday commented on the peculiarities of granular charging during desert sandstorms. Similarly, lightning strikes within volcanic dust plumes have been repeatedly reported for over half a century, but remain unexplained. The problem of granular charging has applied, as well as natural, implications, for charged particle clouds frequently generate spectacularly devastating dust explosions in granular processing plants, and sand becomes strongly electrified by helicopters traveling in desert environments. The issue even has implications for missions to the Moon and to Mars, where charged dust degrades solar cells viability and clings to spacesuits, limiting the lifetime of their joints. Despite the wide-ranging importance of granular charging, even the simplest aspects of its causes remain elusive. To take one example, sand grains in the desert manage to charge one another despite having only similar materials to rub against over expanses of many miles - thus existing theories of charging due to material differences fail entirely to account for the observed charging of desert sands. In this talk, we describe recent progress made in identifying underlying causes of granular charging, both in desert-like environments and in industrial applications, and we examine effects of granular charging on flow, mixing and separation of common granular materials. We find that charging of identical grains can occur under simple laboratory conditions, and we make new predictions for the effects of this charging on granular behaviours.

QCD and Multiparticle Production - Proceedings of the XXIX International Symposium on Multiparticle Dynamics

NASA Astrophysics Data System (ADS)

Sarcevic, Ina; Tan, Chung-I.

2000-07-01

The Table of Contents for the full book PDF is as follows: * Preface * Monday morning session: Hadronic Final States - Conveners: E. de Wolf and J. W. Gary * Session Chairman: J. W. Gary * Inclusive Jets at the Tevatron * Forward Jets, Dijets, and Subjets at the Tevatron * Inclusive Hadron Production and Dijets at HERA * Recent Opal Results on Photon Structure and Interactions * Review of Two-Photon Physics at LEP * Session Chairman: E. de Wolf * An Intriguing Area-Law-Based Hadron Production Scheme in e+e- Annihilation and Its Possible Extensions * Hyperfine Splitting in Hadron Production at High Energies * Event Selection Effects on Multiplicities in Quark and Gluon Jets * Quark and Gluon Jet Properties at LEP * Rapidity Gaps in Quark and Gluon Jets -- A Perturbative Approach * Monday afternoon session: Diffractive and Small-x - Conveners: M. Derrick and A. White * Session Chairman: A. White * Structure Functions: Low x, High y, Low Q2 * The Next-to-Leading Dynamics of the BFKL Pomeron * Renormalization Group Improved BFKL Equation * Session Chairman: G. Briskin * New Experimental Results on Diffraction at HERA * Diffractive Parton Distributions in Light-Cone QCD * The Logarithmic Derivative of the F2 Structure Function and Saturation * Spin Dependence of Diffractive DIS * Monday evening session * Session Chairman: M. Braun * Tests of QCD with Particle Production at HERA: Review and Outlook * Double Parton Scattering and Hadron Structure in Transverse Space * The High Density Parton Dynamics from Eikonal and Dipole Pictures * Hints of Higher Twist Effects in the Slope of the Proton Structure Function * Tuesday morning session: Correlations and Fluctuations - Conveners: R. Hwa and M. Tannenbaum * Session Chairman: A. Giovannini -- Fluctuations and Correlations * Bose-Einstein Results from L3 * Short-Range and Long-Range Correlations in DIS at HERA * Coior Mutation Model, Intermittency, and Erraticity * QCD Queuing and Hadron Multiplicity * Soft and Semi

Dissociation of heavy quarkonia in an anisotropic hot QCD medium in a quasiparticle model

NASA Astrophysics Data System (ADS)

Jamal, Mohammad Yousuf; Nilima, Indrani; Chandra, Vinod; Agotiya, Vineet Kumar

2018-05-01

The present article is the follow-up work of Phys. Rev. D 94, 094006 (2016), 10.1103/PhysRevD.94.094006, where we have extended the study of quarkonia dissociation in (momentum) anisotropic hot QCD medium. As evident by the experimentally observed collective flow at the RHIC and LHC, the momentum anisotropy is present at almost all the stages after the collision, and therefore, it is important to include its effects in the analysis. Employing the in-medium (corrected) potential while considering the anisotropy (both oblate and prolate cases) in the medium, the thermal widths and the binding energies of the heavy quarkonia states (s -wave charmonia and s -wave bottomonia specifically, for radial quantum numbers n =1 and 2) have been determined. The hot QCD medium effects have been included by employing a quasiparticle description. The presence of anisotropy has modified the potential and then the thermal widths and binding energies of these states in a significant manner. The results show a quite visible shift in the values of dissociation temperatures as compared to the isotropic case. Further, the hot QCD medium interaction effects suppress the dissociation temperature as compared to the case where we consider the medium as a noninteracting ultrarelativistic gas of quarks (antiquarks) and gluons.

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.

C P -odd sector and θ dynamics in holographic QCD

NASA Astrophysics Data System (ADS)

Areán, Daniel; Iatrakis, Ioannis; Järvinen, Matti; Kiritsis, Elias

2017-07-01

The holographic model of V-QCD is used to analyze the physics of QCD in the Veneziano large-N limit. An unprecedented analysis of the C P -odd physics is performed going beyond the level of effective field theories. The structure of holographic saddle points at finite θ is determined, as well as its interplay with chiral symmetry breaking. Many observables (vacuum energy and higher-order susceptibilities, singlet and nonsinglet masses and mixings) are computed as functions of θ and the quark mass m . Wherever applicable the results are compared to those of chiral Lagrangians, finding agreement. In particular, we recover the Witten-Veneziano formula in the small x →0 limit, we compute the θ dependence of the pion mass, and we derive the hyperscaling relation for the topological susceptibility in the conformal window in terms of the quark mass.

Topological susceptibility in finite temperature (2 +1 )-flavor QCD using gradient flow

NASA Astrophysics Data System (ADS)

Taniguchi, Yusuke; Kanaya, Kazuyuki; Suzuki, Hiroshi; Umeda, Takashi; WHOT-QCD Collaboration

2017-03-01

We compute the topological charge and its susceptibility in finite temperature (2 +1 )-flavor QCD on the lattice applying a gradient flow method. With the Iwasaki gauge action and nonperturbatively O (a ) -improved Wilson quarks, we perform simulations on a fine lattice with a ≃0.07 fm at a heavy u , d quark mass with mπ/mρ≃0.63 , but approximately physical s quark mass with mηss/mϕ≃0.74 . In a temperature range from T ≃174 MeV (Nt=16 ) to 697 MeV (Nt=4 ), we study two topics on the topological susceptibility. One is a comparison of gluonic and fermionic definitions of the topological susceptibility. Because the two definitions are related by chiral Ward-Takahashi identities, their equivalence is not trivial for lattice quarks which violate the chiral symmetry explicitly at finite lattice spacings. The gradient flow method enables us to compute them without being bothered by the chiral violation. We find a good agreement between the two definitions with Wilson quarks. The other is a comparison with a prediction of the dilute instanton gas approximation, which is relevant in a study of axions as a candidate of the dark matter in the evolution of the Universe. We find that the topological susceptibility shows a decrease in T which is consistent with the predicted χt(T )∝(T /Tpc)-8 for three-flavor QCD even at low temperature Tpc

The quark condensate in multi-flavour QCD – planar equivalence confronting lattice simulations

DOE PAGES

Armoni, Adi; Shifman, Mikhail; Shore, Graham; ...

2015-02-01

Planar equivalence between the large N limits of N=1 Super Yang–Mills (SYM) theory and a variant of QCD with fermions in the antisymmetric representation is a powerful tool to obtain analytic non-perturbative results in QCD itself. In particular, it allows the quark condensate for N=3 QCD with quarks in the fundamental representation to be inferred from exact calculations of the gluino condensate in N=1 SYM. In this paper, we review and refine our earlier predictions for the quark condensate in QCD with a general number nf of flavours and confront these with lattice results.

Assessing the role of the Kelvin-Helmholtz instability at the QCD cosmological transition

NASA Astrophysics Data System (ADS)

Mourão Roque, V. R. C.; Lugones, G.

2018-03-01

We performed numerical simulations with the PLUTO code in order to analyze the non-linear behavior of the Kelvin-Helmholtz instability in non-magnetized relativistic fluids. The relevance of the instability at the cosmological QCD phase transition was explored using an equation of state based on lattice QCD results with the addition of leptons. The results of the simulations were compared with the theoretical predictions of the linearized theory. For small Mach numbers up to Ms ~ 0.1 we find that both results are in good agreement. However, for higher Mach numbers, non-linear effects are significant. In particular, many initial conditions that look stable according to the linear analysis are shown to be unstable according to the full calculation. Since according to lattice calculations the cosmological QCD transition is a smooth crossover, violent fluid motions are not expected. Thus, in order to assess the role of the Kelvin-Helmholtz instability at the QCD epoch, we focus on simulations with low shear velocity and use monochromatic as well as random perturbations to trigger the instability. We find that the Kelvin-Helmholtz instability can strongly amplify turbulence in the primordial plasma and as a consequence it may increase the amount of primordial gravitational radiation. Such turbulence may be relevant for the evolution of the Universe at later stages and may have an impact in the stochastic gravitational wave background.

Lattice QCD inputs to the CKM unitarity triangle analysis

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

Laiho, Jack; Department of Physics and Astronomy, University of Glasgow, Glasgow, G128 QQ; Lunghi, E.

2010-02-01

We perform a global fit to the Cabibbo-Kobayashi-Maskawa unitarity triangle using the latest experimental and theoretical constraints. Our emphasis is on the hadronic weak matrix elements that enter the analysis, which must be computed using lattice QCD or other nonperturbative methods. Realistic lattice QCD calculations which include the effects of the dynamical up, down, and strange quarks are now available for all of the standard inputs to the global fit. We therefore present lattice averages for all of the necessary hadronic weak matrix elements. We attempt to account for correlations between lattice QCD results in a reasonable but conservative manner:more » whenever there are reasons to believe that an error is correlated between two lattice calculations, we take the degree of correlation to be 100%. These averages are suitable for use as inputs both in the global Cabibbo-Kobayashi-Maskawa unitarity triangle fit and other phenomenological analyses. In order to illustrate the impact of the lattice averages, we make standard model predictions for the parameters B-circumflex{sub K}, |V{sub cb}|, and |V{sub ub}|/|V{sub cb}|. We find a (2-3){sigma} tension in the unitarity triangle, depending upon whether we use the inclusive or exclusive determination of |V{sub cb}|. If we interpret the tension as a sign of new physics in either neutral kaon or B mixing, we find that the scenario with new physics in kaon mixing is preferred by present data.« less

Lattice QCD Inputs to the CKM Unitarity Triangle Analysis

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

Van de Water, R.; Lunghi, E; Laiho, J

2010-02-02

We perform a global fit to the Cabibbo-Kobayashi-Maskawa unitarity triangle using the latest experimental and theoretical constraints. Our emphasis is on the hadronic weak matrix elements that enter the analysis, which must be computed using lattice QCD or other nonperturbative methods. Realistic lattice QCD calculations which include the effects of the dynamical up, down, and strange quarks are now available for all of the standard inputs to the global fit. We therefore present lattice averages for all of the necessary hadronic weak matrix elements. We attempt to account for correlations between lattice QCD results in a reasonable but conservative manner:more » whenever there are reasons to believe that an error is correlated between two lattice calculations, we take the degree of correlation to be 100%. These averages are suitable for use as inputs both in the global Cabibbo-Kobayashi-Maskawa unitarity triangle fit and other phenomenological analyses. In order to illustrate the impact of the lattice averages, we make standard model predictions for the parameters B{sub K}, |V{sub cb}|, and |V{sub ub}|/|Vcb|. We find a (2-3){sigma} tension in the unitarity triangle, depending upon whether we use the inclusive or exclusive determination of |V{sub cb}|. If we interpret the tension as a sign of new physics in either neutral kaon or B mixing, we find that the scenario with new physics in kaon mixing is preferred by present data.« less

Additional strange hadrons from QCD thermodynamics and strangeness freezeout in heavy ion collisions.

PubMed

Bazavov, A; Ding, H-T; Hegde, P; Kaczmarek, O; Karsch, F; Laermann, E; Maezawa, Y; Mukherjee, Swagato; Ohno, H; Petreczky, P; Schmidt, C; Sharma, S; Soeldner, W; Wagner, M

2014-08-15

We compare lattice QCD results for appropriate combinations of net strangeness fluctuations and their correlations with net baryon number fluctuations with predictions from two hadron resonance gas (HRG) models having different strange hadron content. The conventionally used HRG model based on experimentally established strange hadrons fails to describe the lattice QCD results in the hadronic phase close to the QCD crossover. Supplementing the conventional HRG with additional, experimentally uncharted strange hadrons predicted by quark model calculations and observed in lattice QCD spectrum calculations leads to good descriptions of strange hadron thermodynamics below the QCD crossover. We show that the thermodynamic presence of these additional states gets imprinted in the yields of the ground-state strange hadrons leading to a systematic 5-8 MeV decrease of the chemical freeze-out temperatures of ground-state strange baryons.

Proper time regularization and the QCD chiral phase transition

PubMed Central

Cui, Zhu-Fang; Zhang, Jin-Li; Zong, Hong-Shi

2017-01-01

We study the QCD chiral phase transition at finite temperature and finite quark chemical potential within the two flavor Nambu–Jona-Lasinio (NJL) model, where a generalization of the proper-time regularization scheme is motivated and implemented. We find that in the chiral limit the whole transition line in the phase diagram is of second order, whereas for finite quark masses a crossover is observed. Moreover, if we take into account the influence of quark condensate to the coupling strength (which also provides a possible way of how the effective coupling varies with temperature and quark chemical potential), it is found that a CEP may appear. These findings differ substantially from other NJL results which use alternative regularization schemes, some explanation and discussion are given at the end. This indicates that the regularization scheme can have a dramatic impact on the study of the QCD phase transition within the NJL model. PMID:28401889

Search for the pentaquark resonance signature in lattice QCD

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

B. G. Lasscock; J. Hedditch; Derek Leinweber

2005-02-01

Claims concerning the possible discovery of the {Theta}{sup +} pentaquark, with minimal quark content uudd{bar s}, have motivated our comprehensive study into possible pentaquark states using lattice QCD. We review various pentaquark interpolating fields in the literature and create a new candidate ideal for lattice QCD simulations. Using these interpolating fields we attempt to isolate a signal for a five-quark resonance. Calculations are performed using improved actions on a large 20{sup 3} x 40 lattice in the quenched approximation. The standard lattice resonance signal of increasing attraction between baryon constituents for increasing quark mass is not observed for spin-1/2 pentaquarkmore » states. We conclude that evidence supporting the existence of a spin-1/2 pentaquark resonance does not exist in quenched QCD.« less

Exposing the QCD Splitting Function with CMS Open Data.

PubMed

Larkoski, Andrew; Marzani, Simone; Thaler, Jesse; Tripathee, Aashish; Xue, Wei

2017-09-29

The splitting function is a universal property of quantum chromodynamics (QCD) which describes how energy is shared between partons. Despite its ubiquitous appearance in many QCD calculations, the splitting function cannot be measured directly, since it always appears multiplied by a collinear singularity factor. Recently, however, a new jet substructure observable was introduced which asymptotes to the splitting function for sufficiently high jet energies. This provides a way to expose the splitting function through jet substructure measurements at the Large Hadron Collider. In this Letter, we use public data released by the CMS experiment to study the two-prong substructure of jets and test the 1→2 splitting function of QCD. To our knowledge, this is the first ever physics analysis based on the CMS Open Data.

Computing the nucleon charge and axial radii directly at Q2=0 in lattice QCD

NASA Astrophysics Data System (ADS)

Hasan, Nesreen; Green, Jeremy; Meinel, Stefan; Engelhardt, Michael; Krieg, Stefan; Negele, John; Pochinsky, Andrew; Syritsyn, Sergey

2018-02-01

We describe a procedure for extracting momentum derivatives of nucleon matrix elements on the lattice directly at Q2=0 . This is based on the Rome method for computing momentum derivatives of quark propagators. We apply this procedure to extract the nucleon isovector magnetic moment and charge radius as well as the isovector induced pseudoscalar form factor at Q2=0 and the axial radius. For comparison, we also determine these quantities with the traditional approach of computing the corresponding form factors, i.e. GEv(Q2) and GMv(Q2) for the case of the vector current and GPv(Q2) and GAv(Q2) for the axial current, at multiple Q2 values followed by z -expansion fits. We perform our calculations at the physical pion mass using a 2HEX-smeared Wilson-clover action. To control the effects of excited-state contamination, the calculations were done at three source-sink separations and the summation method was used. The derivative method produces results consistent with those from the traditional approach but with larger statistical uncertainties especially for the isovector charge and axial radii.

Higher-order QCD predictions for dark matter production at the LHC in simplified models with s-channel mediators.

PubMed

Backović, Mihailo; Krämer, Michael; Maltoni, Fabio; Martini, Antony; Mawatari, Kentarou; Pellen, Mathieu

Weakly interacting dark matter particles can be pair-produced at colliders and detected through signatures featuring missing energy in association with either QCD/EW radiation or heavy quarks. In order to constrain the mass and the couplings to standard model particles, accurate and precise predictions for production cross sections and distributions are of prime importance. In this work, we consider various simplified models with s -channel mediators. We implement such models in the FeynRules/MadGraph5_aMC@NLO framework, which allows to include higher-order QCD corrections in realistic simulations and to study their effect systematically. As a first phenomenological application, we present predictions for dark matter production in association with jets and with a top-quark pair at the LHC, at next-to-leading order accuracy in QCD, including matching/merging to parton showers. Our study shows that higher-order QCD corrections to dark matter production via s -channel mediators have a significant impact not only on total production rates, but also on shapes of distributions. We also show that the inclusion of next-to-leading order effects results in a sizeable reduction of the theoretical uncertainties.

First Simultaneous Extraction of Spin-Dependent Parton Distributions and Fragmentation Functions from a Global QCD Analysis.

PubMed

Ethier, J J; Sato, N; Melnitchouk, W

2017-09-29

We perform the first global QCD analysis of polarized inclusive and semi-inclusive deep-inelastic scattering and single-inclusive e^{+}e^{-} annihilation data, simultaneously fitting the parton distribution and fragmentation functions using the iterative Monte Carlo method. Without imposing SU(3) symmetry relations, we find the strange polarization to be very small, consistent with zero for both inclusive and semi-inclusive data, which provides a resolution to the strange quark polarization puzzle. The combined analysis also allows the direct extraction from data of the isovector and octet axial charges, and is consistent with a small SU(2) flavor asymmetry in the polarized sea.

First Simultaneous Extraction of Spin-Dependent Parton Distributions and Fragmentation Functions from a Global QCD Analysis

DOE PAGES

Ethier, Jacob J.; Sato, Nobuo; Melnitchouk, Wally

2017-09-26

In this paper, we perform the first global QCD analysis of polarized inclusive and semi-inclusive deep-inelastic scattering and single-inclusive $e^+e^-$ annihilation data, simultaneously fitting the parton distribution and fragmentation functions using the iterative Monte Carlo method. Without imposing SU(3) symmetry relations, we find the strange polarization to be very small, consistent with zero for both inclusive and semi-inclusive data, which provides a resolution to the strange quark polarization puzzle. Finally, the combined analysis also allows the direct extraction from data of the isovector and octet axial charges, and is consistent with a small SU(2) flavor asymmetry in the polarized sea.

Large N[sub c], constituent quarks, and N, [Delta] charge radii

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

Alfons J. Buchmann; Richard F. Lebed.

2000-03-01

The authors show how one may define baryon constituent quarks in a rigorous manner, given physical assumptions that hold in the large-N[sub c] limit of QCD. This constituent picture gives rise to an operator expansion that has been used to study large-N[sub c] baryon observables; here they apply it to the case of charge radii of the N and [Delta] states. For example, one finds the relation r[sub p][sup 2] [minus] r[sub [Delta][sup +

QCDOC: A 10-teraflops scale computer for lattice QCD

NASA Astrophysics Data System (ADS)

Chen, D.; Christ, N. H.; Cristian, C.; Dong, Z.; Gara, A.; Garg, K.; Joo, B.; Kim, C.; Levkova, L.; Liao, X.; Mawhinney, R. D.; Ohta, S.; Wettig, T.

2001-03-01

The architecture of a new class of computers, optimized for lattice QCD calculations, is described. An individual node is based on a single integrated circuit containing a PowerPC 32-bit integer processor with a 1 Gflops 64-bit IEEE floating point unit, 4 Mbyte of memory, 8 Gbit/sec nearest-neighbor communications and additional control and diagnostic circuitry. The machine's name, QCDOC, derives from "QCD On a Chip".

QCD Resummation for Single Spin Asymmetries

NASA Astrophysics Data System (ADS)

Kang, Zhong-Bo; Xiao, Bo-Wen; Yuan, Feng

2011-10-01

We study the transverse momentum dependent factorization for single spin asymmetries in Drell-Yan and semi-inclusive deep inelastic scattering processes at one-loop order. The next-to-leading order hard factors are calculated in the Ji-Ma-Yuan factorization scheme. We further derive the QCD resummation formalisms for these observables following the Collins-Soper-Sterman method. The results are expressed in terms of the collinear correlation functions from initial and/or final state hadrons coupled with the Sudakov form factor containing all order soft-gluon resummation effects. The scheme-independent coefficients are calculated up to one-loop order.

QCD Resummation for Single Spin Asymmetries

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

Kang Z.; Xiao, Bo-Wen; Yuan, Feng

We study the transverse momentum dependent factorization for single spin asymmetries in Drell-Yan and semi-inclusive deep inelastic scattering processes at one-loop order. The next-to-leading order hard factors are calculated in the Ji-Ma-Yuan factorization scheme. We further derive the QCD resummation formalisms for these observables following the Collins-Soper-Sterman method. The results are expressed in terms of the collinear correlation functions from initial and/or final state hadrons coupled with the Sudakov form factor containing all order soft-gluon resummation effects. The scheme-independent coefficients are calculated up to one-loop order.

Nuclear physics from lattice QCD at strong coupling.

PubMed

de Forcrand, Ph; Fromm, M

2010-03-19

We study numerically the strong coupling limit of lattice QCD with one flavor of massless staggered quarks. We determine the complete phase diagram as a function of temperature and chemical potential, including a tricritical point. We clarify the nature of the low temperature dense phase, which is strongly bound "nuclear" matter. This strong binding is explained by the nuclear potential, which we measure. Finally, we determine, from this first-principles limiting case of QCD, the masses of "atomic nuclei" up to A=12 "carbon".

Hard QCD processes in the nuclear medium

NASA Astrophysics Data System (ADS)

Freese, Adam

The environment inside the atomic nucleus is one of the most fascinating arenas for the study of quantum chromodynamics (QCD). The strongly-interacting nature of the nuclear medium a?ects the nature of both QCD processes and the quark-gluon structure of hadrons, allowing several unique aspects of the strong nuclear force to be investigated in reactions involving nuclear targets. The research presented in this dissertation explores two aspects of nuclear QCD: firstly, the partonic structure of the nucleus itself; and secondly, the use of the nucleus as a micro-laboratory in which QCD processes can be studied. The partonic structure of the nucleus is calculated in this work by deriving and utilizing a convolution formula. The hadronic structure of the nucleus and the quark-gluon structure of its constituent nucleons are taken together to determine the nuclear partonic structure. Light cone descriptions of short range correlations, in terms of both hadronic and partonic structure, are derived and taken into account. Medium modifications of the bound nucleons are accounted for using the color screening model, and QCD evolution is used to connect nuclear partonic structure at vastly di?erent energy scales. The formalism developed for calculating nuclear partonic structure is applied to inclusive dijet production from proton-nucleus collisions at LHC kinematics, and novel predictions are calculated and presented for the dijet cross section. The nucleus is investigated as a micro-laboratory in vector meson photoproduction reactions. In particular, the deuteron is studied in the break-up reaction gammad → Vpn, for both the φ(1020) and J/v vector mesons. The generalized eikonal approximation is utilized, allowing unambiguous separation of the impulse approximation and final state interactions (FSIs). Two peaks or valleys are seen in the angular distribution of the reaction cross section, each of which is due to an FSI between either the proton and neutron, or the

Prediction of the bottomonium D-wave spectrum from full lattice QCD.

PubMed

Daldrop, J O; Davies, C T H; Dowdall, R J

2012-03-09

We calculate the full spectrum of D-wave states in the Υ system in lattice QCD for the first time, by using an improved version of nonrelativistic QCD on coarse and fine "second-generation" gluon field configurations from the MILC Collaboration that include the effect of up, down, strange, and charm quarks in the sea. By taking the 2S-1S splitting to set the lattice spacing, we determine the (3)D2-1S splitting to 2.3% and find agreement with experiment. Our prediction of the fine structure relative to the (3)D2 gives the (3)D3 at 10.181(5) GeV and the (3)D1 at 10.147(6) GeV. We also discuss the overlap of (3)D1 operators with (3)S1 states.

Charge Splitting In Situ Recorder (CSIR) for Real-Time Examination of Plasma Charging Effect in FinFET BEOL Processes

NASA Astrophysics Data System (ADS)

Tsai, Yi-Pei; Hsieh, Ting-Huan; Lin, Chrong Jung; King, Ya-Chin

2017-09-01

A novel device for monitoring plasma-induced damage in the back-end-of-line (BEOL) process with charge splitting capability is first-time proposed and demonstrated. This novel charge splitting in situ recorder (CSIR) can independently trace the amount and polarity of plasma charging effects during the manufacturing process of advanced fin field-effect transistor (FinFET) circuits. Not only does it reveal the real-time and in situ plasma charging levels on the antennas, but it also separates positive and negative charging effect and provides two independent readings. As CMOS technologies push for finer metal lines in the future, the new charge separation scheme provides a powerful tool for BEOL process optimization and further device reliability improvements.

Higgs pair production at NLO QCD for CP-violating Higgs sectors

NASA Astrophysics Data System (ADS)

Gröber, R.; Mühlleitner, M.; Spira, M.

2017-12-01

Higgs pair production through gluon fusion is an important process at the LHC to test the dynamics underlying electroweak symmetry breaking. Higgs sectors beyond the Standard Model (SM) can substantially modify this cross section through novel couplings not present in the SM or the on-shell production of new heavy Higgs bosons that subsequently decay into Higgs pairs. CP violation in the Higgs sector is important for the explanation of the observed matter-antimatter asymmetry through electroweak baryogenesis. In this work we compute the next-to-leading order (NLO) QCD corrections in the heavy top quark limit, including the effects of CP violation in the Higgs sector. We choose the effective theory (EFT) approach, which provides a rather model-independent way to explore New Physics (NP) effects by adding dimension-6 operators, both CP-conserving and CP-violating ones, to the SM Lagrangian. Furthermore, we perform the computation within a specific UV-complete model and choose as benchmark model the general 2-Higgs-Doublet Model with CP violation, the C2HDM. Depending on the dimension-6 coefficients, the relative NLO QCD corrections are affected by several per cent through the new CP-violating operators. This is also the case for SM-like Higgs pair production in the C2HDM, while the relative QCD corrections in the production of heavier C2HDM Higgs boson pairs deviate more strongly from the SM case. The absolute cross sections both in the EFT and the C2HDM can be modified by more than an order of magnitude. In particular, in the C2HDM the resonant production of Higgs pairs can by far exceed the SM cross section.

Associated Higgs-W-boson production at hadron colliders: a fully exclusive QCD calculation at NNLO.

PubMed

Ferrera, Giancarlo; Grazzini, Massimiliano; Tramontano, Francesco

2011-10-07

We consider QCD radiative corrections to standard model Higgs-boson production in association with a W boson in hadron collisions. We present a fully exclusive calculation up to next-to-next-to-leading order (NNLO) in QCD perturbation theory. To perform this NNLO computation, we use a recently proposed version of the subtraction formalism. Our calculation includes finite-width effects, the leptonic decay of the W boson with its spin correlations, and the decay of the Higgs boson into a bb pair. We present selected numerical results at the Tevatron and the LHC.

Merging weak and QCD showers with matrix elements

DOE PAGES

Christiansen, Jesper Roy; Prestel, Stefan

2016-01-22

In this study, we present a consistent way of combining associated weak boson radiation in hard dijet events with hard QCD radiation in Drell–Yan-like scatterings. This integrates multiple tree-level calculations with vastly different cross sections, QCD- and electroweak parton-shower resummation into a single framework. The new merging strategy is implemented in the P ythia event generator and predictions are confronted with LHC data. Improvements over the previous strategy are observed. Results of the new electroweak-improved merging at a future 100 TeV proton collider are also investigated.

Merging weak and QCD showers with matrix elements

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

Christiansen, Jesper Roy; Prestel, Stefan

In this study, we present a consistent way of combining associated weak boson radiation in hard dijet events with hard QCD radiation in Drell–Yan-like scatterings. This integrates multiple tree-level calculations with vastly different cross sections, QCD- and electroweak parton-shower resummation into a single framework. The new merging strategy is implemented in the P ythia event generator and predictions are confronted with LHC data. Improvements over the previous strategy are observed. Results of the new electroweak-improved merging at a future 100 TeV proton collider are also investigated.

Moving Forward to Constrain the Shear Viscosity of QCD Matter

DOE PAGES

Denicol, Gabriel; Monnai, Akihiko; Schenke, Björn

2016-05-26

In this work, we demonstrate that measurements of rapidity differential anisotropic flow in heavy-ion collisions can constrain the temperature dependence of the shear viscosity to entropy density ratio η/s of QCD matter. Comparing results from hydrodynamic calculations with experimental data from the RHIC, we find evidence for a small η/s ≈ 0.04 in the QCD crossover region and a strong temperature dependence in the hadronic phase. A temperature independent η/s is disfavored by the data. We further show that measurements of the event-by-event flow as a function of rapidity can be used to independently constrain the initial state fluctuations inmore » three dimensions and the temperature dependent transport properties of QCD matter.« less

Effect of Charged-Magnetic Grains in Protoplanetary Disks

NASA Astrophysics Data System (ADS)

Perry, Jonathan; Matthews, Lorin; Hyde, Truell

Effects of Charged-Magnetic Grains in Protoplanetary Disks Jonathan, Perry, Lorin Swint Matthews, and Truell W. Hyde Center for Astrophysics, Space Physics, and Engi-neering Research, addressPlaceNamePlaceNameplaceBaylor StreetPlaceTypeUniversity, Stree-taddressOne Bear Place 97316 Waco, TX 76798 USA The interaction and growth of dust grains is an important process in early planetesimal formation. The structure of aggregates formed from dust depend largely on the initial properties within the dust population, whether the grains are charged or uncharged, magnetic or non-magnetic. Theoretical simulations exam-ining pair-wise interactions between aggregates indicate that charged magnetic grains exhibit different growth behavior than populations consisting of exclusively charged or exclusively mag-netic grains. This study extends that work to predict how charged-magnetic grains influence grain growth within a protoplanetary disk. An N-body simulation containing various mixtures of dust materials is used to examine the differences in dust coagulation in the presence of charged magnetic aggregates. The growth of the dust aggregates is analyzed to determine the effects that charged magnetic grains contribute to the evolution of the dust cloud. Comparison of the rate of aggregation as well as the dynamic exponent relating mass of a cluster to the elapsed time will both be discussed.

Non-Abelian semilocal strings in N=2 supersymmetric QCD

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

Shifman, M.; Yung, A.; Petersburg Nuclear Physics Institute, Gatchina, St. Petersburg 188300

2006-06-15

We consider a benchmark bulk theory in four dimensions: N=2 supersymmetric QCD with the gauge group U(N) and N{sub f} flavors of fundamental matter hypermultiplets (quarks). The nature of the Bogomol'nyi-Prasad-Sommerfield (BPS) strings in this benchmark theory crucially depends on N{sub f}. If N{sub f}{>=}N and all quark masses are equal, it supports non-Abelian BPS strings which have internal (orientational) moduli. If N{sub f}>N these strings become semilocal, developing additional moduli {rho} related to (unlimited) variations of their transverse size. Using the U(2) gauge group with N{sub f}=3, 4 as an example, we derive an effective low-energy theory on themore » (two-dimensional) string world sheet. Our derivation is field theoretic, direct and explicit: we first analyze the Bogomol'nyi equations for string-geometry solitons, suggest an ansatz, and solve it at large {rho}. Then we use this solution to obtain the world-sheet theory. In the semiclassical limit our result confirms the Hanany-Tong conjecture, which rests on brane-based arguments, that the world-sheet theory is an N=2 supersymmetric U(1) gauge theory with N positively and N{sub e}=N{sub f}-N negatively charged matter multiplets and the Fayet-Iliopoulos term determined by the four-dimensional coupling constant. We conclude that the Higgs branch of this model is not lifted by quantum effects. As a result, such strings cannot confine. Our analysis of infrared effects, not seen in the Hanany-Tong consideration, shows that, in fact, the derivative expansion can make sense only provided that the theory under consideration is regularized in the infrared, e.g. by the quark mass differences. The world-sheet action discussed in this paper becomes a bona fide low-energy effective action only if {delta}m{sub AB}{ne}0.« less

A threshold effect for spacecraft charging

NASA Technical Reports Server (NTRS)

Olsen, R. C.

1983-01-01

The borderline case between no charging and large (kV) negative potentials for eclipse charging events on geosynchronous satellites is investigated, and the dependence of this transition on a threshold energy in the ambient plasma is examined. Data from the Applied Technology Satellite 6 and P78-2 (SCATHA) show that plasma sheet fluxes must extend above 10 keV for these satellites to charge in eclipse. The threshold effect is a result of the shape of the normal secondary yield curve, in particular the high energy crossover, where the secondary yield drops below 1. It is found that a large portion of the ambient electron flux must exceed this energy for a negative current to exist.

Charge multiplication effect in thin diamond films

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

Skukan, N., E-mail: nskukan@irb.hr; Grilj, V.; Sudić, I.

2016-07-25

Herein, we report on the enhanced sensitivity for the detection of charged particles in single crystal chemical vapour deposition (scCVD) diamond radiation detectors. The experimental results demonstrate charge multiplication in thin planar diamond membrane detectors, upon impact of 18 MeV O ions, under high electric field conditions. Avalanche multiplication is widely exploited in devices such as avalanche photo diodes, but has never before been reproducibly observed in intrinsic CVD diamond. Because enhanced sensitivity for charged particle detection is obtained for short charge drift lengths without dark counts, this effect could be further exploited in the development of sensors based on avalanchemore » multiplication and radiation detectors with extreme radiation hardness.« less

NNLO QCD corrections to associated W H production and H →b b ¯ decay

NASA Astrophysics Data System (ADS)

Caola, Fabrizio; Luisoni, Gionata; Melnikov, Kirill; Röntsch, Raoul

2018-04-01

We present a computation of the next-to-next-to-leading-order (NNLO) QCD corrections to the production of a Higgs boson in association with a W boson at the LHC and the subsequent decay of the Higgs boson into a b b ¯ pair, treating the b quarks as massless. We consider various kinematic distributions and find significant corrections to observables that resolve the Higgs decay products. We also find that a cut on the transverse momentum of the W boson, important for experimental analyses, may have a significant impact on kinematic distributions and radiative corrections. We show that some of these effects can be adequately described by simulating QCD radiation in Higgs boson decays to b quarks using parton showers. We also describe contributions to Higgs decay to a b b ¯ pair that first appear at NNLO and that were not considered in previous fully differential computations. The calculation of NNLO QCD corrections to production and decay sub-processes is carried out within the nested soft-collinear subtraction scheme presented by some of us earlier this year. We demonstrate that this subtraction scheme performs very well, allowing a computation of the coefficient of the second-order QCD corrections at the level of a few per mill.

New QCD sum rules based on canonical commutation relations

NASA Astrophysics Data System (ADS)

Hayata, Tomoya

2012-04-01

New derivation of QCD sum rules by canonical commutators is developed. It is the simple and straightforward generalization of Thomas-Reiche-Kuhn sum rule on the basis of Kugo-Ojima operator formalism of a non-abelian gauge theory and a suitable subtraction of UV divergences. By applying the method to the vector and axial vector current in QCD, the exact Weinberg’s sum rules are examined. Vector current sum rules and new fractional power sum rules are also discussed.

Charged particle multiplicities in deep inelastic scattering at HERA

NASA Astrophysics Data System (ADS)

Aid, S.; Anderson, M.; Andreev, V.; Andrieu, B.; Appuhn, R.-D.; 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.; Bertrand-Coremans, G.; Besançon, M.; Beyer, R.; Biddulph, P.; Bispham, P.; Bizot, J. C.; Blobel, V.; Borras, K.; Botterweck, F.; Boudry, V.; Braemer, A.; Braunschweig, W.; Brisson, V.; Bruel, P.; Bruncko, D.; Brune, C.; Buchholz, R.; Büngener, L.; Bürger, J.; Büsser, F. W.; Buniatian, A.; Burke, S.; Burton, M. J.; Calvet, D.; Campbell, A. J.; Carli, T.; Charlet, M.; Clarke, D.; Clegg, A. B.; Clerbaux, B.; Cocks, S.; Contreras, J. G.; Cormack, C.; Coughlan, J. A.; Courau, A.; Cousinou, M.-C.; Cozzika, G.; Criegee, L.; Cussans, D. G.; Cvach, J.; Dagoret, S.; Dainton, J. B.; Dau, W. D.; Daum, K.; David, M.; Davis, C. L.; Delcourt, B.; de Roeck, A.; de Wolf, E. A.; Dirkmann, M.; Dixon, P.; di Nezza, P.; Dlugosz, W.; Dollfus, C.; Dowell, J. D.; Dreis, H. B.; Droutskoi, A.; Dünger, O.; Duhm, H.; Ebert, J.; Ebert, T. R.; Eckerlin, G.; Efremenko, V.; Egli, S.; Eichler, R.; Eisele, F.; Eisenhandler, E.; Elsen, E.; Erdmann, M.; Erdmann, W.; Evrard, E.; Fahr, A. B.; 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.; Formánek, J.; Foster, J. M.; Franke, G.; Fretwurst, E.; Gabathuler, E.; Gabathuler, K.; Gaede, F.; Garvey, J.; Gayler, J.; Gebauer, M.; Genzel, H.; Gerhards, R.; Glazov, A.; Goerlach, U.; Goerlich, L.; Gogitidze, N.; Goldberg, M.; Goldner, D.; Golec-Biernat, K.; Gonzalez-Pineiro, B.; Gorelov, I.; Grab, C.; Grässler, H.; Greenshaw, T.; Griffiths, R. K.; Grindhammer, G.; Gruber, A.; Gruber, C.; Haack, J.; Hadig, T.; Haidt, D.; Hajduk, L.; Hampel, M.; Haynes, W. J.; Heinzelmann, G.; Henderson, R. C. W.; Henschel, H.; Herynek, I.; Hess, M. F.; Hewitt, K.; Hildesheim, W.; Hiller, K. H.; Hilton, C. D.; Hladký, J.; Hoeger, K. C.; Höppner, M.; Hoffmann, D.; Holtom, T.; Horisberger, R.; Hudgson, V. L.; Hütte, M.; Ibbotson, M.; Itterbeck, H.; Jacholkowska, A.; Jacobsson, C.; Jaffre, M.; Janoth, J.; Jansen, T.; Jönsson, L.; Johnson, D. P.; Jung, H.; Kalmus, P. I. P.; Kander, M.; Kant, D.; Kaschowitz, R.; Kathage, U.; Katzy, J.; Kaufmann, H. H.; Kaufmann, O.; Kazarian, S.; Kenyon, I. R.; Kermiche, S.; Keuker, C.; Kiesling, C.; Klein, M.; Kleinwort, C.; Knies, G.; 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.; Küster, H.; Kuhlen, M.; Kurča, T.; Kurzhöfer, J.; Lacour, D.; Laforge, B.; Lander, R.; Landon, M. P. J.; Lange, W.; Langenegger, U.; Laporte, J.-F.; Lebedev, A.; Lehner, F.; Levonian, S.; Lindström, G.; Lindstroem, M.; Link, J.; Linsel, F.; Lipinski, J.; List, B.; Lobo, G.; Lomas, J. W.; Lopez, G. C.; Lubimov, 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.; Mavroidis, T.; Maxfield, S. J.; McMahon, S. J.; Mehta, A.; Meier, K.; Meyer, A.; Meyer, A.; Meyer, H.; Meyer, J.; Meyer, P.-O.; Migliori, A.; Mikocki, S.; Milstead, D.; Moeck, J.; Moreau, F.; Morris, J. V.; Mroczko, E.; Müller, D.; Müller, G.; Müller, K.; Müller, M.; 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.; Nisius, R.; Nowak, G.; Noyes, G. W.; Nyberg-Werther, M.; Oakden, M.; Oberlack, H.; Olsson, J. E.; Ozerov, D.; Palmen, P.; Panaro, E.; Panitch, A.; Pascaud, C.; Patel, G. D.; Pawletta, H.; Peppel, E.; Perez, E.; Phillips, J. P.; Pieuchot, A.; Pitzl, D.; Pope, G.; Prell, S.; Rabbertz, K.; Rädel, G.; Reimer, P.; Reinshagen, S.; Rick, H.; Riech, V.; Riedlberger, J.; Riepenhausen, F.; Riess, S.; 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.; 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.; 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.; Specka, A.; Spiekermann, J.; Spielman, S.; Spitzer, H.; Squinabol, F.; Steenbock, M.; Steffen, P.; Steinberg, R.; Steiner, H.; Steinhart, J.; Stella, B.; Stellberger, A.; Stier, J.; Stiewe, J.; Stößlein, U.; Stolze, K.; Straumann, U.; Struczinski, W.; Sutton, J. P.; Tapprogge, S.; Taševský, M.; Tchernyshov, V.; Tchetchelnitski, S.; Theissen, J.; Thiebaux, C.; Thompson, G.; Truöl, P.; Tsipolitis, G.; Turnau, J.; Tutas, J.; Uelkes, P.; Usik, A.; Valkár, S.; Valkárová, A.; Vallée, C.; Vandenplas, D.; van Esch, P.; van Mechelen, P.; Vazdik, Y.; Verrecchia, P.; Villet, G.; Wacker, K.; Wagener, A.; Wagener, M.; Walther, A.; Waugh, B.; Weber, G.; Weber, M.; Wegener, D.; Wegner, A.; Wengler, T.; Werner, M.; West, L. R.; Wilksen, T.; Willard, S.; Winde, M.; Winter, G.-G.; Wittek, C.; Wobisch, M.; Wünsch, E.; Žáček, J.; Zarbock, D.; Zhang, Z.; Zhokin, A.; Zini, P.; Zomer, F.; Zsembery, J.; Zuber, K.; Zurnedden, M.

1996-12-01

Using the H1 detector at HERA, charged particle multiplicity distributions in deep inelastic e + p scattering have been measured over a large kinematical region. The evolution with W and Q 2 of the multiplicity distribution and of the multiplicity moments in pseudorapidity domains of varying size is studied in the current fragmentation region of the hadronic centre-of-mass frame. The results are compared with data from fixed target lepton-nucleon interactions, e + e - annihilations and hadron-hadron collisions as well as with expectations from QCD based parton models. Fits to the Negative Binomial and Lognormal distributions are presented.

Inclusive charged particle cross sections in photoproduction at HERA

NASA Astrophysics Data System (ADS)

Abt, I.; Ahmed, T.; Andreev, V.; Aid, S.; Andrieu, B.; Appuhn, R.-D.; Arpagaus, M.; Babaev, A.; Bärwolff, H.; Bán, J.; Baranov, P.; Barrelet, E.; Bartel, W.; Bassler, U.; Beck, H. P.; Behrend, H.-J.; Belousov, A.; Berger, Ch.; Bergstein, H.; Bernardi, G.; Bernet, R.; Bertrand-Coremans, G.; Besançon, M.; Biddulph, P.; Binder, E.; Bizot, J. C.; Blobel, V.; Borras, K.; Bosetti, P. C.; Boudry, V.; Bourdarios, C.; Braemer, A.; Brasse, F.; Braun, U.; Braunschweig, W.; Brisson, V.; Bruncko, D.; Büngener, L.; Bürger, J.; Büsser, F. W.; Buniatian, A.; Burke, S.; Buschhorn, G.; Campbell, A. J.; Carli, T.; Charles, F.; Chyla, J.; Clarke, D.; Clegg, A. B.; Colombo, M.; Coughlan, J. A.; Courau, A.; Coutures, Ch.; Cozzika, G.; Criegee, L.; Cvach, J.; Dagoret, S.; Dainton, J. B.; Danilov, M.; Dann, A. W. E.; Dau, W. D.; David, M.; Deffur, E.; Delcourt, B.; Del Buono, L.; Devel, M.; De Roeck, A.; Di Nezza, P.; Dingus, P.; Dollfus, C.; Dowell, J. D.; Dreis, H. B.; Drescher, A.; Duboc, J.; Düllmann, D.; Dünger, O.; Duhm, H.; Ebbinghaus, R.; Eberle, M.; Ebert, J.; Ebert, T. R.; Eckerlin, G.; Efremenko, V.; Egli, S.; Ehrlichmann, H.; Eichenberger, S.; Eichler, R.; Eisele, F.; Eisenhandler, E.; Ellis, N. N.; Ellison, R. J.; Elsen, E.; Erdmann, M.; Evrard, E.; Favart, L.; Fedotov, A.; Feeken, D.; Felst, R.; Feltesse, J.; Fensome, I. F.; Ferencei, J.; Ferrarotto, F.; Flamm, K.; Flauger, W.; Fleischer, M.; Flieser, M.; Flügge, G.; Fomenko, A.; Fominykh, B.; Forbush, M.; Formánek, J.; Foster, J. M.; Franke, G.; Fretwurst, E.; Fuhrmann, P.; Gabathuler, E.; Gamerdinger, K.; Garvey, J.; Gayler, J.; Gebauer, M.; Gellrich, A.; Gennis, M.; Genzel, H.; Gerhards, R.; Godfrey, L.; Goerlach, U.; Goerlich, L.; Gogitidze, N.; Goldberg, M.; Goldner, D.; Goodall, A. M.; Gorelov, I.; Goritchev, P.; Grab, C.; Grässler, H.; Grässler, R.; Greenshaw, T.; Greif, H.; Grindhammer, G.; Gruber, A.; Gruber, C.; Haack, J.; Haidt, D.; Hajduk, L.; Hamon, O.; Hampel, M.; Hanlon, E. M.; Hapke, M.; Harjes, J.; Haydar, R.; Haynes, W. J.; Heatherington, J.; Hedberg, V.; Heinzelmann, G.; Henderson, R. C. W.; Henschel, H.; Herma, R.; Herynek, I.; Hildesheim, W.; Hill, P.; Hilton, C. D.; Hladký, J.; Hoeger, K. C.; Höppner, M.; Huet, Ph.; Hufnagel, H.; Huot, N.; Ibbotson, M.; Itterbeck, H.; Jabiol, M.-A.; Jacholkowska, A.; Jacobsson, C.; Jaffre, M.; Jansen, T.; Jönsson, L.; Johannsen, K.; Johnson, D. P.; Johnson, L.; Jung, H.; Kalmus, P. I. P.; Kant, D.; Kazarian, S.; Kaschowitz, R.; Kasselmann, P.; Kathage, U.; Kaufmann, H. H.; Kenyon, I. R.; Kermiche, S.; Keuker, C.; Kiesling, C.; Klein, M.; Kleinwort, C.; Knies, G.; Ko, W.; Köhler, T.; Kolanoski, H.; Kole, F.; Kolya, S. D.; Korbel, V.; Korn, M.; Kostka, P.; Kotelnikov, S. K.; Krasny, M. W.; Krehbiel, H.; Krücker, D.; Krüger, 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.; Langkau, R.; Lanius, P.; Laporte, J. F.; Lebedev, A.; Leuschner, A.; Leverenz, C.; Levonian, S.; Lewin, D.; Ley, Ch.; Lindner, A.; Lindström, G.; Linsel, F.; Lipinski, J.; Loch, P.; Lohmander, H.; Lopez, G. C.; Lüers, D.; Lüke, D.; Magnussen, N.; Malinovski, E.; Mani, S.; Marage, P.; Marks, J.; Marshall, R.; Martens, J.; Martin, R.; Martyn, H.-U.; Martyniak, J.; Masson, S.; Mavroidis, A.; Maxfiedl, S. J.; McMahon, S. J.; Mehta, A.; Meier, K.; Mercer, D.; Merz, T.; Meyer, C. A.; Meyer, H.; Meyer, J.; Mikocki, S.; Monnier, E.; Moreau, F.; Moreels, J.; Morris, J. V.; Müller, K.; Murín, P.; Murray, S. A.; Nagovizin, V.; Naroska, B.; Naumann, Th.; Newman, P. R.; Newton, D.; Neyret, D.; Nguyen, H. K.; Niebergall, F.; Niebuhr, C.; Nisius, R.; Nowak, G.; Noyes, G. W.; Nyberg, M.; Oberlack, H.; Obrock, U.; Olsson, J. E.; Orenstein, S.; Ould-Saada, F.; Pascaud, C.; Patel, G. D.; Peppel, E.; Peters, S.; Phillips, H. T.; Phillips, J. P.; Pichler, Ch.; Pilgram, W.; Pitzl, D.; Prell, S.; Prosi, R.; Rädel, G.; Raupach, F.; Rauschnabel, K.; Reimer, P.; Reinshagen, S.; Ribarics, P.; Riech, V.; Riedlberger, J.; Riess, S.; Rietz, M.; Robertson, S. M.; Robmann, P.; Roosen, R.; Rosenbauer, K.; Rostovtsev, A.; Royon, C.; Rudowicz, M.; Ruffer, M.; Rusakov, S.; Rybicki, K.; Sahlmann, N.; Sanchez, E.; Sankey, D. P. C.; Savitsky, M.; Schacht, P.; Schleper, P.; von Schlippe, W.; Schmidt, C.; Schmidt, D.; Schmitz, W.; Schöning, A.; Schröder, V.; Schuhmann, E.; Schulz, M.; Schwab, B.; Schwind, A.; Scobel, W.; Seehausen, U.; 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.; Soloviev, Y.; Spitzer, H.; Steenbock, M.; Steffen, P.; Steinberg, R.; Stella, B.; Stephens, K.; Stier, J.; Stösslein, U.; Strachota, J.; Straumann, U.; Struczinski, W.; Sutton, J. P.; Taylor, R. E.; Tchernyshov, V.; Thiebaux, C.; Thompson, G.; Tichomirov, I.; Truöl, P.; Turnau, J.; Tutas, J.; Urban, L.; Usik, A.; Valkar, S.; Valkarova, A.; Vallée, C.; Van Esch, P.; Vartapetian, A.; Vazdik, Y.; Vecko, M.; Verrecchia, P.; Vick, R.; Villet, G.; Vogel, E.; Wacker, K.; Walker, I. W.; Walther, A.; Weber, G.; Wegener, D.; Wegner, A.; Wellisch, H. P.; West, L. R.; Willard, S.; Winde, M.; Winter, G.-G.; Wolff, Th.; Womersley, L. A.; Wright, A. E.; Wulff, N.; Yiou, T. P.; Žáček, J.; Zeitnitz, C.; Ziaeepour, H.; Zimmer, M.; Zimmermann, W.; Zomer, F.; H1 Collaboration

1994-05-01

Cross sections are presented for the inclusive production of charged particles measured in electron-proton collisions at low Q2 with the H1 detector at HERA. The transverse momentum distribution extends up to 8 GeV/ c. Its shape is found to be harder than that observed in overlinepp collisions at comparable centre-of-mass energies √S γp ≈ √S overlinepp ≈ 200 GeV, and also harder than in γp collisions at lower energies √ Sγp ≈ 18 GeV. Results from quantum chromodynamics (QCD) calculations agree with the measured transverse momentum and pseudorapidity cross sections.

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.

Flavor-singlet baryons in the graded symmetry approach to partially quenched QCD

NASA Astrophysics Data System (ADS)

Hall, Jonathan M. M.; Leinweber, Derek B.

2016-11-01

Progress in the calculation of the electromagnetic properties of baryon excitations in lattice QCD presents new challenges in the determination of sea-quark loop contributions to matrix elements. A reliable estimation of the sea-quark loop contributions represents a pressing issue in the accurate comparison of lattice QCD results with experiment. In this article, an extension of the graded symmetry approach to partially quenched QCD is presented, which builds on previous theory by explicitly including flavor-singlet baryons in its construction. The formalism takes into account the interactions among both octet and singlet baryons, octet mesons, and their ghost counterparts; the latter enables the isolation of the quark-flow disconnected sea-quark loop contributions. The introduction of flavor-singlet states enables systematic studies of the internal structure of Λ -baryon excitations in lattice QCD, including the topical Λ (1405 ).

QCD equation of state for heavy ion collisions

NASA Astrophysics Data System (ADS)

Zhao, A.-Meng; Shi, Yuan-Mei; Li, Jian-Feng; Zong, Hong-Shi

2017-10-01

In this work, we calculate the equation of state (EoS) of quark gluon-plasma (QGP) using the Cornwall-Jackiw-Tomboulis (CJT) effective action. We get the quark propagator by using the rank-1 separable model within the framework of the Dyson-Schwinger equations (DSEs). The results from CJT effective action are compared with lattice QCD data. We find that, when μ is small, our results generally fit the lattice QCD data when T > T c, but show deviations at and below T c. It can be concluded that the EoS of CJT is reliable when T > T c. Then, by adopting the hydrodynamic code UVH2+1, we compare the CJT results of the multiplicity and elliptic flow ν 2 with the PHENIX data and the results from the original EoS in UVH2+1. While the CJT results of multiplicities generally match the original UVH2+1 results and fit the experimental data, the CJT results of ν 2 are slightly larger than the original UVH2+1 results for centralities smaller than 40% and smaller than the original UVH2+1 results for higher centralities. Supported by National Natural Science Foundation of China (11447121, 11475085, 11535005, 11690030), Fundamental Research Funds for the Central Universities (020414380074), Jiangsu Planned Projects for Postdoctoral Research Funds (1501035B) and Natural Science Foundation of Jiangsu Province (BK20130078, BK20130387)

High energy scattering in QCD and in quantum gravity

NASA Astrophysics Data System (ADS)

Lipatov, L. N.

2014-06-01

The theory of the high energy scattering in QCD is based on the BFKL equation for the Pomeron wave function and on its generalization for composite multi-gluon states in the crossing channel. At a large number of colors the equations for the gluon composite states have remarkable mathematical properties including their Möbius invariance, holomorphic separability, duality symmetry and integrability. High energy QCD interactions local in the particle rapidities are formulated in the form of the gauge invariant effective action. In the maximally extended N = 4 super-symmetry the Pomeron turns out to be dual to the reggeized graviton in the 10-dimensional anti-de-Sitter space. As a result, the Gribov calculus for the Pomeron interactions should be reformulated here as a generally covariant effective field theory for the reggeized gravitons. We construct the corresponding effective action, which gives a possibility to calculate their trajectory and couplings. The graviton trajectory in the leading order contains an ultraviolet divergency meaning the presence of the double-logarithmic (DL) terms. We sum the DL contributions in all orders of the perturbation theory in the Einstein-Hilbert gravity and in its super-symmetric generalizations. In the N = 8 super gravity the ratio of the scattering amplitude in the DL approximation to the Born expression tends to zero at large energies.

Three-point Green functions in the odd sector of QCD

NASA Astrophysics Data System (ADS)

Kadavý, T.; Kampf, K.; Novotný, J.

2016-11-01

A review of familiar results of the three-point Green functions of currents in the odd-intrinsic parity sector of QCD is presented. Such Green functions include very well-known examples of VVP, VAS or AAP correlators. We also shortly present some of the new results for VVA and AAA Green functions with a discussion of their high-energy behaviour and its relation to the QCD condensates.

Determination of electric dipole transitions in heavy quarkonia using potential non-relativistic QCD

NASA Astrophysics Data System (ADS)

Segovia, Jorge; Steinbeißer, Sebastian

2018-05-01

The electric dipole transitions {χ }bJ(1P)\\to γ \\Upsilon (1S) with J = 0, 1, 2 and {h}b(1P)\\to γ {η }b(1S) are computed using the weak-coupling version of a low-energy effective field theory named potential non-relativistic QCD (pNRQCD). In order to improve convergence and thus give firm predictions for the studied reactions, the full static potential is incorporated into the leading order Hamiltonian; moreover, we must handle properly renormalon effects and re-summation of large logarithms. The precision we reach is {k}γ 3/{(mv)}2× O({v}2), where kγ is the photon energy, m is the mass of the heavy quark and v its velocity. Our analysis separates those relativistic contributions that account for the electromagnetic interaction terms in the pNRQCD Lagrangian which are v 2 suppressed and those that account for wave function corrections of relative order v 2. Among the last ones, corrections from 1/m and 1/m2 potentials are computed, but not those coming from higher Fock states since they demand non-perturbative input and are {{{Λ }}}{{QCD}}2/{(mv)}2 or {{{Λ }}}{{QCD}}3/({m}3{v}4) suppressed, at least, in the strict weak coupling regime. These proceedings are based on the forthcoming publication [1].

Effective dynamics of a classical point charge

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

Polonyi, Janos, E-mail: polonyi@iphc.cnrs.fr

2014-03-15

The effective Lagrangian of a point charge is derived by eliminating the electromagnetic field within the framework of the classical closed time path formalism. The short distance singularity of the electromagnetic field is regulated by an UV cutoff. The Abraham–Lorentz force is recovered and its similarity to quantum anomalies is underlined. The full cutoff-dependent linearized equation of motion is obtained, no runaway trajectories are found but the effective dynamics shows acausality if the cutoff is beyond the classical charge radius. The strength of the radiation reaction force displays a pole in its cutoff-dependence in a manner reminiscent of the Landau-polemore » of perturbative QED. Similarity between the dynamical breakdown of the time reversal invariance and dynamical symmetry breaking is pointed out. -- Highlights: •Extension of the classical action principle for dissipative systems. •New derivation of the Abraham–Lorentz force for a point charge. •Absence of a runaway solution of the Abraham–Lorentz force. •Acausality in classical electrodynamics. •Renormalization of classical electrodynamics of point charges.« less

Nucleon axial charge in (2+1)-flavor dynamical-lattice QCD with domain-wall fermions.

PubMed

Yamazaki, T; Aoki, Y; Blum, T; Lin, H W; Lin, M F; Ohta, S; Sasaki, S; Tweedie, R J; Zanotti, J M

2008-05-02

We present results for the nucleon axial charge g{A} at a fixed lattice spacing of 1/a=1.73(3) GeV using 2+1 flavors of domain wall fermions on size 16;{3} x 32 and 24;{3} x 64 lattices (L=1.8 and 2.7 fm) with length 16 in the fifth dimension. The length of the Monte Carlo trajectory at the lightest m_{pi} is 7360 units, including 900 for thermalization. We find finite volume effects are larger than the pion mass dependence at m{pi}=330 MeV. We also find a scaling with the single variable m{pi}L which can also be seen in previous two-flavor domain wall and Wilson fermion calculations. Using this scaling to eliminate the finite-volume effect, we obtain g{A}=1.20(6)(4) at the physical pion mass, m_{pi}=135 MeV, where the first and second errors are statistical and systematic. The observed finite-volume scaling also appears in similar quenched simulations, but disappear when V>or=(2.4 fm);{3}. We argue this is a dynamical quark effect.

Top-pair production at the LHC through NNLO QCD and NLO EW

NASA Astrophysics Data System (ADS)

Czakon, Michał; Heymes, David; Mitov, Alexander; Pagani, Davide; Tsinikos, Ioannis; Zaro, Marco

2017-10-01

In this work we present for the first time predictions for top-quark pair differential distributions at the LHC at NNLO QCD accuracy and including EW corrections. For the latter we include not only contributions of O({α}_s^2α ) , but also those of order O({α}_s{α}^2) and O({α}^3) . Besides providing phenomenological predictions for all main differential distributions with stable top quarks, we also study the following issues. 1) The effect of the photon PDF on top-pair spectra: we find it to be strongly dependent on the PDF set used — especially for the top p T distribution. 2) The difference between the additive and multiplicative approaches for combining QCD and EW corrections: with our scale choice, we find relatively small differences between the central predictions, but reduced scale dependence within the multiplicative approach. 3) The potential effect from the radiation of heavy bosons on inclusive top-pair spectra: we find it to be, typically, negligible.

NΩ interaction from two approaches in lattice QCD

NASA Astrophysics Data System (ADS)

Etminan, Faisal; Firoozabadi, Mohammad Mehdi

2014-10-01

We compare the standard finite volume method by Lüscher with the potential method by HAL QCD collaboration, by calculating the ground state energy of N(nucleon)-Ω(Omega) system in 5 S2 channel. We employ 2+1 flavor full QCD configurations on a (1.9 fm)3×3.8 fm lattice at the lattice spacing a≃0.12 fm, whose ud(s) quark mass corresponds to mπ = 875(1) (mK = 916(1)) MeV. We have found that both methods give reasonably consistent results that there is one NΩ bound state at this parameter.

Exploring Flavor Physics with Lattice QCD

NASA Astrophysics Data System (ADS)

Du, Daping; Fermilab/MILC Collaborations Collaboration

2016-03-01

The Standard Model has been a very good description of the subatomic particle physics. In the search for physics beyond the Standard Model in the context of flavor physics, it is important to sharpen our probes using some gold-plated processes (such as B rare decays), which requires the knowledge of the input parameters, such as the Cabibbo-Kobayashi-Maskawa (CKM) matrix elements and other nonperturbative quantities, with sufficient precision. Lattice QCD is so far the only first-principle method which could compute these quantities with competitive and systematically improvable precision using the state of the art simulation techniques. I will discuss the recent progress of lattice QCD calculations on some of these nonpurturbative quantities and their applications in flavor physics. I will also discuss the implications and future perspectives of these calculations in flavor physics.

QCD Sum Rules and Models for Generalized Parton Distributions

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

Anatoly Radyushkin

2004-10-01

I use QCD sum rule ideas to construct models for generalized parton distributions. To this end, the perturbative parts of QCD sum rules for the pion and nucleon electromagnetic form factors are interpreted in terms of GPDs and two models are discussed. One of them takes the double Borel transform at adjusted value of the Borel parameter as a model for nonforward parton densities, and another is based on the local duality relation. Possible ways of improving these Ansaetze are briefly discussed.

Equation of state and QCD transition at finite temperature

NASA Astrophysics Data System (ADS)

Bazavov, A.; Bhattacharya, T.; Cheng, M.; Christ, N. H.; Detar, C.; Ejiri, S.; Gottlieb, Steven; Gupta, R.; Heller, U. M.; Huebner, K.; Jung, C.; Karsch, F.; Laermann, E.; Levkova, L.; Miao, C.; Mawhinney, R. D.; Petreczky, P.; Schmidt, C.; Soltz, R. A.; Soeldner, W.; Sugar, R.; Toussaint, D.; Vranas, P.

2009-07-01

We calculate the equation of state in 2+1 flavor QCD at finite temperature with physical strange quark mass and almost physical light quark masses using lattices with temporal extent Nτ=8. Calculations have been performed with two different improved staggered fermion actions, the asqtad and p4 actions. Overall, we find good agreement between results obtained with these two O(a2) improved staggered fermion discretization schemes. A comparison with earlier calculations on coarser lattices is performed to quantify systematic errors in current studies of the equation of state. We also present results for observables that are sensitive to deconfining and chiral aspects of the QCD transition on Nτ=6 and 8 lattices. We find that deconfinement and chiral symmetry restoration happen in the same narrow temperature interval. In an appendix we present a simple parametrization of the equation of state that can easily be used in hydrodynamic model calculations. In this parametrization we include an estimate of current uncertainties in the lattice calculations which arise from cutoff and quark mass effects.

Interquark potential with finite quark mass from lattice QCD.

PubMed

Kawanai, Taichi; Sasaki, Shoichi

2011-08-26

We present an investigation of the interquark potential determined from the q ̄q Bethe-Salpeter (BS) amplitude for heavy quarkonia in lattice QCD. The q ̄q potential at finite quark mass m(q) can be calculated from the equal-time and Coulomb gauge BS amplitude through the effective Schrödinger equation. The definition of the potential itself requires information about a kinetic mass of the quark. We then propose a self-consistent determination of the quark kinetic mass on the same footing. To verify the proposed method, we perform quenched lattice QCD simulations with a relativistic heavy-quark action at a lattice cutoff of 1/a≈2.1  GeV in a range 1.0≤m(q)≤3.6 GeV. Our numerical results show that the q ̄q potential in the m(q)→∞ limit is fairly consistent with the conventional one obtained from Wilson loops. The quark-mass dependence of the q ̄q potential and the spin-spin potential are also examined. © 2011 American Physical Society

Chiral phase transition at finite chemical potential in 2 +1 -flavor soft-wall anti-de Sitter space QCD

NASA Astrophysics Data System (ADS)

Bartz, Sean P.; Jacobson, Theodore

2018-04-01

The phase transition from hadronic matter to chirally symmetric quark-gluon plasma is expected to be a rapid crossover at zero quark chemical potential (μ ), becoming first order at some finite value of μ , indicating the presence of a critical point. Using a three-flavor soft-wall model of anti-de Sitter/QCD, we investigate the effect of varying the light and strange quark masses on the order of the chiral phase transition. At zero quark chemical potential, we reproduce the Columbia Plot, which summarizes the results of lattice QCD and other holographic models. We then extend this holographic model to examine the effects of finite quark chemical potential. We find that the the chemical potential does not affect the critical line that separates first-order from rapid crossover transitions. This excludes the possibility of a critical point in this model, suggesting that a different setup is necessary to reproduce all the features of the QCD phase diagram.

End point of a first-order phase transition in many-flavor lattice QCD at finite temperature and density.

PubMed

Ejiri, Shinji; Yamada, Norikazu

2013-04-26

Towards the feasibility study of the electroweak baryogenesis in realistic technicolor scenario, we investigate the phase structure of (2+N(f))-flavor QCD, where the mass of two flavors is fixed to a small value and the others are heavy. For the baryogenesis, an appearance of a first-order phase transition at finite temperature is a necessary condition. Using a set of configurations of two-flavor lattice QCD and applying the reweighting method, the effective potential defined by the probability distribution function of the plaquette is calculated in the presence of additional many heavy flavors. Through the shape of the effective potential, we determine the critical mass of heavy flavors separating the first-order and crossover regions and find it to become larger with N(f). We moreover study the critical line at finite density and the first-order region is found to become wider as increasing the chemical potential. Possible applications to real (2+1)-flavor QCD are discussed.

QCD corrections to decay-lepton polar and azimuthal angular distributions in e+e- --> tt(bar) in the soft-gluon approximation

NASA Astrophysics Data System (ADS)

Rindani, Saurabh D.

2002-04-01

QCD corrections to order as in the soft-gluon approximation to angular distributions of decay charged leptons in the process e+e- --> t t(bar), followed by semileptonic decay of t or t(bar), are obtained in the e+e- centre-of-mass frame. As compared to distributions in the top rest frame, these have the advantage that they would allow direct comparison with experiment without the need to reconstruct the top rest frame. The results also do not depend on the choice of a spin quantization axis for t or t (bar). Analytic expression for the triple distribution in the polar angle of t and polar and azimuthal angles of the lepton is obtained. Analytic expression is also derived for the distribution in the charged-lepton polar angle. Numerical values are discussed for (s) 1/2 = 400, 800 and 1500 GeV.

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

The Light-Front Schrödinger Equation and Determination of the Perturbative QCD Scale from Color Confinement

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

Brodsky, Stanley J.; de Teramond, Guy F.; Deur, Alexandre P.

2015-09-01

The valence Fock-state wavefunctions of the light-front QCD Hamiltonian satisfy a relativistic equation of motion with an effective confining potential U which systematically incorporates the effects of higher quark and gluon Fock states. If one requires that the effective action which underlies the QCD Lagrangian remains conformally invariant and extends the formalism of de Alfaro, Fubini and Furlan to light front Hamiltonian theory, the potential U has a unique form of a harmonic oscillator potential, and a mass gap arises. The result is a nonperturbative relativistic light-front quantum mechanical wave equation which incorporates color confinement and other essential spectroscopic andmore » dynamical features of hadron physics, including a massless pion for zero quark mass and linear Regge trajectories with the same slope in the radial quantum number n and orbital angular momentum L. Only one mass parameter κ appears. Light-front holography thus provides a precise relation between the bound-state amplitudes in the fifth dimension of AdS space and the boost-invariant light-front wavefunctions describing the internal structure of hadrons in physical space-time. We also show how the mass scale κ underlying confinement and hadron masses determines the scale Λ {ovr MS} controlling the evolution of the perturbative QCD coupling. The relation between scales is obtained by matching the nonperturbative dynamics, as described by an effective conformal theory mapped to the light-front and its embedding in AdS space, to the perturbative QCD regime computed to four-loop order. The result is an effective coupling defined at all momenta. The predicted value Λ {ovr MS}=0.328±0.034 GeV is in agreement with the world average 0.339±0.010 GeV. The analysis applies to any renormalization scheme.« less

Nucleon PDFs and TMDs from Continuum QCD

NASA Astrophysics Data System (ADS)

Bednar, Kyle; Cloet, Ian; Tandy, Peter

2017-09-01

The parton structure of the nucleon is investigated in an approach based upon QCD's Dyson-Schwinger equations. The method accommodates a variety of QCD's dynamical outcomes including: the running mass of quark propagators and formation of non-pointlike di-quark correlations. All needed elements, including the nucleon wave function solution from a Poincaré covariant Faddeev equation, are encoded in spectral-type representations in the Nakanishi style to facilitate Feynman integral procedures and allow insight into key underlying mechanisms. Results will be presented for spin-independent PDFs and TMDs arising from a truncation to allow only scalar di-quark correlations. The influence of axial-vector di-quark correlations may be discussed if results are available. Supported by NSF Grant No. PHY-1516138.

Nuclear Physics and Lattice QCD

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

Beane, Silas

2003-11-01

Impressive progress is currently being made in computing properties and interac- tions of the low-lying hadrons using lattice QCD. However, cost limitations will, for the foreseeable future, necessitate the use of quark masses, Mq, that are signif- icantly larger than those of nature, lattice spacings, a, that are not significantly smaller than the physical scale of interest, and lattice sizes, L, that are not sig- nificantly larger than the physical scale of interest. Extrapolations in the quark masses, lattice spacing and lattice volume are therefore required. The hierarchy of mass scales is: L 1 j Mq j â ºC jmore » a 1 . The appropriate EFT for incorporating the light quark masses, the finite lattice spacing and the lattice size into hadronic observables is C-PT, which provides systematic expansions in the small parame- ters e m L, 1/ Lâ ºC, p/â ºC, Mq/â ºC and aâ ºC . The lattice introduces other unphysical scales as well. Lattice QCD quarks will increasingly be artificially separated« less

Predictions for diphoton production at the LHC through NNLO in QCD

DOE PAGES

Campbell, John M.; Ellis, R. Keith; Li, Ye; ...

2016-07-29

In this paper we present a next-to-next-to-leading order (NNLO) calculation of the processmore » $$pp\\rightarrow \\gamma\\gamma$$ that we have implemented into the parton level Monte Carlo code MCFM. We do not find agreement with the previous calculation of this process in the literature. In addition to the $$\\mathcal{O}(\\alpha_s^2)$$ corrections present at NNLO, we include some effects arising at $$\\mathcal{O}(\\alpha_s^3)$$, namely those associated with gluon-initiated closed fermion loops. We investigate the role of this process in the context of studies of QCD at colliders and as a background for searches for new physics, paying particular attention to the diphoton invariant mass spectrum. We demonstrate that the NNLO QCD prediction for the shape of this spectrum agrees well with functional forms used in recent data-driven fits.« less

Design guidelines for assessing and controlling spacecraft charging effects

NASA Technical Reports Server (NTRS)

Purvis, C. K.; Garrett, H. B.; Whittlesey, A. C.; Stevens, N. J.

1984-01-01

The need for uniform criteria, or guidelines, to be used in all phases of spacecraft design is discussed. Guidelines were developed for the control of absolute and differential charging of spacecraft surfaces by the lower energy space charged particle environment. Interior charging due to higher energy particles is not considered. A guide to good design practices for assessing and controlling charging effects is presented. Uniform design practices for all space vehicles are outlined.

Design guidelines for assessing and controlling spacecraft charging effects

NASA Technical Reports Server (NTRS)

Purvis, C. K.; Garrett, H. B.; Whittlesey, A.; Stevens, N. J.

1985-01-01

The need for uniform criteria, or guidelines, to be used in all phases of spacecraft design is discussed. Guidelines were developed for the control of absolute and differential charging of spacecraft surfaces by the lower energy space charged particle environment. Interior charging due to higher energy particles is not considered. A guide to good design practices for assessing and controlling charging effects is presented. Uniform design practices for all space vehicles are outlined.

On the interface between perturbative and nonperturbative QCD

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

Deur, Alexandre; Brodsky, Stanley J.; de Teramond, Guy F.

2016-04-04

The QCD running couplingmore » $$\\alpha_s(Q^2)$$ sets the strength of the interactions of quarks and gluons as a function of the momentum transfer $Q$. The $Q^2$ dependence of the coupling is required to describe hadronic interactions at both large and short distances. In this article we adopt the light-front holographic approach to strongly-coupled QCD, a formalism which incorporates confinement, predicts the spectroscopy of hadrons composed of light quarks, and describes the low-$Q^2$ analytic behavior of the strong coupling $$\\alpha_s(Q^2)$$. The high-$Q^2$ dependence of the coupling $$\\alpha_s(Q^2)$$ is specified by perturbative QCD and its renormalization group equation. The matching of the high and low $Q^2$ regimes of $$\\alpha_s(Q^2)$$ then determines the scale $$Q_0$$ which sets the interface between perturbative and nonperturbative hadron dynamics. The value of $$Q_0$$ can be used to set the factorization scale for DGLAP evolution of hadronic structure functions and the ERBL evolution of distribution amplitudes. We discuss the scheme-dependence of the value of $$Q_0$$ and the infrared fixed-point of the QCD coupling. Our analysis is carried out for the $$\\bar{MS}$$, $$g_1$$, $MOM$ and $V$ renormalization schemes. Our results show that the discrepancies on the value of $$\\alpha_s$$ at large distance seen in the literature can be explained by different choices of renormalization schemes. Lastly, we also provide the formulae to compute $$\\alpha_s(Q^2)$$ over the entire range of space-like momentum transfer for the different renormalization schemes discussed in this article.« 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

Inertial effects in systems with magnetic charge

NASA Astrophysics Data System (ADS)

Armitage, N. P.

2018-05-01

This short article sets out some of the basic considerations that go into detecting the mass of quasiparticles with effective magnetic charge in solids. Effective magnetic charges may be appear as defects in particular magnetic textures. A magnetic monopole is a defect in this texture and as such these are not monopoles in the actual magnetic field B, but instead in the auxiliary field H. They may have particular properties expected for such quasiparticles such as magnetic charge and mass. This effective mass may-in principle-be detected in the same fashion that the mass is detected of other particles classically e.g. through their inertial response to time-dependent electromagnetic fields. I discuss this physics in the context of the "simple" case of the quantum spin ices, but aspects are broadly applicable. Based on extensions to Ryzkhin's model for classical spin ice, a hydrodynamic formulation can be given that takes into account inertial and entropic forces. Ultimately, a form for the susceptibility is obtained that is equivalent to the Rocard equation, which is a classic form used to account for inertial effects in the context of Debye-like relaxation.

QCD for Postgraduates (3/5)

ScienceCinema

Zanderighi, Giulia

2018-04-27

Modern QCD - Lecture 3 We will introduce processes with initial-state hadrons and discuss parton distributions, sum rules, as well as the need for a factorization scale once radiative corrections are taken into account. We will then discuss the DGLAP equation, the evolution of parton densities, as well as ways in which parton densities are extracted from data.

Equivalence of the AdS-metric and the QCD running coupling

NASA Astrophysics Data System (ADS)

Pirner, H. J.; Galow, B.

2009-08-01

We use the functional form of the QCD running coupling to modify the conformal metric in AdS/CFT mapping the fifth-dimensional z-coordinate to the energy scale in the four-dimensional QCD. The resulting type-0 string theory in five dimensions is solved with the Nambu-Goto action giving good agreement with the Coulombic and confinement QQbar potential.

D → Klv semileptonic decay using lattice QCD with HISQ at physical pion masses

NASA Astrophysics Data System (ADS)

Chakraborty, Bipasha; Davies, Christine; Koponen, Jonna; Lepage, G. Peter

2018-03-01

he quark flavor sector of the Standard Model is a fertile ground to look for new physics effects through a unitarity test of the Cabbibo-Kobayashi-Maskawa (CKM) matrix. We present a lattice QCD calculation of the scalar and the vector form factors (over a large q2 region including q2 = 0) associated with the D→ Klv semi-leptonic decay. This calculation will then allow us to determine the central CKM matrix element, Vcs in the Standard Model, by comparing the lattice QCD results for the form factors and the experimental decay rate. This form factor calculation has been performed on the Nf = 2 + 1 + 1 MILC HISQ ensembles with the physical light quark masses.

Measurement of the W boson production charge asymmetry in proton-antiproton collisions

NASA Astrophysics Data System (ADS)

Han, Bo-Young

We present a measurement of the W boson production charge asymmetry using the W → enu decay channel. We use data collected the Collider Detector at Fermilab (CDF) from pp¯ collisions at s = 1.96 TeV. The data were collected up to February 2006 (Run II) and represent an integrated luminosity of 1 fb-1. The experimental measurement of W production charge asymmetry is compared to higher order QCD predictions generated using MRST2006 and CTEQ6 parton distribution functions (PDF). The asymmetry provides new input on the momentum fraction dependence of the u and d quark parton distribution functions (PDF) within the proton over the fraction of proton's momentum range from 0.002 < x < 0.8 corresponding to -3.0 < yW < 3.0 at Q 2 ≈ M2W .

Measurement of charged jet production cross sections and nuclear modification in p-Pb collisions at √{sNN} = 5.02 TeV

NASA Astrophysics Data System (ADS)

Adam, J.; Adamová, D.; Aggarwal, M. M.; Aglieri Rinella, G.; Agnello, M.; Agrawal, N.; Ahammed, Z.; Ahn, S. U.; Aimo, I.; Aiola, S.; Ajaz, M.; Akindinov, A.; Alam, S. N.; Aleksandrov, D.; Alessandro, B.; Alexandre, D.; Alfaro Molina, R.; Alici, A.; Alkin, A.; Alme, J.; Alt, T.; Altinpinar, S.; Altsybeev, I.; Alves Garcia Prado, C.; Andrei, C.; Andronic, A.; Anguelov, V.; Anielski, J.; Antičić, T.; Antinori, F.; Antonioli, P.; Aphecetche, L.; Appelshäuser, H.; Arcelli, S.; Armesto, N.; Arnaldi, R.; Aronsson, T.; Arsene, I. C.; Arslandok, M.; Augustinus, A.; Averbeck, R.; Azmi, M. D.; Bach, M.; Badalà, A.; Baek, Y. W.; Bagnasco, S.; Bailhache, R.; Bala, R.; Baldisseri, A.; Baltasar Dos Santos Pedrosa, F.; Baral, R. C.; Barbano, A. M.; Barbera, R.; Barile, F.; Barnaföldi, G. G.; Barnby, L. S.; Barret, V.; Bartalini, P.; Bartke, J.; Bartsch, E.; Basile, M.; Bastid, N.; Basu, S.; Bathen, B.; Batigne, G.; Batista Camejo, A.; Batyunya, B.; Batzing, P. C.; Bearden, I. G.; Beck, H.; Bedda, C.; Behera, N. K.; Belikov, I.; Bellini, F.; Bello Martinez, H.; Bellwied, R.; Belmont, R.; Belmont-Moreno, E.; Belyaev, V.; Bencedi, G.; Beole, S.; Berceanu, I.; Bercuci, A.; Berdnikov, Y.; Berenyi, D.; Bertens, R. A.; Berzano, D.; Betev, L.; Bhasin, A.; Bhat, I. R.; Bhati, A. K.; Bhattacharjee, B.; Bhom, J.; Bianchi, L.; Bianchi, N.; Bianchin, C.; Bielčík, J.; Bielčíková, J.; Bilandzic, A.; Biswas, S.; Bjelogrlic, S.; Blanco, F.; Blau, D.; Blume, C.; Bock, F.; Bogdanov, A.; Bøggild, H.; Boldizsár, L.; Bombara, M.; Book, J.; Borel, H.; Borissov, A.; Borri, M.; Bossú, F.; Botje, M.; Botta, E.; Böttger, S.; Braun-Munzinger, P.; Bregant, M.; Breitner, T.; Broker, T. A.; Browning, T. A.; Broz, M.; Brucken, E. J.; Bruna, E.; Bruno, G. E.; Budnikov, D.; Buesching, H.; Bufalino, S.; Buncic, P.; Busch, O.; Buthelezi, Z.; Buxton, J. T.; Caffarri, D.; Cai, X.; Caines, H.; Calero Diaz, L.; Caliva, A.; Calvo Villar, E.; Camerini, P.; Carena, F.; Carena, W.; Castillo Castellanos, J.; Castro, A. J.; Casula, E. A. R.; Cavicchioli, C.; Ceballos Sanchez, C.; Cepila, J.; Cerello, P.; Chang, B.; Chapeland, S.; Chartier, M.; Charvet, J. L.; Chattopadhyay, S.; Chattopadhyay, S.; Chelnokov, V.; Cherney, M.; Cheshkov, C.; Cheynis, B.; Chibante Barroso, V.; Chinellato, D. D.; Chochula, P.; Choi, K.; Chojnacki, M.; Choudhury, S.; Christakoglou, P.; Christensen, C. H.; Christiansen, P.; Chujo, T.; Chung, S. U.; Chunhui, Z.; Cicalo, C.; Cifarelli, L.; Cindolo, F.; Cleymans, J.; Colamaria, F.; Colella, D.; Collu, A.; Colocci, M.; Conesa Balbastre, G.; Conesa del Valle, Z.; Connors, M. E.; Contreras, J. G.; Cormier, T. M.; Corrales Morales, Y.; Cortés Maldonado, I.; Cortese, P.; Cosentino, M. R.; Costa, F.; Crochet, P.; Cruz Albino, R.; Cuautle, E.; Cunqueiro, L.; Dahms, T.; Dainese, A.; Danu, A.; Das, D.; Das, I.; Das, S.; Dash, A.; Dash, S.; De, S.; De Caro, A.; de Cataldo, G.; de Cuveland, J.; De Falco, A.; De Gruttola, D.; De Marco, N.; De Pasquale, S.; Deisting, A.; Deloff, A.; Dénes, E.; D'Erasmo, G.; Di Bari, D.; Di Mauro, A.; Di Nezza, P.; Diaz Corchero, M. A.; Dietel, T.; Dillenseger, P.; Divià, R.; Djuvsland, Ø.; Dobrin, A.; Dobrowolski, T.; Domenicis Gimenez, D.; Dönigus, B.; Dordic, O.; Dubey, A. K.; Dubla, A.; Ducroux, L.; Dupieux, P.; Ehlers, R. J.; Elia, D.; Engel, H.; Erazmus, B.; Erhardt, F.; Eschweiler, D.; Espagnon, B.; Estienne, M.; Esumi, S.; Eum, J.; Evans, D.; Evdokimov, S.; Eyyubova, G.; Fabbietti, L.; Fabris, D.; Faivre, J.; Fantoni, A.; Fasel, M.; Feldkamp, L.; Felea, D.; Feliciello, A.; Feofilov, G.; Ferencei, J.; Fernández Téllez, A.; Ferreiro, E. G.; Ferretti, A.; Festanti, A.; Figiel, J.; Figueredo, M. A. S.; Filchagin, S.; Finogeev, D.; Fionda, F. M.; Fiore, E. M.; Fleck, M. G.; Floris, M.; Foertsch, S.; Foka, P.; Fokin, S.; Fragiacomo, E.; Francescon, A.; Frankenfeld, U.; Fuchs, U.; Furget, C.; Furs, A.; Fusco Girard, M.; Gaardhøje, J. J.; Gagliardi, M.; Gago, A. M.; Gallio, M.; Gangadharan, D. R.; Ganoti, P.; Gao, C.; Garabatos, C.; Garcia-Solis, E.; Gargiulo, C.; Gasik, P.; Germain, M.; Gheata, A.; Gheata, M.; Ghosh, P.; Ghosh, S. K.; Gianotti, P.; Giubellino, P.; Giubilato, P.; Gladysz-Dziadus, E.; Glässel, P.; Gomez Ramirez, A.; González-Zamora, P.; Gorbunov, S.; Görlich, L.; Gotovac, S.; Grabski, V.; Graczykowski, L. K.; Grelli, A.; Grigoras, A.; Grigoras, C.; Grigoriev, V.; Grigoryan, A.; Grigoryan, S.; Grinyov, B.; Grion, N.; Grosse-Oetringhaus, J. F.; Grossiord, J.-Y.; Grosso, R.; Guber, F.; Guernane, R.; Guerzoni, B.; Gulbrandsen, K.; Gulkanyan, H.; Gunji, T.; Gupta, A.; Gupta, R.; Haake, R.; Haaland, Ø.; Hadjidakis, C.; Haiduc, M.; Hamagaki, H.; Hamar, G.; Hanratty, L. D.; Hansen, A.; Harris, J. W.; Hartmann, H.; Harton, A.; Hatzifotiadou, D.; Hayashi, S.; Heckel, S. T.; Heide, M.; Helstrup, H.; Herghelegiu, A.; Herrera Corral, G.; Hess, B. A.; Hetland, K. F.; Hilden, T. E.; Hillemanns, H.; Hippolyte, B.; Hristov, P.; Huang, M.; Humanic, T. J.; Hussain, N.; Hussain, T.; Hutter, D.; Hwang, D. S.; Ilkaev, R.; Ilkiv, I.; Inaba, M.; Ionita, C.; Ippolitov, M.; Irfan, M.; Ivanov, M.; Ivanov, V.; Izucheev, V.; Jacobs, P. M.; Jahnke, C.; Jang, H. J.; Janik, M. A.; Jayarathna, P. H. S. Y.; Jena, C.; Jena, S.; Jimenez Bustamante, R. T.; Jones, P. G.; Jung, H.; Jusko, A.; Kalinak, P.; Kalweit, A.; Kamin, J.; Kang, J. H.; Kaplin, V.; Kar, S.; Karasu Uysal, A.; Karavichev, O.; Karavicheva, T.; Karpechev, E.; Kebschull, U.; Keidel, R.; Keijdener, D. L. D.; Keil, M.; Khan, K. H.; Khan, M. M.; Khan, P.; Khan, S. A.; Khanzadeev, A.; Kharlov, Y.; Kileng, B.; Kim, B.; Kim, D. W.; Kim, D. J.; Kim, H.; Kim, J. S.; Kim, M.; Kim, M.; Kim, S.; Kim, T.; Kirsch, S.; Kisel, I.; Kiselev, S.; Kisiel, A.; Kiss, G.; Klay, J. L.; Klein, C.; Klein, J.; Klein-Bösing, C.; Kluge, A.; Knichel, M. L.; Knospe, A. G.; Kobayashi, T.; Kobdaj, C.; Kofarago, M.; Köhler, M. K.; Kollegger, T.; Kolojvari, A.; Kondratiev, V.; Kondratyeva, N.; Kondratyuk, E.; Konevskikh, A.; Kouzinopoulos, C.; Kovalenko, O.; Kovalenko, V.; Kowalski, M.; Kox, S.; Koyithatta Meethaleveedu, G.; Kral, J.; Králik, I.; Kravčáková, A.; Krelina, M.; Kretz, M.; Krivda, M.; Krizek, F.; Kryshen, E.; Krzewicki, M.; Kubera, A. M.; Kučera, V.; Kugathasan, T.; Kuhn, C.; Kuijer, P. G.; Kulakov, I.; Kumar, J.; Kumar, L.; Kurashvili, P.; Kurepin, A.; Kurepin, A. B.; Kuryakin, A.; Kushpil, S.; Kweon, M. J.; Kwon, Y.; La Pointe, S. L.; La Rocca, P.; Lagana Fernandes, C.; Lakomov, I.; Langoy, R.; Lara, C.; Lardeux, A.; Lattuca, A.; Laudi, E.; Lea, R.; Leardini, L.; Lee, G. R.; Lee, S.; Legrand, I.; Lemmon, R. C.; Lenti, V.; Leogrande, E.; León Monzón, I.; Leoncino, M.; Lévai, P.; Li, S.; Li, X.; Lien, J.; Lietava, R.; Lindal, S.; Lindenstruth, V.; Lippmann, C.; Lisa, M. A.; Ljunggren, H. M.; Lodato, D. F.; Loenne, P. I.; Loggins, V. R.; Loginov, V.; Loizides, C.; Lopez, X.; López Torres, E.; Lowe, A.; Luettig, P.; Lunardon, M.; Luparello, G.; Luz, P. H. F. N. D.; Maevskaya, A.; Mager, M.; Mahajan, S.; Mahmood, S. M.; Maire, A.; Majka, R. D.; Malaev, M.; Maldonado Cervantes, I.; Malinina, L.; Mal'Kevich, D.; Malzacher, P.; Mamonov, A.; Manceau, L.; Manko, V.; Manso, F.; Manzari, V.; Marchisone, M.; Mareš, J.; Margagliotti, G. V.; Margotti, A.; Margutti, J.; Marín, A.; Markert, C.; Marquard, M.; Martin, N. A.; Martin Blanco, J.; Martinengo, P.; Martínez, M. I.; Martínez García, G.; Martinez Pedreira, M.; Martynov, Y.; Mas, A.; Masciocchi, S.; Masera, M.; Masoni, A.; Massacrier, L.; Mastroserio, A.; Masui, H.; Matyja, A.; Mayer, C.; Mazer, J.; Mazzoni, M. A.; Mcdonald, D.; Meddi, F.; Menchaca-Rocha, A.; Meninno, E.; Mercado Pérez, J.; Meres, M.; Miake, Y.; Mieskolainen, M. M.; Mikhaylov, K.; Milano, L.; Milosevic, J.; Minervini, L. M.; Mischke, A.; Mishra, A. N.; Miśkowiec, D.; Mitra, J.; Mitu, C. M.; Mohammadi, N.; Mohanty, B.; Molnar, L.; Montaño Zetina, L.; Montes, E.; Morando, M.; Moreira De Godoy, D. A.; Moretto, S.; Morreale, A.; Morsch, A.; Muccifora, V.; Mudnic, E.; Mühlheim, D.; Muhuri, S.; Mukherjee, M.; Müller, H.; Mulligan, J. D.; Munhoz, M. G.; Murray, S.; Musa, L.; Musinsky, J.; Nandi, B. K.; Nania, R.; Nappi, E.; Naru, M. U.; Nattrass, C.; Nayak, K.; Nayak, T. K.; Nazarenko, S.; Nedosekin, A.; Nellen, L.; Ng, F.; Nicassio, M.; Niculescu, M.; Niedziela, J.; Nielsen, B. S.; Nikolaev, S.; Nikulin, S.; Nikulin, V.; Noferini, F.; Nomokonov, P.; Nooren, G.; Norman, J.; Nyanin, A.; Nystrand, J.; Oeschler, H.; Oh, S.; Oh, S. K.; Ohlson, A.; Okatan, A.; Okubo, T.; Olah, L.; Oleniacz, J.; Oliveira Da Silva, A. C.; Oliver, M. H.; Onderwaater, J.; Oppedisano, C.; Ortiz Velasquez, A.; Oskarsson, A.; Otwinowski, J.; Oyama, K.; Ozdemir, M.; Pachmayer, Y.; Pagano, P.; Paić, G.; Pajares, C.; Pal, S. K.; Pan, J.; Pandey, A. K.; Pant, D.; Papikyan, V.; Pappalardo, G. S.; Pareek, P.; Park, W. J.; Parmar, S.; Passfeld, A.; Paticchio, V.; Paul, B.; Peitzmann, T.; Pereira Da Costa, H.; Pereira De Oliveira Filho, E.; Peresunko, D.; Pérez Lara, C. E.; Peskov, V.; Pestov, Y.; Petráček, V.; Petrov, V.; Petrovici, M.; Petta, C.; Piano, S.; Pikna, M.; Pillot, P.; Pinazza, O.; Pinsky, L.; Piyarathna, D. B.; Płoskoń, M.; Planinic, M.; Pluta, J.; Pochybova, S.; Podesta-Lerma, P. L. M.; Poghosyan, M. G.; Polichtchouk, B.; Poljak, N.; Poonsawat, W.; Pop, A.; Porteboeuf-Houssais, S.; Porter, J.; Pospisil, J.; Prasad, S. K.; Preghenella, R.; Prino, F.; Pruneau, C. A.; Pshenichnov, I.; Puccio, M.; Puddu, G.; Pujahari, P.; Punin, V.; Putschke, J.; Qvigstad, H.; Rachevski, A.; Raha, S.; Rajput, S.; Rak, J.; Rakotozafindrabe, A.; Ramello, L.; Raniwala, R.; Raniwala, S.; Räsänen, S. S.; Rascanu, B. T.; Rathee, D.; Read, K. F.; Real, J. S.; Redlich, K.; Reed, R. J.; Rehman, A.; Reichelt, P.; Reicher, M.; Reidt, F.; Ren, X.; Renfordt, R.; Reolon, A. R.; Reshetin, A.; Rettig, F.; Revol, J.-P.; Reygers, K.; Riabov, V.; Ricci, R. A.; Richert, T.; Richter, M.; Riedler, P.; Riegler, W.; Riggi, F.; Ristea, C.; Rivetti, A.; Rocco, E.; Rodríguez Cahuantzi, M.; Rodriguez Manso, A.; Røed, K.; Rogochaya, E.; Rohr, D.; Röhrich, D.; Romita, R.; Ronchetti, F.; Ronflette, L.; Rosnet, P.; Rossi, A.; Roukoutakis, F.; Roy, A.; Roy, C.; Roy, P.; Rubio Montero, A. J.; Rui, R.; Russo, R.; Ryabinkin, E.; Ryabov, Y.; Rybicki, A.; Sadovsky, S.; Šafařík, K.; Sahlmuller, B.; Sahoo, P.; Sahoo, R.; Sahoo, S.; Sahu, P. K.; Saini, J.; Sakai, S.; Saleh, M. A.; Salgado, C. A.; Salzwedel, J.; Sambyal, S.; Samsonov, V.; Sanchez Castro, X.; Šándor, L.; Sandoval, A.; Sano, M.; Santagati, G.; Sarkar, D.; Scapparone, E.; Scarlassara, F.; Scharenberg, R. P.; Schiaua, C.; Schicker, R.; Schmidt, C.; Schmidt, H. R.; Schuchmann, S.; Schukraft, J.; Schulc, M.; Schuster, T.; Schutz, Y.; Schwarz, K.; Schweda, K.; Scioli, G.; Scomparin, E.; Scott, R.; Seeder, K. S.; Seger, J. E.; Sekiguchi, Y.; Selyuzhenkov, I.; Senosi, K.; Seo, J.; Serradilla, E.; Sevcenco, A.; Shabanov, A.; Shabetai, A.; Shadura, O.; Shahoyan, R.; Shangaraev, A.; Sharma, A.; Sharma, N.; Shigaki, K.; Shtejer, K.; Sibiriak, Y.; Siddhanta, S.; Sielewicz, K. M.; Siemiarczuk, T.; Silvermyr, D.; Silvestre, C.; Simatovic, G.; Simonetti, G.; Singaraju, R.; Singh, R.; Singha, S.; Singhal, V.; Sinha, B. C.; Sinha, T.; Sitar, B.; Sitta, M.; Skaali, T. B.; Slupecki, M.; Smirnov, N.; Snellings, R. J. M.; Snellman, T. W.; Søgaard, C.; Soltz, R.; Song, J.; Song, M.; Song, Z.; Soramel, F.; Sorensen, S.; Spacek, M.; Spiriti, E.; Sputowska, I.; Spyropoulou-Stassinaki, M.; Srivastava, B. K.; Stachel, J.; Stan, I.; Stefanek, G.; Steinpreis, M.; Stenlund, E.; Steyn, G.; Stiller, J. H.; Stocco, D.; Strmen, P.; Suaide, A. A. P.; Sugitate, T.; Suire, C.; Suleymanov, M.; Sultanov, R.; Šumbera, M.; Symons, T. J. M.; Szabo, A.; Szanto de Toledo, A.; Szarka, I.; Szczepankiewicz, A.; Szymanski, M.; Takahashi, J.; Tanaka, N.; Tangaro, M. A.; Tapia Takaki, J. D.; Tarantola Peloni, A.; Tariq, M.; Tarzila, M. G.; Tauro, A.; Tejeda Muñoz, G.; Telesca, A.; Terasaki, K.; Terrevoli, C.; Teyssier, B.; Thäder, J.; Thomas, D.; Tieulent, R.; Timmins, A. R.; Toia, A.; Trogolo, S.; Trubnikov, V.; Trzaska, W. H.; Tsuji, T.; Tumkin, A.; Turrisi, R.; Tveter, T. S.; Ullaland, K.; Uras, A.; Usai, G. L.; Utrobicic, A.; Vajzer, M.; Vala, M.; Valencia Palomo, L.; Vallero, S.; Van Der Maarel, J.; Van Hoorne, J. W.; van Leeuwen, M.; Vanat, T.; Vande Vyvre, P.; Varga, D.; Vargas, A.; Vargyas, M.; Varma, R.; Vasileiou, M.; Vasiliev, A.; Vauthier, A.; Vechernin, V.; Veen, A. M.; Veldhoen, M.; Velure, A.; Venaruzzo, M.; Vercellin, E.; Vergara Limón, S.; Vernet, R.; Verweij, M.; Vickovic, L.; Viesti, G.; Viinikainen, J.; Vilakazi, Z.; Villalobos Baillie, O.; Vinogradov, A.; Vinogradov, L.; Vinogradov, Y.; Virgili, T.; Vislavicius, V.; Viyogi, Y. P.; Vodopyanov, A.; Völkl, M. A.; Voloshin, K.; Voloshin, S. A.; Volpe, G.; von Haller, B.; Vorobyev, I.; Vranic, D.; Vrláková, J.; Vulpescu, B.; Vyushin, A.; Wagner, B.; Wagner, J.; Wang, H.; Wang, M.; Wang, Y.; Watanabe, D.; Weber, M.; Weber, S. G.; Wessels, J. P.; Westerhoff, U.; Wiechula, J.; Wikne, J.; Wilde, M.; Wilk, G.; Wilkinson, J.; Williams, M. C. S.; Windelband, B.; Winn, M.; Yaldo, C. G.; Yamaguchi, Y.; Yang, H.; Yang, P.; Yano, S.; Yin, Z.; Yokoyama, H.; Yoo, I.-K.; Yurchenko, V.; Yushmanov, I.; Zaborowska, A.; Zaccolo, V.; Zaman, A.; Zampolli, C.; Zanoli, H. J. C.; Zaporozhets, S.; Zarochentsev, A.; Závada, P.; Zaviyalov, N.; Zbroszczyk, H.; Zgura, I. S.; Zhalov, M.; Zhang, H.; Zhang, X.; Zhang, Y.; Zhao, C.; Zhigareva, N.; Zhou, D.; Zhou, Y.; Zhou, Z.; Zhu, H.; Zhu, J.; Zhu, X.; Zichichi, A.; Zimmermann, A.; Zimmermann, M. B.; Zinovjev, G.; Zyzak, M.

2015-10-01

Charged jet production cross sections in p-Pb collisions at √{sNN} = 5.02 TeV measured with the ALICE detector at the LHC are presented. Using the anti-kT algorithm, jets have been reconstructed in the central rapidity region from charged particles with resolution parameters R = 0.2 and R = 0.4. The reconstructed jets have been corrected for detector effects and the underlying event background. To calculate the nuclear modification factor, RpPb, of charged jets in p-Pb collisions, a pp reference was constructed by scaling previously measured charged jet spectra at √{ s} = 7 TeV. In the transverse momentum range 20 ≤p T , ch jet ≤ 120 GeV / c, RpPb is found to be consistent with unity, indicating the absence of strong nuclear matter effects on jet production. Major modifications to the radial jet structure are probed via the ratio of jet production cross sections reconstructed with the two different resolution parameters. This ratio is found to be similar to the measurement in pp collisions at √{ s} = 7 TeV and to the expectations from PYTHIA pp simulations and NLO pQCD calculations at √{sNN} = 5.02 TeV.

Measurement of charged jet production cross sections and nuclear modification in p–Pb collisions at s NN = 5.02  TeV

DOE PAGES

Adam, J.

2015-07-26

Charged jet production cross sections in p-Pb collisions at √s(NN) = 5.02 TeV measured with the ALICE detector at the LHC are presented. Using the anti-k T algorithm, jets have been reconstructed in the central rapidity region from charged particles with resolution parameters R = 0.2 and R = 0.4. The reconstructed jets have been corrected for detector effects and the underlying event background. To calculate the nuclear modification factor, R- pPb, of charged jets in p-Pb collisions, a pp reference was constructed by scaling previously measured charged jet spectra at √s = 7 TeV. In the transverse momentum rangemore » 20 ≤ p T, ch jet ≤ 120 GeV/c, R- pPb is found to be consistent with unity, indicating the absence of strong nuclear matter effects on jet production. Major modifications to the radial jet structure are probed via the ratio of jet production cross sections reconstructed with the two different resolution parameters. In conclusion, this ratio is found to be similar to the measurement in pp collisions at √s = 7 TeV and to the expectations from PYTHIA pp simulations and NLO pQCD calculations at √s(NN) = 5.02 TeV.« less

S-matrix analysis of the baryon electric charge correlation

NASA Astrophysics Data System (ADS)

Lo, Pok Man; Friman, Bengt; Redlich, Krzysztof; Sasaki, Chihiro

2018-03-01

We compute the correlation of the net baryon number with the electric charge (χBQ) for an interacting hadron gas using the S-matrix formulation of statistical mechanics. The observable χBQ is particularly sensitive to the details of the pion-nucleon interaction, which are consistently incorporated in the current scheme via the empirical scattering phase shifts. Comparing to the recent lattice QCD studies in the (2 + 1)-flavor system, we find that the natural implementation of interactions and the proper treatment of resonances in the S-matrix approach lead to an improved description of the lattice data over that obtained in the hadron resonance gas model.

Two loop renormalization of the magnetic coupling in hot QCD

NASA Astrophysics Data System (ADS)

Giovannangeli, P.

2004-04-01

Well above the critical temperature hot QCD is described by 3d electrostatic QCD with gauge coupling gE and Debye mass mE. We integrate out the Debye scales to two loop accuracy and find for the gauge coupling in the resulting magnetostatic action gM2=gE21-{1}/{48}{gE2N}/{πmE}-{17}/{4608}{gE2N}/{πmE}2+O{gE2N}/{πmE}3.

OPE of Green functions in the odd sector of QCD

NASA Astrophysics Data System (ADS)

Kadavý, T.; Kampf, K.; Novotný, J.

2017-03-01

A review of familiar results of the three-point Green functions of currents in the odd-intrinsic parity sector of QCD is presented. Such Green functions include very well-known examples of VVP, VAS or AAP correlators. We also present new results for VVA and AAA Green functions that have not yet been studied extensively in the literature before, more importantly with a phenomenological study and a discussion of the highenergy behaviour and its relation to the QCD condensates.

Effective charges and virial pressure of concentrated macroion solutions

DOE PAGES

Boon, Niels; Guerrero-García, Guillermo Ivan; van Roij, René; ...

2015-07-13

The stability of colloidal suspensions is crucial in a wide variety of processes, including the fabrication of photonic materials and scaffolds for biological assemblies. The ionic strength of the electrolyte that suspends charged colloids is widely used to control the physical properties of colloidal suspensions. The extensively used two-body Derjaguin-Landau-Verwey-Overbeek (DLVO) approach allows for a quantitative analysis of the effective electrostatic forces between colloidal particles. DLVO relates the ionic double layers, which enclose the particles, to their effective electrostatic repulsion. Nevertheless, the double layer is distorted at high macroion volume fractions. Therefore, DLVO cannot describe the many-body effects that arisemore » in concentrated suspensions. In this paper, we show that this problem can be largely resolved by identifying effective point charges for the macroions using cell theory. This extrapolated point charge (EPC) method assigns effective point charges in a consistent way, taking into account the excluded volume of highly charged macroions at any concentration, and thereby naturally accounting for high volume fractions in both salt-free and added-salt conditions. We provide an analytical expression for the effective pair potential and validate the EPC method by comparing molecular dynamics simulations of macroions and monovalent microions that interact via Coulombic potentials to simulations of macroions interacting via the derived EPC effective potential. The simulations reproduce the macroion-macroion spatial correlation and the virial pressure obtained with the EPC model. Finally, our findings provide a route to relate the physical properties such as pressure in systems of screened Coulomb particles to experimental measurements.« less

Applications of QCD factorization in multiscale Hadronic scattering

NASA Astrophysics Data System (ADS)

Wang, Bowen

In this thesis I apply QCD factorization theorems to two important hadronic processes. In the first study, I treat the inclusive cross section of the production of massive quarks through neutral current deep inelasitc scattering (DIS): (n/a). In this study I work out a method to consistently organize the QCD radiative contributions up to O(alphas 3) (N3LO), with a proper inclusion of the heavy quark mass dependence at different momentum scales. The generic implementation of the mass dependence developed in this thesis can be used by calculations in both an intermediate-mass factorization scheme and a general-mass factorization scheme. The mass effect is relevant to the predictions for Higgs, and W and Z cross sections measured at the LHC. The second study examines the transverse-momentum distribution of the lepton-pair production in Drell-yan process. The theory predictions based on the Collins-Soper-Sterman (CSS) resummation formalism at NNLL accuracy are compared with the new data on the angular distribution *eta of Drell-Yan pairs measured at the Tevatron and the LHC. The main finding is that the nonperturbative component of the CSS resummed cross section plays a crucial part in explaining the data in the small transverse momentum region.

Topology in the SU(Nf) chiral symmetry restored phase of unquenched QCD and axion cosmology

NASA Astrophysics Data System (ADS)

Azcoiti, Vicente

2018-03-01

The axion is one of the more interesting candidates to make the dark matter of the universe, and the axion potential plays a fundamental role in the determination of the dynamics of the axion field. Moreover, the way in which the U(1)A anomaly manifests itself in the chiral symmetry restored phase of QCD at high temperature could be tested when probing the QCD phase transition in relativistic heavy ion collisions. With these motivations, we investigate the physical consequences of the survival of the effects of the U(1)A anomaly in the chiral symmetric phase of QCD, and show that the free energy density is a singular function of the quark mass m, in the chiral limit, and that the σ and π susceptibilities diverge in this limit at any T ≥ Tc. We also show that the difference between the π and t;δ susceptibilities diverges in the chiral limit at any T ≥ Tc, a result that can be contrasted with the existing lattice calculations; and discuss on the generalization of these results to the Nf ≥ 3 model.

QCD triple Pomeron coupling from string amplitudes

NASA Astrophysics Data System (ADS)

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

1998-06-01

Using the recent solution of the triple Pomeron coupling in the QCD dipole picture as a closed string amplitude with six legs, its analytical form in terms of hypergeometric functions and numerical value are derived.

Charge Fractionalization in the Two-Channel Kondo Effect

NASA Astrophysics Data System (ADS)

Landau, L. Aviad; Cornfeld, Eyal; Sela, Eran

2018-05-01

The phenomenon of charge fractionalization describes the emergence of novel excitations with fractional quantum numbers, as predicted in strongly correlated systems such as spin liquids. We elucidate that precisely such an unusual effect may occur in the simplest possible non-Fermi liquid, the two-channel Kondo effect. To bring this concept down to experimental test, we study nonequilibrium transport through a device realizing the charge two-channel Kondo critical point in a recent experiment by Iftikhar et al. [Nature (London) 526, 233 (2015), 10.1038/nature15384]. The shot noise at low voltages is predicted to result in a universal Fano factor e*/e =1 /2 . This allows us to experimentally identify elementary transport processes of emergent fermions carrying half-integer charge.

QCD inequalities for the nucleon mass and the free energy of baryonic matter.

PubMed

Cohen, Thomas D

2003-07-18

The positivity of the integrand of certain Euclidean space functional integrals for two flavor QCD with degenerate quark masses implies that the free energy per unit volume for QCD with a baryon chemical potential mu(B) (and zero isospin chemical potential) is greater than the free energy with an isospin chemical potential mu(I)=(2 mu(B)/N(c)) (and zero baryon chemical potential). The same result applies to QCD with any number of heavy flavors in addition to the two light flavors so long as the chemical potential is understood as applying to the light quark contributions to the baryon number. This relation implies a bound on the nucleon mass: there exists a particle X in QCD (presumably the pion) such that M(N)> or =(N(c) m(X)/2 I(X)) where m(X) is the mass of the particle and I(X) is its isospin.

Lattice QCD calculations of nucleon transverse momentum-dependent parton distributions using clover and domain wall fermions

DOE PAGES

Yoon, Boram; Bhattacharya, Tanmoy; Gupta, Rajan; ...

2015-01-01

Here, we present a lattice QCD calculation of transverse momentum dependent parton distribution functions (TMDs) of protons using staple-shaped Wilson lines. For time-reversal odd observables, we calculate the generalized Sivers and Boer-Mulders transverse momentum shifts in SIDIS and DY cases, and for T-even observables we calculate the transversity related to the tensor charge and the generalized worm-gear shift. The calculation is done on two different n f = 2+1 ensembles: domain-wall fermion (DWF) with lattice spacing 0:084fm and pion mass of 297 MeV, and clover fermion with lattice spacing 0:114 fm and pion mass of 317 MeV. The results frommore » those two different discretizations are consistent with each other.« less

Determination of the chiral condensate from (2+1)-flavor lattice QCD.

PubMed

Fukaya, H; Aoki, S; Hashimoto, S; Kaneko, T; Noaki, J; Onogi, T; Yamada, N

2010-03-26

We perform a precise calculation of the chiral condensate in QCD using lattice QCD with 2+1 flavors of dynamical overlap quarks. Up and down quark masses cover a range between 3 and 100 MeV on a 16{3}x48 lattice at a lattice spacing approximately 0.11 fm. At the lightest sea quark mass, the finite volume system on the lattice is in the regime. By matching the low-lying eigenvalue spectrum of the Dirac operator with the prediction of chiral perturbation theory at the next-to-leading order, we determine the chiral condensate in (2+1)-flavor QCD with strange quark mass fixed at its physical value as Sigma;{MS[over ]}(2 GeV)=[242(04)(+19/-18) MeV]{3} where the errors are statistical and systematic, respectively.

Effect of Stochastic Charge Fluctuations on Dust Dynamics

NASA Astrophysics Data System (ADS)

Matthews, Lorin; Shotorban, Babak; Hyde, Truell

2017-10-01

The charging of particles in a plasma environment occurs through the collection of electrons and ions on the particle surface. Depending on the particle size and the plasma density, the standard deviation of the number of collected elementary charges, which fluctuates due to the randomness in times of collisions with electrons or ions, may be a significant fraction of the equilibrium charge. We use a discrete stochastic charging model to simulate the variations in charge across the dust surface as well as in time. The resultant asymmetric particle potentials, even for spherical grains, has a significant impact on the particle coagulation rate as well as the structure of the resulting aggregates. We compare the effects on particle collisions and growth in typical laboratory and astrophysical plasma environments. This work was supported by the National Science Foundation under Grant PHY-1414523.

Effect of electric charge on the adhesion of human blood platelets.

PubMed

Lowkis, B; Szymonowicz, M

1993-01-01

The paper presents the results of research into the effect of the size and depth of the implanted electric charge on the adhesion of human blood platelets. The experiments were carried out on polyethylene terephthalate PET foil of 36 microns thickness. The electret formation process was carried out in an electron-beam device. The electrization conditions were such that electrets with the excess electric charge accumulated at various depths were obtained. The selection of conditions was verified by investigating the space charge distribution with the use of the virtual electrode method. The microscopic observation of non-electrified foils and electrets as well as the quantitative examination of the adhesion of human blood platelets has explicitly confirmed the positive influence of the electret effect on the thrombogenesis of PET foil. This made it possible to define the optimum electrization conditions. The research has additionally indicated that the relationship between the amount of adherent blood platelets and the size of the electric charge is not a simple relation of the kind: the larger negative charge, the more thrombogenic material. The decisive and positive effect of the space charge has been confirmed by analysing the effectiveness of the surface and space charge.

Hyperasymptotics and quark-hadron duality violations in QCD

NASA Astrophysics Data System (ADS)

Boito, Diogo; Caprini, Irinel; Golterman, Maarten; Maltman, Kim; Peris, Santiago

2018-03-01

We investigate the origin of the quark-hadron duality-violating terms in the expansion of the QCD two-point vector correlation function at large energies in the complex q2 plane. Starting from the dispersive representation for the associated polarization, the analytic continuation of the operator product expansion from the Euclidean to the Minkowski region is performed by means of a generalized Borel-Laplace transform, borrowing techniques from hyperasymptotics. We establish a connection between singularities in the Borel plane and quark-hadron duality-violating contributions. Starting with the assumption that for QCD at Nc=∞ the spectrum approaches a Regge trajectory at large energy, we obtain an expression for quark-hadron duality violations at large, but finite Nc.

Lattice QCD results on soft and hard probes of strongly interacting matter

NASA Astrophysics Data System (ADS)

Kaczmarek, Olaf

2017-11-01

We present recent results from lattice QCD relevant for the study of strongly interacting matter as it is produced in heavy ion collision experiments. The equation of state at non-vanishing density from a Taylor expansion up to 6th order will be discussed for a strangeness neutral system and using the expansion coefficients of the series limits on the critical point are estimated. Chemical freeze-out temperatures from the STAR and ALICE Collaborations will be compared to lines of constant physics calculated from the Taylor expansion of QCD bulk thermodynamic quantities. We show that qualitative features of the √{sNN} dependence of skewness and kurtosis ratios of net proton-number fluctuations measured by the STAR Collaboration can be understood from QCD results for cumulants of conserved baryon-number fluctuations. As an example for recent progress towards the determination of spectral and transport properties of the QGP from lattice QCD, we will present constraints on the thermal photon rate determined from a spectral reconstruction of continuum extrapolated lattice correlation functions in combination with input from most recent perturbative calculations.

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.

Charged-particle mutagenesis II. Mutagenic effects of high energy charged particles in normal human fibroblasts

NASA Technical Reports Server (NTRS)

Chen, D. J.; Tsuboi, K.; Nguyen, T.; Yang, T. C.

1994-01-01

The biological effects of high LET charged particles are a subject of great concern with regard to the prediction of radiation risk in space. In this report, mutagenic effects of high LET charged particles are quantitatively measured using primary cultures of human skin fibroblasts, and the spectrum of induced mutations are analyzed. The LET of the charged particles ranged from 25 KeV/micrometer to 975 KeV/micrometer with particle energy (on the cells) between 94-603 MeV/u. The X-chromosome linked hypoxanthine guanine phosphoribosyl transferase (hprt) locus was used as the target gene. Exposure to these high LET charged particles resulted in exponential survival curves; whereas, mutation induction was fitted by a linear model. The Relative Biological Effect (RBE) for cell-killing ranged from 3.73 to 1.25, while that for mutant induction ranged from 5.74 to 0.48. Maximum RBE values were obtained at the LET of 150 keV/micrometer. The inactivation cross-section (alpha i) and the action cross-section for mutant induction (alpha m) ranged from 2.2 to 92.0 micrometer2 and 0.09 to 5.56 x 10(-3) micrometer2, respectively. The maximum values were obtained by 56Fe with an LET of 200 keV/micrometer. The mutagenicity (alpha m/alpha i) ranged from 2.05 to 7.99 x 10(-5) with the maximum value at 150 keV/micrometer. Furthermore, molecular analysis of mutants induced by charged particles indicates that higher LET beams are more likely to cause larger deletions in the hprt locus.

Effect of Charge Patterning on the Phase Behavior of Polymer Coacervates for Charge Driven Self Assembly

NASA Astrophysics Data System (ADS)

Radhakrishna, Mithun; Sing, Charles E.

Oppositely charged polymers can undergo associative liquid-liquid phase separation when mixed under suitable conditions of ionic strength, temperature and pH to form what are known as `polymeric complex coacervates'. Polymer coacervates find use in diverse array of applications like microencapsulation, drug delivery, membrane filtration and underwater adhesives. The similarity between complex coacervate environments and those in biological systems has also found relevance in areas of bio-mimicry. Our previous works have demonstrated how local charge correlations and molecular connectivity can drastically affect the phase behavior of coacervates. The precise location of charges along the chain therefore dramatically influences the local charge correlations, which consequently influences the phase behavior of coacervates. We investigate the effect of charge patterning along the polymer chain on the phase behavior of coacervates in the framework of the Restricted Primitive Model using Gibbs Ensemble Monte Carlo simulations. Our results show that charge patterning dramatically changes the phase behavior of polymer coacervates, which contrasts with the predictions of the classical Voorn-Overbeek theory. This provides the basis for designing new materials through charge driven self assembly by controlling the positioning of the charged monomers along the chain.

Unified models of the QCD axion and supersymmetry breaking

NASA Astrophysics Data System (ADS)

Harigaya, Keisuke; Leedom, Jacob M.

2017-08-01

Similarities between the gauge meditation of supersymmetry breaking and the QCD axion model suggest that they originate from the same dynamics. We present a class of models where supersymmetry and the Peccei-Quinn symmetry are simultaneously broken. The messengers that mediate the effects of these symmetry breakings to the Standard Model are identical. Since the axion resides in the supersymmetry breaking sector, the saxion and the axino are heavy. We show constraints on the axion decay constant and the gravitino mass.

Study of the Z c + channel using lattice QCD

DOE PAGES

Prelovsek, Sasa; Lang, C. B.; Leskovec, Luka; ...

2015-01-01

Recently experimentalists have discovered several charged charmoniumlike hadronsmore » $$Z^{+}_{c}$$ with unconventional quark content $$\\bar{c}c\\bar{d} u$$ We perform a search for $$Z^{+}_{c}$$ with mass below 4.2 GeV in the channel $$I^G(J^{PC}) = 1^+ (^{1+-})$$ using lattice QCD. The major challenge is presented by the two-meson states $$J/ψπ, ψ_{2s}π, ψ_{1D}π, D\\bar{D}^*, D^*\\bar{D}^*, η_cρ$$ that are inevitably present in this channel. The spectrum of eigenstates is extracted using a number of meson-meson and diquark-antidiquark interpolating fields. For our pion mass of 266 MeV we find all the expected two-meson states but no additional candidate for $$Z^{+}_{c}$$ below 4.2 GeV. Possible reasons for not seeing an additional eigenstate related to $$Z^{+}_{c}$$ are discussed. We also illustrate how a simulation incorporating interpolators with a structure resembling low-lying two-meson states seems to render a $$Z^{+}_{c}$$ candidate, which is however not robust after further two-meson states around 4.2 GeV are implemented.« less

QCD analysis of neutrino charged current structure function F2 in deep inelastic scattering

NASA Technical Reports Server (NTRS)

Saleem, M.; Aleem, F.

1985-01-01

An analytic expression for the neutrino charged current structure function F sub 2 (x, Q sup 2) in deep inelastic scattering, consistent with quantum chromodynamics, is proposed. The calculated results are in good agreement with experiment.

QCD sum rules study of meson-baryon sigma terms

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

Erkol, Gueray; Oka, Makoto; Turan, Guersevil

2008-11-01

The pion-baryon sigma terms and the strange-quark condensates of the octet and the decuplet baryons are calculated by employing the method of QCD sum rules. We evaluate the vacuum-to-vacuum transition matrix elements of two baryon interpolating fields in an external isoscalar-scalar field and use a Monte Carlo-based approach to systematically analyze the sum rules and the uncertainties in the results. We extract the ratios of the sigma terms, which have rather high accuracy and minimal dependence on QCD parameters. We discuss the sources of uncertainties and comment on possible strangeness content of the nucleon and the Delta.

Charmed tetraquarks Tcc and Tcs from dynamical lattice QCD simulations

NASA Astrophysics Data System (ADS)

Ikeda, Yoichi; Charron, Bruno; Aoki, Sinya; Doi, Takumi; Hatsuda, Tetsuo; Inoue, Takashi; Ishii, Noriyoshi; Murano, Keiko; Nemura, Hidekatsu; Sasaki, Kenji

2014-02-01

Charmed tetraquarks Tcc=(ccubardbar) and Tcs=(csubardbar) are studied through the S-wave meson-meson interactions, D-D, Kbar-D, D-D* and Kbar-D*, on the basis of the (2+1)-flavor lattice QCD simulations with the pion mass mπ≃410, 570 and 700 MeV. For the charm quark, the relativistic heavy quark action is employed to treat its dynamics on the lattice. Using the HAL QCD method, we extract the S-wave potentials in lattice QCD simulations, from which the meson-meson scattering phase shifts are calculated. The phase shifts in the isospin triplet (I=1) channels indicate repulsive interactions, while those in the I=0 channels suggest attraction, growing as mπ decreases. This is particularly prominent in the Tcc (JP=1+,I=0) channel, though neither bound state nor resonance are found in the range mπ=410-700 MeV. We make a qualitative comparison of our results with the phenomenological diquark picture.

Searching for beauty-fully bound tetraquarks using lattice nonrelativistic QCD

NASA Astrophysics Data System (ADS)

Hughes, Ciaran; Eichten, Estia; Davies, Christine T. H.

2018-03-01

Motivated by multiple phenomenological considerations, we perform the first search for the existence of a b ¯b ¯b b tetraquark bound state with a mass below the lowest noninteracting bottomonium-pair threshold using the first-principles lattice nonrelativistic QCD methodology. We use a full S -wave color/spin basis for the b ¯b ¯b b operators in the three 0++, 1+- and 2++ channels. We employ four gluon field ensembles at multiple lattice spacing values ranging from a =0.06 - 0.12 fm , all of which include u , d , s and c quarks in the sea, and one ensemble which has physical light-quark masses. Additionally, we perform novel exploratory work with the objective of highlighting any signal of a near threshold tetraquark, if it existed, by adding an auxiliary potential into the QCD interactions. With our results we find no evidence of a QCD bound tetraquark below the lowest noninteracting thresholds in the channels studied.

Searching for beauty-fully bound tetraquarks using lattice nonrelativistic QCD

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

Hughes, Ciaran; Eichten, Estia; Davies, Christine T. H.

Motivated by multiple phenomenological considerations, we perform the first search for the existence of amore » $$\\bar{bb}bb$$ tetraquark bound state with a mass below the lowest noninteracting bottomonium-pair threshold using the first-principles lattice nonrelativistic QCD methodology. Here, we use a full S-wave color/spin basis for the $$\\bar{bb}bb$$ operators in the three 0 ++, 1 +- and 2 ++ channels. We employ four gluon field ensembles at multiple lattice spacing values ranging from a=0.06–0.12 fm, all of which include u, d, s and c quarks in the sea, and one ensemble which has physical light-quark masses. Additionally, we perform novel exploratory work with the objective of highlighting any signal of a near threshold tetraquark, if it existed, by adding an auxiliary potential into the QCD interactions. With our results we find no evidence of a QCD bound tetraquark below the lowest noninteracting thresholds in the channels studied.« less

Searching for beauty-fully bound tetraquarks using lattice nonrelativistic QCD

DOE PAGES

Hughes, Ciaran; Eichten, Estia; Davies, Christine T. H.

2018-03-14

Motivated by multiple phenomenological considerations, we perform the first search for the existence of amore » $$\\bar{bb}bb$$ tetraquark bound state with a mass below the lowest noninteracting bottomonium-pair threshold using the first-principles lattice nonrelativistic QCD methodology. Here, we use a full S-wave color/spin basis for the $$\\bar{bb}bb$$ operators in the three 0 ++, 1 +- and 2 ++ channels. We employ four gluon field ensembles at multiple lattice spacing values ranging from a=0.06–0.12 fm, all of which include u, d, s and c quarks in the sea, and one ensemble which has physical light-quark masses. Additionally, we perform novel exploratory work with the objective of highlighting any signal of a near threshold tetraquark, if it existed, by adding an auxiliary potential into the QCD interactions. With our results we find no evidence of a QCD bound tetraquark below the lowest noninteracting thresholds in the channels studied.« less

Cosmological abundance of the QCD axion coupled to hidden photons

NASA Astrophysics Data System (ADS)

Kitajima, Naoya; Sekiguchi, Toyokazu; Takahashi, Fuminobu

2018-06-01

We study the cosmological evolution of the QCD axion coupled to hidden photons. For a moderately strong coupling, the motion of the axion field leads to an explosive production of hidden photons by tachyonic instability. We use lattice simulations to evaluate the cosmological abundance of the QCD axion. In doing so, we incorporate the backreaction of the produced hidden photons on the axion dynamics, which becomes significant in the non-linear regime. We find that the axion abundance is suppressed by at most O (102) for the decay constant fa =1016GeV, compared to the case without the coupling. For a sufficiently large coupling, the motion of the QCD axion becomes strongly damped, and as a result, the axion abundance is enhanced. Our results show that the cosmological upper bound on the axion decay constant can be relaxed by a few hundred for a certain range of the coupling to hidden photons.

Charmonium-nucleon interactions from the time-dependent HAL QCD method

NASA Astrophysics Data System (ADS)

Sugiura, Takuya; Ikeda, Yoichi; Ishii, Noriyoshi

2018-03-01

The charmonium-nucleon effective central interactions have been computed by the time-dependent HAL QCD method. This gives an updated result of a previous study based on the time-independent method, which is now known to be problematic because of the difficulty in achieving the ground-state saturation. We discuss that the result is consistent with the heavy quark symmetry. No bound state is observed from the analysis of the scattering phase shift; however, this shall lead to a future search of the hidden-charm pentaquarks by considering channel-coupling effects.

Determination of $${{\\rm{\\Lambda }}}_{\\overline{{\\rm{MS}}}}$$ at five loops from holographic QCD

DOE PAGES

Deur, Alexandre; Brodsky, Stanley J.; de Téramond, Guy F.

2017-08-25

Here, the recent determination of themore » $$\\beta$$--function of the QCD running coupling $$\\alpha_{\\overline{MS}}(Q^2)$$ to five-loops, provides a verification of the convergence of a novel method for determining the fundamental QCD parameter $$\\Lambda_s$$ based on the Light-Front Holographic approach to nonperturbative QCD. The new 5-loop analysis, together with improvements in determining the holographic QCD nonperturbative scale parameter $$\\kappa$$ from hadronic spectroscopy, leads to an improved precision of the value of $$\\Lambda_s$$ in the $${\\overline{MS}}$$ scheme close to a factor of two; we find $$\\Lambda^{(3)}_{\\overline{MS}}=0.339\\pm0.019$$ GeV for $$n_{f}=3$$, in excellent agreement with the world average, $$\\Lambda_{\\overline{MS}}^{(3)}=0.332\\pm0.017$$ GeV. Lastly, we also discuss the constraints imposed on the scale dependence of the strong coupling in the nonperturbative domain by superconformal quantum mechanics and its holographic embedding in anti-de Sitter space.« less

Space charge effect in spectrometers of ion mobility increment with cylindrical drift chamber.

PubMed

Elistratov, A A; Sherbakov, L A

2007-01-01

We have amplified the model for the drift of ions under a non-uniform high-frequency electric field by taking space charge effect into account. By this means, we have investigated the effect of space charge on the dynamics of a single type of ions in a spectrometer of ion mobility increment with a cylindrical drift chamber. The counteraction of the space charge effect and the focusing effect is investigated. The output ion current saturation caused by the effect of the space charge is observed. The shape of the ion peak taking into consideration the space charge effect has been obtained. We show that the effect of the space charge is sufficient for the relative ion density greater than 10 ppt by order of magnitude (for a cylindrical geometry spectrometer with typical parameters).

Higgs boson production at hadron colliders at N3LO in QCD

NASA Astrophysics Data System (ADS)

Mistlberger, Bernhard

2018-05-01

We present the Higgs boson production cross section at Hadron colliders in the gluon fusion production mode through N3LO in perturbative QCD. Specifically, we work in an effective theory where the top quark is assumed to be infinitely heavy and all other quarks are considered to be massless. Our result is the first exact formula for a partonic hadron collider cross section at N3LO in perturbative QCD. Furthermore, our result is an analytic computation of a hadron collider cross section involving elliptic integrals. We derive numerical predictions for the Higgs boson cross section at the LHC. Previously this result was approximated by an expansion of the cross section around the production threshold of the Higgs boson and we compare our findings. Finally, we study the impact of our new result on the state of the art prediction for the Higgs boson cross section at the LHC.

Shear viscosity of the quark-gluon plasma in a weak magnetic field in perturbative QCD: Leading log

NASA Astrophysics Data System (ADS)

Li, Shiyong; Yee, Ho-Ung

2018-03-01

We compute the shear viscosity of two-flavor QCD plasma in an external magnetic field in perturbative QCD at leading log order, assuming that the magnetic field is weak or soft: e B ˜g4log (1 /g )T2. We work in the assumption that the magnetic field is homogeneous and static, and the electrodynamics is nondynamical in a formal limit e →0 while e B is kept fixed. We show that the shear viscosity takes a form η =η ¯(B ¯)T3/(g4log (1 /g )) with a dimensionless function η ¯(B ¯) in terms of a dimensionless variable B ¯=(e B )/(g4log (1 /g )T2). The variable B ¯ corresponds to the relative strength of the effect of cyclotron motions compared to the QCD collisions: B ¯˜lmfp/lcyclo. We provide a full numerical result for the scaled shear viscosity η ¯(B ¯).

The QCD corrections of the process h → ηbZ

NASA Astrophysics Data System (ADS)

Zhu, Rong-Fei; Feng, Tai-Fu; Zhang, Hai-Bin

2018-05-01

We investigate the 125 GeV Higgs boson decay to a pseudoscalar quarkonium ηb and Z boson. We calculate the quantum chromodynamics (QCD) one-loop corrections to the branching ratio of the process, Br(h → ηbZ), both in the Standard Model (SM) and in the two Higgs double models (THDM). Adding the QCD one-loop corrections, the branching ratio of h → ηbZ in the SM is Br(h → ηbZ) = (4.739‑0.244+0.276) × 10‑5. The relative correction of that QCD one-loop level relative to the tree level of Br(h → ηbZ) is around 76% in the SM. Similarly, the relative correction in the THDM also can be around 75%. The key parameter, tan β, can affect the relative correction in the THDM.

Constructing a neutron star from the lattice in G2-QCD

NASA Astrophysics Data System (ADS)

Hajizadeh, Ouraman; Maas, Axel

2017-10-01

The inner structure of neutron stars is still an open question. One obstacle is the infamous sign problem of lattice QCD, which bars access to the high-density equation of state. A possibility to make progress and understand the qualitative impact of gauge interactions on the neutron star structure is to study a modified version of QCD without the sign problem. In the modification studied here the gauge group of QCD is replaced by the exceptional Lie group G_2 , which keeps neutrons in the spectrum. Using an equation of state from lattice calculations only we determine the mass-radius-relation for a neutron star using the Tolman-Oppenheimer-Volkoff equation. This allows us to understand the challenges and approximations currently necessary to use lattice data for this purpose. We discuss in detail the particular uncertainties and systematic problems of this approach.

Space-charge Effect on Electroresistance in Metal-Ferroelectric-Metal capacitors

PubMed Central

Tian, Bo Bo; Liu, Yang; Chen, Liu Fang; Wang, Jian Lu; Sun, Shuo; Shen, Hong; Sun, Jing Lan; Yuan, Guo Liang; Fusil, Stéphane; Garcia, Vincent; Dkhil, Brahim; Meng, Xiang Jian; Chu, Jun Hao

2015-01-01

Resistive switching through electroresistance (ER) effect in metal-ferroelectric-metal (MFM) capacitors has attracted increasing interest due to its potential applications as memories and logic devices. However, the detailed electronic mechanisms resulting in large ER when polarisation switching occurs in the ferroelectric barrier are still not well understood. Here, ER effect up to 1000% at room temperature is demonstrated in C-MOS compatible MFM nanocapacitors with a 8.8 nm-thick poly(vinylidene fluoride) (PVDF) homopolymer ferroelectric, which is very promising for silicon industry integration. Most remarkably, using theory developed for metal-semiconductor rectifying contacts, we derive an analytical expression for the variation of interfacial barrier heights due to space-charge effect that can interpret the observed ER response. We extend this space-charge model, related to the release of trapped charges by defects, to MFM structures made of ferroelectric oxides. This space-charge model provides a simple and straightforward tool to understand recent unusual reports. Finally, this work suggests that defect-engineering could be an original and efficient route for tuning the space-charge effect and thus the ER performances in future electronic devices. PMID:26670138

Space-charge Effect on Electroresistance in Metal-Ferroelectric-Metal capacitors

NASA Astrophysics Data System (ADS)

Tian, Bo Bo; Liu, Yang; Chen, Liu Fang; Wang, Jian Lu; Sun, Shuo; Shen, Hong; Sun, Jing Lan; Yuan, Guo Liang; Fusil, Stéphane; Garcia, Vincent; Dkhil, Brahim; Meng, Xiang Jian; Chu, Jun Hao

2015-12-01

Resistive switching through electroresistance (ER) effect in metal-ferroelectric-metal (MFM) capacitors has attracted increasing interest due to its potential applications as memories and logic devices. However, the detailed electronic mechanisms resulting in large ER when polarisation switching occurs in the ferroelectric barrier are still not well understood. Here, ER effect up to 1000% at room temperature is demonstrated in C-MOS compatible MFM nanocapacitors with a 8.8 nm-thick poly(vinylidene fluoride) (PVDF) homopolymer ferroelectric, which is very promising for silicon industry integration. Most remarkably, using theory developed for metal-semiconductor rectifying contacts, we derive an analytical expression for the variation of interfacial barrier heights due to space-charge effect that can interpret the observed ER response. We extend this space-charge model, related to the release of trapped charges by defects, to MFM structures made of ferroelectric oxides. This space-charge model provides a simple and straightforward tool to understand recent unusual reports. Finally, this work suggests that defect-engineering could be an original and efficient route for tuning the space-charge effect and thus the ER performances in future electronic devices.

Hadronic decays of B →a1(1260 )b1(1235 ) in the perturbative QCD approach

NASA Astrophysics Data System (ADS)

Jing, Hao-Yang; Liu, Xin; Xiao, Zhen-Jun

2017-12-01

We calculate the branching ratios and polarization fractions of the B →a1b1 decays in the perturbative QCD(pQCD) approach at leading order, where a1(b1) stands for the axial-vector a1(1260 )[b1(1235 )] state. By combining the phenomenological analyses with the perturbative calculations, we find the following results: (a) the large decay rates around 10-5 to 10-6 of the B →a1b1 decays dominated by the longitudinal polarization(except for the B+→b1+a10 mode) are predicted and basically consistent with those in the QCD factorization(QCDF) within errors, which are expected to be tested by the Large Hadron Collider and Belle-II experiments. The large B0→a10b10 branching ratio could provide hints to help explore the mechanism of the color-suppressed decays. (b) the rather different QCD behaviors between the a1 and b1 mesons result in the destructive(constructive) contributions in the nonfactorizable spectator diagrams with a1(b1) emission. Therefore, an interesting pattern of the branching ratios appears for the color-suppressed B0→a10a10,a10b10, and b10b10 modes in the pQCD approach, BR (B0→b10b10)>BR (B0→a10b10)≳BR (B0→a10a10), which is different from BR (B0→b10b10)˜BR (B0→a10b10)≳BR (B0→a10a10) in the QCDF and would be verified at future experiments. (c) the large naive factorization breaking effects are observed in these B →a1b1 decays. Specifically, the large nonfactorizable spectator(weak annihilation) amplitudes contribute to the B0→b1+a1-(B+→a1+b10andB+→b1+a10) mode(s), which demand confirmations via the precise measurements. Furthermore, the different phenomenologies shown among B →a1b1, B →a1a1, and B →b1b1 decays are also expected to be tested stringently, which could shed light on the typical QCD dynamics involved in these modes, even further distinguish those two popular pQCD and QCDF approaches.

Quantification of surface charge density and its effect on boundary slip.

PubMed

Jing, Dalei; Bhushan, Bharat

2013-06-11

Reduction of fluid drag is important in the micro-/nanofluidic systems. Surface charge and boundary slip can affect the fluid drag, and surface charge is also believed to affect boundary slip. The quantification of surface charge and boundary slip at a solid-liquid interface has been widely studied, but there is a lack of understanding of the effect of surface charge on boundary slip. In this paper, the surface charge density of borosilicate glass and octadecyltrichlorosilane (OTS) surfaces immersed in saline solutions with two ionic concentrations and deionized (DI) water with different pH values and electric field values is quantified by fitting experimental atomic force microscopy (AFM) electrostatic force data using a theoretical model relating the surface charge density and electrostatic force. Results show that pH and electric field can affect the surface charge density of glass and OTS surfaces immersed in saline solutions and DI water. The mechanisms of the effect of pH and electric field on the surface charge density are discussed. The slip length of the OTS surface immersed in saline solutions with two ionic concentrations and DI water with different pH values and electric field values is measured, and their effects on the slip length are analyzed from the point of surface charge. Results show that a larger absolute value of surface charge density leads to a smaller slip length for the OTS surface.

Effective Charge Carrier Utilization in Photocatalytic Conversions.

PubMed

Zhang, Peng; Wang, Tuo; Chang, Xiaoxia; Gong, Jinlong

2016-05-17

Continuous efforts have been devoted to searching for sustainable energy resources to alleviate the upcoming energy crises. Among various types of new energy resources, solar energy has been considered as one of the most promising choices, since it is clean, sustainable, and safe. Moreover, solar energy is the most abundant renewable energy, with a total power of 173 000 terawatts striking Earth continuously. Conversion of solar energy into chemical energy, which could potentially provide continuous and flexible energy supplies, has been investigated extensively. However, the conversion efficiency is still relatively low since complicated physical, electrical, and chemical processes are involved. Therefore, carefully designed photocatalysts with a wide absorption range of solar illumination, a high conductivity for charge carriers, a small number of recombination centers, and fast surface reaction kinetics are required to achieve a high activity. This Account describes our recent efforts to enhance the utilization of charge carriers for semiconductor photocatalysts toward efficient solar-to-chemical energy conversion. During photocatalytic reactions, photogenerated electrons and holes are involved in complex processes to convert solar energy into chemical energy. The initial step is the generation of charge carriers in semiconductor photocatalysts, which could be enhanced by extending the light absorption range. Integration of plasmonic materials and introduction of self-dopants have been proved to be effective methods to improve the light absorption ability of photocatalysts to produce larger amounts of photogenerated charge carriers. Subsequently, the photogenerated electrons and holes migrate to the surface. Therefore, acceleration of the transport process can result in enhanced solar energy conversion efficiency. Different strategies such as morphology control and conductivity improvement have been demonstrated to achieve this goal. Fine-tuning of the

Charged-particle mutagenesis 2. Mutagenic effects of high energy charged particles in normal human fibroblasts

NASA Technical Reports Server (NTRS)

Chen, D. J.; Tsuboi, K.; Nguyen, T.; Yang, T. C.

1994-01-01

The biological effects of high Linear Energy Transfer (LET) charged particles are a subject of great concern with regard to the prediction of radiation risk in space. In this report, mutagenic effects of high LET charged particles are quantitatively measured using primary cultures of human skin fibroblasts, and the spectrum of induced mutations are analyzed. The LET of the charged particles ranged from 25 KeV/micrometer to 975 KeV/micrometer with particle energy (on the cells) between 94-603 MeV/u. The X-chromosome linked hypoxanthine guanine phosphoribosyl transferase (hprt) locus was used as the target gene. Exposure to these high LET charged particles resulted in exponential survival curves; whereas, mutation induction was fitted by a linear model. The Relative Biological Effect (RBE) for cell-killing ranged from 3.73 to 1.25, while that for mutant induction ranged from 5.74 to 0.48. Maximum RBE values were obtained at the LET of 150 keV/micrometer. The inactivation cross-section (alpha i) and the action cross-section for mutant induction (alpha m) ranged from 2.2 to 92.0 sq micrometer and 0.09 to 5.56 x 10(exp -3) sq micrometer respectively. The maximum values were obtained by Fe-56 with an LET of 200 keV/micrometer. The mutagenicity (alpha m/alpha i) ranged from 2.05 to 7.99 x 10(exp -5) with the maximum value at 150 keV/micrometer. Furthermore, molecular analysis of mutants induced by charged particles indicates that higher LET beams are more likely to cause larger deletions in the hprt locus.

openQ*D simulation code for QCD+QED

NASA Astrophysics Data System (ADS)

Campos, Isabel; Fritzsch, Patrick; Hansen, Martin; Krstić Marinković, Marina; Patella, Agostino; Ramos, Alberto; Tantalo, Nazario

2018-03-01

The openQ*D code for the simulation of QCD+QED with C* boundary conditions is presented. This code is based on openQCD-1.6, from which it inherits the core features that ensure its efficiency: the locally-deflated SAP-preconditioned GCR solver, the twisted-mass frequency splitting of the fermion action, the multilevel integrator, the 4th order OMF integrator, the SSE/AVX intrinsics, etc. The photon field is treated as fully dynamical and C* boundary conditions can be chosen in the spatial directions. We discuss the main features of openQ*D, and we show basic test results and performance analysis. An alpha version of this code is publicly available and can be downloaded from http://rcstar.web.cern.ch/.

Form factors and differential branching ratio of B →K μ+μ- in AdS/QCD

NASA Astrophysics Data System (ADS)

Momeni, S.; Khosravi, R.

2018-03-01

The holographic distribution amplitudes (DAs) for the K pseudoscalar meson are derived. For this aim, the light-front wave function (LFWF) of the K meson is extracted within the framework of the anti-de Sitter/quantum chromodynamics (AdS/QCD) correspondence. We consider a momentum-dependent (dynamical) helicity wave function that contains the dynamical spin effects. We use the LFWF to predict the radius and the electromagnetic form factor of the kaon and compare them with the experimental values. Then, the holographic twist-2 DA of K meson ϕK(α ,μ ) is investigated and compared with the result of the light-cone sum rules (LCSR). The transition form factors of the semileptonic B →K ℓ+ℓ- decays are derived from the holographic DAs of the kaon. With the help of these form factors, the differential branching ratio of the B →K μ+μ- on q2 is plotted. A comparison is made between our prediction in AdS/QCD and the results obtained from two models including the LCSR and the lattice QCD as well as the experimental values.

Transverse momentum dependent parton distribution and fragmentation functions with QCD evolution

NASA Astrophysics Data System (ADS)

Aybat, S. Mert; Rogers, Ted C.

2011-06-01

We assess the current phenomenological status of transverse momentum dependent (TMD) parton distribution functions (PDFs) and fragmentation functions (FFs) and study the effect of consistently including perturbative QCD (pQCD) evolution. Our goal is to initiate the process of establishing reliable, QCD-evolved parametrizations for the TMD PDFs and TMD FFs that can be used both to test TMD factorization and to search for evidence of the breakdown of TMD factorization that is expected for certain processes. In this article, we focus on spin-independent processes because they provide the simplest illustration of the basic steps and can already be used in direct tests of TMD factorization. Our calculations are based on the Collins-Soper-Sterman (CSS) formalism, supplemented by recent theoretical developments which have clarified the precise definitions of the TMD PDFs and TMD FFs needed for a valid TMD-factorization theorem. Starting with these definitions, we numerically generate evolved TMD PDFs and TMD FFs using as input existing parametrizations for the collinear PDFs, collinear FFs, nonperturbative factors in the CSS factorization formalism, and recent fixed-scale fits. We confirm that evolution has important consequences, both qualitatively and quantitatively, and argue that it should be included in future phenomenological studies of TMD functions. Our analysis is also suggestive of extensions to processes that involve spin-dependent functions such as the Boer-Mulders, Sivers, or Collins functions, which we intend to pursue in future publications. At our website [http://projects.hepforge.org/tmd/], we have made available the tables and calculations needed to obtain the TMD parametrizations presented herein.

Topological susceptibility of QCD with dynamical Möbius domain-wall fermions

NASA Astrophysics Data System (ADS)

Aoki, S.; Cossu, G.; Fukaya, H.; Hashimoto, S.; Kaneko, T.

2018-04-01

We compute the topological susceptibility χ_t of lattice QCD with 2+1 dynamical quark flavors described by the Möbius domain-wall fermion. Violation of chiral symmetry as measured by the residual mass is kept at ˜1 MeV or smaller. We measure the fluctuation of the topological charge density in a "slab" sub-volume of the simulated lattice using the method proposed by W. Bietenholz, P. de Forcrand, and U. Gerber, J. High Energy Phys. 12, 070 (2015) and W. Bietenholz, K. Cichy, P. de Forcrand, A. Dromard, and U. Gerber, PoS LATTICE 2016, 321 (2016). The quark mass dependence of χ_t is consistent with the prediction of chiral perturbation theory, from which the chiral condensate is extracted as Σ^{\\overlineMS}(2 GeV) = [274(13)(29) MeV]^3, where the first error is statistical and the second one is systematic. Combining the results for the pion mass M_π and decay constant F_π, we obtain χ_t = 0.229(03)(13)M_π^2F_π^2 at the physical point.

Berry Phase in Lattice QCD.

PubMed

Yamamoto, Arata

2016-07-29

We propose the lattice QCD calculation of the Berry phase, which is defined by the ground state of a single fermion. We perform the ground-state projection of a single-fermion propagator, construct the Berry link variable on a momentum-space lattice, and calculate the Berry phase. As the first application, the first Chern number of the (2+1)-dimensional Wilson fermion is calculated by the Monte Carlo simulation.

The singular behavior of massive QCD amplitudes

NASA Astrophysics Data System (ADS)

Mitov, Alexander; Moch, Sven-Olaf

2007-05-01

We discuss the structure of infrared singularities in on-shell QCD amplitudes with massive partons and present a general factorization formula in the limit of small parton masses. The factorization formula gives rise to an all-order exponentiation of both, the soft poles in dimensional regularization and the large collinear logarithms of the parton masses. Moreover, it provides a universal relation between any on-shell amplitude with massive external partons and its corresponding massless amplitude. For the form factor of a heavy quark we present explicit results including the fixed-order expansion up to three loops in the small mass limit. For general scattering processes we show how our constructive method applies to the computation of all singularities as well as the constant (mass-independent) terms of a generic massive n-parton QCD amplitude up to the next-to-next-to-leading order corrections.

Searching for the QCD Axion with Gravitational Microlensing

NASA Astrophysics Data System (ADS)

Fairbairn, Malcolm; Marsh, David J. E.; Quevillon, Jérémie

2017-07-01

The phase transition responsible for axion dark matter (DM) production can create large amplitude isocurvature perturbations, which collapse into dense objects known as axion miniclusters. We use microlensing data from the EROS survey and from recent observations with the Subaru Hyper Suprime Cam to place constraints on the minicluster scenario. We compute the microlensing event rate for miniclusters, treating them as spatially extended objects. Using the published bounds on the number of microlensing events, we bound the fraction of DM collapsed into miniclusters fMC. For an axion with temperature-dependent mass consistent with the QCD axion, we find fMC<0.083 (ma/100 μ eV )0.12 , which represents the first observational constraint on the minicluster fraction. We forecast that a high-efficiency observation of around ten nights with Subaru would be sufficient to constrain fMC≲0.004 over the entire QCD axion mass range. We make various approximations to derive these constraints, and dedicated analyses by the observing teams of EROS and Subaru are necessary to confirm our results. If accurate theoretical predictions for fMC can be made in the future, then microlensing can be used to exclude or discover the QCD axion. Further details of our computations are presented in a companion paper [M. Fairbairn, D. J. E. Marsh, J. Quevillon, and S. Rozier (to be published)].

Quenching parameter in a holographic thermal QCD

NASA Astrophysics Data System (ADS)

Patra, Binoy Krishna; Arya, Bhaskar

2017-01-01

We have calculated the quenching parameter, q ˆ in a model-independent way using the gauge-gravity duality. In earlier calculations, the geometry in the gravity side at finite temperature was usually taken as the pure AdS black hole metric for which the dual gauge theory becomes conformally invariant unlike QCD. Therefore we use a metric which incorporates the fundamental quarks by embedding the coincident D7 branes in the Klebanov-Tseytlin background and a finite temperature is switched on by inserting a black hole into the background, known as OKS-BH metric. Further inclusion of an additional UV cap to the metric prepares the dual gauge theory to run similar to thermal QCD. Moreover q ˆ is usually defined in the literature from the Glauber model perturbative QCD evaluation of the Wilson loop, which has no reasons to hold if the coupling is large and is thus against the main idea of gauge-gravity duality. Thus we use an appropriate definition of q ˆ : q ˆ L- = 1 /L2, where L is the separation for which the Wilson loop is equal to some specific value. The above two refinements cause q ˆ to vary with the temperature as T4 always and to depend linearly on the light-cone time L- with an additional (1 /L-) correction term in the short-distance limit whereas in the long-distance limit, q ˆ depends only linearly on L- with no correction term. These observations agree with other holographic calculations directly or indirectly.

Study on temperature distribution effect on internal charging by computer simulation

NASA Astrophysics Data System (ADS)

Yi, Zhong

2016-07-01

Internal charging (or deep dielectric charging) is a great threaten to spacecraft. Dielectric conductivity is an important parameter for internal charging and it is sensitive to temperature. Considering the exposed dielectric outside a spacecraft may experience a relatively large temperature range, temperature effect can't be ignored in internal charging assessment. We can see some reporters on techniques of computer simulation of internal charging, but the temperature effect has not been taken into accounts. In this paper, we realize the internal charging simulation with consideration of temperature distribution inside the dielectric. Geant4 is used for charge transportation, and a numerical method is proposed for solving the current reservation equation. The conductivity dependences on temperature, radiation dose rate and intense electric field are considered. Compared to the case of uniform temperature, the internal charging with temperature distribution is more complicated. Results show that temperature distribution can cause electric field distortion within the dielectric. This distortion refers to locally considerable enlargement of electric field. It usually corresponds to the peak electric field which is critical for dielectric breakdown judgment. The peak electric field can emerge inside the dielectric, or appear on the boundary. This improvement of internal charging simulation is beneficial for the assessment of internal charging under multiple factors.

Two-baryon systems from HAL QCD method and the mirage in the temporal correlation of the direct method

NASA Astrophysics Data System (ADS)

Iritani, Takumi

2018-03-01

Both direct and HAL QCD methods are currently used to study the hadron interactions in lattice QCD. In the direct method, the eigen-energy of two-particle is measured from the temporal correlation. Due to the contamination of excited states, however, the direct method suffers from the fake eigen-energy problem, which we call the "mirage problem," while the HAL QCD method can extract information from all elastic states by using the spatial correlation. In this work, we further investigate systematic uncertainties of the HAL QCD method such as the quark source operator dependence, the convergence of the derivative expansion of the non-local interaction kernel, and the single baryon saturation, which are found to be well controlled. We also confirm the consistency between the HAL QCD method and the Lüscher's finite volume formula. Based on the HAL QCD potential, we quantitatively confirm that the mirage plateau in the direct method is indeed caused by the contamination of excited states.

QCD Sum Rules for Magnetically Induced Mixing between ηc and J/ψ

DOE PAGES

Cho, Sungtae; Hattori, Koichi; Lee, Su Houng; ...

2014-10-20

We investigate the properties of charmonia in strong magnetic fields by using QCD sum rules. We show how to implement the mixing effects between ηc and J/ψ on the basis of field-theoretical approaches, and then show that the sum rules are saturated by the mixing effects with phenomenologically determined parameters. Consequently, we find that the mixing effects are the dominant contribution to the mass shifts of the static charmonia in strong magnetic fields.

QCD nature of dark energy at finite temperature: Cosmological implications

NASA Astrophysics Data System (ADS)

Azizi, K.; Katırcı, N.

2016-05-01

The Veneziano ghost field has been proposed as an alternative source of dark energy, whose energy density is consistent with the cosmological observations. In this model, the energy density of the QCD ghost field is expressed in terms of QCD degrees of freedom at zero temperature. We extend this model to finite temperature to search the model predictions from late time to early universe. We depict the variations of QCD parameters entering the calculations, dark energy density, equation of state, Hubble and deceleration parameters on temperature from zero to a critical temperature. We compare our results with the observations and theoretical predictions existing at different eras. It is found that this model safely defines the universe from quark condensation up to now and its predictions are not in tension with those of the standard cosmology. The EoS parameter of dark energy is dynamical and evolves from -1/3 in the presence of radiation to -1 at late time. The finite temperature ghost dark energy predictions on the Hubble parameter well fit to those of Λ CDM and observations at late time.

Symmetries and mass splittings QCD 2 coupled to adjoint fermions

NASA Astrophysics Data System (ADS)

Boorstein, Joshua; Kutasov, David

1994-06-01

Two-dimensional QCD coupled to fermions in the adjoint representation of the gauge group SU( N), a useful toy model of QCD strings, is supersymmetric for a certain ratio of quark mass and gauge coupling constant. Here we study the theory in the vicinity of the supersymmetric point; in particular we exhibit the algebraic structure of the model and show that the mass splittings as one moves away from the supersymmetric point obey a universal relation of the form Mi2(B)- Mi2(F) = Miδm + O( δm3). We discuss the connection of this relation to string and quark model expectations and verify it numerically for large N. At least for low lying states the O( δm3) corrections are extremely small. We also discuss a natural generalization of QCD 2 with an infinite number of couplings, which preserves SUSY. This leads to a Landau-Ginzburg description of the theory, and may be useful for defining a scaling limit in which smooth worldsheets appear.

Space charge effects on the third order coupled resonance

NASA Astrophysics Data System (ADS)

Franchetti, Giuliano; Gilardoni, Simone; Huschauer, Alexander; Schmidt, Frank; Wasef, Raymond

2017-08-01

The effect of space charge on bunched beams has been the subject of numerous numerical and experimental studies in the first decade of 2000. Experimental campaigns performed at the CERN Proton Synchrotron in 2002 and at the GSI SIS18 in 2008 confirmed the existence of an underlying mechanism in the beam dynamics of periodic resonance crossing induced by the synchrotron motion and space charge. In this article we present an extension of the previous studies to describe the effect of space charge on a controlled coupled (2D) third order resonance. The experimental and simulation results of this latest campaign shed a new light on the difficulties of the 2D particle dynamics. We find striking experimental evidence that space charge and the coupled resonance create an unusual coupling in the phase space, leading to the formation of an asymmetric halo. Moreover, this study demonstrates a clear link between halo formation and fixed-lines.

QCD studies in ep collisions

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

Smith, W.H.

1997-06-01

These lectures describe QCD physics studies over the period 1992--1996 from data taken with collisions of 27 GeV electrons and positrons with 820 GeV protons at the HERA collider at DESY by the two general-purpose detectors H1 and ZEUS. The focus of these lectures is on structure functions and jet production in deep inelastic scattering, photoproduction, and diffraction. The topics covered start with a general introduction to HERA and ep scattering. Structure functions are discussed. This includes the parton model, scaling violation, and the extraction of F{sub 2}, which is used to determine the gluon momentum distribution. Both low andmore » high Q{sup 2} regimes are discussed. The low Q{sup 2} transition from perturbative QCD to soft hadronic physics is examined. Jet production in deep inelastic scattering to measure {alpha}{sub s}, and in photoproduction to study resolved and direct photoproduction, is also presented. This is followed by a discussion of diffraction that begins with a general introduction to diffraction in hadronic collisions and its relation to ep collisions, and moves on to deep inelastic scattering, where the structure of diffractive exchange is studied, and in photoproduction, where dijet production provides insights into the structure of the Pomeron. 95 refs., 39 figs.« less

Strong coupling electrostatics for randomly charged surfaces: antifragility and effective interactions.

PubMed

Ghodrat, Malihe; Naji, Ali; Komaie-Moghaddam, Haniyeh; Podgornik, Rudolf

2015-05-07

We study the effective interaction mediated by strongly coupled Coulomb fluids between dielectric surfaces carrying quenched, random monopolar charges with equal mean and variance, both when the Coulomb fluid consists only of mobile multivalent counterions and when it consists of an asymmetric ionic mixture containing multivalent and monovalent (salt) ions in equilibrium with an aqueous bulk reservoir. We analyze the consequences that follow from the interplay between surface charge disorder, dielectric and salt image effects, and the strong electrostatic coupling that results from multivalent counterions on the distribution of these ions and the effective interaction pressure they mediate between the surfaces. In a dielectrically homogeneous system, we show that the multivalent counterions are attracted towards the surfaces with a singular, disorder-induced potential that diverges logarithmically on approach to the surfaces, creating a singular but integrable counterion density profile that exhibits an algebraic divergence at the surfaces with an exponent that depends on the surface charge (disorder) variance. This effect drives the system towards a state of lower thermal 'disorder', one that can be described by a renormalized temperature, exhibiting thus a remarkable antifragility. In the presence of an interfacial dielectric discontinuity, the singular behavior of counterion density at the surfaces is removed but multivalent counterions are still accumulated much more strongly close to randomly charged surfaces as compared with uniformly charged ones. The interaction pressure acting on the surfaces displays in general a highly non-monotonic behavior as a function of the inter-surface separation with a prominent regime of attraction at small to intermediate separations. This attraction is caused directly by the combined effects from charge disorder and strong coupling electrostatics of multivalent counterions, which dominate the surface-surface repulsion due to

A model for pion-pion scattering in large- N QCD

NASA Astrophysics Data System (ADS)

Veneziano, G.; Yankielowicz, S.; Onofri, E.

2017-04-01

Following up on recent work by Caron-Huot et al. we consider a generalization of the old Lovelace-Shapiro model as a toy model for ππ scattering satisfying (most of) the properties expected to hold in ('t Hooft's) large- N limit of massless QCD. In particular, the model has asymptotically linear and parallel Regge trajectories at positive t, a positive leading Regge intercept α 0 < 1, and an effective bending of the trajectories in the negative- t region producing a fixed branch point at J = 0 for t < t 0 < 0. Fixed (physical) angle scattering can be tuned to match the power-like behavior (including logarithmic corrections) predicted by perturbative QCD: A( s, t) ˜ s - β log( s)-γ F ( θ). Tree-level unitarity (i.e. positivity of residues for all values of s and J ) imposes strong constraints on the allowed region in the α0- β-γ parameter space, which nicely includes a physically interesting region around α 0 = 0 .5, β = 2 and γ = 3. The full consistency of the model would require an extension to multi-pion processes, a program we do not undertake in this paper.

Heavy ion charge-state distribution effects on energy loss in plasmas.

PubMed

Barriga-Carrasco, Manuel D

2013-10-01

According to dielectric formalism, the energy loss of the heavy ion depends on its velocity and its charge density. Also, it depends on the target through its dielectric function; here the random phase approximation is used because it correctly describes fully ionized plasmas at any degeneracy. On the other hand, the Brandt-Kitagawa (BK) model is employed to depict the projectile charge space distribution, and the stripping criterion of Kreussler et al. is used to determine its mean charge state [Q]. This latter criterion implies that the mean charge state depends on the electron density and temperature of the plasma. Also, the initial charge state of the heavy ion is crucial for calculating [Q] inside the plasma. Comparing our models and estimations with experimental data, a very good agreement is found. It is noticed that the energy loss in plasmas is higher than that in the same cold gas cases, confirming the well-known enhanced plasma stopping (EPS). In this case, EPS is only due to the increase in projectile effective charge Q(eff), which is obtained as the ratio between the energy loss of each heavy ion and that of the proton in the same plasma conditions. The ratio between the effective charges in plasmas and in cold gases is higher than 1, but it is not as high as thought in the past. Finally, another significant issue is that the calculated effective charge in plasmas Q(eff) is greater than the mean charge state [Q], which is due to the incorporation of the BK charge distribution. When estimations are performed without this distribution, they do not fit well with experimental data.

Lattice gauge theory for QCD

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

DeGrand, T.

1997-06-01

These lectures provide an introduction to lattice methods for nonperturbative studies of Quantum Chromodynamics. Lecture 1: Basic techniques for QCD and results for hadron spectroscopy using the simplest discretizations; lecture 2: Improved actions--what they are and how well they work; lecture 3: SLAC physics from the lattice-structure functions, the mass of the glueball, heavy quarks and {alpha}{sub s} (M{sub z}), and B-{anti B} mixing. 67 refs., 36 figs.

Inverse magnetic catalysis from improved holographic QCD in the Veneziano limit

NASA Astrophysics Data System (ADS)

Gürsoy, Umut; Iatrakis, Ioannis; Järvinen, Matti; Nijs, Govert

2017-03-01

We study the dependence of the chiral condensate on external magnetic field in the context of holographic QCD at large number of flavors. We consider a holographic QCD model where the flavor degrees of freedom fully backreact on the color dynamics. Perturbative QCD calculations have shown that B acts constructively on the chiral condensate, a phenomenon called "magnetic catalysis". In contrast, recent lattice calculations show that, depending on the number of flavors and temperature, the magnetic field may also act destructively, which is called "inverse magnetic catalysis". Here we show that the holographic theory is capable of both behaviors depending on the choice of parameters. For reasonable choice of the potentials entering the model we find qualitative agreement with the lattice expectations. Our results provide insight for the physical reasons behind the inverse magnetic catalysis. In particular, we argue that the backreaction of the flavors to the background geometry decatalyzes the condensate.

Measurement of the W boson production charge asymmetry in p$$\\bar{p}$$ collisions

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

Han, Bo-Young

We present a measurement of the W boson production charge asymmetry using the W → ev decay channel. We use data collected the Collider Detector at Fermilab (CDF) from pmore » $$\\bar{p}$$ collisions at √s = 1.96 TeV. The data were collected up to February 2006 (Run II) and represent an integrated luminosity of 1 fb -1. The experimental measurement of W production charge asymmetry is compared to higher order QCD predictions generated using MRST2006 and CTEQ6 parton distribution functions (PDF). The asymmetry provides new input on the momentum fraction dependence of the u and d quark parton distribution functions (PDF) within the proton over the fraction of proton's momentum range from 0.002 < x < 0.8 corresponding to -3.0 < y W < 3.0 at Q 2 ~ M W 2.« less

QCD and strongly coupled gauge theories: challenges and perspectives.

PubMed

Brambilla, N; Eidelman, S; Foka, P; Gardner, S; Kronfeld, A S; Alford, M G; Alkofer, R; Butenschoen, M; Cohen, T D; Erdmenger, J; Fabbietti, L; Faber, M; Goity, J L; Ketzer, B; Lin, H W; Llanes-Estrada, F J; Meyer, H B; Pakhlov, P; Pallante, E; Polikarpov, M I; Sazdjian, H; Schmitt, A; Snow, W M; Vairo, A; Vogt, R; Vuorinen, A; Wittig, H; Arnold, P; Christakoglou, P; Di Nezza, P; Fodor, Z; Garcia I Tormo, X; Höllwieser, R; Janik, M A; Kalweit, A; Keane, D; Kiritsis, E; Mischke, A; Mizuk, R; Odyniec, G; Papadodimas, K; Pich, A; Pittau, R; Qiu, J-W; Ricciardi, G; Salgado, C A; Schwenzer, K; Stefanis, N G; von Hippel, G M; Zakharov, V I

We highlight the progress, current status, and open challenges of QCD-driven physics, in theory and in experiment. We discuss how the strong interaction is intimately connected to a broad sweep of physical problems, in settings ranging from astrophysics and cosmology to strongly coupled, complex systems in particle and condensed-matter physics, as well as to searches for physics beyond the Standard Model. We also discuss how success in describing the strong interaction impacts other fields, and, in turn, how such subjects can impact studies of the strong interaction. In the course of the work we offer a perspective on the many research streams which flow into and out of QCD, as well as a vision for future developments.

Lattice QCD Calculation of Hadronic Light-by-Light Scattering.

PubMed

Green, Jeremy; Gryniuk, Oleksii; von Hippel, Georg; Meyer, Harvey B; Pascalutsa, Vladimir

2015-11-27

We perform a lattice QCD calculation of the hadronic light-by-light scattering amplitude in a broad kinematical range. At forward kinematics, the results are compared to a phenomenological analysis based on dispersive sum rules for light-by-light scattering. The size of the pion pole contribution is investigated for momenta of typical hadronic size. The presented numerical methods can be used to compute the hadronic light-by-light contribution to the anomalous magnetic moment of the muon. Our calculations are carried out in two-flavor QCD with the pion mass in the range of 270-450 MeV and contain so far only the diagrams with fully connected quark lines.

Light composite scalar in twelve-flavor QCD on the lattice.

PubMed

Aoki, Yasumichi; Aoyama, Tatsumi; Kurachi, Masafumi; Maskawa, Toshihide; Nagai, Kei-ichi; Ohki, Hiroshi; Rinaldi, Enrico; Shibata, Akihiro; Yamawaki, Koichi; Yamazaki, Takeshi

2013-10-18

On the basis of lattice simulations using highly improved staggered quarks for twelve-flavor QCD with several bare fermion masses, we observe a flavor-singlet scalar state lighter than the pion in the correlators of fermionic interpolating operators. The same state is also investigated using correlators of gluonic interpolating operators. Combined with our previous study that showed twelve-flavor QCD to be consistent with being in the conformal window, we infer that the lightness of the scalar state is due to infrared conformality. This result shed some light on the possibility of a light composite Higgs boson ("technidilaton") in walking technicolor theories.

Relating quark confinement and chiral symmetry breaking in QCD

NASA Astrophysics Data System (ADS)

Suganuma, Hideo; Doi, Takahiro M.; Redlich, Krzysztof; Sasaki, Chihiro

2017-12-01

We study the relation between quark confinement and chiral symmetry breaking in QCD. Using lattice QCD formalism, we analytically express the various ‘confinement indicators’, such as the Polyakov loop, its fluctuations, the Wilson loop, the inter-quark potential and the string tension, in terms of the Dirac eigenmodes. In the Dirac spectral representation, there appears a power of the Dirac eigenvalue {λ }n such as {λ }n{Nt-1}, which behaves as a reduction factor for small {λ }n. Consequently, since this reduction factor cannot be cancelled, the low-lying Dirac eigenmodes give negligibly small contribution to the confinement quantities, while they are essential for chiral symmetry breaking. These relations indicate that there is no direct one-to-one correspondence between confinement and chiral symmetry breaking in QCD. In other words, there is some independence of quark confinement from chiral symmetry breaking, which can generally lead to different transition temperatures/densities for deconfinement and chiral restoration. We also investigate the Polyakov loop in terms of the eigenmodes of the Wilson, the clover and the domain-wall fermion kernels, and find similar results. The independence of quark confinement from chiral symmetry breaking seems to be natural, because confinement is realized independently of quark masses and heavy quarks are also confined even without the chiral symmetry.

Grain Boundary Effect on Charge Transport in Pentacene Thin Films

NASA Astrophysics Data System (ADS)

Weis, Martin; Gmucová, Katarína; Nádaždy, Vojtech; Majková, Eva; Haško, Daniel; Taguchi, Dai; Manaka, Takaaki; Iwamoto, Mitsumasa

2011-04-01

We report on charge transport properties of polycrystalline pentacene films with variable average grain size in the range from 0.1 to 0.3 µm controlled by the preparation technology. We illustrate with the organic field-effect transistors decrease of the effective mobility and presence of traps with decrease of the grain size. Analysis of the charge transfer excitons reveals decrease of the mobile charge density and the steady-state voltammetry showed significant increase of oxygen- and hydrogen-related defects. We also briefly discuss accumulation of the defects on the grain boundary and show relation between the defect density and grain boundary length.

Finite-volume and partial quenching effects in the magnetic polarizability of the neutron

NASA Astrophysics Data System (ADS)

Hall, J. M. M.; Leinweber, D. B.; Young, R. D.

2014-03-01

There has been much progress in the experimental measurement of the electric and magnetic polarizabilities of the nucleon. Similarly, lattice QCD simulations have recently produced dynamical QCD results for the magnetic polarizability of the neutron approaching the chiral regime. In order to compare the lattice simulations with experiment, calculation of partial quenching and finite-volume effects is required prior to an extrapolation in quark mass to the physical point. These dependencies are described using chiral effective field theory. Corrections to the partial quenching effects associated with the sea-quark-loop electric charges are estimated by modeling corrections to the pion cloud. These are compared to the uncorrected lattice results. In addition, the behavior of the finite-volume corrections as a function of pion mass is explored. Box sizes of approximately 7 fm are required to achieve a result within 5% of the infinite-volume result at the physical pion mass. A variety of extrapolations are shown at different box sizes, providing a benchmark to guide future lattice QCD calculations of the magnetic polarizabilities. A relatively precise value for the physical magnetic polarizability of the neutron is presented, βn=1.93(11)stat(11)sys×10-4 fm3, which is in agreement with current experimental results.

The effect of solvent relaxation time constants on free energy gap law for ultrafast charge recombination following photoinduced charge separation.

PubMed

Mikhailova, Valentina A; Malykhin, Roman E; Ivanov, Anatoly I

2018-05-16

To elucidate the regularities inherent in the kinetics of ultrafast charge recombination following photoinduced charge separation in donor-acceptor dyads in solutions, the simulations of the kinetics have been performed within the stochastic multichannel point-transition model. Increasing the solvent relaxation time scales has been shown to strongly vary the dependence of the charge recombination rate constant on the free energy gap. In slow relaxing solvents the non-equilibrium charge recombination occurring in parallel with solvent relaxation is very effective so that the charge recombination terminates at the non-equilibrium stage. This results in a crucial difference between the free energy gap laws for the ultrafast charge recombination and the thermal charge transfer. For the thermal reactions the well-known Marcus bell-shaped dependence of the rate constant on the free energy gap is realized while for the ultrafast charge recombination only a descending branch is predicted in the whole area of the free energy gap exceeding 0.2 eV. From the available experimental data on the population kinetics of the second and first excited states for a series of Zn-porphyrin-imide dyads in toluene and tetrahydrofuran solutions, an effective rate constant of the charge recombination into the first excited state has been calculated. The obtained rate constant being very high is nearly invariable in the area of the charge recombination free energy gap from 0.2 to 0.6 eV that supports the theoretical prediction.

Space charge characteristics of fluorinated polyethylene: Different effects of fluorine and oxygen

NASA Astrophysics Data System (ADS)

Zhao, Ni; Nie, Yongjie; Li, Shengtao

2018-04-01

Direct fluorination are proved having obvious effect on space charge characteristics of polyethylene. It is believed that fluorine has a positive effect on suppressing space charge injection while oxygen impurity has a negative effect. However, the mechanism for the opposite effect of fluorine and oxygen is still not clear. In this paper, the different effects of fluorine and oxygen on space charge characteristics of fluorinated low density polyethylene (LDPE) are investigated on the basis of dielectric property, chemical constitutes and trap performance of surface fluorinated layers. The results show that direct fluorination has obvious effect on chemical constitutes and dielectric properties of surface fluorinated layer. Introduced fluorine is the main factor for suppressing charge injection from the electrodes, because it seriously changes the chemical constitutes and further the trap properties of the surface fluorinated layer. While introduction of oxygen results in heterocharges and makes space charge distribution complex, due to the ionization of generated small groups like C=O containing groups. Moreover, direct fluorination will result in cleavage of some LDPE molecules whatever there is oxygen impurity or not.

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

A collider observable QCD axion

DOE PAGES

Dimopoulos, Savas; Hook, Anson; Huang, Junwu; ...

2016-11-09

Here, we present a model where the QCD axion is at the TeV scale and visible at a collider via its decays. Conformal dynamics and strong CP considerations account for the axion coupling strongly enough to the standard model to be produced as well as the coincidence between the weak scale and the axion mass. The model predicts additional pseudoscalar color octets whose properties are completely determined by the axion properties rendering the theory testable.

Space charge effects in ultrafast electron diffraction and imaging

NASA Astrophysics Data System (ADS)

Tao, Zhensheng; Zhang, He; Duxbury, P. M.; Berz, Martin; Ruan, Chong-Yu

2012-02-01

Understanding space charge effects is central for the development of high-brightness ultrafast electron diffraction and microscopy techniques for imaging material transformation with atomic scale detail at the fs to ps timescales. We present methods and results for direct ultrafast photoelectron beam characterization employing a shadow projection imaging technique to investigate the generation of ultrafast, non-uniform, intense photoelectron pulses in a dc photo-gun geometry. Combined with N-particle simulations and an analytical Gaussian model, we elucidate three essential space-charge-led features: the pulse lengthening following a power-law scaling, the broadening of the initial energy distribution, and the virtual cathode threshold. The impacts of these space charge effects on the performance of the next generation high-brightness ultrafast electron diffraction and imaging systems are evaluated.

Aspects of baryon structure in lattice QCD

NASA Astrophysics Data System (ADS)

Babich, Ronald

Despite the long success of Quantum Chromodynamics (QCD) as the theory of the strong interactions, there remains much to be understood about the structure of hadrons and the consequences of QCD in the nonperturbative regime. Lattice gauge theory, a framework nearly as old as QCD itself, makes calculations in this regime possible, starting from first principles. With advances in theoretical understanding, methods, and computer technology, the lattice has found application to an ever-widening range of problems. In this dissertation, I consider two such problems having to do with the structure of baryons. The first concerns the contribution of sea quarks, and the strange quark in particular, to form factors of the nucleon. This has been a long-standing challenge for the lattice, because such contributions involve the insertion of a current on a quark loop, demanding the full inversion of the discretized Dirac operator, conceptually a large sparse matrix. I discuss methods for addressing this challenge and present a calculation of the strange scalar form factor and the related parameter fTs. The latter is of great theoretical interest, since it enters into the cross section for the scattering of dark matter off nuclei in supersymmetric extensions of the standard model. As such, it represents a major uncertainty in the interpretation of direct detection experiments. I also present results for the strange quark contribution to the nucleon's axial and electromagnetic form factors, which are themselves the subject of active experimental programs. These calculations were performed using the Wilson fermion formulation on a 243 x 64 anisotropic lattice. In the second part of the dissertation, I turn to the valence sector and address the role of diquark correlations in the observed spectrum of hadrons and their properties. A diquark is a correlated pair of quarks, thought to play an important role in certain phenomenological models of hadrons. I present results for baryon wave

Effective electrostatic interactions among charged thermo-responsive microgels immersed in a simple electrolyte

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

González-Mozuelos, P.

This work explores the nature and thermodynamic behavior of the effective electrostatic interactions among charged microgels immersed in a simple electrolyte, taking special interest in the effects due to the thermally induced variation of the microgel size while the remaining parameters (microgel charge and concentration, plus the amount of added salt) are kept constant. To this end, the rigorous approach obtained from applying the precise methodology of the dressed ion theory to the proper definition of the effective direct correlation functions, which emerge from tracing-out the degrees of freedom of the microscopic ions, is employed to provide an exact descriptionmore » of the parameters characterizing such interactions: screening length, effective permittivity, and renormalized charges. A model solution with three components is assumed: large permeable anionic spheres for the microgels, plus small charged hard spheres of equal size for the monovalent cations and anions. The two-body correlations among the components of this model suspension, used as the input for the determination of the effective interaction parameters, are here calculated by using the hyper-netted chain approximation. It is then found that at finite microgel concentrations the values of these parameters change as the microgel size increases, even though the ionic strength of the supporting electrolyte and the bare charge of the microgels remain fixed during this process. The variation of the screening length, as well as that of the effective permittivity, is rather small, but still interesting in view of the fact that the corresponding Debye length stays constant. The renormalized charges, in contrast, increase markedly as the microgels swell. The ratio of the renormalized charge to the corresponding analytic result obtained in the context of an extended linear response theory allows us to introduce an effective charge that accounts for the non-linear effects induced by the short

QCD, OZI, and evidence for glueballs

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

Lindenbaum, S.J.

1981-01-01

The characteristics expected from low Q-QCD for the behavior of glueballs and the OZI rule is discussed. The reaction ..pi../sup -/p ..-->.. phi phi n represents on OZI forbidden (hairpin) diagram. It has been observed at the Brookhaven National Laboratory multiparticle spectrometer by the Brookhaven National Laboratory/City College of New York group. The author has shown that the expected OZI suppression is essentially entirely absent and in fact the Isobar Model which does not contain OZI suppression quantitatively explains the observed results. A general evaluation of the special characteristics of the data compared to other related reactions plus the foregoingmore » facts leads the author to conclude that the intervention of glueball resonances is the likely explanation in the context of QCD. Other explanations are shown to be improbable. In particular the hypothesis that decay of a radial excitation of the eta' is responsible for lack of OZI suppression is ruled out. Planned experiments with the purpose of explicity discovering glueballs will be discussed. The OZI rule peculiarities such as violation of crossing symmetry and unitarity are attributed to color confinement.« less

Lattice QCD Application Development within the US DOE Exascale Computing Project

NASA Astrophysics Data System (ADS)

Brower, Richard; Christ, Norman; DeTar, Carleton; Edwards, Robert; Mackenzie, Paul

2018-03-01

In October, 2016, the US Department of Energy launched the Exascale Computing Project, which aims to deploy exascale computing resources for science and engineering in the early 2020's. The project brings together application teams, software developers, and hardware vendors in order to realize this goal. Lattice QCD is one of the applications. Members of the US lattice gauge theory community with significant collaborators abroad are developing algorithms and software for exascale lattice QCD calculations. We give a short description of the project, our activities, and our plans.

Inclusive heavy flavor hadroproduction in NLO QCD: The exact analytic result

NASA Astrophysics Data System (ADS)

Czakon, M.; Mitov, A.

2010-01-01

We present the first exact analytic result for all partonic channels contributing to the total cross section for the production of a pair of heavy flavors in hadronic collisions in NLO QCD. Our calculation is a step in the derivation of the top quark pair production cross section at NNLO in QCD, which is a cornerstone of the precision LHC program. Our results uncover the analytical structures behind observables with heavy flavors at higher orders. They also reveal surprising and non-trivial implications for kinematics close to partonic threshold.

Lattice QCD Application Development within the US DOE Exascale Computing Project

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

Brower, Richard; Christ, Norman; DeTar, Carleton

In October, 2016, the US Department of Energy launched the Exascale Computing Project, which aims to deploy exascale computing resources for science and engineering in the early 2020's. The project brings together application teams, software developers, and hardware vendors in order to realize this goal. Lattice QCD is one of the applications. Members of the US lattice gauge theory community with significant collaborators abroad are developing algorithms and software for exascale lattice QCD calculations. We give a short description of the project, our activities, and our plans.

Space-charge effects in Penning ion traps

NASA Astrophysics Data System (ADS)

Porobić, T.; Beck, M.; Breitenfeldt, M.; Couratin, C.; Finlay, P.; Knecht, A.; Fabian, X.; Friedag, P.; Fléchard, X.; Liénard, E.; Ban, G.; Zákoucký, D.; Soti, G.; Van Gorp, S.; Weinheimer, Ch.; Wursten, E.; Severijns, N.

2015-06-01

The influence of space-charge on ion cyclotron resonances and magnetron eigenfrequency in a gas-filled Penning ion trap has been investigated. Off-line measurements with K39+ using the cooling trap of the WITCH retardation spectrometer-based setup at ISOLDE/CERN were performed. Experimental ion cyclotron resonances were compared with ab initio Coulomb simulations and found to be in agreement. As an important systematic effect of the WITCH experiment, the magnetron eigenfrequency of the ion cloud was studied under increasing space-charge conditions. Finally, the helium buffer gas pressure in the Penning trap was determined by comparing experimental cooling rates with simulations.

Nucleon resonance structure in the finite volume of lattice QCD

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

Wu, Jia -Jun; Kamano, H.; Lee, T. -S. H.

An approach for relating the nucleon resonances extracted from πN reaction data to lattice QCD calculations has been developed by using the finite-volume Hamiltonian method. Within models of πN reactions, bare states are introduced to parametrize the intrinsic excitations of the nucleon. We show that the resonance can be related to the probability P N*(E) of finding the bare state, N*, in the πN scattering states in infinite volume. We further demonstrate that the probability P V N*(E) of finding the same bare states in the eigenfunctions of the underlying Hamiltonian in finite volume approaches P N*(E) as the volumemore » increases. Our findings suggest that the comparison of P N*(E) and P V N*(E) can be used to examine whether the nucleon resonances extracted from the πN reaction data within the dynamical models are consistent with lattice QCD calculation. We also discuss the measurement of P V N*(E) directly from lattice QCD. Furthermore, the practical differences between our approach and the approach using the Lüscher formalism to relate LQCD calculations to the nucleon resonance poles embedded in the data are also discussed.« less

Nucleon resonance structure in the finite volume of lattice QCD

DOE PAGES

Wu, Jia -Jun; Kamano, H.; Lee, T. -S. H.; ...

2017-06-19

An approach for relating the nucleon resonances extracted from πN reaction data to lattice QCD calculations has been developed by using the finite-volume Hamiltonian method. Within models of πN reactions, bare states are introduced to parametrize the intrinsic excitations of the nucleon. We show that the resonance can be related to the probability P N*(E) of finding the bare state, N*, in the πN scattering states in infinite volume. We further demonstrate that the probability P V N*(E) of finding the same bare states in the eigenfunctions of the underlying Hamiltonian in finite volume approaches P N*(E) as the volumemore » increases. Our findings suggest that the comparison of P N*(E) and P V N*(E) can be used to examine whether the nucleon resonances extracted from the πN reaction data within the dynamical models are consistent with lattice QCD calculation. We also discuss the measurement of P V N*(E) directly from lattice QCD. Furthermore, the practical differences between our approach and the approach using the Lüscher formalism to relate LQCD calculations to the nucleon resonance poles embedded in the data are also discussed.« less

Calculation of neutral weak nucleon form factors with the AdS/QCD correspondence

NASA Astrophysics Data System (ADS)

Lohmann, Mark

The AdS/QCD (Anti-de Sitter/Quantum Chromodynamics) is a mathematical formalism applied to a theory based on the original AdS/CFT (Anti-de Sitter/ Conformal Field Theory) correspondence. The aim is to describe properties of the strong force in an essentially non-perturbative way. AdS/QCD theories break the conformal symmetry of the AdS metric (a sacrifice) to arrive at a boundary theory which is QCD-like (a payoff). This correspondence has been used to calculate well-known quantities in nucleon spectra and structure like Regge trajectories, form factors, and many others within an error of less than 20% from experiment. This is impressive considering that ordinary perturbation theory in QCD applied to the strongly interacting domain usually obtains an error of about 30%. In this thesis, the AdS/QCD correspondence method of light-front holography established by Brodsky and de Teramond is used in an attempt to calculate the Dirac and Pauli neutral weak form factors, FZ1 (Q2) and FZ2 (Q 2) respectively, for both the proton and the neutron. With this approach, we were able to determine the neutral weak Dirac form factor for both nucleons and the Pauli form factor for the proton, while the method did not succeed at determining the neutral weak Pauli form factor for the neutron. With these we were also able to extract the proton's strange electric and magnetic form factor, which addresses important questions in nucleon sub-structure that are currently being investigated through experiments at the Thomas Jefferson National Accelerator Facility.

Glueball spectrum and hadronic processes in low-energy QCD

NASA Astrophysics Data System (ADS)

Frasca, Marco

2010-10-01

Low-energy limit of quantum chromodynamics (QCD) is obtained using a mapping theorem recently proved. This theorem states that, classically, solutions of a massless quartic scalar field theory are approximate solutions of Yang-Mills equations in the limit of the gauge coupling going to infinity. Low-energy QCD is described by a Yukawa theory further reducible to a Nambu-Jona-Lasinio model. At the leading order one can compute glue-quark interactions and one is able to calculate the properties of the σ and η-η mesons. Finally, it is seen that all the physics of strong interactions, both in the infrared and ultraviolet limit, is described by a single constant Λ arising in the ultraviolet by dimensional transmutation and in the infrared as an integration constant.

QCD and strongly coupled gauge theories: Challenges and perspectives

DOE PAGES

Brambilla, N.; Eidelman, S.; Foka, P.; ...

2014-10-21

We highlight the progress, current status, and open challenges of QCD-driven physics, in theory and in experiment. We discuss how the strong interaction is intimately connected to a broad sweep of physical problems, in settings ranging from astrophysics and cosmology to stongly-coupled, complex systems in particle and condensed-matter physics, as well as to searches for physics beyond the Standard Model. We also discuss how success in describing the strong interaction impacts other fields, and, in turn, how such subjects can impact studies of the strong interaction. In the course of the work we offer a perspective on the many researchmore » streams which flow into and out of QCD, as well as a vision for future developments.« less

Spontaneous supersymmetry breaking in two dimensional lattice super QCD

DOE PAGES

Catterall, Simon; Veernala, Aarti

2015-10-02

We report on a non-perturbative study of two dimensional N=(2,2) super QCD. Our lattice formulation retains a single exact supersymmetry at non-zero lattice spacing, and contains N f fermions in the fundamental representation of a U(N c) gauge group. The lattice action we employ contains an additional Fayet-Iliopoulos term which is also invariant under the exact lattice supersymmetry. This work constitutes the first numerical study of this theory which serves as a toy model for understanding some of the issues that are expected to arise in four dimensional super QCD. As a result, we present evidence that the exact supersymmetrymore » breaks spontaneously when N f < N c in agreement with theoretical expectations.« less

Charmless hadronic B →(f1(1285 ),f1(1420 ))P decays in the perturbative QCD approach

NASA Astrophysics Data System (ADS)

Liu, Xin; Xiao, Zhen-Jun; Li, Jing-Wu; Zou, Zhi-Tian

2015-01-01

We study 20 charmless hadronic B →f1P decays in the perturbative QCD (pQCD) formalism with B denoting Bu, Bd, and Bs mesons; P standing for the light pseudoscalar mesons; and f1 representing axial-vector mesons f1(1285 ) and f1(1420 ) that result from a mixing of quark-flavor f1 q[u/u ¯ +d d ¯ √{2 } ] and f1 s[s s ¯ ] states with the angle ϕf1.The estimations of C P -averaged branching ratios and C P asymmetries of the considered B →f1P decays, in which the Bs→f1P modes are investigated for the first time, are presented in the pQCD approach with ϕf 1˜24 ° from recently measured Bd /s→J /ψ f1(1285 ) decays. It is found that (a) the tree (penguin) dominant B+→f1π+(K+) decays with large branching ratios [O (10-6) ] and large direct C P violations (around 14%-28% in magnitude) simultaneously are believed to be clearly measurable at the LHCb and Belle II experiments; (b) the Bd→f1KS0 and Bs→f1(η ,η') decays with nearly pure penguin contributions and safely negligible tree pollution also have large decay rates in the order of 10-6- 10-5 , which can be confronted with the experimental measurements in the near future; (c) as the alternative channels, the B+→f1(π+,K+) and Bd→f1KS0 decays have the supplementary power in providing more effective constraints on the Cabibbo-Kobayashi-Maskawa weak phases α , γ , and β , correspondingly, which are explicitly analyzed through the large decay rates and the direct and mixing-induced C P asymmetries in the pQCD approach and are expected to be stringently examined by the measurements with high precision; (d) the weak annihilation amplitudes play important roles in the B+→f1(1420 )K+ , Bd→f1(1420 )KS0 , Bs→f1(1420 )η' decays, and so on, which would offer more evidence, once they are confirmed by the experiments, to identify the soft-collinear effective theory and the pQCD approach on the evaluations of annihilation diagrams and to help further understand the annihilation mechanism in the heavy

REMARKS ON THE MAXIMUM ENTROPY METHOD APPLIED TO FINITE TEMPERATURE LATTICE QCD.

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

UMEDA, T.; MATSUFURU, H.

2005-07-25

We make remarks on the Maximum Entropy Method (MEM) for studies of the spectral function of hadronic correlators in finite temperature lattice QCD. We discuss the virtues and subtlety of MEM in the cases that one does not have enough number of data points such as at finite temperature. Taking these points into account, we suggest several tests which one should examine to keep the reliability for the results, and also apply them using mock and lattice QCD data.

A computational system for lattice QCD with overlap Dirac quarks

NASA Astrophysics Data System (ADS)

Chiu, Ting-Wai; Hsieh, Tung-Han; Huang, Chao-Hsi; Huang, Tsung-Ren

2003-05-01

We outline the essential features of a Linux PC cluster which is now being developed at National Taiwan University, and discuss how to optimize its hardware and software for lattice QCD with overlap Dirac quarks. At present, the cluster constitutes of 30 nodes, with each node consisting of one Pentium 4 processor (1.6/2.0 GHz), one Gbyte of PC800 RDRAM, one 40/80 Gbyte hard disk, and a network card. The speed of this system is estimated to be 30 Gflops, and its price/performance ratio is better than $1.0/Mflops for 64-bit (double precision) computations in quenched lattice QCD with overlap Dirac quarks.

Cyclic Mario worlds — color-decomposition for one-loop QCD

NASA Astrophysics Data System (ADS)

Kälin, Gregor

2018-04-01

We present a new color decomposition for QCD amplitudes at one-loop level as a generalization of the Del Duca-Dixon-Maltoni and Johansson-Ochirov decomposition at tree level. Starting from a minimal basis of planar primitive amplitudes we write down a color decomposition that is free of linear dependencies among appearing primitive amplitudes or color factors. The conjectured decomposition applies to any number of quark flavors and is independent of the choice of gauge group and matter representation. The results also hold for higher-dimensional or supersymmetric extensions of QCD. We provide expressions for any number of external quark-antiquark pairs and gluons. [Figure not available: see fulltext.

Associated production of a Higgs boson decaying into bottom quarks at the LHC in full NNLO QCD

NASA Astrophysics Data System (ADS)

Ferrera, Giancarlo; Somogyi, Gábor; Tramontano, Francesco

2018-05-01

We consider the production of a Standard Model Higgs boson decaying to bottom quarks in association with a vector boson W± / Z in hadron collisions. We present a fully exclusive calculation of QCD radiative corrections both for the production cross section and for the Higgs boson decay rate up to next-to-next-to-leading order (NNLO) accuracy. Our calculation also includes the leptonic decay of the vector boson with finite-width effects and spin correlations. We consider typical kinematical cuts applied in the experimental analyses at the Large Hadron Collider (LHC) and we find that the full NNLO QCD corrections significantly decrease the accepted cross section and have a substantial impact on the shape of distributions. We point out that these additional effects are essential to obtain precise theoretical predictions to be compared with the LHC data.

ΛcN interaction from lattice QCD and its application to Λc hypernuclei

NASA Astrophysics Data System (ADS)

Miyamoto, Takaya; Aoki, Sinya; Doi, Takumi; Gongyo, Shinya; Hatsuda, Tetsuo; Ikeda, Yoichi; Inoue, Takashi; Iritani, Takumi; Ishii, Noriyoshi; Kawai, Daisuke; Murano, Keiko; Nemura, Hidekatsu; Sasaki, Kenji

2018-03-01

The interaction between Λc and a nucleon (N) is investigated by employing the HAL QCD method in the (2 + 1)-flavor lattice QCD on a (2.9fm) 3 volume at mπ ≃ 410 , 570 , 700 MeV. We study the central potential in S10 channel as well as central and tensor potentials in S31-3D1 channel, and find that the tensor potential for Λc N is negligibly weak and central potentials in both S10 and S31-3D1 channels are almost identical with each other except at short distances. Phase shifts and scattering lengths calculated with these potentials show that the interaction of Λc N system is attractive and has a similar strength in S10 and S31 channels at low energies (i.e. the kinetic energy less than about 40 MeV). While the attractions are not strong enough to form two-body bound states, our results lead to a possibility to form Λc hypernuclei for sufficiently large atomic numbers (A). To demonstrate this, we derive a single-folding potential for Λc hypernuclei from the Λc-nucleon potential obtained in lattice QCD, and find that Λc hypernuclei can exist for A ≥ 12 with the binding energies of a few MeV. We also estimate the Coulomb effect for the Λc hypernuclei.

Dynamics of Bulk vs. Nanoscale WS2: Local Strain and Charging Effects

NASA Astrophysics Data System (ADS)

Musfeldt, J. L.; Brown, S.; Luttrell, R. D.; Cao, J.; Rosentsveig, R.; Tenne, R.

2006-03-01

We measured the infrared vibrational properties of bulk and nanoparticle WS2 in order to investigate the structure- property relations in these novel materials. In addition to the symmetry-breaking effects of local strain, nanoparticle curvature modifies the local charging environment of the bulk material. Performing a charge analysis on the xy-polarized E1u vibrational mode, we find an approximate 1.5:1 intralayer charge difference between the layered 2H material and inorganic fullerene-like (IF) nanoparticles. This effective charge difference may impact the solid-state lubrication properties of nanoscale metal dichalcogenides.

Electromagnetic effects on the light hadron spectrum

DOE PAGES

Basak, S.; Bazavov, A.; Bernard, C.; ...

2015-09-28

Calculations studying electromagnetic effects on light mesons are reported. The calculations use fully dynamical QCD, but only quenched photons, which suffices to NLO in χPT; that is, the sea quarks are electrically neutral, while the valence quarks carry charge. The non-compact formalism is used for photons. New results are obtained with lattice spacing as small as 0.045 fm and a large range of volumes. The success of chiral perturbation theory in describing these results and the implications for light quark masses are considered.

Advances in QCD sum-rule calculations

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

Melikhov, Dmitri

2016-01-22

We review the recent progress in the applications of QCD sum rules to hadron properties with the emphasis on the following selected problems: (i) development of new algorithms for the extraction of ground-state parameters from two-point correlators; (ii) form factors at large momentum transfers from three-point vacuum correlation functions: (iii) properties of exotic tetraquark hadrons from correlation functions of four-quark currents.

Quark-hadron phase structure of QCD matter from SU(4) Polyakov linear sigma model

NASA Astrophysics Data System (ADS)

Diab, Abdel Magied Abdel Aal; Tawfik, Abdel Nasser

2018-04-01

The SU(4) Polyakov linear sigma model (PLSM) is extended towards characterizing the chiral condensates, σl, σs and σc of light, strange and charm quarks, respectively and the deconfinement order-parameters φ and φ at finite temperatures and densities (chemical potentials). The PLSM is considered to study the QCD equation of state in the presence of the chiral condensate of charm for different finite chemical potentials. The PLSM results are in a good agreement with the recent lattice QCD simulations. We conclude that, the charm condensate is likely not affected by the QCD phase-transition, where the corresponding critical temperature is greater than that of the light and strange quark condensates.

Challenges in QCD matter physics -The scientific programme of the Compressed Baryonic Matter experiment at FAIR

NASA Astrophysics Data System (ADS)

Ablyazimov, T.; Abuhoza, A.; Adak, R. P.; Adamczyk, M.; Agarwal, K.; Aggarwal, M. M.; Ahammed, Z.; Ahmad, F.; Ahmad, N.; Ahmad, S.; Akindinov, A.; Akishin, P.; Akishina, E.; Akishina, T.; Akishina, V.; Akram, A.; Al-Turany, M.; Alekseev, I.; Alexandrov, E.; Alexandrov, I.; Amar-Youcef, S.; Anđelić, M.; Andreeva, O.; Andrei, C.; Andronic, A.; Anisimov, Yu.; Appelshäuser, H.; Argintaru, D.; Atkin, E.; Avdeev, S.; Averbeck, R.; Azmi, M. D.; Baban, V.; Bach, M.; Badura, E.; Bähr, S.; Balog, T.; Balzer, M.; Bao, E.; Baranova, N.; Barczyk, T.; Bartoş, D.; Bashir, S.; Baszczyk, M.; Batenkov, O.; Baublis, V.; Baznat, M.; Becker, J.; Becker, K.-H.; Belogurov, S.; Belyakov, D.; Bendarouach, J.; Berceanu, I.; Bercuci, A.; Berdnikov, A.; Berdnikov, Y.; Berendes, R.; Berezin, G.; Bergmann, C.; Bertini, D.; Bertini, O.; Beşliu, C.; Bezshyyko, O.; Bhaduri, P. P.; Bhasin, A.; Bhati, A. K.; Bhattacharjee, B.; Bhattacharyya, A.; Bhattacharyya, T. K.; Biswas, S.; Blank, T.; Blau, D.; Blinov, V.; Blume, C.; Bocharov, Yu.; Book, J.; Breitner, T.; Brüning, U.; Brzychczyk, J.; Bubak, A.; Büsching, H.; Bus, T.; Butuzov, V.; Bychkov, A.; Byszuk, A.; Cai, Xu; Cãlin, M.; Cao, Ping; Caragheorgheopol, G.; Carević, I.; Cătănescu, V.; Chakrabarti, A.; Chattopadhyay, S.; Chaus, A.; Chen, Hongfang; Chen, LuYao; Cheng, Jianping; Chepurnov, V.; Cherif, H.; Chernogorov, A.; Ciobanu, M. I.; Claus, G.; Constantin, F.; Csanád, M.; D'Ascenzo, N.; Das, Supriya; Das, Susovan; de Cuveland, J.; Debnath, B.; Dementiev, D.; Deng, Wendi; Deng, Zhi; Deppe, H.; Deppner, I.; Derenovskaya, O.; Deveaux, C. A.; Deveaux, M.; Dey, K.; Dey, M.; Dillenseger, P.; Dobyrn, V.; Doering, D.; Dong, Sheng; Dorokhov, A.; Dreschmann, M.; Drozd, A.; Dubey, A. K.; Dubnichka, S.; Dubnichkova, Z.; Dürr, M.; Dutka, L.; Dželalija, M.; Elsha, V. V.; Emschermann, D.; Engel, H.; Eremin, V.; Eşanu, T.; Eschke, J.; Eschweiler, D.; Fan, Huanhuan; Fan, Xingming; Farooq, M.; Fateev, O.; Feng, Shengqin; Figuli, S. P. D.; Filozova, I.; Finogeev, D.; Fischer, P.; Flemming, H.; Förtsch, J.; Frankenfeld, U.; Friese, V.; Friske, E.; Fröhlich, I.; Frühauf, J.; Gajda, J.; Galatyuk, T.; Gangopadhyay, G.; García Chávez, C.; Gebelein, J.; Ghosh, P.; Ghosh, S. K.; Gläßel, S.; Goffe, M.; Golinka-Bezshyyko, L.; Golovatyuk, V.; Golovnya, S.; Golovtsov, V.; Golubeva, M.; Golubkov, D.; Gómez Ramírez, A.; Gorbunov, S.; Gorokhov, S.; Gottschalk, D.; Gryboś, P.; Grzeszczuk, A.; Guber, F.; Gudima, K.; Gumiński, M.; Gupta, A.; Gusakov, Yu.; Han, Dong; Hartmann, H.; He, Shue; Hehner, J.; Heine, N.; Herghelegiu, A.; Herrmann, N.; Heß, B.; Heuser, J. M.; Himmi, A.; Höhne, C.; Holzmann, R.; Hu, Dongdong; Huang, Guangming; Huang, Xinjie; Hutter, D.; Ierusalimov, A.; Ilgenfritz, E.-M.; Irfan, M.; Ivanischev, D.; Ivanov, M.; Ivanov, P.; Ivanov, Valery; Ivanov, Victor; Ivanov, Vladimir; Ivashkin, A.; Jaaskelainen, K.; Jahan, H.; Jain, V.; Jakovlev, V.; Janson, T.; Jiang, Di; Jipa, A.; Kadenko, I.; Kähler, P.; Kämpfer, B.; Kalinin, V.; Kallunkathariyil, J.; Kampert, K.-H.; Kaptur, E.; Karabowicz, R.; Karavichev, O.; Karavicheva, T.; Karmanov, D.; Karnaukhov, V.; Karpechev, E.; Kasiński, K.; Kasprowicz, G.; Kaur, M.; Kazantsev, A.; Kebschull, U.; Kekelidze, G.; Khan, M. M.; Khan, S. A.; Khanzadeev, A.; Khasanov, F.; Khvorostukhin, A.; Kirakosyan, V.; Kirejczyk, M.; Kiryakov, A.; Kiš, M.; Kisel, I.; Kisel, P.; Kiselev, S.; Kiss, T.; Klaus, P.; Kłeczek, R.; Klein-Bösing, Ch.; Kleipa, V.; Klochkov, V.; Kmon, P.; Koch, K.; Kochenda, L.; Koczoń, P.; Koenig, W.; Kohn, M.; Kolb, B. W.; Kolosova, A.; Komkov, B.; Korolev, M.; Korolko, I.; Kotte, R.; Kovalchuk, A.; Kowalski, S.; Koziel, M.; Kozlov, G.; Kozlov, V.; Kramarenko, V.; Kravtsov, P.; Krebs, E.; Kreidl, C.; Kres, I.; Kresan, D.; Kretschmar, G.; Krieger, M.; Kryanev, A. V.; Kryshen, E.; Kuc, M.; Kucewicz, W.; Kucher, V.; Kudin, L.; Kugler, A.; Kumar, Ajit; Kumar, Ashwini; Kumar, L.; Kunkel, J.; Kurepin, A.; Kurepin, N.; Kurilkin, A.; Kurilkin, P.; Kushpil, V.; Kuznetsov, S.; Kyva, V.; Ladygin, V.; Lara, C.; Larionov, P.; Laso García, A.; Lavrik, E.; Lazanu, I.; Lebedev, A.; Lebedev, S.; Lebedeva, E.; Lehnert, J.; Lehrbach, J.; Leifels, Y.; Lemke, F.; Li, Cheng; Li, Qiyan; Li, Xin; Li, Yuanjing; Lindenstruth, V.; Linnik, B.; Liu, Feng; Lobanov, I.; Lobanova, E.; Löchner, S.; Loizeau, P.-A.; Lone, S. A.; Lucio Martínez, J. A.; Luo, Xiaofeng; Lymanets, A.; Lyu, Pengfei; Maevskaya, A.; Mahajan, S.; Mahapatra, D. P.; Mahmoud, T.; Maj, P.; Majka, Z.; Malakhov, A.; Malankin, E.; Malkevich, D.; Malyatina, O.; Malygina, H.; Mandal, M. M.; Mandal, S.; Manko, V.; Manz, S.; Marin Garcia, A. M.; Markert, J.; Masciocchi, S.; Matulewicz, T.; Meder, L.; Merkin, M.; Mialkovski, V.; Michel, J.; Miftakhov, N.; Mik, L.; Mikhailov, K.; Mikhaylov, V.; Milanović, B.; Militsija, V.; Miskowiec, D.; Momot, I.; Morhardt, T.; Morozov, S.; Müller, W. F. J.; Müntz, C.; Mukherjee, S.; Muñoz Castillo, C. E.; Murin, Yu.; Najman, R.; Nandi, C.; Nandy, E.; Naumann, L.; Nayak, T.; Nedosekin, A.; Negi, V. S.; Niebur, W.; Nikulin, V.; Normanov, D.; Oancea, A.; Oh, Kunsu; Onishchuk, Yu.; Ososkov, G.; Otfinowski, P.; Ovcharenko, E.; Pal, S.; Panasenko, I.; Panda, N. R.; Parzhitskiy, S.; Patel, V.; Pauly, C.; Penschuck, M.; Peshekhonov, D.; Peshekhonov, V.; Petráček, V.; Petri, M.; Petriş, M.; Petrovici, A.; Petrovici, M.; Petrovskiy, A.; Petukhov, O.; Pfeifer, D.; Piasecki, K.; Pieper, J.; Pietraszko, J.; Płaneta, R.; Plotnikov, V.; Plujko, V.; Pluta, J.; Pop, A.; Pospisil, V.; Poźniak, K.; Prakash, A.; Prasad, S. K.; Prokudin, M.; Pshenichnov, I.; Pugach, M.; Pugatch, V.; Querchfeld, S.; Rabtsun, S.; Radulescu, L.; Raha, S.; Rami, F.; Raniwala, R.; Raniwala, S.; Raportirenko, A.; Rautenberg, J.; Rauza, J.; Ray, R.; Razin, S.; Reichelt, P.; Reinecke, S.; Reinefeld, A.; Reshetin, A.; Ristea, C.; Ristea, O.; Rodriguez Rodriguez, A.; Roether, F.; Romaniuk, R.; Rost, A.; Rostchin, E.; Rostovtseva, I.; Roy, Amitava; Roy, Ankhi; Rożynek, J.; Ryabov, Yu.; Sadovsky, A.; Sahoo, R.; Sahu, P. K.; Sahu, S. K.; Saini, J.; Samanta, S.; Sambyal, S. S.; Samsonov, V.; Sánchez Rosado, J.; Sander, O.; Sarangi, S.; Satława, T.; Sau, S.; Saveliev, V.; Schatral, S.; Schiaua, C.; Schintke, F.; Schmidt, C. J.; Schmidt, H. R.; Schmidt, K.; Scholten, J.; Schweda, K.; Seck, F.; Seddiki, S.; Selyuzhenkov, I.; Semennikov, A.; Senger, A.; Senger, P.; Shabanov, A.; Shabunov, A.; Shao, Ming; Sheremetiev, A. D.; Shi, Shusu; Shumeiko, N.; Shumikhin, V.; Sibiryak, I.; Sikora, B.; Simakov, A.; Simon, C.; Simons, C.; Singaraju, R. N.; Singh, A. K.; Singh, B. K.; Singh, C. P.; Singhal, V.; Singla, M.; Sitzmann, P.; Siwek-Wilczyńska, K.; Škoda, L.; Skwira-Chalot, I.; Som, I.; Song, Guofeng; Song, Jihye; Sosin, Z.; Soyk, D.; Staszel, P.; Strikhanov, M.; Strohauer, S.; Stroth, J.; Sturm, C.; Sultanov, R.; Sun, Yongjie; Svirida, D.; Svoboda, O.; Szabó, A.; Szczygieł, R.; Talukdar, R.; Tang, Zebo; Tanha, M.; Tarasiuk, J.; Tarassenkova, O.; Târzilă, M.-G.; Teklishyn, M.; Tischler, T.; Tlustý, P.; Tölyhi, T.; Toia, A.; Topil'skaya, N.; Träger, M.; Tripathy, S.; Tsakov, I.; Tsyupa, Yu.; Turowiecki, A.; Tuturas, N. G.; Uhlig, F.; Usenko, E.; Valin, I.; Varga, D.; Vassiliev, I.; Vasylyev, O.; Verbitskaya, E.; Verhoeven, W.; Veshikov, A.; Visinka, R.; Viyogi, Y. P.; Volkov, S.; Volochniuk, A.; Vorobiev, A.; Voronin, Aleksey; Voronin, Alexander; Vovchenko, V.; Vznuzdaev, M.; Wang, Dong; Wang, Xi-Wei; Wang, Yaping; Wang, Yi; Weber, M.; Wendisch, C.; Wessels, J. P.; Wiebusch, M.; Wiechula, J.; Wielanek, D.; Wieloch, A.; Wilms, A.; Winckler, N.; Winter, M.; Wiśniewski, K.; Wolf, Gy.; Won, Sanguk; Wu, Ke-Jun; Wüstenfeld, J.; Xiang, Changzhou; Xu, Nu; Yang, Junfeng; Yang, Rongxing; Yin, Zhongbao; Yoo, In-Kwon; Yuldashev, B.; Yushmanov, I.; Zabołotny, W.; Zaitsev, Yu.; Zamiatin, N. I.; Zanevsky, Yu.; Zhalov, M.; Zhang, Yifei; Zhang, Yu; Zhao, Lei; Zheng, Jiajun; Zheng, Sheng; Zhou, Daicui; Zhou, Jing; Zhu, Xianglei; Zinchenko, A.; Zipper, W.; Żoładź, M.; Zrelov, P.; Zryuev, V.; Zumbruch, P.; Zyzak, M.

2017-03-01

Substantial experimental and theoretical efforts worldwide are devoted to explore the phase diagram of strongly interacting matter. At LHC and top RHIC energies, QCD matter is studied at very high temperatures and nearly vanishing net-baryon densities. There is evidence that a Quark-Gluon-Plasma (QGP) was created at experiments at RHIC and LHC. The transition from the QGP back to the hadron gas is found to be a smooth cross over. For larger net-baryon densities and lower temperatures, it is expected that the QCD phase diagram exhibits a rich structure, such as a first-order phase transition between hadronic and partonic matter which terminates in a critical point, or exotic phases like quarkyonic matter. The discovery of these landmarks would be a breakthrough in our understanding of the strong interaction and is therefore in the focus of various high-energy heavy-ion research programs. The Compressed Baryonic Matter (CBM) experiment at FAIR will play a unique role in the exploration of the QCD phase diagram in the region of high net-baryon densities, because it is designed to run at unprecedented interaction rates. High-rate operation is the key prerequisite for high-precision measurements of multi-differential observables and of rare diagnostic probes which are sensitive to the dense phase of the nuclear fireball. The goal of the CBM experiment at SIS100 (√{s_{NN}}= 2.7-4.9 GeV) is to discover fundamental properties of QCD matter: the phase structure at large baryon-chemical potentials ( μ_B > 500 MeV), effects of chiral symmetry, and the equation of state at high density as it is expected to occur in the core of neutron stars. In this article, we review the motivation for and the physics programme of CBM, including activities before the start of data taking in 2024, in the context of the worldwide efforts to explore high-density QCD matter.

NNLO QCD corrections to Higgs boson production at large transverse momentum

NASA Astrophysics Data System (ADS)

Chen, X.; Cruz-Martinez, J.; Gehrmann, T.; Glover, E. W. N.; Jaquier, M.

2016-10-01

We derive the second-order QCD corrections to the production of a Higgs boson recoiling against a parton with finite transverse momentum, working in the effective field theory in which the top quark contributions are integrated out. To account for quark mass effects, we supplement the effective field theory result by the full quark mass dependence at leading order. Our calculation is fully differential in the final state kinematics and includes the decay of the Higgs boson to a photon pair. It allows one to make next-to-next-to-leading order (NNLO)-accurate theory predictions for Higgs-plus-jet final states and for the transverse momentum distribution of the Higgs boson, accounting for the experimental definition of the fiducial cross sections. The NNLO QCD corrections are found to be moderate and positive, they lead to a substantial reduction of the theory uncertainty on the predictions. We compare our results to 8 TeV LHC data from ATLAS and CMS. While the shape of the data is well-described for both experiments, we agree on the normalization only for CMS. By normalizing data and theory to the inclusive fiducial cross section for Higgs production, good agreement is found for both experiments, however at the expense of an increased theory uncertainty. We make predictions for Higgs production observables at the 13 TeV LHC, which are in good agreement with recent ATLAS data. At this energy, the leading order mass corrections to the effective field theory prediction become significant at large transverse momenta, and we discuss the resulting uncertainties on the predictions.

Mass spectrometer with electron source for reducing space charge effects in sample beam

DOEpatents

Houk, Robert S.; Praphairaksit, Narong

2003-10-14

A mass spectrometer includes an ion source which generates a beam including positive ions, a sampling interface which extracts a portion of the beam from the ion source to form a sample beam that travels along a path and has an excess of positive ions over at least part of the path, thereby causing space charge effects to occur in the sample beam due to the excess of positive ions in the sample beam, an electron source which adds electrons to the sample beam to reduce space charge repulsion between the positive ions in the sample beam, thereby reducing the space charge effects in the sample beam and producing a sample beam having reduced space charge effects, and a mass analyzer which analyzes the sample beam having reduced space charge effects.

Generalized parton distributions and transversity from full lattice QCD

NASA Astrophysics Data System (ADS)

Göckeler, M.; Hägler, Ph.; Horsley, R.; Pleiter, D.; Rakow, P. E. L.; Schäfer, A.; Schierholz, G.; Zanotti, J. M.; Qcdsf Collaboration

2005-06-01

We present here the latest results from the QCDSF collaboration for moments of gener- alized parton distributions and transversity in two-flavour QCD, including a preliminary analysis of the pion mass dependence.

Miracles in Scattering Amplitudes: from QCD to Gravity

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

Volovich, Anastasia

2016-10-09

The goal of my research project "Miracles in Scattering Amplitudes: from QCD to Gravity" involves deepening our understanding of gauge and gravity theories by exploring hidden structures in scattering amplitudes and using these rich structures as much as possible to aid practical calculations.

Duality between QCD perturbative series and power corrections

NASA Astrophysics Data System (ADS)

Narison, S.; Zakharov, V. I.

2009-08-01

We elaborate on the relation between perturbative and power-like corrections to short-distance sensitive QCD observables. We confront theoretical expectations with explicit perturbative calculations existing in literature. As is expected, the quadratic correction is dual to a long perturbative series and one should use one of them but not both. However, this might be true only for very long perturbative series, with number of terms needed in most cases exceeding the number of terms available. What has not been foreseen, the quartic corrections might also be dual to the perturbative series. If confirmed, this would imply a crucial modification of the dogma. We confront this quadratic correction against existing phenomenology (QCD (spectral) sum rules scales, determinations of light quark masses and of αs from τ-decay). We find no contradiction and (to some extent) better agreement with the data and with recent lattice calculations.

Effect of pulsed current charging on the performance of nickel-cadium cells

NASA Technical Reports Server (NTRS)

Bedrossian, A. A.; Cheh, H. Y.

1977-01-01

The effect of pulsed current charging on the charge acceptance of NiCd cells in terms of mass transfer, kinetic, and structural considerations was investigated. A systemic investigation on the performance of Ni-Cd cells by pulsed current charging was conducted under a variety of well-defined charge-discharge conditions. Experiments were carried out with half cells and film electrodes. The system behavior was studied by charge acceptance, mechanistic, and structural measurements.

Low-energy effective worldsheet theory of a non-Abelian vortex in high-density QCD revisited: A regular gauge construction

NASA Astrophysics Data System (ADS)

Chatterjee, Chandrasekhar; Nitta, Muneto

2017-04-01

Color symmetry is spontaneously broken in quark matter at high density as a consequence of di-quark condensations with exhibiting color superconductivity. Non-Abelian vortices or color magnetic flux tubes stably exist in the color-flavor locked phase at asymptotically high density. The effective worldsheet theory of a single non-Abelian vortex was previously calculated in the singular gauge to obtain the C P2 model [1,2]. Here, we reconstruct the effective theory in a regular gauge without taking a singular gauge, confirming the previous results in the singular gauge. As a byproduct of our analysis, we find that non-Abelian vortices in high-density QCD do not suffer from any obstruction for the global definition of a symmetry breaking.

Lattice QCD spectroscopy for hadronic CP violation

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

de Vries, Jordy; Mereghetti, Emanuele; Seng, Chien -Yeah

Here, the interpretation of nuclear electric dipole moment (EDM) experiments is clouded by large theoretical uncertainties associated with nonperturbative matrix elements. In various beyond-the-Standard Model scenarios nuclear and diamagnetic atomic EDMs are expected to be dominated by CP-violating pion–nucleon interactions that arise from quark chromo-electric dipole moments. The corresponding CP-violating pion–nucleon coupling strengths are, however, poorly known. In this work we propose a strategy to calculate these couplings by using spectroscopic lattice QCD techniques. Instead of directly calculating the pion–nucleon coupling constants, a challenging task, we use chiral symmetry relations that link the pion–nucleon couplings to nucleon sigma terms andmore » mass splittings that are significantly easier to calculate. In this work, we show that these relations are reliable up to next-to-next-to-leading order in the chiral expansion in both SU(2) and SU(3) chiral perturbation theory. We conclude with a brief discussion about practical details regarding the required lattice QCD calculations and the phenomenological impact of an improved understanding of CP-violating matrix elements.« less

Lattice QCD spectroscopy for hadronic CP violation

DOE PAGES

de Vries, Jordy; Mereghetti, Emanuele; Seng, Chien -Yeah; ...

2017-01-16

Here, the interpretation of nuclear electric dipole moment (EDM) experiments is clouded by large theoretical uncertainties associated with nonperturbative matrix elements. In various beyond-the-Standard Model scenarios nuclear and diamagnetic atomic EDMs are expected to be dominated by CP-violating pion–nucleon interactions that arise from quark chromo-electric dipole moments. The corresponding CP-violating pion–nucleon coupling strengths are, however, poorly known. In this work we propose a strategy to calculate these couplings by using spectroscopic lattice QCD techniques. Instead of directly calculating the pion–nucleon coupling constants, a challenging task, we use chiral symmetry relations that link the pion–nucleon couplings to nucleon sigma terms andmore » mass splittings that are significantly easier to calculate. In this work, we show that these relations are reliable up to next-to-next-to-leading order in the chiral expansion in both SU(2) and SU(3) chiral perturbation theory. We conclude with a brief discussion about practical details regarding the required lattice QCD calculations and the phenomenological impact of an improved understanding of CP-violating matrix elements.« less

A Semiclassical Derivation of the QCD Coupling

NASA Technical Reports Server (NTRS)

Batchelor, David

2009-01-01

The measured value of the QCD coupling alpha(sub s) at the energy M(sub Zo), the variation of alpha(sub s) as a function of energy in QCD, and classical relativistic dynamics are used to investigate virtual pairs of quarks and antiquarks in vacuum fluctuations. For virtual pairs of bottom quarks and antiquarks, the pair lifetime in the classical model agrees with the lifetime from quantum mechanics to good approximation, and the action integral in the classical model agrees as well with the action that follows from the Uncertainty Principle. This suggests that the particles might have small de Broglie wavelengths and behave with well-localized pointlike dynamics. It also permits alpha(sub s) at the mass energy twice the bottom quark mass to be expressed as a simple fraction: 3/16. This is accurate to approximately 10%. The model in this paper predicts the measured value of alpha(sub s)(M(sub Zo)) to be 0.121, which is in agreement with recent measurements within statistical uncertainties.

Azimuthal anisotropy of charged jet production in √{sNN} = 2.76 TeV Pb-Pb collisions

NASA Astrophysics Data System (ADS)

Adam, J.; Adamová, D.; Aggarwal, M. M.; Aglieri Rinella, G.; Agnello, M.; Agrawal, N.; Ahammed, Z.; Ahn, S. U.; Aiola, S.; Akindinov, A.; Alam, S. N.; Aleksandrov, D.; Alessandro, B.; Alexandre, D.; Alfaro Molina, R.; Alici, A.; Alkin, A.; Almaraz, J. R. M.; Alme, J.; Alt, T.; Altinpinar, S.; Altsybeev, I.; Alves Garcia Prado, C.; Andrei, C.; Andronic, A.; Anguelov, V.; Anielski, J.; Antičić, T.; Antinori, F.; Antonioli, P.; Aphecetche, L.; Appelshäuser, H.; Arcelli, S.; Arnaldi, R.; Arnold, O. W.; Arsene, I. C.; Arslandok, M.; Audurier, B.; Augustinus, A.; Averbeck, R.; Azmi, M. D.; Badalà, A.; Baek, Y. W.; Bagnasco, S.; Bailhache, R.; Bala, R.; Baldisseri, A.; Baral, R. C.; Barbano, A. M.; Barbera, R.; Barile, F.; Barnaföldi, G. G.; Barnby, L. S.; Barret, V.; Bartalini, P.; Barth, K.; Bartke, J.; Bartsch, E.; Basile, M.; Bastid, N.; Basu, S.; Bathen, B.; Batigne, G.; Batista Camejo, A.; Batyunya, B.; Batzing, P. C.; Bearden, I. G.; Beck, H.; Bedda, C.; Behera, N. K.; Belikov, I.; Bellini, F.; Bello Martinez, H.; Bellwied, R.; Belmont, R.; Belmont-Moreno, E.; Belyaev, V.; Bencedi, G.; Beole, S.; Berceanu, I.; Bercuci, A.; Berdnikov, Y.; Berenyi, D.; Bertens, R. A.; Berzano, D.; Betev, L.; Bhasin, A.; Bhat, I. R.; Bhati, A. K.; Bhattacharjee, B.; Bhom, J.; Bianchi, L.; Bianchi, N.; Bianchin, C.; Bielčík, J.; Bielčíková, J.; Bilandzic, A.; Biswas, R.; Biswas, S.; Bjelogrlic, S.; Blair, J. T.; Blau, D.; Blume, C.; Bock, F.; Bogdanov, A.; Bøggild, H.; Boldizsár, L.; Bombara, M.; Book, J.; Borel, H.; Borissov, A.; Borri, M.; Bossú, F.; Botta, E.; Böttger, S.; Bourjau, C.; Braun-Munzinger, P.; Bregant, M.; Breitner, T.; Broker, T. A.; Browning, T. A.; Broz, M.; Brucken, E. J.; Bruna, E.; Bruno, G. E.; Budnikov, D.; Buesching, H.; Bufalino, S.; Buncic, P.; Busch, O.; Buthelezi, Z.; Butt, J. B.; Buxton, J. T.; Caffarri, D.; Cai, X.; Caines, H.; Calero Diaz, L.; Caliva, A.; Calvo Villar, E.; Camerini, P.; Carena, F.; Carena, W.; Carnesecchi, F.; Castillo Castellanos, J.; Castro, A. J.; Casula, E. A. R.; Ceballos Sanchez, C.; Cepila, J.; Cerello, P.; Cerkala, J.; Chang, B.; Chapeland, S.; Chartier, M.; Charvet, J. L.; Chattopadhyay, S.; Chattopadhyay, S.; Chelnokov, V.; Cherney, M.; Cheshkov, C.; Cheynis, B.; Chibante Barroso, V.; Chinellato, D. D.; Cho, S.; Chochula, P.; Choi, K.; Chojnacki, M.; Choudhury, S.; Christakoglou, P.; Christensen, C. H.; Christiansen, P.; Chujo, T.; Chung, S. U.; Cicalo, C.; Cifarelli, L.; Cindolo, F.; Cleymans, J.; Colamaria, F.; Colella, D.; Collu, A.; Colocci, M.; Conesa Balbastre, G.; Conesa Del Valle, Z.; Connors, M. E.; Contreras, J. G.; Cormier, T. M.; Corrales Morales, Y.; Cortés Maldonado, I.; Cortese, P.; Cosentino, M. R.; Costa, F.; Crochet, P.; Cruz Albino, R.; Cuautle, E.; Cunqueiro, L.; Dahms, T.; Dainese, A.; Danu, A.; Das, D.; Das, I.; Das, S.; Dash, A.; Dash, S.; de, S.; de Caro, A.; de Cataldo, G.; de Conti, C.; de Cuveland, J.; de Falco, A.; de Gruttola, D.; De Marco, N.; de Pasquale, S.; Deisting, A.; Deloff, A.; Dénes, E.; Deplano, C.; Dhankher, P.; di Bari, D.; di Mauro, A.; di Nezza, P.; Diaz Corchero, M. A.; Dietel, T.; Dillenseger, P.; Divià, R.; Djuvsland, Ø.; Dobrin, A.; Domenicis Gimenez, D.; Dönigus, B.; Dordic, O.; Drozhzhova, T.; Dubey, A. K.; Dubla, A.; Ducroux, L.; Dupieux, P.; Ehlers, R. J.; Elia, D.; Engel, H.; Epple, E.; Erazmus, B.; Erdemir, I.; Erhardt, F.; Espagnon, B.; Estienne, M.; Esumi, S.; Eum, J.; Evans, D.; Evdokimov, S.; Eyyubova, G.; Fabbietti, L.; Fabris, D.; Faivre, J.; Fantoni, A.; Fasel, M.; Feldkamp, L.; Feliciello, A.; Feofilov, G.; Ferencei, J.; Fernández Téllez, A.; Ferreiro, E. G.; Ferretti, A.; Festanti, A.; Feuillard, V. J. G.; Figiel, J.; Figueredo, M. A. S.; Filchagin, S.; Finogeev, D.; Fionda, F. M.; Fiore, E. M.; Fleck, M. G.; Floris, M.; Foertsch, S.; Foka, P.; Fokin, S.; Fragiacomo, E.; Francescon, A.; Frankenfeld, U.; Fuchs, U.; Furget, C.; Furs, A.; Fusco Girard, M.; Gaardhøje, J. J.; Gagliardi, M.; Gago, A. M.; Gallio, M.; Gangadharan, D. R.; Ganoti, P.; Gao, C.; Garabatos, C.; Garcia-Solis, E.; Gargiulo, C.; Gasik, P.; Gauger, E. F.; Germain, M.; Gheata, A.; Gheata, M.; Ghosh, P.; Ghosh, S. K.; Gianotti, P.; Giubellino, P.; Giubilato, P.; Gladysz-Dziadus, E.; Glässel, P.; Goméz Coral, D. M.; Gomez Ramirez, A.; Gonzalez, V.; González-Zamora, P.; Gorbunov, S.; Görlich, L.; Gotovac, S.; Grabski, V.; Grachov, O. A.; Graczykowski, L. K.; Graham, K. L.; Grelli, A.; Grigoras, A.; Grigoras, C.; Grigoriev, V.; Grigoryan, A.; Grigoryan, S.; Grinyov, B.; Grion, N.; Gronefeld, J. M.; Grosse-Oetringhaus, J. F.; Grossiord, J.-Y.; Grosso, R.; Guber, F.; Guernane, R.; Guerzoni, B.; Gulbrandsen, K.; Gunji, T.; Gupta, A.; Gupta, R.; Haake, R.; Haaland, Ø.; Hadjidakis, C.; Haiduc, M.; Hamagaki, H.; Hamar, G.; Harris, J. W.; Harton, A.; Hatzifotiadou, D.; Hayashi, S.; Heckel, S. T.; Heide, M.; Helstrup, H.; Herghelegiu, A.; Herrera Corral, G.; Hess, B. A.; Hetland, K. F.; Hillemanns, H.; Hippolyte, B.; Hosokawa, R.; Hristov, P.; Huang, M.; Humanic, T. J.; Hussain, N.; Hussain, T.; Hutter, D.; Hwang, D. S.; Ilkaev, R.; Inaba, M.; Ippolitov, M.; Irfan, M.; Ivanov, M.; Ivanov, V.; Izucheev, V.; Jacobs, P. M.; Jadhav, M. B.; Jadlovska, S.; Jadlovsky, J.; Jahnke, C.; Jakubowska, M. J.; Jang, H. J.; Janik, M. A.; Jayarathna, P. H. S. Y.; Jena, C.; Jena, S.; Jimenez Bustamante, R. T.; Jones, P. G.; Jung, H.; Jusko, A.; Kalinak, P.; Kalweit, A.; Kamin, J.; Kang, J. H.; Kaplin, V.; Kar, S.; Karasu Uysal, A.; Karavichev, O.; Karavicheva, T.; Karayan, L.; Karpechev, E.; Kebschull, U.; Keidel, R.; Keijdener, D. L. D.; Keil, M.; Mohisin Khan, M.; Khan, P.; Khan, S. A.; Khanzadeev, A.; Kharlov, Y.; Kileng, B.; Kim, D. W.; Kim, D. J.; Kim, D.; Kim, H.; Kim, J. S.; Kim, M.; Kim, M.; Kim, S.; Kim, T.; Kirsch, S.; Kisel, I.; Kiselev, S.; Kisiel, A.; Kiss, G.; Klay, J. L.; Klein, C.; Klein, J.; Klein-Bösing, C.; Klewin, S.; Kluge, A.; Knichel, M. L.; Knospe, A. G.; Kobayashi, T.; Kobdaj, C.; Kofarago, M.; Kollegger, T.; Kolojvari, A.; Kondratiev, V.; Kondratyeva, N.; Kondratyuk, E.; Konevskikh, A.; Kopcik, M.; Kour, M.; Kouzinopoulos, C.; Kovalenko, O.; Kovalenko, V.; Kowalski, M.; Koyithatta Meethaleveedu, G.; Králik, I.; Kravčáková, A.; Kretz, M.; Krivda, M.; Krizek, F.; Kryshen, E.; Krzewicki, M.; Kubera, A. M.; Kučera, V.; Kuhn, C.; Kuijer, P. G.; Kumar, A.; Kumar, J.; Kumar, L.; Kumar, S.; Kurashvili, P.; Kurepin, A.; Kurepin, A. B.; Kuryakin, A.; Kweon, M. J.; Kwon, Y.; La Pointe, S. L.; La Rocca, P.; Ladron de Guevara, P.; Lagana Fernandes, C.; Lakomov, I.; Langoy, R.; Lara, C.; Lardeux, A.; Lattuca, A.; Laudi, E.; Lea, R.; Leardini, L.; Lee, G. R.; Lee, S.; Lehas, F.; Lemmon, R. C.; Lenti, V.; Leogrande, E.; León Monzón, I.; León Vargas, H.; Leoncino, M.; Lévai, P.; Li, S.; Li, X.; Lien, J.; Lietava, R.; Lindal, S.; Lindenstruth, V.; Lippmann, C.; Lisa, M. A.; Ljunggren, H. M.; Lodato, D. F.; Loenne, P. I.; Loginov, V.; Loizides, C.; Lopez, X.; López Torres, E.; Lowe, A.; Luettig, P.; Lunardon, M.; Luparello, G.; Maevskaya, A.; Mager, M.; Mahajan, S.; Mahmood, S. M.; Maire, A.; Majka, R. D.; Malaev, M.; Maldonado Cervantes, I.; Malinina, L.; Mal'Kevich, D.; Malzacher, P.; Mamonov, A.; Manko, V.; Manso, F.; Manzari, V.; Marchisone, M.; Mareš, J.; Margagliotti, G. V.; Margotti, A.; Margutti, J.; Marín, A.; Markert, C.; Marquard, M.; Martin, N. A.; Martin Blanco, J.; Martinengo, P.; Martínez, M. I.; Martínez García, G.; Martinez Pedreira, M.; Mas, A.; Masciocchi, S.; Masera, M.; Masoni, A.; Massacrier, L.; Mastroserio, A.; Matyja, A.; Mayer, C.; Mazer, J.; Mazzoni, M. A.; McDonald, D.; Meddi, F.; Melikyan, Y.; Menchaca-Rocha, A.; Meninno, E.; Mercado Pérez, J.; Meres, M.; Miake, Y.; Mieskolainen, M. M.; Mikhaylov, K.; Milano, L.; Milosevic, J.; Minervini, L. M.; Mischke, A.; Mishra, A. N.; Miśkowiec, D.; Mitra, J.; Mitu, C. M.; Mohammadi, N.; Mohanty, B.; Molnar, L.; Montaño Zetina, L.; Montes, E.; Moreira de Godoy, D. A.; Moreno, L. A. P.; Moretto, S.; Morreale, A.; Morsch, A.; Muccifora, V.; Mudnic, E.; Mühlheim, D.; Muhuri, S.; Mukherjee, M.; Mulligan, J. D.; Munhoz, M. G.; Munzer, R. H.; Murray, S.; Musa, L.; Musinsky, J.; Naik, B.; Nair, R.; Nandi, B. K.; Nania, R.; Nappi, E.; Naru, M. U.; Natal da Luz, H.; Nattrass, C.; Nayak, K.; Nayak, T. K.; Nazarenko, S.; Nedosekin, A.; Nellen, L.; Ng, F.; Nicassio, M.; Niculescu, M.; Niedziela, J.; Nielsen, B. S.; Nikolaev, S.; Nikulin, S.; Nikulin, V.; Noferini, F.; Nomokonov, P.; Nooren, G.; Noris, J. C. C.; Norman, J.; Nyanin, A.; Nystrand, J.; Oeschler, H.; Oh, S.; Oh, S. K.; Ohlson, A.; Okatan, A.; Okubo, T.; Olah, L.; Oleniacz, J.; Oliveira da Silva, A. C.; Oliver, M. H.; Onderwaater, J.; Oppedisano, C.; Orava, R.; Ortiz Velasquez, A.; Oskarsson, A.; Otwinowski, J.; Oyama, K.; Ozdemir, M.; Pachmayer, Y.; Pagano, P.; Paić, G.; Pal, S. K.; Pan, J.; Pandey, A. K.; Papcun, P.; Papikyan, V.; Pappalardo, G. S.; Pareek, P.; Park, W. J.; Parmar, S.; Passfeld, A.; Paticchio, V.; Patra, R. N.; Paul, B.; Peitzmann, T.; Pereira da Costa, H.; Pereira de Oliveira Filho, E.; Peresunko, D.; Pérez Lara, C. E.; Perez Lezama, E.; Peskov, V.; Pestov, Y.; Petráček, V.; Petrov, V.; Petrovici, M.; Petta, C.; Piano, S.; Pikna, M.; Pillot, P.; Pinazza, O.; Pinsky, L.; Piyarathna, D. B.; Płoskoń, M.; Planinic, M.; Pluta, J.; Pochybova, S.; Podesta-Lerma, P. L. M.; Poghosyan, M. G.; Polichtchouk, B.; Poljak, N.; Poonsawat, W.; Pop, A.; Porteboeuf-Houssais, S.; Porter, J.; Pospisil, J.; Prasad, S. K.; Preghenella, R.; Prino, F.; Pruneau, C. A.; Pshenichnov, I.; Puccio, M.; Puddu, G.; Pujahari, P.; Punin, V.; Putschke, J.; Qvigstad, H.; Rachevski, A.; Raha, S.; Rajput, S.; Rak, J.; Rakotozafindrabe, A.; Ramello, L.; Rami, F.; Raniwala, R.; Raniwala, S.; Räsänen, S. S.; Rascanu, B. T.; Rathee, D.; Read, K. F.; Redlich, K.; Reed, R. J.; Rehman, A.; Reichelt, P.; Reidt, F.; Ren, X.; Renfordt, R.; Reolon, A. R.; Reshetin, A.; Revol, J.-P.; Reygers, K.; Riabov, V.; Ricci, R. A.; Richert, T.; Richter, M.; Riedler, P.; Riegler, W.; Riggi, F.; Ristea, C.; Rocco, E.; Rodríguez Cahuantzi, M.; Rodriguez Manso, A.; Røed, K.; Rogochaya, E.; Rohr, D.; Röhrich, D.; Romita, R.; Ronchetti, F.; Ronflette, L.; Rosnet, P.; Rossi, A.; Roukoutakis, F.; Roy, A.; Roy, C.; Roy, P.; Rubio Montero, A. J.; Rui, R.; Russo, R.; Ryabinkin, E.; Ryabov, Y.; Rybicki, A.; Sadovsky, S.; Šafařík, K.; Sahlmuller, B.; Sahoo, P.; Sahoo, R.; Sahoo, S.; Sahu, P. K.; Saini, J.; Sakai, S.; Saleh, M. A.; Salzwedel, J.; Sambyal, S.; Samsonov, V.; Šándor, L.; Sandoval, A.; Sano, M.; Sarkar, D.; Scapparone, E.; Scarlassara, F.; Schiaua, C.; Schicker, R.; Schmidt, C.; Schmidt, H. R.; Schuchmann, S.; Schukraft, J.; Schulc, M.; Schuster, T.; Schutz, Y.; Schwarz, K.; Schweda, K.; Scioli, G.; Scomparin, E.; Scott, R.; Šefčík, M.; Seger, J. E.; Sekiguchi, Y.; Sekihata, D.; Selyuzhenkov, I.; Senosi, K.; Senyukov, S.; Serradilla, E.; Sevcenco, A.; Shabanov, A.; Shabetai, A.; Shadura, O.; Shahoyan, R.; Shangaraev, A.; Sharma, A.; Sharma, M.; Sharma, M.; Sharma, N.; Shigaki, K.; Shtejer, K.; Sibiriak, Y.; Siddhanta, S.; Sielewicz, K. M.; Siemiarczuk, T.; Silvermyr, D.; Silvestre, C.; Simatovic, G.; Simonetti, G.; Singaraju, R.; Singh, R.; Singha, S.; Singhal, V.; Sinha, B. C.; Sinha, T.; Sitar, B.; Sitta, M.; Skaali, T. B.; Slupecki, M.; Smirnov, N.; Snellings, R. J. M.; Snellman, T. W.; Søgaard, C.; Song, J.; Song, M.; Song, Z.; Soramel, F.; Sorensen, S.; Sozzi, F.; Spacek, M.; Spiriti, E.; Sputowska, I.; Spyropoulou-Stassinaki, M.; Stachel, J.; Stan, I.; Stefanek, G.; Stenlund, E.; Steyn, G.; Stiller, J. H.; Stocco, D.; Strmen, P.; Suaide, A. A. P.; Sugitate, T.; Suire, C.; Suleymanov, M.; Suljic, M.; Sultanov, R.; Šumbera, M.; Szabo, A.; Szanto de Toledo, A.; Szarka, I.; Szczepankiewicz, A.; Szymanski, M.; Tabassam, U.; Takahashi, J.; Tambave, G. J.; Tanaka, N.; Tangaro, M. A.; Tarhini, M.; Tariq, M.; Tarzila, M. G.; Tauro, A.; Tejeda Muñoz, G.; Telesca, A.; Terasaki, K.; Terrevoli, C.; Teyssier, B.; Thäder, J.; Thomas, D.; Tieulent, R.; Timmins, A. R.; Toia, A.; Trogolo, S.; Trombetta, G.; Trubnikov, V.; Trzaska, W. H.; Tsuji, T.; Tumkin, A.; Turrisi, R.; Tveter, T. S.; Ullaland, K.; Uras, A.; Usai, G. L.; Utrobicic, A.; Vajzer, M.; Vala, M.; Valencia Palomo, L.; Vallero, S.; van der Maarel, J.; van Hoorne, J. W.; van Leeuwen, M.; Vanat, T.; Vande Vyvre, P.; Varga, D.; Vargas, A.; Vargyas, M.; Varma, R.; Vasileiou, M.; Vasiliev, A.; Vauthier, A.; Vechernin, V.; Veen, A. M.; Veldhoen, M.; Velure, A.; Venaruzzo, M.; Vercellin, E.; Vergara Limón, S.; Vernet, R.; Verweij, M.; Vickovic, L.; Viesti, G.; Viinikainen, J.; Vilakazi, Z.; Villalobos Baillie, O.; Villatoro Tello, A.; Vinogradov, A.; Vinogradov, L.; Vinogradov, Y.; Virgili, T.; Vislavicius, V.; Viyogi, Y. P.; Vodopyanov, A.; Völkl, M. A.; Voloshin, K.; Voloshin, S. A.; Volpe, G.; von Haller, B.; Vorobyev, I.; Vranic, D.; Vrláková, J.; Vulpescu, B.; Vyushin, A.; Wagner, B.; Wagner, J.; Wang, H.; Wang, M.; Watanabe, D.; Watanabe, Y.; Weber, M.; Weber, S. G.; Weiser, D. F.; Wessels, J. P.; Westerhoff, U.; Whitehead, A. M.; Wiechula, J.; Wikne, J.; Wilde, M.; Wilk, G.; Wilkinson, J.; Williams, M. C. S.; Windelband, B.; Winn, M.; Yaldo, C. G.; Yang, H.; Yang, P.; Yano, S.; Yasar, C.; Yin, Z.; Yokoyama, H.; Yoo, I.-K.; Yoon, J. H.; Yurchenko, V.; Yushmanov, I.; Zaborowska, A.; Zaccolo, V.; Zaman, A.; Zampolli, C.; Zanoli, H. J. C.; Zaporozhets, S.; Zardoshti, N.; Zarochentsev, A.; Závada, P.; Zaviyalov, N.; Zbroszczyk, H.; Zgura, I. S.; Zhalov, M.; Zhang, H.; Zhang, X.; Zhang, Y.; Zhang, C.; Zhang, Z.; Zhao, C.; Zhigareva, N.; Zhou, D.; Zhou, Y.; Zhou, Z.; Zhu, H.; Zhu, J.; Zichichi, A.; Zimmermann, A.; Zimmermann, M. B.; Zinovjev, G.; Zyzak, M.; Alice Collaboration

2016-02-01

We present measurements of the azimuthal dependence of charged jet production in central and semi-central √{sNN} = 2.76 TeV Pb-Pb collisions with respect to the second harmonic event plane, quantified as v2chjet. Jet finding is performed employing the anti-kT algorithm with a resolution parameter R = 0.2 using charged tracks from the ALICE tracking system. The contribution of the azimuthal anisotropy of the underlying event is taken into account event-by-event. The remaining (statistical) region-to-region fluctuations are removed on an ensemble basis by unfolding the jet spectra for different event plane orientations independently. Significant non-zero v2chjet is observed in semi-central collisions (30-50% centrality) for 20 charged jet production is similar to the dependence observed for jets comprising both charged and neutral fragments, and compatible with measurements of the v2 of single charged particles at high pT. Good agreement between the data and predictions from JEWEL, an event generator simulating parton shower evolution in the presence of a dense QCD medium, is found in semi-central collisions.

Baryogenesis from strong CP violation and the QCD axion.

PubMed

Servant, Géraldine

2014-10-24

We show that strong CP violation from the QCD axion can be responsible for the matter antimatter asymmetry of the Universe in the context of cold electroweak baryogenesis if the electroweak phase transition is delayed below the GeV scale. This can occur naturally if the Higgs couples to a O(100)  GeV dilaton, as expected in some models where the Higgs is a pseudo-Nambu-Goldstone boson of a new strongly interacting sector at the TeV scale. The existence of such a second scalar resonance with a mass and properties similar to the Higgs boson will soon be tested at the LHC. In this context, the QCD axion would not only solve the strong CP problem, but also the matter antimatter asymmetry and dark matter.

Experimental Evidence for Space-Charge Effects between Ions of the Same Mass-to-Charge in Fourier-Transform Ion Cyclotron Resonance Mass Spectrometry

PubMed Central

Wong, Richard L.; Amster, I. Jonathan

2009-01-01

It is often stated that ions of the same mass-to-charge do not induce space-charge frequency shifts among themselves in an ion cyclotron resonance mass spectrometry measurement. Here, we demonstrate space-charge induced frequency shifts for ions of a single mass-to-charge. The monoisotopic atomic ion, Cs+, was used for this study. The measured frequency is observed to decrease linearly with an increase in the number of ions, as has been reported previously for space-charge effects between ions of different mass-to-charge. The frequency shift between ions of the same m/z value are compared to that induced between ions of different m/z value, and is found to be 7.5 times smaller. Control experiments were performed to ensure that the observed space-charge effects are not artifacts of the measurement or of experimental design. The results can be rationalized by recognizing that the electric forces between ions in a magnetic field conform to the weak form of the Newton's third law, where the action and reaction forces do not cancel exactly. PMID:19562102

Renormalization group invariance and optimal QCD renormalization scale-setting: a key issues review.

PubMed

Wu, Xing-Gang; Ma, Yang; Wang, Sheng-Quan; Fu, Hai-Bing; Ma, Hong-Hao; Brodsky, Stanley J; Mojaza, Matin

2015-12-01

A valid prediction for a physical observable from quantum field theory should be independent of the choice of renormalization scheme--this is the primary requirement of renormalization group invariance (RGI). Satisfying scheme invariance is a challenging problem for perturbative QCD (pQCD), since a truncated perturbation series does not automatically satisfy the requirements of the renormalization group. In a previous review, we provided a general introduction to the various scale setting approaches suggested in the literature. As a step forward, in the present review, we present a discussion in depth of two well-established scale-setting methods based on RGI. One is the 'principle of maximum conformality' (PMC) in which the terms associated with the β-function are absorbed into the scale of the running coupling at each perturbative order; its predictions are scheme and scale independent at every finite order. The other approach is the 'principle of minimum sensitivity' (PMS), which is based on local RGI; the PMS approach determines the optimal renormalization scale by requiring the slope of the approximant of an observable to vanish. In this paper, we present a detailed comparison of the PMC and PMS procedures by analyzing two physical observables R(e+e-) and [Formula: see text] up to four-loop order in pQCD. At the four-loop level, the PMC and PMS predictions for both observables agree within small errors with those of conventional scale setting assuming a physically-motivated scale, and each prediction shows small scale dependences. However, the convergence of the pQCD series at high orders, behaves quite differently: the PMC displays the best pQCD convergence since it eliminates divergent renormalon terms; in contrast, the convergence of the PMS prediction is questionable, often even worse than the conventional prediction based on an arbitrary guess for the renormalization scale. PMC predictions also have the property that any residual dependence on the choice

Renormalization group invariance and optimal QCD renormalization scale-setting: a key issues review

NASA Astrophysics Data System (ADS)

Wu, Xing-Gang; Ma, Yang; Wang, Sheng-Quan; Fu, Hai-Bing; Ma, Hong-Hao; Brodsky, Stanley J.; Mojaza, Matin

2015-12-01

A valid prediction for a physical observable from quantum field theory should be independent of the choice of renormalization scheme—this is the primary requirement of renormalization group invariance (RGI). Satisfying scheme invariance is a challenging problem for perturbative QCD (pQCD), since a truncated perturbation series does not automatically satisfy the requirements of the renormalization group. In a previous review, we provided a general introduction to the various scale setting approaches suggested in the literature. As a step forward, in the present review, we present a discussion in depth of two well-established scale-setting methods based on RGI. One is the ‘principle of maximum conformality’ (PMC) in which the terms associated with the β-function are absorbed into the scale of the running coupling at each perturbative order; its predictions are scheme and scale independent at every finite order. The other approach is the ‘principle of minimum sensitivity’ (PMS), which is based on local RGI; the PMS approach determines the optimal renormalization scale by requiring the slope of the approximant of an observable to vanish. In this paper, we present a detailed comparison of the PMC and PMS procedures by analyzing two physical observables R e+e- and Γ(H\\to b\\bar{b}) up to four-loop order in pQCD. At the four-loop level, the PMC and PMS predictions for both observables agree within small errors with those of conventional scale setting assuming a physically-motivated scale, and each prediction shows small scale dependences. However, the convergence of the pQCD series at high orders, behaves quite differently: the PMC displays the best pQCD convergence since it eliminates divergent renormalon terms; in contrast, the convergence of the PMS prediction is questionable, often even worse than the conventional prediction based on an arbitrary guess for the renormalization scale. PMC predictions also have the property that any residual dependence on

Spacecraft Charging: Hazard Causes, Hazard Effects, Hazard Controls

NASA Technical Reports Server (NTRS)

Koontz, Steve.

2018-01-01

Spacecraft flight environments are characterized both by a wide range of space plasma conditions and by ionizing radiation (IR), solar ultraviolet and X-rays, magnetic fields, micrometeoroids, orbital debris, and other environmental factors, all of which can affect spacecraft performance. Dr. Steven Koontz's lecture will provide a solid foundation in the basic engineering physics of spacecraft charging and charging effects that can be applied to solving practical spacecraft and spacesuit engineering design, verification, and operations problems, with an emphasis on spacecraft operations in low-Earth orbit, Earth's magnetosphere, and cis-Lunar space.

Gating capacitive field-effect sensors by the charge of nanoparticle/molecule hybrids.

PubMed

Poghossian, Arshak; Bäcker, Matthias; Mayer, Dirk; Schöning, Michael J

2015-01-21

The semiconductor field-effect platform is a powerful tool for chemical and biological sensing with direct electrical readout. In this work, the field-effect capacitive electrolyte-insulator-semiconductor (EIS) structure - the simplest field-effect (bio-)chemical sensor - modified with citrate-capped gold nanoparticles (AuNPs) has been applied for a label-free electrostatic detection of charged molecules by their intrinsic molecular charge. The EIS sensor detects the charge changes in AuNP/molecule inorganic/organic hybrids induced by the molecular adsorption or binding events. The feasibility of the proposed detection scheme has been exemplarily demonstrated by realizing capacitive EIS sensors consisting of an Al-p-Si-SiO2-silane-AuNP structure for the label-free detection of positively charged cytochrome c and poly-d-lysine molecules as well as for monitoring the layer-by-layer formation of polyelectrolyte multilayers of poly(allylamine hydrochloride)/poly(sodium 4-styrene sulfonate), representing typical model examples of detecting small proteins and macromolecules and the consecutive adsorption of positively/negatively charged polyelectrolytes, respectively. For comparison, EIS sensors without AuNPs have been investigated, too. The adsorption of molecules on the surface of AuNPs has been verified via the X-ray photoelectron spectroscopy method. In addition, a theoretical model of the functioning of the capacitive field-effect EIS sensor functionalized with AuNP/charged-molecule hybrids has been discussed.

Measurements of event properties and multi-differential jet cross sections and impact of CMS measurements on Proton Structure and QCD parameters

NASA Astrophysics Data System (ADS)

Kaur, Anterpreet

2018-01-01

We present results on the measurements of characteristics of events with jets including jet-charge, investigations of shapes and jet mass distributions. The measurements are compared to theoretical predictions including those matched to parton shower and hadronization. Multi-differential jet cross sections are also presented over a wide range in transverse momenta from inclusive jets to multi-jet final states. These measurements have an impact on the determination of the strong coupling constant as well as on parton distribution functions (PDFs) and are helpful in the treatment of heavy flavours in QCD analyses. We also show angular correlations in multi-jet events at highest center-of-mass energies and compare the measurements to theoretical predictions including higher order parton radiation and coherence effects. Measurements of cross sections of jet and top-quark pair production are in particular sensitive to the gluon distribution in the proton, while the electroweak boson production - inclusive or associated with charm or beauty quarks - gives insight into the flavour separation of the proton sea and to the treatment of heavy quarks in PDF-related studies.