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Sample records for one-loop scalar pentagon

  1. ONELOOP: For the evaluation of one-loop scalar functions

    NASA Astrophysics Data System (ADS)

    van Hameren, A.

    2011-11-01

    ONELOOP is a program to evaluate the one-loop scalar 1-point, 2-point, 3-point and 4-point functions, for all kinematical configurations relevant for collider-physics, and for any non-positive imaginary parts of the internal squared masses. It deals with all UV and IR divergences within dimensional regularization. Furthermore, it provides routines to evaluate these functions using straightforward numerical integration. Program summaryProgram title: OneLOop Catalogue identifier: AEJO_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEJO_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 12 061 No. of bytes in distributed program, including test data, etc.: 74 163 Distribution format: tar.gz Programming language: Fortran Computer: Workstations Operating system: Linux, Unix RAM: Negligible Classification: 4.4, 11.1 Nature of problem: In order to reach next-to-leading order precision in the calculation of cross sections of hard scattering processes, one-loop amplitudes have to be evaluated. This is done by expressing them as linear combination of one-loop scalar functions. In a concrete calculation, these functions eventually have to be evaluated. If the scattering process involves unstable particles, consistency requires the evaluation of these functions with complex internal masses. Solution method: Expressions for the one-loop scalar functions in terms of single-variable analytic functions existing in literature have been implemented. Restrictions: The applicability is restricted to the kinematics occurring in collider-physics. Running time: The evaluation of the most general 4-point function with 4 complex masses takes about 180 μs, and the evaluation of the 4-point function with 4 real masses takes about 18 μs on a 2.80 GHz Intel Xeon processor.

  2. One-loop pentagon integral in d dimensions from differential equations in ɛ-form

    NASA Astrophysics Data System (ADS)

    Kozlov, Mikhail G.; Lee, Roman N.

    2016-02-01

    We apply the differential equation technique to the calculation of the one-loop massless diagram with five onshell legs. Using the reduction to ɛ-form, we manage to obtain a simple one-fold integral representation exact in space-time dimensionality. The expansion of the obtained result in ɛ and the analytical continuation to physical regions are discussed.

  3. High-temperature expansion of the one-loop free energy of a scalar field on a curved background

    NASA Astrophysics Data System (ADS)

    Kalinichenko, I. S.; Kazinski, P. O.

    2013-04-01

    The complete form of the high-temperature expansion of the one-loop contribution to the free energy of a scalar field on a stationary gravitational background is derived. The explicit expressions for the divergent and finite parts of the high-temperature expansion in a three-dimensional space without boundaries are obtained. These formulas generalize the known one for the stationary spacetime. In particular, we confirm that for a massless conformal scalar field the leading correction to the Planck law proportional to the temperature squared turns out to be nonzero due to the nonstatic nature of the metric. The explicit expression for the so-called energy-time anomaly is found. The interrelation between this anomaly and the conformal (trace) anomaly is established. The natural simplest Lagrangian for the “Killing vector field” is given.

  4. On a family of (1+1)-dimensional scalar field theory models: Kinks, stability, one-loop mass shifts

    SciTech Connect

    Alonso-Izquierdo, A.; Mateos Guilarte, J.

    2012-09-15

    In this paper we construct a one-parametric family of (1+1)-dimensional one-component scalar field theory models supporting kinks. Inspired by the sine-Gordon and {phi}{sup 4} models, we look at all possible extensions such that the kink second-order fluctuation operators are Schroedinger differential operators with Poeschl-Teller potential wells. In this situation, the associated spectral problem is solvable and therefore we shall succeed in analyzing the kink stability completely and in computing the one-loop quantum correction to the kink mass exactly. When the parameter is a natural number, the family becomes the hierarchy for which the potential wells are reflectionless, the two first levels of the hierarchy being the sine-Gordon and {phi}{sup 4} models. - Highlights: Black-Right-Pointing-Pointer We construct a family of scalar field theory models supporting kinks. Black-Right-Pointing-Pointer The second-order kink fluctuation operators involve Poeschl-Teller potential wells. Black-Right-Pointing-Pointer We compute the one-loop quantum correction to the kink mass with different methods.

  5. Non-perturbative corrections to the one-loop free energy induced by a massive scalar field on a stationary slowly varying in space gravitational background

    NASA Astrophysics Data System (ADS)

    Kalinichenko, Igor; Kazinski, Peter

    2014-08-01

    The explicit expressions for the one-loop non-perturbative corrections to the gravitational effective action induced by a scalar field on a stationary gravitational background are obtained both at zero and finite temperatures. The perturbative and non-perturbative contributions to the one-loop effective action are explicitly separated. It is proved that, after a suitable renormalization, the perturbative part of the effective action at zero temperature can be expressed in a covariant form solely in terms of the metric and its derivatives. This part coincides with the known large mass expansion of the one-loop effective action. The non-perturbative part of the renormalized one-loop effective action at zero temperature is proved to depend explicitly on the Killing vector defining the vacuum state of quantum fields. This part cannot be expressed in a covariant way through the metric and its derivatives alone. The implications of this result for the structure and symmetries of the effective action for gravity are discussed.

  6. One-loop effective lagrangians after matching

    NASA Astrophysics Data System (ADS)

    del Aguila, F.; Kunszt, Z.; Santiago, J.

    2016-05-01

    We discuss the limitations of the covariant derivative expansion prescription advocated to compute the one-loop Standard Model (SM) effective lagrangian when the heavy fields couple linearly to the SM. In particular, one-loop contributions resulting from the exchange of both heavy and light fields must be explicitly taken into account through matching because the proposed functional approach alone does not account for them. We review a simple case with a heavy scalar singlet of charge -1 to illustrate the argument. As two other examples where this matching is needed and this functional method gives a vanishing result, up to renormalization of the heavy sector parameters, we re-evaluate the one-loop corrections to the T-parameter due to a heavy scalar triplet with vanishing hypercharge coupling to the Brout-Englert-Higgs boson and to a heavy vector-like quark singlet of charged 2 / 3 mixing with the top quark, respectively. In all cases we make use of a new code for matching fundamental and effective theories in models with arbitrary heavy field additions.

  7. Analytic structure of one-loop coefficients

    NASA Astrophysics Data System (ADS)

    Feng, Bo; Wang, Honghui

    2013-05-01

    By the unitarity cut method, analytic expressions of one-loop coefficients have been given in spinor forms. In this paper, we present one-loop coefficients of various bases in Lorentz-invariant contraction forms of external momenta. Using these forms, the analytic structure of these coefficients becomes manifest. Firstly, coefficients of bases contain only second-type singularities while the first-type singularities are included inside scalar bases. Secondly, the highest degree of each singularity is correlated with the degree of the inner momentum in the numerator. Thirdly, the same singularities will appear in different coefficients, thus our explicit results could be used to provide a clear physical picture under various limits (such as soft or collinear limits) when combining contributions from all bases.

  8. Pentagon-pentagon correlations in water

    SciTech Connect

    Speedy, R.J.; Mezei, M.

    1985-01-03

    Computer simulation studies on the concentration of pentagonal rings of hydrogen-bonded water molecules (pentagons) and the spatial correlation of pentagons in liquid water are detailed. The pentagon-pentagon correlation function g/sub 55/(r) has a peak at r similarly ordered 3.2 A. The results support the idea that the anomalies of water may be related to the self-replicating propensity of pentagons in the random network. 24 references, 8 figures, 1 table.

  9. One-loop corrections to vector Galileon theory

    NASA Astrophysics Data System (ADS)

    Charmchi, Farid; Haghani, Zahra; Shahidi, Shahab; Shahkarami, Leila

    2016-06-01

    The effective action of the recently proposed vector Galileon theory is considered. Using the background field method, we obtain the one-loop correction to the propagator of the Proca field from vector Galileon self-interactions. Contrary to the so-called scalar Galileon interactions, the two-point function of the vector field gets renormalized at the one-loop level, indicating that there is no nonrenormalization theorem in the vector Galileon theory. Using dimensional regularization, we remove the divergences and obtain the counterterms of the theory. The finite term is analytically calculated, which modifies the propagator and the mass term and generates some new terms also.

  10. Semi-numerical evaluation of one-loop corrections

    SciTech Connect

    Ellis, R.K.; Giele, W.T.; Zanderighi, G.; /Fermilab

    2005-08-01

    We present a semi-numerical algorithm to calculate one-loop virtual corrections to scattering amplitudes. The divergences of the loop amplitudes are regulated using dimensional regularization. We treat in detail the case of amplitudes with up to five external legs and massless internal lines, although the method is more generally applicable. Tensor integrals are reduced to generalized scalar integrals, which in turn are reduced to a set of known basis integrals using recursion relations. The reduction algorithm is modified near exceptional configurations to ensure numerical stability. To test the procedure we apply these techniques to one-loop corrections to the Higgs to four quark process for which analytic results have recently become available.

  11. Direct Extraction of One-loop Integral Coefficients

    SciTech Connect

    Forde, Darren

    2007-04-16

    We present a general procedure for obtaining the coefficients of the scalar bubble and triangle integral functions of one-loop amplitudes. Coefficients are extracted by considering two-particle and triple unitarity cuts of the corresponding bubble and triangle integral functions. After choosing a specific parameterization of the cut loop momentum we can uniquely identify the coefficients of the desired integral functions simply by examining the behavior of the cut integrand as the unconstrained parameters of the cut loop momentum approach infinity. In this way we can produce compact forms for scalar integral coefficients. Applications of this method are presented for both QCD and electroweak processes, including an alternative form for the recently computed three-mass triangle coefficient in the six-photon amplitude A{sub 6}(1{sup -}, 2{sup +}, 3{sup -}, 4{sup +}, 5{sup -}, 6{sup +}). The direct nature of this extraction procedure allows for a very straightforward automation of the procedure.

  12. One-loop kink mass shifts: A computational approach

    NASA Astrophysics Data System (ADS)

    Alonso Izquierdo, A.; Guilarte, J. Mateos

    2011-11-01

    In this paper we develop a procedure to compute the one-loop quantum correction to the kink masses in generic (1+1)-dimensional one-component scalar field theoretical models. The procedure uses the generalized zeta function regularization method helped by the Gilkey-de Witt asymptotic expansion of the heat function via Mellin's transform. We find a formula for the one-loop kink mass shift that depends only on the part of the energy density with no field derivatives, evaluated by means of a symbolic software algorithm that automates the computation. The improved algorithm with respect to earlier work in this subject has been tested in the sine-Gordon and λ(ϕ)24 models. The quantum corrections of the sG-soliton and λ(-kink masses have been estimated with a relative error of 0.00006% and 0.00007% respectively. Thereafter, the algorithm is applied to other models. In particular, an interesting one-parametric family of double sine-Gordon models interpolating between the ordinary sine-Gordon and a re-scaled sine-Gordon model is addressed. Another one-parametric family, in this case of ϕ models, is analyzed. The main virtue of our procedure is its versatility: it can be applied to practically any type of relativistic scalar field models supporting kinks.

  13. Reduction of One-Loop Amplitudes at the Integrand Level -- NLO QCD Calculations

    NASA Astrophysics Data System (ADS)

    Ossola, G.; Papadopoulos, C. G.; Pittau, R.

    2008-07-01

    The recently proposed method (OPP) to extract the coefficients of the scalar one-loop integrals to any multi-particle (sub)-amplitude is described. Within this method no analytical information on the structure of the amplitude is needed, allowing for a purely numerical, but still algebraic, implementation of the algorithm. The algorithm can be used to automatically perform one-loop calculation both in QCD and in the EW Theory. As an application, we give QCD one-loop results for the process p p to ZZZ at the LHC.

  14. The universal one-loop effective action

    NASA Astrophysics Data System (ADS)

    Drozd, Aleksandra; Ellis, John; Quevillon, Jérémie; You, Tevong

    2016-03-01

    We present the universal one-loop effective action for all operators of dimension up to six obtained by integrating out massive, non-degenerate multiplets. Our general expression may be applied to loops of heavy fermions or bosons, and has been checked against partial results available in the literature. The broad applicability of this approach simplifies one-loop matching from an ultraviolet model to a lower-energy effective field theory (EFT), a procedure which is now reduced to the evaluation of a combination of matrices in our universal expression, without any loop integrals to evaluate. We illustrate the relationship of our results to the Standard Model (SM) EFT, using as an example the supersymmetric stop and sbottom squark Lagrangian and extracting from our universal expression the Wilson coefficients of dimension-six operators composed of SM fields.

  15. One-loop gluonic amplitudes from single unitarity cuts

    NASA Astrophysics Data System (ADS)

    Glover, E. W. Nigel; Williams, Ciaran

    2008-12-01

    We show that one-loop amplitudes in massless gauge theories can be determined from single cuts. By cutting a single propagator and putting it on-shell, the integrand of an n-point one-loop integral is transformed into an (n+2)-particle tree level amplitude. The single-cut approach described here is complementary to the double or multiple unitarity cut approaches commonly used in the literature. In common with these approaches, if the cut is taken in four dimensions, one finds only the cut-constructible parts of the amplitude, while if the cut is in D = 4-2epsilon dimensions, both rational and cut-constructible parts are obtained. We test our method by reproducing the known results for the fully rational all-plus and mostly-plus QCD amplitudes, A(1)4(1+, 2+, 3+, 4+) and A(1)5(1+, 2+, 3+, 4+, 5+). We also rederive expressions for the scalar loop contribution to the four-gluon MHV amplitude, A4(1,Script N = 0)(-, -, +, +) which has both cut-constructible and rational contributions, and the fully cut-constructible n-gluon MHV amplitude in Script N = 4 Supersymmetric Yang-Mills, A4(1,Script N = 4)(-, -, +, ..., +).

  16. One loop superstring effective actions and N=8 supergravity

    SciTech Connect

    Moura, Filipe

    2008-06-15

    In a previous article we have shown the existence of a new independent R{sup 4} term, at one loop, in the type IIA and heterotic effective actions, after reduction to four dimensions, besides the usual square of the Bel-Robinson tensor. It had been shown that such a term could not be directly supersymmetrized, but we showed that was possible after coupling to a scalar chiral multiplet. In this article, we study the extended (N=8) supersymmetrization of this term, where no other coupling can be taken. We show that such supersymmetrization cannot be achieved at the linearized level. This is in conflict with the theory one gets after toroidal compactification of type II superstrings being N=8 supersymmetric. We interpret this result in the face of the recent claim that perturbative supergravity cannot be decoupled from string theory in d{>=}4, and N=8, d=4 supergravity is in the swampland.

  17. Nonorientable one-loop amplitudes for the bosonic open string: Electrostatics on a Moebius strip

    SciTech Connect

    Rodrigues, J.P.

    1987-11-01

    The partition function, N-point scalar, and four-point vector nonorientable one-loop amplitudes for the bosonic open string in the critical dimension are obtained using a first quantized path integral treatment of Polyakov's string that assumes scale independence.

  18. Calculating soft radiation at one loop

    NASA Astrophysics Data System (ADS)

    Kasemets, Tomas; Waalewijn, Wouter J.; Zeune, Lisa

    2016-03-01

    We present an efficient way to calculate the effect of soft QCD radiation at one loop, which is needed for predictions at next-to-next-to-leading logarithmic accuracy. We use rapidity coordinates and isolate the divergences in the integrand. By performing manipulations with cumulative variables, we avoid complications from plus distributions. We address rapidity divergences, divergences with an azimuthal dependence, complicated jet boundaries and multi-differential measurements. The process and measurements can be easily adjusted, as we demonstrate by reproducing many existing soft functions. The results for a general LHC process with multiple Wilson lines are obtained by treating Wilson lines that are not back-to-back using a boost. We also obtain, for the first time, the N-jettiness soft function for generic jet angularities, and the collinear-soft function for the measurement of two angularities.

  19. One-loop corrections from higher dimensional tree amplitudes

    NASA Astrophysics Data System (ADS)

    Cachazo, Freddy; He, Song; Yuan, Ellis Ye

    2016-08-01

    We show how one-loop corrections to scattering amplitudes of scalars and gauge bosons can be obtained from tree amplitudes in one higher dimension. Starting with a complete tree-level scattering amplitude of n + 2 particles in five dimensions, one assumes that two of them cannot be "detected" and therefore an integration over their LIPS is carried out. The resulting object, function of the remaining n particles, is taken to be four-dimensional by restricting the corresponding momenta. We perform this procedure in the context of the tree-level CHY formulation of amplitudes. The scattering equations obtained in the procedure coincide with those derived by Geyer et al. from ambitwistor constructions and recently studied by two of the authors for bi-adjoint scalars. They have two sectors of solutions: regular and singular. We prove that the contribution from regular solutions generically gives rise to unphysical poles. However, using a BCFW argument we prove that the unphysical contributions are always homogeneous functions of the loop momentum and can be discarded. We also show that the contribution from singular solutions turns out to be homogeneous as well.

  20. Effective nonrenormalizable theories at one loop

    SciTech Connect

    Gaillard, M.K.

    1987-10-12

    The paper focuses on a nonrenormalizable theory that is more closely related to those suggested by superstrings, namely a gauged nonlinear delta-model, but one which can also be obtained analytically in a particular limit of a parameter (m/sub H/ ..-->.. infinity) of the standard, renormalizable electroweak theory. This will provide another laboratory for testing the validity of calculations using the effective theory. We find (as for certain superstring inspired models to be discussed later) features similar to those for the Fermi theory: quadratic divergences can be reinterpreted as renormalizations, while new terms are generated at the level of logarithmic divergences. Also introduced in the context of more familiar physics are notions such as scalar metric, scalar curvature and nonlinear symmetries, that play an important role in formal aspects of string theories. 58 refs., 12 figs.

  1. One-loop graviton corrections to the curvature perturbation from inflation

    SciTech Connect

    Dimastrogiovanni, Emanuela; Bartolo, Nicola E-mail: nicola.bartolo@pd.infn.it

    2008-11-15

    We compute one-loop corrections to the power spectrum of the curvature perturbation in single-field slow-roll inflation arising from gravitons and inflaton interactions. The quantum corrections due to gravitons to the power spectrum of the inflaton field are computed around the time of horizon crossing and their effect on the curvature perturbation is obtained on superhorizon scales through the {delta}N formalism. We point out that one-loop corrections from the tensor modes are of the same magnitude as those coming from scalar self-interactions; therefore they cannot be neglected in a self-consistent calculation.

  2. PV at the Pentagon

    SciTech Connect

    Bing, J.

    2000-02-01

    The US Department of Defense joins the battle against global warming with a photovoltaic installation at the Pentagon heating and refrigeration plant. Sitting in a line between the Pentagon and the Oval Office are four concentric arcs of iridescent silicon. In June 1999, the first half of this thirty kilowatt photovoltaic (PV) system was dedicated on the grounds of the heating and refrigeration plant that serves the Pentagon near Washington, DC. This first half of the system (the two center arcs) is the world's largest array composed solely of Ascension Technology's SunSine{reg{underscore}sign}300 AC modules. Each of these photovoltaic panels has its own DC to AC inverter mounted directly on its back side. The second half of the installation, brought on line in October 1999, includes a conventional DC array that powers a pair of newly developed Trace Technologies 10 kW inverters. The AC output of these two unique PV systems is combined at a central collection point and funneled into the electric grid that supplies power to the Pentagon. The project is a collaboration of the US Department of Defense (DoD) and the US Department of Energy (DOE), with cost-sharing support from Virginia Power, Johnson Controls, the Utility Photovoltaic Group (UPVG), and Applied Power Corporation. The systems were designed and installed by Ascension Technology, a division of Applied Power Corporation, with modules supplied by ASE Americas. This installation provides a unique real-world environment for researchers, utility engineers and power plant managers to test and compare the reliability, scalability, noise immunity and power quality of these two distinct approaches to PV energy production.

  3. Third generation sfermion decays into Z and W gauge bosons: Full one-loop analysis

    SciTech Connect

    Arhrib, Abdesslam; Benbrik, Rachid

    2005-05-01

    The complete one-loop radiative corrections to third-generation scalar fermions into gauge bosons Z and W{sup {+-}} is considered. We focus on f-tilde{sub 2}{yields}Zf-tilde{sub 1} and f-tilde{sub i}{yields}W{sup {+-}}f-tilde{sub j}{sup '}, f,f{sup '}=t,b. We include SUSY-QCD, QED, and full electroweak corrections. It is found that the electroweak corrections can be of the same order as the SUSY-QCD corrections. The two sets of corrections interfere destructively in some region of parameter space. The full one-loop correction can reach 10% in some supergravity scenario, while in model independent analysis like general the minimal supersymmetric standard model, the one-loop correction can reach 20% for large tan{beta} and large trilinear soft breaking terms A{sub b}.

  4. One-loop gravitational wave spectrum in de Sitter spacetime

    SciTech Connect

    Fröb, Markus B.; Verdaguer, Enric

    2012-08-01

    The two-point function for tensor metric perturbations around de Sitter spacetime including one-loop corrections from massless conformally coupled scalar fields is calculated exactly. We work in the Poincare patch (with spatially flat sections) and employ dimensional regularization for the renormalization process. Unlike previous studies we obtain the result for arbitrary time separations rather than just equal times. Moreover, in contrast to existing results for tensor perturbations, ours is manifestly invariant with respect to the subgroup of de Sitter isometries corresponding to a simultaneous time translation and rescaling of the spatial coordinates. Having selected the right initial state for the interacting theory via an appropriate iε prescription is crucial for that. Finally, we show that although the two-point function is a well-defined spacetime distribution, the equal-time limit of its spatial Fourier transform is divergent. Therefore, contrary to the well-defined distribution for arbitrary time separations, the power spectrum is strictly speaking ill-defined when loop corrections are included.

  5. The graviton one-loop effective action in cosmological space-times with constant deceleration

    NASA Astrophysics Data System (ADS)

    Janssen, T. M.; Prokopec, T.

    2010-05-01

    We consider the quantum Friedmann equations which include one-loop vacuum fluctuations due to gravitons and scalar field matter in a FLRW background with constant γ=-H˙/H2. After several field redefinitions, to remove the mixing between the gravitational and matter degrees of freedom, we can construct the one-loop correction to the Friedmann equations. Due to cosmological particle creation, the propagators needed in such a calculation are typically infrared divergent. In this paper we construct the graviton and matter propagators, making use of the recent construction of the infrared finite scalar propagators calculated on a compact spatial manifold in Janssen et al. (2008) [1]. The resulting correction to the Friedman equations is suppressed with respect to the tree level contribution by a factor of H2/mp2 and shows no secular growth.

  6. A Mathematica package for calculation of one-loop penguins in FCNC processes

    NASA Astrophysics Data System (ADS)

    Bednyakov, Alexander Vadimovich; Tanyıldızı, Şükrü Hanif

    2015-09-01

    In this work, we present a Mathematica package Peng4BSM@LO which calculates the contributions to the Wilson Coefficients of certain effective operators originating from the one-loop penguin Feynman diagrams. Both vector and scalar external legs are considered. The key feature of our package is the ability to find the corresponding expressions in almost any New Physics model which extends the SM and has no flavor changing neutral current (FCNC) transitions at the tree level.

  7. Triple gauge vertices at one-loop level in two-Higgs-doublet model

    NASA Astrophysics Data System (ADS)

    Malinský, M.; Hořejší, J.

    2004-05-01

    Renormalized triple gauge vertices (TGV) are examined within the two-Higgs-doublet model of the electroweak interactions. Deviations of the TGV from their standard-model values are calculated at the one-loop level, in the on-shell renormalization scheme. As a consistency check, UV divergence cancellations anticipated on symmetry grounds are verified explicitly. The dependence of the TGV finite parts on the masses of possible heavy Higgs scalars is discussed briefly.

  8. On the low-energy limit of one-loop photon-graviton amplitudes

    NASA Astrophysics Data System (ADS)

    Bastianelli, F.; Corradini, O.; Dávila, J. M.; Schubert, C.

    2012-09-01

    We present first results of a systematic study of the structure of the low-energy limit of the one-loop photon-graviton amplitudes induced by massive scalars and spinors. Our main objective is the search of KLT-type relations where effectively two photons merge into a graviton. We find such a relation at the graviton-photon-photon level. We also derive the diffeomorphism Ward identity for the 1PI one-graviton-N-photon amplitudes.

  9. One-loop QCD contribution to the potential of QQ¯

    NASA Astrophysics Data System (ADS)

    Liu, Li-Quan; Zhao, Shu-Min; Zhang, Jian-Jun; Yang, Bao-Zhu; Huang, De-Bao

    2011-02-01

    Without the non-relativistic approximation in one-loop function, the dominating one-loop contribution to the quark-antiquark potential is studied numerically in terms of perturbative Quantum Chromo Dynamics (QCD). For Coulomb-like potential, the ratio of the one-loop correction to the tree diagram contribution is presented, whose absolute value is about 20%. Our result is consistent with the analysis that the one-loop contribution should be suppressed by a factor αs/π to the leading order contribution. This work can deepen the comprehension of αs in Cornel potential.

  10. Complete algebraic reduction of one-loop tensor Feynman integrals

    SciTech Connect

    Fleischer, J.; Riemann, T.

    2011-04-01

    We set up a new, flexible approach for the tensor reduction of one-loop Feynman integrals. The 5-point tensor integrals up to rank R=5 are expressed by 4-point tensor integrals of rank R-1, such that the appearance of the inverse 5-point Gram determinant is avoided. The 4-point tensor coefficients are represented in terms of 4-point integrals, defined in d dimensions, 4-2{epsilon}{<=}d{<=}4-2{epsilon}+2(R-1), with higher powers of the propagators. They can be further reduced to expressions which stay free of the inverse 4-point Gram determinants but contain higher-dimensional 4-point integrals with only the first power of scalar propagators, plus 3-point tensor coefficients. A direct evaluation of the higher-dimensional 4-point functions would avoid the appearance of inverse powers of the Gram determinants completely. The simplest approach, however, is to apply here dimensional recurrence relations in order to reduce them to the familiar 2- to 4-point functions in generic dimension d=4-2{epsilon}, introducing thereby coefficients with inverse 4-point Gram determinants up to power R for tensors of rank R. For small or vanishing Gram determinants--where this reduction is not applicable--we use analytic expansions in positive powers of the Gram determinants. Improving the convergence of the expansions substantially with Pade approximants we close up to the evaluation of the 4-point tensor coefficients for larger Gram determinants. Finally, some relations are discussed which may be useful for analytic simplifications of Feynman diagrams.

  11. A critical analysis of one-loop neutrino mass models with minimal dark matter

    NASA Astrophysics Data System (ADS)

    Ahriche, Amine; McDonald, Kristian L.; Nasri, Salah; Picek, Ivica

    2016-06-01

    A recent paper investigated minimal RνMDM models with the type T1-iii and T3 one-loop topologies. However, the candidate most-minimal model does not possess an accidental symmetry - the scalar potential contains an explicit symmetry breaking term, rendering the dark matter unstable. We present two models that cure this problem. However, we further show that all of the proposed minimal one-loop RνMDM models suffer from a second problem - an additional source of explicit Z2 symmetry breaking in the Yukawa sector. We perform a more-general analysis to show that neutrino mass models using either the type T3 or type T1-iii one-loop topologies do not give viable minimal dark matter candidates. Consequently, one-loop models of neutrino mass with minimal dark matter do not appear possible. Thus, presently there remains a single known (three-loop) model of neutrino mass that gives stable dark matter without invoking any new symmetries.

  12. Non-Gaussianity at tree and one-loop levels from vector field perturbations

    SciTech Connect

    Valenzuela-Toledo, Cesar A.; Rodriguez, Yeinzon; Lyth, David H.

    2009-11-15

    We study the spectrum P{sub {zeta}} and bispectrum B{sub {zeta}} of the primordial curvature perturbation {zeta} when the latter is generated by scalar and vector field perturbations. The tree-level and one-loop contributions from vector field perturbations are worked out considering the possibility that the one-loop contributions may be dominant over the tree-level terms [both (either) in P{sub {zeta}} and (or) in B{sub {zeta}}] and vice versa. The level of non-Gaussianity in the bispectrum, f{sub NL}, is calculated and related to the level of statistical anisotropy in the power spectrum, g{sub {zeta}}. For very small amounts of statistical anisotropy in the power spectrum, the level of non-Gaussianity may be very high, in some cases exceeding the current observational limit.

  13. Off-Shell Green Functions: One-Loop with Growing Legs

    SciTech Connect

    Bashir, A.; Concha-Sanchez, Y.; Delbourgo, R.; Tejeda-Yeomans, M. E.

    2008-07-02

    One loop calculations in gauge theories in arbitrary gauge and dimensions become exceedingly hard with growing number of external off-shell legs. Let alone higher point functions, such a calculation for even the three point one-loop vertices for quantum electrodynamics (QED) and quantum chromodynamics (QCD) has been made available only recently. In this article, we discuss how Ward-Fradkin-Green-Takahashi identities (WFGTI) may provide a helpful tool in these computations. After providing a glimpse of our suggestion for the case of the 3-point vertex, we present our preliminary findings towards our similar efforts for the 4-point function. We restrict ourselves to the example of scalar quantum electrodynamics (SQED)

  14. One-loop amplitudes on the Riemann sphere

    NASA Astrophysics Data System (ADS)

    Geyer, Yvonne; Mason, Lionel; Monteiro, Ricardo; Tourkine, Piotr

    2016-03-01

    The scattering equations provide a powerful framework for the study of scattering amplitudes in a variety of theories. Their derivation from ambitwistor string theory led to proposals for formulae at one loop on a torus for 10 dimensional supergravity, and we recently showed how these can be reduced to the Riemann sphere and checked in simple cases. We also proposed analogous formulae for other theories including maximal super-Yang-Mills theory and supergravity in other dimensions at one loop. We give further details of these results and extend them in two directions. Firstly, we propose new formulae for the one-loop integrands of Yang-Mills theory and gravity in the absence of supersymmetry. These follow from the identification of the states running in the loop as expressed in the ambitwistor-string correlator. Secondly, we give a systematic proof of the non-supersymmetric formulae using the worldsheet factorisation properties of the nodal Riemann sphere underlying the scattering equations at one loop. Our formulae have the same decomposition under the recently introduced Q-cuts as one-loop integrands and hence give the correct amplitudes.

  15. Superstring one-loop and gravitino contributions to planckian scattering

    NASA Astrophysics Data System (ADS)

    Bellini, Alessandro; Ademollo, Marco; Ciafaloni, Marcello

    1993-03-01

    Corrections to the semiclassical approximation in nearly forward planckian energy collisions are reconsidered. Starting from the one-loop superstring amplitude, we are able to disentangle the first subleading high-energy contribution at large impact parameters, and we thus directly compute the one-loop correction to the superstring eikonal. By comparing this result with previous ones by Amati, Ciafaloni and Veneziano (ACV) for pure gravity, we identify one-loop gravitino contributions which agree with previous results by Lipatov. We finally argue, on the basis of analyticity and unitarity, that gravitinos do not contribute at all the large-distance two-loop ACV correction, which thus acquires a universal "classical" interpretation.

  16. One-loop soft theorems via dual superconformal symmetry

    NASA Astrophysics Data System (ADS)

    Brandhuber, Andreas; Hughes, Edward; Spence, Bill; Travaglini, Gabriele

    2016-03-01

    We study soft theorems at one loop in planar {N}=4 super Yang-Mills theory through finite order in the infrared regulator and to subleading order in the soft parameter δ. In particular, we derive a universal constraint from dual superconformal symmetry, which we use to bootstrap subleading log δ behaviour. Moreover, we determine the complete infrared-finite subleading soft contribution of n-point MHV amplitudes using momentum twistors. Finally, we compute the subleading log δ behaviour of one-loop NMHV ratio functions at six and seven points, finding that universality holds within but not between helicity sectors.

  17. Automatic one-loop calculations with Sherpa+OpenLoops

    NASA Astrophysics Data System (ADS)

    Cascioli, F.; Höche, S.; Krauss, F.; Maierhöfer, P.; Pozzorini, S.; Siegert, F.

    2014-06-01

    We report on the OpenLoops generator for one-loop matrix elements and its application to four-lepton production in association with up to one jet. The open loops algorithm uses a numerical recursion to construct the numerator of one-loop Feynman diagrams as functions of the loop momentum. In combination with tensor integrals this results in a highly efficient and numerically stable matrix element generator. In order to obtain a fully automated setup for the simulation of next-to-leading order scattering processes we interfaced OpenLoops to the Sherpa Monte Carlo event generator.

  18. One-loop effective action and Schwinger effect in (anti-) de Sitter space

    NASA Astrophysics Data System (ADS)

    Cai, Rong-Gen; Kim, Sang Pyo

    2014-09-01

    We study the Schwinger mechanism by a uniform electric field in dS2 and AdS2 and the curvature effect on the Schwinger effect, and further propose a thermal interpretation of the Schwinger formula in terms of the Gibbons-Hawking temperature and the Unruh temperature for an accelerating charge in dS2 and an analogous expression in AdS2. The exact one-loop effective action is found in the proper-time integral in each space, which is determined by the effective mass, the Maxwell scalar, and the scalar curvature, and whose pole structure gives the imaginary part of the effective action and the exact pair-production rate. The exact pair-production rate is also given the thermal interpretation.

  19. One Loop Superstring Effective Actions and d = 4 Supergravity

    SciTech Connect

    Moura, Filipe

    2008-06-25

    We review our recent work on the existence of a new independent R{sup 4} term, at one loop, in the type IIA and heterotic effective actions, after reduction to four dimensions, besides the usual square of the Bel-Robinson tensor. We discuss its supersymmetrization.

  20. One-loop test of free SU( N ) adjoint model holography

    NASA Astrophysics Data System (ADS)

    Bae, Jin-Beom; Joung, Euihun; Lal, Shailesh

    2016-04-01

    We consider the holographic duality where the CFT side is given by SU( N ) adjoint free scalar field theory. Compared to the vector models, the set of single trace operators is immensely extended so that the corresponding AdS theory also contains infinitely many massive higher spin fields on top of the massless ones. We compute the one-loop vacuum energy of these AdS fields to test this duality at the subleading order in large N expansion. The determination of the bulk vacuum energy requires a proper scheme to sum up the infinitely many contributions. For that, we develop a new method and apply it first to calculate the vacuum energies for the first few `Regge trajectories' in AdS4 and AdS5 . In considering the full vacuum energy of AdS theory dual to a matrix model CFT, we find that there exist more than one available prescriptions for the one-loop vacuum energy. Taking a particular prescription, we determine the full vacuum energy of the AdS5 theory, whereas the AdS4 calculation still remains technically prohibitive. This result shows that the full vacuum energy of the AdS5 theory coincides with minus of the free energy of a single scalar field on the boundary. This is analogous to the O( N ) vector model case, hence suggests an interpretation of the positive shift of the bulk coupling constant, i.e. from N 2 - 1 to N 2.

  1. One-loop radiative corrections to the QED Casimir energy

    NASA Astrophysics Data System (ADS)

    Moazzemi, Reza; Mojavezi, Amirhosein

    2016-05-01

    In this paper, we investigate one-loop radiative corrections to the Casimir energy in the presence of two perfectly conducting parallel plates for QED theory within the renormalized perturbation theory. In fact, there are three contributions for radiative corrections to the Casimir energy, up to order α . Only the two-loop diagram, which is of order α , has been computed by Bordag et. al (Ann. Phys. 165:192, 1985), approximately. Here, up to this order, we consider corrections due to two one-loop terms, i.e., photonic and fermionic loop corrections resulting from renormalized QED Lagrangian, more precisely. Our results show that only the fermionic loop has a very minor correction and the correction of photonic loop vanishes.

  2. N >= 4 Supergravity Amplitudes from Gauge Theory at One Loop

    SciTech Connect

    Bern, Z.; Boucher-Veronneau, C.; Johansson, H.; /Saclay

    2011-08-19

    We expose simple and practical relations between the integrated four- and five-point one-loop amplitudes of N {ge} 4 supergravity and the corresponding (super-)Yang-Mills amplitudes. The link between the amplitudes is simply understood using the recently uncovered duality between color and kinematics that leads to a double-copy structure for gravity. These examples provide additional direct confirmations of the duality and double-copy properties at loop level for a sample of different theories.

  3. Pentagon getting first energy audit

    SciTech Connect

    Betts, M.

    1982-03-29

    The General Services Administration is conducting the first comprehensive energy audit of the Pentagon, the world's largest office building, after criticism from the General Accounting Office over the delay. The auditors will identify both low-cost options with quick returns and opportunities for major retrofit projects. The building design is not energy-efficient, and had the second highest use of Btus per gross square foot of area buildings in 1981. (DCK)

  4. One-loop effective potential of the Higgs field on the Schwarzschild background

    NASA Astrophysics Data System (ADS)

    Kazinski, P. O.

    2009-12-01

    A one-loop effective potential of the Higgs field on the Schwarzschild background is derived in the framework of a toy model: a SO(N) scalar multiplet interacting with the gauge fields, the SO(N) gauge symmetry being broken by the Higgs mechanism. As expected, the potential depends on the space point and results in a mass shift of all massive particles near a black hole. It is shown that the obtained potential is generally covariant, depends on the space point through the metric component g00 in the adapted coordinates, and has the same form for an arbitrary static, spherically symmetric background. Some properties of this potential are investigated. In particular, if the conformal symmetry holds valid for massless particles on the given background, there exist only two possible scenarios depending on the sign of an arbitrary constant arising from the regularization procedure: the masses of all massive particles grow infinitely, when they approach the black hole horizon, or the gauge symmetry is restored at a finite distance from the horizon and all particles become massless. If the conformal symmetry is spoiled, an additional term in the effective potential appears and the intermediate regime arises. Several normalization conditions fixing the undefined constants are proposed, and estimations for the mass shifts are given in these cases. It should be mentioned that the use of the one-loop approximation becomes questionable in the region where the one-loop effective potential acquires large values. So, in that region, we can believe in the obtained results only to a certain extent.

  5. Closed-form decomposition of one-loop massive amplitudes

    SciTech Connect

    Britto, Ruth; Feng Bo; Mastrolia, Pierpaolo

    2008-07-15

    We present formulas for the coefficients of 2-, 3-, 4-, and 5-point master integrals for one-loop massive amplitudes. The coefficients are derived from unitarity cuts in D dimensions. The input parameters can be read off from any unitarity-cut integrand, as assembled from tree-level expressions, after simple algebraic manipulations. The formulas presented here are suitable for analytical as well as numerical evaluation. Their validity is confirmed in two known cases of helicity amplitudes contributing to gg{yields}gg and gg{yields}gH, where the masses of the Higgs and the fermion circulating in the loop are kept as free parameters.

  6. The one loop corrections to the neutrino masses in BLMSSM

    NASA Astrophysics Data System (ADS)

    Zhao, Shu-Min; Feng, Tai-Fu; Dong, Xing-Xing; Zhang, Hai-Bin; Ning, Guo-Zhu; Guo, Tao

    2016-09-01

    The neutrino masses and mixings are studied in the model which is the supersymmetric extension of the standard model with local gauged baryon and lepton numbers (BLMSSM). At tree level the neutrinos can obtain tiny masses through the See-Saw mechanism in the BLMSSM. The one-loop corrections to the neutrino masses and mixings are important, and they are studied in this work with the mass insertion approximation. We study the numerical results and discuss the allowed parameter space of BLMSSM. It can contribute to study the neutrino masses and to explore the new physics beyond the standard model (SM).

  7. A simple method for one-loop renormalization in curved space-time

    SciTech Connect

    Markkanen, Tommi; Tranberg, Anders E-mail: anders.tranberg@uis.no

    2013-08-01

    We present a simple method for deriving the renormalization counterterms from the components of the energy-momentum tensor in curved space-time. This method allows control over the finite parts of the counterterms and provides explicit expressions for each term separately. As an example, the method is used for the self-interacting scalar field in a Friedmann-Robertson-Walker metric in the adiabatic approximation, where we calculate the renormalized equation of motion for the field and the renormalized components of the energy-momentum tensor to fourth adiabatic order while including interactions to one-loop order. Within this formalism the trace anomaly, including contributions from interactions, is shown to have a simple derivation. We compare our results to those obtained by two standard methods, finding agreement with the Schwinger-DeWitt expansion but disagreement with adiabatic subtractions for interacting theories.

  8. An explanation of one-loop induced h → μτ decay

    NASA Astrophysics Data System (ADS)

    Baek, Seungwon; Nomura, Takaaki; Okada, Hiroshi

    2016-08-01

    We discuss a possibility to explain the excess of h → μτ at one-loop level. We introduce three generations of vector-like lepton doublet L‧ and two singlet scalars S1,2 which are odd under Z2, while all the standard model fields are even under this discrete symmetry. We show that S1 can be a good dark matter candidate. We show that we can explain the dark matter relic abundance, large part of the discrepancy of muon g - 2 between experiments and the standard model predictions, as well as the h → μτ excess of ∼ 1%, while evading constraints from experiments of dark matter direct detection and charged lepton flavor violating processes. We also consider prospects of production of S2 at LHC with energy √{ s} = 14 TeV.

  9. Bootstrapping One-Loop QCD Amplitudeswith General Helicities

    SciTech Connect

    Berger, Carola F.; Bern, Zvi; Dixon, Lance J.; Forde, Darren; Kosower, David A.

    2006-04-25

    The recently developed on-shell bootstrap for computing one-loop amplitudes in non-supersymmetric theories such as QCD combines the unitarity method with loop-level on-shell recursion. For generic helicity configurations, the recursion relations may involve undetermined contributions from non-standard complex singularities or from large values of the shift parameter. Here we develop a strategy for sidestepping difficulties through use of pairs of recursion relations. To illustrate the strategy, we present sets of recursion relations needed for obtaining n-gluon amplitudes in QCD. We give a recursive solution for the one-loop n-gluon QCD amplitudes with three or four color-adjacent gluons of negative helicity and the remaining ones of positive helicity. We provide an explicit analytic formula for the QCD amplitude A{sub 6;1}(1{sup -}, 2{sup -}, 3{sup -}, 4{sup +}, 5{sup +}, 6{sup +}), as well as numerical results for A{sub 7;1}(1{sup -}, 2{sup -}, 3{sup -}, 4{sup +}, 5{sup +}, 6{sup +}, 7{sup +}), A{sub 8;1}(1{sup -}, 2{sup -}, 3{sup -}, 4{sup +}, 5{sup +}, 6{sup +}, 7{sup +}, 8{sup +}), and A{sub 8;1}(1{sup -}, 2{sup -}, 3{sup -}, 4{sup -}, 5{sup +}, 6{sup +}, 7{sup +}, 8{sup +}). We expect the on-shell bootstrap approach to have widespread applications to phenomenological studies at colliders.

  10. Dirac dark matter with a charged mediator: a comprehensive one-loop analysis of the direct detection phenomenology

    SciTech Connect

    Ibarra, Alejandro; Wild, Sebastian

    2015-05-26

    We analyze the direct detection signals of a toy model consisting of a Dirac dark matter particle which couples to one Standard Model fermion via a scalar mediator. For all scenarios, the dark matter particle scatters off nucleons via one loop-induced electromagnetic and electroweak moments, as well as via the one-loop exchange of a Higgs boson. Besides, and depending on the details of the model, the scattering can also be mediated at tree level via the exchange of the scalar mediator or at one loop via gluon-gluon interactions. We show that, for thermally produced dark matter particles, the current limits from the LUX experiment on these scenarios are remarkably strong, even for dark matter coupling only to leptons. We also discuss future prospects for XENON1T and DARWIN and we argue that multi-ton xenon detectors will be able to probe practically the whole parameter space of the model consistent with thermal production and perturbativity. We also discuss briefly the implications of our results for the dark matter interpretation of the Galactic GeV excess.

  11. Pentagon clings to costly lifestyle

    SciTech Connect

    Isaacs, J.

    1993-04-01

    Chairman of the Joint Chiefs of Staff Colin Powell worked for more than half a year on a plan to save money by reducing duplication in the armed services. A few days before Powell released his report, Defense Secretary Les Aspin told the services to reduce the leftover Bush Defense budget by about $11 billion. Reporters outcried that President Clinton had ordered the budget slashed. The Pentagon's budget is expected to shrink from $274 billion in 1993 to $264 billion in 1994. The end result is that the reductions advocated by the Bush and Clinton administrations are essentially indistinguishable.

  12. Regioselective Oxidation of Fused-Pentagon Chlorofullerenes.

    PubMed

    Zhang, Zhen-Qiang; Chen, Shu-Fen; Gao, Cong-Li; Zhou, Ting; Shan, Gui-Juan; Tan, Yuan-Zhi; Xie, Su-Yuan; Huang, Rong-Bin; Zheng, Lan-Sun

    2016-01-19

    Two monoxides of typical smaller chlorofullerenes, (#271)C50Cl10O and (#913)C56Cl10O, featured with double-fused-pentagons, were synthesized to demonstrate further regioselective functionalization of non-IPR (IPR = isolated pentagon rule) chlorofullerenes. Both non-IPR chlorofullerene oxides exhibit an epoxy structure at the ortho-site of fused pentagons. In terms of the geometrical analysis and theoretical calculations, the principles for regioselective epoxy oxidation of non-IPR chlorofullerenes are revealed to follow both "fused-pentagon ortho-site" and "olefinic bond" rules, which are valuable for prediction of oxidation of non-IPR chlorofullerenes. PMID:26726707

  13. Simplifying one-loop amplitudes in superstring theory

    NASA Astrophysics Data System (ADS)

    Bianchi, Massimo; Consoli, Dario

    2016-01-01

    We show that 4-point vector boson one-loop amplitudes, computed in [1] in the RNS formalism, around vacuum configurations with open unoriented strings, preserving at least N=1 SUSY in D = 4, satisfy the correct supersymmetry Ward identities, in that they vanish for non MHV configurations (++++) and ( -+++). In the MHV case ( --++) we drastically simplify their expressions. We then study factorisation and the limiting IR and UV behaviours and find some unexpected results. In particular no massless poles are exposed at generic values of the modular parameter. Relying on the supersymmetric properties of our bosonic amplitudes, we extend them to manifestly supersymmetric super-amplitudes and compare our results with those obtained in the D = 4 hybrid formalism, pointing out difficulties in reconciling the two approaches for contributions from N=1,2 sectors.

  14. One-Loop Calculations with BlackHat

    SciTech Connect

    Berger, C.F.; Bern, Z.; Dixon, L.J.; Cordero, F.Febres; Forde, D.; Ita, H.; Kosower, D.A.; Maitre, D.

    2008-08-01

    We describe BlackHat, an automated C++ program for calculating one-loop amplitudes, and the techniques used in its construction. These include the unitarity method and on-shell recursion. The other ingredients are compact analytic formulae for tree amplitudes for four-dimensional helicity states. The program computes amplitudes numerically, using analytic formula only for the tree amplitudes, the starting point for the recursion, and the loop integrals. We make use of recently developed on-shell methods for evaluating coefficients of loop integrals, in particular a discrete Fourier projection as a means of improving numerical stability. We illustrate the good numerical stability of this approach by computing six-, seven- and eight-gluon amplitudes in QCD and comparing against known analytic results.

  15. Pentagon After Action Reports: The Jack Taylor Debate.

    ERIC Educational Resources Information Center

    Abbott, Stan

    In requesting after action reports--Pentagon-prepared summaries of interviews between reporters and Pentagon officials--investigative reporter Jack Taylor both aroused Pentagon opposition and created a rift between the Pentagon press corps and outside reporters. To investigate whether the full-time Pentagon press corps was reporting as…

  16. Fermionic pentagons and NMHV hexagon

    NASA Astrophysics Data System (ADS)

    Belitsky, A. V.

    2015-05-01

    We analyze the near-collinear limit of the null polygonal hexagon super Wilson loop in the planar N = 4 super-Yang-Mills theory. We focus on its Grassmann components which are dual to next-to-maximal helicity-violating (NMHV) scattering amplitudes. The kinematics in question is studied within a framework of the operator product expansion that encodes propagation of excitations on the background of the color flux tube stretched between the sides of Wilson loop contour. While their dispersion relation is known to all orders in 't Hooft coupling from previous studies, we find their form factor couplings to the Wilson loop. This is done making use of a particular tessellation of the loop where pentagon transitions play a fundamental role. Being interested in NMHV amplitudes, the corresponding building blocks carry a nontrivial charge under the SU(4) R-symmetry group. Restricting the current consideration to twist-two accuracy, we analyze two-particle contributions with a fermion as one of the constituents in the pair. We demonstrate that these nonsinglet pentagons obey bootstrap equations that possess consistent solutions for any value of the coupling constant. To confirm the correctness of these predictions, we calculate their contribution to the super Wilson loop demonstrating agreement with recent results to four-loop order in 't Hooft coupling.

  17. 14. Detail of possible entrance on north side of Pentagon ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. Detail of possible entrance on north side of Pentagon 2 (note leaning logs at center). View to west. - Pentagon Site, Pentagon 2, West of Barry's Landing off Highway 37, Fort Smith, Big Horn County, MT

  18. 15. Detail of log cribbing on southeast side of Pentagon ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    15. Detail of log cribbing on southeast side of Pentagon 1 (note stone in center). View to northwest. - Pentagon Site, Pentagon 1, West of Barry's Landing off Highway 37, Fort Smith, Big Horn County, MT

  19. 1. Overall view of Pentagon 2 (in center of photo), ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. Overall view of Pentagon 2 (in center of photo), with Bad Pass Trail in background. View to southeast. - Pentagon Site, Pentagon 2, West of Barry's Landing off Highway 37, Fort Smith, Big Horn County, MT

  20. 11. Detail of log cribbing on north side of Pentagon ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. Detail of log cribbing on north side of Pentagon 1, (note stone in left foreground). View to south. - Pentagon Site, Pentagon 1, West of Barry's Landing off Highway 37, Fort Smith, Big Horn County, MT

  1. Regular Pentagons and the Fibonacci Sequence.

    ERIC Educational Resources Information Center

    French, Doug

    1989-01-01

    Illustrates how to draw a regular pentagon. Shows the sequence of a succession of regular pentagons formed by extending the sides. Calculates the general formula of the Lucas and Fibonacci sequences. Presents a regular icosahedron as an example of the golden ratio. (YP)

  2. Pentagon chain in external fields

    NASA Astrophysics Data System (ADS)

    Kovács, György; Gulácsi, Zsolt

    2015-11-01

    We consider a pentagon chain described by a Hubbard type of model considered under periodic boundary conditions. The system (i) is placed in an external magnetic field perpendicular to the plane of the cells, and (ii) is in a site-selective manner under the action of an external electric potential. In these conditions, we show in an exact manner that the physical properties of the system can be qualitatively changed. The changes cause first strong modifications of the band structure of the system created by the one-particle part of the Hamiltonian, and second, produce marked changes of the phase diagram. We exemplify this by deducing ferromagnetic ground states in the presence of external fields in two different domains of the parameter space.

  3. Activities: Golden Triangles, Pentagons, and Pentagrams.

    ERIC Educational Resources Information Center

    Miller, William A.; Clason, Robert G.

    1994-01-01

    Presents lesson plans for activities to introduce recursive sequences of polygons: golden triangles, regular pentagons, and pentagrams. The resulting number patterns involve Fibonacci sequences. Includes reproducible student worksheets. (MKR)

  4. The Pentagon Problem: Geometric Reasoning with Technology.

    ERIC Educational Resources Information Center

    Zbiek, Rose Mary

    1996-01-01

    Presents an activity, involving pentagons and using a figure manipulator such as The Geometer's Sketchpad, that requires students to reason geometrically without making unsubstantiated assumptions based on diagrams. (MKR)

  5. Automated One-loop Computation in Quarkonium Process within NRQCD Framework

    NASA Astrophysics Data System (ADS)

    Feng, Feng

    2014-06-01

    In last decades, it has been realized that the next-to-leading order corrections may become very important, and sometimes requisite, for some processes involving quarkoinum production or decay, e.g., e+e- → J/ψ + ηc and J/ψ → 3γ. In this article, we review some basic steps to perform automated one-loop computations in quarkonium process within the Non-relativistic Quantum Chromodynamics (NRQCD) factorization framework1 and we give an introduction to some related public tools or packages and their usages in each step. We start from generating Feynman diagrams and amplitudes with FEYNARTS for the quarkonium process, performing Dirac- and Color- algebras simplifications using FEYNCALC and FEYNCALCFORMLINK, and then to doing partial fractions on the linear-dependent propagators by APART, and finally to reducing the Tensor Integrals (TI) into Scalar Integrals (SI) or Master Integrals (MI) using Integration-By-Parts (IBP) method with the help of FIRE. We will use a simple concrete example to demonstrate the basic usages of the corresponding packages or tools in each step.

  6. Analytic one-loop amplitudes for a Higgs boson plus four partons

    SciTech Connect

    Dixon, Lance J.; Sofianatos, Yorgos; /SLAC

    2009-06-02

    We compute the one-loop QCD amplitudes for the processes H{anti q}q{anti Q}Q and H{anti q}qgg, the latter restricted to the case of opposite-helicity gluons. Analytic expressions are presented for the color- and helicity-decomposed amplitudes. The coupling of the Higgs boson to gluons is treated by an effective interaction in the limit of large top quark mass. The Higgs field is split into a complex field {phi} and its complex conjugate {phi}{sup {dagger}}. The split is useful because amplitudes involving {phi} have different analytic structure from those involving {phi}{sup {dagger}}. We compute the cut-containing pieces of the amplitudes using generalized unitarity. The remaining rational parts are obtained by on-shell recursion. Our results for H{anti q}q{anti Q}Q agree with previous semi-numerical computations. We also show how to convert existing semi-numerical results for the production of a scalar Higgs boson into analogous results for a pseudoscalar Higgs boson.

  7. Scalar Quantum Electrodynamics: Perturbation Theory and Beyond

    SciTech Connect

    Bashir, A.; Gutierrez-Guerrero, L. X.; Concha-Sanchez, Y.

    2006-09-25

    In this article, we calculate scalar propagator in arbitrary dimensions and gauge and the three-point scalar-photon vertex in arbitrary dimensions and Feynman gauge, both at the one loop level. We also discuss constraints on their non perturbative structure imposed by requirements of gauge invariance and perturbation theory.

  8. Experimental Realization of a Quantum Pentagonal Lattice

    PubMed Central

    Yamaguchi, Hironori; Okubo, Tsuyoshi; Kittaka, Shunichiro; Sakakibara, Toshiro; Araki, Koji; Iwase, Kenji; Amaya, Naoki; Ono, Toshio; Hosokoshi, Yuko

    2015-01-01

    Geometric frustration, in which competing interactions give rise to degenerate ground states, potentially induces various exotic quantum phenomena in magnetic materials. Minimal models comprising triangular units, such as triangular and Kagome lattices, have been investigated for decades to realize novel quantum phases, such as quantum spin liquid. A pentagon is the second-minimal elementary unit for geometric frustration. The realization of such systems is expected to provide a distinct platform for studying frustrated magnetism. Here, we present a spin-1/2 quantum pentagonal lattice in the new organic radical crystal α-2,6-Cl2-V [=α-3-(2,6-dichlorophenyl)-1,5-diphenylverdazyl]. Its unique molecular arrangement allows the formation of a partially corner-shared pentagonal lattice (PCPL). We find a clear 1/3 magnetization plateau and an anomalous change in magnetization in the vicinity of the saturation field, which originate from frustrated interactions in the PCPL. PMID:26468930

  9. Experimental Realization of a Quantum Pentagonal Lattice.

    PubMed

    Yamaguchi, Hironori; Okubo, Tsuyoshi; Kittaka, Shunichiro; Sakakibara, Toshiro; Araki, Koji; Iwase, Kenji; Amaya, Naoki; Ono, Toshio; Hosokoshi, Yuko

    2015-01-01

    Geometric frustration, in which competing interactions give rise to degenerate ground states, potentially induces various exotic quantum phenomena in magnetic materials. Minimal models comprising triangular units, such as triangular and Kagome lattices, have been investigated for decades to realize novel quantum phases, such as quantum spin liquid. A pentagon is the second-minimal elementary unit for geometric frustration. The realization of such systems is expected to provide a distinct platform for studying frustrated magnetism. Here, we present a spin-1/2 quantum pentagonal lattice in the new organic radical crystal α-2,6-Cl2-V [=α-3-(2,6-dichlorophenyl)-1,5-diphenylverdazyl]. Its unique molecular arrangement allows the formation of a partially corner-shared pentagonal lattice (PCPL). We find a clear 1/3 magnetization plateau and an anomalous change in magnetization in the vicinity of the saturation field, which originate from frustrated interactions in the PCPL. PMID:26468930

  10. Experimental Realization of a Quantum Pentagonal Lattice

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Hironori; Okubo, Tsuyoshi; Kittaka, Shunichiro; Sakakibara, Toshiro; Araki, Koji; Iwase, Kenji; Amaya, Naoki; Ono, Toshio; Hosokoshi, Yuko

    2015-10-01

    Geometric frustration, in which competing interactions give rise to degenerate ground states, potentially induces various exotic quantum phenomena in magnetic materials. Minimal models comprising triangular units, such as triangular and Kagome lattices, have been investigated for decades to realize novel quantum phases, such as quantum spin liquid. A pentagon is the second-minimal elementary unit for geometric frustration. The realization of such systems is expected to provide a distinct platform for studying frustrated magnetism. Here, we present a spin-1/2 quantum pentagonal lattice in the new organic radical crystal α-2,6-Cl2-V [=α-3-(2,6-dichlorophenyl)-1,5-diphenylverdazyl]. Its unique molecular arrangement allows the formation of a partially corner-shared pentagonal lattice (PCPL). We find a clear 1/3 magnetization plateau and an anomalous change in magnetization in the vicinity of the saturation field, which originate from frustrated interactions in the PCPL.

  11. The One-Loop Six-Dimensional Hexagon Integral and its Relation to MHV Amplitudes in N=4 SYM

    SciTech Connect

    Dixon, Lance J.; Drummond, James M.; Henn, Johannes M.; /Humboldt U., Berlin

    2011-08-19

    We provide an analytic formula for the (rescaled) one-loop scalar hexagon integral {tilde {Phi}}{sub 6} with all external legs massless, in terms of classical polylogarithms. We show that this integral is closely connected to two integrals appearing in one- and two-loop amplitudes in planar N = 4 super-Yang-Mills theory, {Omega}{sup (1)} and {Omega}{sup (2)}. The derivative of {Omega}{sup (2)} with respect to one of the conformal invariants yields {tilde {Phi}}{sub 6}, while another first-order differential operator applied to {tilde {Phi}}{sub 6} yields {Omega}{sup (1)}. We also introduce some kinematic variables that rationalize the arguments of the polylogarithms, making it easy to verify the latter differential equation. We also give a further example of a six-dimensional integral relevant for amplitudes in N = 4 super-Yang-Mills.

  12. The corrections from one loop and two-loop Barr-Zee type diagrams to muon MDM in BLMSSM

    NASA Astrophysics Data System (ADS)

    Zhao, Shu-Min; Feng, Tai-Fu; Zhang, Hai-Bin; Yan, Ben; Zhan, Xi-Jie

    2014-11-01

    In a supersymmetric extension of the standard model where baryon and lepton numbers are local gauge symmetries(BLMSSM) and the Yukawa couplings between Higgs doublets and exotic quarks are considered, we study the one loop diagrams and the two-loop Barr-Zee type diagrams with a closed Fermi(scalar) loop between the vector Boson and Higgs. Using the effective Lagrangian method, we deduce the Wilson coefficients of dimension 6 operators contributing to the anomalous magnetic moment of muon, which satisfies the electromagnetic gauge invariance. In the numerical analysis, we consider the experiment constraints from Higgs and neutrino data. In some parameter space, the new physics contribution is large and even reaches 24 × 10-10, which can remedy the deviation well.

  13. Hexagonal and Pentagonal Fractal Multiband Antennas

    NASA Technical Reports Server (NTRS)

    Tang, Philip W.; Wahid, Parveen

    2005-01-01

    Multiband dipole antennas based on hexagonal and pentagonal fractals have been analyzed by computational simulations and functionally demonstrated in experiments on prototypes. These antennas are capable of multiband or wide-band operation because they are subdivided into progressively smaller substructures that resonate at progressively higher frequencies by virtue of their smaller dimensions. The novelty of the present antennas lies in their specific hexagonal and pentagonal fractal configurations and the resonant frequencies associated with them. These antennas are potentially applicable to a variety of multiband and wide-band commercial wireless-communication products operating at different frequencies, including personal digital assistants, cellular telephones, pagers, satellite radios, Global Positioning System receivers, and products that combine two or more of the aforementioned functions. Perhaps the best-known prior multiband antenna based on fractal geometry is the Sierpinski triangle antenna (also known as the Sierpinski gasket), shown in the top part of the figure. In this antenna, the scale length at each iteration of the fractal is half the scale length of the preceding iteration, yielding successive resonant frequencies related by a ratio of about 2. The middle and bottom parts of the figure depict the first three iterations of the hexagonal and pentagonal fractals along with typical dipole-antenna configuration based on the second iteration. Successive resonant frequencies of the hexagonal fractal antenna have been found to be related by a ratio of about 3, and those of the pentagonal fractal antenna by a ratio of about 2.59.

  14. Pentagon Seeks to Build Bridges to Academe.

    ERIC Educational Resources Information Center

    Norman, Colin

    1985-01-01

    The Department of Defense is increasing funding for high-risk basic research, research fellowships, multidisciplinary centers, and purchase of research equipment at universities. Disputes on publishing unclassified data remain, but the Pentagon supports broad university programs and the education of scientists and engineers to meet defense and…

  15. A New Angle for Constructing Pentagons.

    ERIC Educational Resources Information Center

    Benson, John; Borkovitz, Debra

    1982-01-01

    The construction of a pentagon is divided into three problems, designed to enhance the traditional high school geometry class. The material is seen to serve as a potential springboard for many other activities. It is felt most students could not realistically be expected to solve the third problem by themselves. (MP)

  16. The ILS--The Pentagon Library's Experience.

    ERIC Educational Resources Information Center

    Mullane, Ruth

    1984-01-01

    Describes implementation of five subsystems of Integrated Library System's (ILS) version 2.1 (minicomputer-based automated library system) at the Pentagon Library: online catalog (search strategies, user acceptance); bibliographic subsystems (cataloging, retrospective conversion); circulation; serials check-in; administrative subsystem (report…

  17. One-Loop Helicity Amplitudes for tt Production at Hadron Colliders

    SciTech Connect

    Badger, Simon; Sattler, Ralf; Yundin, Valery

    2011-04-01

    We present compact analytic expressions for all one-loop helicity amplitudes contributing to tt production at hadron colliders. Using recently developed generalized unitarity methods and a traditional Feynman based approach we produce a fast and flexible implementation.

  18. One-loop gauge theory amplitudes with an arbitrary number of external legs

    SciTech Connect

    Bern, Z.; Dunbar, D.C.; Dixon, L.; Kosower, D.A.

    1994-05-01

    The authors review recent progress in calculations of one-loop QCD amplitudes. By imposing the consistency requirements of unitarity and correct behavior as the momenta of two legs become collinear, they construct ansaetze for one-loop amplitudes with an arbitrary number of external legs. For supersymmetric amplitudes, which can be thought of as components of QCD amplitudes, the cuts uniquely specify the amplitude.

  19. The pentagon relation and incidence geometry

    SciTech Connect

    Doliwa, Adam; Sergeev, Sergey M.

    2014-06-01

    We define a map S:D²×D²→D²×D², where D is an arbitrary division ring (skew field), associated with the Veblen configuration, and we show that such a map provides solutions to the functional dynamical pentagon equation. We explain that fact in elementary geometric terms using the symmetry of the Veblen and Desargues configurations. We introduce also another map of a geometric origin with the pentagon property. We show equivalence of these maps with recently introduced Desargues maps which provide geometric interpretation to a non-commutative version of Hirota's discrete Kadomtsev–Petviashvili equation. Finally, we demonstrate that in an appropriate gauge the (commutative version of the) maps preserves a natural Poisson structure—the quasiclassical limit of the Weyl commutation relations. The corresponding quantum reduction is then studied. In particular, we discuss uniqueness of the Weyl relations for the ultra-local reduction of the map. We give then the corresponding solution of the quantum pentagon equation in terms of the non-compact quantum dilogarithm function.

  20. Systematic study of the d = 5 Weinberg operator at one-loop order

    NASA Astrophysics Data System (ADS)

    Bonnet, Florian; Hirsch, Martin; Ota, Toshihiko; Winter, Walter

    2012-07-01

    We perform a systematic study of the d = 5 Weinberg operator at the one-loop level. We identify three different categories of neutrino mass generation: (1) finite irreducible diagrams; (2) finite extensions of the usual seesaw mechanisms at one-loop and (3) divergent loop realizations of the seesaws. All radiative one-loop neutrino mass models must fall into one of these classes. Case (1) gives the leading contribution to neutrino mass naturally and a classic example of this class is the Zee model. We demonstrate that in order to prevent that a tree level contribution dominates in case (2), Majorana fermions running in the loop and an additional {Z_2} symmetry are needed for a genuinely leading one-loop contribution. In the type-II loop extensions, the Yukawa coupling will be generated at one loop, whereas the type-I/III extensions can be interpreted as loop-induced inverse or linear seesaw mechanisms. For the divergent diagrams in category (3), the tree level contribution cannot be avoided and is in fact needed as counter term to absorb the divergence.

  1. One-loop calculations in quantum field theory: from Feynman diagrams to unitarity cuts

    SciTech Connect

    Ellis, R. Keith; Kunszt, Zoltan; Melnikov, Kirill; Zanderighi, Giulia

    2012-09-01

    The success of the experimental program at the Tevatron re-inforced the idea that precision physics at hadron colliders is desirable and, indeed, possible. The Tevatron data strongly suggests that one-loop computations in QCD describe hard scattering well. Extrapolating this observation to the LHC, we conclude that knowledge of many short-distance processes at next-to-leading order may be required to describe the physics of hard scattering. While the field of one-loop computations is quite mature, parton multiplicities in hard LHC events are so high that traditional computational techniques become inefficient. Recently new approaches based on unitarity have been developed for calculating one-loop scattering amplitudes in quantum field theory. These methods are especially suitable for the description of multi-particle processes in QCD and are amenable to numerical implementations. We present a systematic pedagogical description of both conceptual and technical aspects of the new methods.

  2. A Proposal for a Standard Interface Between Monte Carlo Tools And One-Loop Programs

    SciTech Connect

    Binoth, T.; Boudjema, F.; Dissertori, G.; Lazopoulos, A.; Denner, A.; Dittmaier, S.; Frederix, R.; Greiner, N.; Hoeche, Stefan; Giele, W.; Skands, P.; Winter, J.; Gleisberg, T.; Archibald, J.; Heinrich, G.; Krauss, F.; Maitre, D.; Huber, M.; Huston, J.; Kauer, N.; Maltoni, F.; /Louvain U., CP3 /Milan Bicocca U. /INFN, Turin /Turin U. /Granada U., Theor. Phys. Astrophys. /CERN /NIKHEF, Amsterdam /Heidelberg U. /Oxford U., Theor. Phys.

    2011-11-11

    Many highly developed Monte Carlo tools for the evaluation of cross sections based on tree matrix elements exist and are used by experimental collaborations in high energy physics. As the evaluation of one-loop matrix elements has recently been undergoing enormous progress, the combination of one-loop matrix elements with existing Monte Carlo tools is on the horizon. This would lead to phenomenological predictions at the next-to-leading order level. This note summarises the discussion of the next-to-leading order multi-leg (NLM) working group on this issue which has been taking place during the workshop on Physics at TeV Colliders at Les Houches, France, in June 2009. The result is a proposal for a standard interface between Monte Carlo tools and one-loop matrix element programs.

  3. Integrand oxidation and one-loop colour-dual numerators in {N}=4 gauge theory

    NASA Astrophysics Data System (ADS)

    Bjerrum-Bohr, N. Emil J.; Dennen, Tristan; Monteiro, Ricardo; O'Connell, Donal

    2013-07-01

    We present a systematic method to determine BCJ numerators for one-loop amplitudes that explores the global constraints on the loop momentum dependence. We apply this method to amplitudes in {N}=4 gauge theory, working out detailed examples up to seven points in both the MHV and the NMHV sectors. We see no obstruction to the application of our method to higher point one-loop amplitudes. The structure of Jacobi identities between BCJ numerators is seen to be closely connected to that of algebraic integrand reductions. We discuss the consequences for one-loop {N}=8 supergravity amplitudes obtained through the double copy prescription. Moreover, in the MHV sector, we show how to obtain simple BCJ box numerators using a relationship with amplitudes in self-dual gauge theory. We also introduce simpler trace-type formulas for integrand reductions.

  4. A proposal for a standard interface between Monte Carlo tools and one-loop programs

    SciTech Connect

    Binoth, T.; Boudjema, F.; Dissertori, G.; Lazopoulos, A.; Denner, A.; Dittmaier, S.; Frederix, R.; Greiner, N.; Hoche, S.; Giele, W.; Skands, P.

    2010-01-01

    Many highly developed Monte Carlo tools for the evaluation of cross sections based on tree matrix elements exist and are used by experimental collaborations in high energy physics. As the evaluation of one-loop matrix elements has recently been undergoing enormous progress, the combination of one-loop matrix elements with existing Monte Carlo tools is on the horizon. This would lead to phenomenological predictions at the next-to-leading order level. This note summarizes the discussion of the next-to-leading order multi-leg (NLM) working group on this issue which has been taking place during the workshop on Physics at TeV colliders at Les Houches, France, in June 2009. The result is a proposal for a standard interface between Monte Carlo tools and one-loop matrix element programs.

  5. Bond resonance energy and verification of the isolated pentagon rule

    SciTech Connect

    Aihara, Jun Ichi

    1995-04-12

    The isolated pentagon rule (IPR) states that fullerenes with isolated pentagons are kinetically much more stable than their fused pentagon counterparts. This rule can be verified in terms of a graph-theoretically defined bond resonance energy. In general, a {pi} bond shared by two pentagons has a large negative bond resonance energy, thus contributing significantly to the increase in kinetic instability or chemical reactivity of the molecule. The existence of such highly antiaromatic local structures sharply distinguishes IPR-violating fullerenes from isolated-pentagon isomers. {pi}bonds shared by two pentagons are shared by many antiaromatic conjugated circuits but not by relatively small aromatic conjugated circuits. 39 refs., 3 figs., 5 tabs.

  6. Non-BPS interactions from the type II one loop four graviton amplitude

    NASA Astrophysics Data System (ADS)

    Basu, Anirban

    2016-06-01

    We obtain T-duality invariant second order differential equations satisfied by the {D}8{{ R }}4 and {D}10{{ R }}4 interactions from the low energy expansion of the one loop four graviton amplitude in toroidally compactified type II string theory. The eigenvalues of these equations are completely determined by the structure of the one loop integrands. Unlike the BPS interactions, these non-BPS interactions satisfy Poisson equations having source terms that receive contributions from both the bulk and boundary of the worldsheet moduli space. We explicitly solve these equations in nine-dimensions.

  7. Scalar scattering via conformal higher spin exchange

    NASA Astrophysics Data System (ADS)

    Joung, Euihun; Nakach, Simon; Tseytlin, Arkady A.

    2016-02-01

    Theories containing infinite number of higher spin fields require a particular definition of summation over spins consistent with their underlying symmetries. We consider a model of massless scalars interacting (via bilinear conserved currents) with conformal higher spin fields in flat space. We compute the tree-level four-scalar scattering amplitude using a natural prescription for summation over an infinite set of conformal higher spin exchanges and find that it vanishes. Independently, we show that the vanishing of the scalar scattering amplitude is, in fact, implied by the global conformal higher spin symmetry of this model. We also discuss one-loop corrections to the four-scalar scattering amplitude.

  8. Renovating the Pentagon's heating and refrigeration plant

    SciTech Connect

    Snyder, G.C. Jr. )

    1992-07-01

    This paper reports that the Pentagon heating plant originally burned coal, but has since been converted to natural gas and oil. Fifty years of service have caught up with the facility and now none of the five original boilers remains operational. Much of the old coal and ash handling equipment remain in the plant but have not been used since the conversion from coal. The inoperative conveyors and bins stand in silent testimony to a time of simpler environmental and licensing concerns. Rented, temporary, trailer-mounted boilers now supply most of the heating needs. The existing plant is on a small site about 1,500 ft (460 m) southeast of the Pentagon. Chilled water and steam are supplied to the Pentagon through steel piping in an underground concrete tunnel. Chilled water and steam are also supplied to Federal Office Building 2 (FOB-2) and Henderson Hall. FOB-2 is a 1,028,000 ft{sup 2} (95,500 m{sup 2}) office building now used by the U.S. Navy. Henderson Hall (steam only) is a 22 acre (8.9 hectares) complex of buildings that serves elements of the headquarters of the U.S. Marine Corps. FOB-2 and Henderson Hall are situated on the far west side of the Pentagon from the central plant. This necessitates piping runs of over 7,000 ft (2,100 m) one way. Distribution of chilled water is now made using a radial arrangement of progressively smaller lines that branch from the single 36 in. (91 cm) supply and return mains from the plant. A single 24 in. (61 cm) branch conveys chilled water to FOB-2 using the central plant pumps. The existing heating distribution also is a radial arrangement that conveys saturated steam at 125 psig (860 kPa). The system's age and inefficiency are exhibited by the need to have a makeup water rate that is, at times, 50% of the total steam delivery rate.

  9. One-loop Einstein-Hilbert term in minimally supersymmetric type IIB orientifolds

    NASA Astrophysics Data System (ADS)

    Haack, Michael; Kang, Jin U.

    2016-02-01

    We evaluate string one-loop contributions to the Einstein-Hilbert term in toroidal minimally supersymmetric type IIB orientifolds with D-branes. These have potential applications to the determination of quantum corrections to the moduli Kähler metric in these models.

  10. Higgs Decay to Two Photons at One Loop in the Standard Model Effective Field Theory.

    PubMed

    Hartmann, Christine; Trott, Michael

    2015-11-01

    We present the calculation of the CP conserving contributions to Γ(h→γγ), from dimension six operators at one-loop order, in the linear standard model effective field theory. We discuss the impact of these corrections on interpreting current and future experimental bounds on this decay. PMID:26588371

  11. Numerical evaluation of one-loop diagrams near exceptional momentum configurations

    SciTech Connect

    Walter T Giele; Giulia Zanderighi; E.W.N. Glover

    2004-07-06

    One problem which plagues the numerical evaluation of one-loop Feynman diagrams using recursive integration by part relations is a numerical instability near exceptional momentum configurations. In this contribution we will discuss a generic solution to this problem. As an example we consider the case of forward light-by-light scattering.

  12. Towards the one-loop Kähler metric of Calabi-Yau orientifolds

    NASA Astrophysics Data System (ADS)

    Berg, Marcus; Haack, Michael; Kang, Jin U.; Sjörs, Stefan

    2014-12-01

    We evaluate string one-loop contributions to the Kähler metric of closed string moduli in toroidal minimally supersymmetric (Calabi-Yau) orientifolds with D-branes. We focus on the poorly understood = 1 sectors that receive contributions from all massive string states.

  13. Vortices in superconducting MoGe pentagon

    NASA Astrophysics Data System (ADS)

    Ishida, Takekazu; Thanh Huy, Ho; Kato, Masaru; Hayashhi, Masahiko

    2013-03-01

    Vortices in bulk prefer to form a triangular lattice while a mesoscopic superconductor with a size comparable to coherence length ξ or the magnetic penetration depth λ is quite different so as to create particular configuration of vortices. The behavior of such structures in an external magnetic field is strongly influenced by the boundary conditions. Vortex states in superconducting disk, triangle and square pattern have been extensively studied both theoretically and experimentally [B. J. Baelus et al., Phys. Rev. B 69, 064506 (2004)]. We present vortex structures in MoGe pentagon disks imaged by means of a scanning quantum interference device (SQUID) microscopy [Ho Thanh Huy et al., Physica C, in press; DOI 10.1016/j.physc.2012.03.037.] Systematic measurements allow us to reveal how vortex arrangement evolves with the applied magnetic field. Moreover, we found that shell filling rule is subjected to change when a pinning center is introduced. Numerical calculations of vortex structure in pentagon disks on the basis of the nonlinear Ginzburg-Landau theory reveal that there are good agreement between experimental data and theoretical calculations.

  14. Constructing I[subscript h] Symmetrical Fullerenes from Pentagons

    ERIC Educational Resources Information Center

    Gan, Li-Hua

    2008-01-01

    Twelve pentagons are sufficient and necessary to form a fullerene cage. According to this structural feature of fullerenes, we propose a simple and efficient method for the construction of I[subscript h] symmetrical fullerenes from pentagons. This method does not require complicated mathematical knowledge; yet it provides an excellent paradigm for…

  15. Pentagon Spending on Research Sees Largest Increase in a Decade.

    ERIC Educational Resources Information Center

    Brainard, Jeffrey

    1999-01-01

    Examines trends in Pentagon support of campus-based military research and reports that lawmakers gave the Defense Department a science budget 11 percent higher in 2000 than in 1999. Notes critics' concerns about Pentagon priorities versus the nation's science needs and lobbying by university and industry groups in the Coalition for National…

  16. Complete one-loop electroweak corrections to ZZZ production at the ILC

    NASA Astrophysics Data System (ADS)

    Ji-Juan, Su; Wen-Gan, Ma; Ren-You, Zhang; Shao-Ming, Wang; Lei, Guo

    2008-07-01

    We study the complete O(αew) electroweak (EW) corrections to the production of three Z0 bosons in the framework of the standard model (SM) at the ILC. The leading-order and the EW next-to-leading-order corrected cross sections are presented, and their dependence on the colliding energy s and Higgs-boson mass mH is analyzed. We investigate also the LO and one-loop EW corrected distributions of the transverse momentum of the final Z0 boson, and the invariant mass of the Z0Z0 pair. Our numerical results show that the EW one-loop correction generally suppresses the tree-level cross section, and the relative correction with mH=120GeV(150GeV) varies between -15.8%(-13.9%) and -7.5%(-6.2%) when s goes up from 350 GeV to 1 TeV.

  17. String-inspired BCJ numerators for one-loop MHV amplitudes

    NASA Astrophysics Data System (ADS)

    He, Song; Monteiro, Ricardo; Schlotterer, Oliver

    2016-01-01

    We find simple expressions for the kinematic numerators of one-loop MHV amplitudes in maximally supersymmetric Yang-Mills theory and supergravity, at any multiplicity. The gauge-theory numerators satisfy the Bern-Carrasco-Johansson (BCJ) duality between color and kinematics, so that the gravity numerators are simply the square of the gauge-theory ones. The duality holds because the numerators can be written in terms of structure constants of a kinematic algebra, which is familiar from the BCJ organization of self-dual gauge theory and gravity. The close connection that we find between one-loop amplitudes in the self-dual case and in the maximally supersymmetric case is reminiscent of the dimension-shifting formula. The starting point for arriving at our expressions is the dimensional reduction of ten-dimensional amplitudes obtained in the field-theory limit of open superstrings.

  18. Quantum magnetic flux lines, BPS vortex zero modes, and one-loop string tension shifts

    NASA Astrophysics Data System (ADS)

    Alonso-Izquierdo, A.; Mateos Guilarte, J.; de la Torre Mayado, M.

    2016-08-01

    Spectral heat kernel/zeta function regularization procedures are employed in this paper to control the divergences arising from vacuum fluctuations of Bogomolnyi-Prasad-Sommerfield vortices in the Abelian Higgs model. Zero modes of vortex fluctuations are the source of difficulties appearing when the standard Gilkey-de Witt expansion is the tool used in the calculations of one-loop shifts of vortex masses and string tensions. A modified GdW expansion is developed to diminish the impact of the infrared divergences due to the vortex zero modes of fluctuation. With this new technique at our disposal we compute the one-loop vortex mass shifts in the planar AHM and the quantum corrections to the string tension of the magnetic flux tubes living in three dimensions. In both cases it is observed that weak repulsive forces surge between these classically noninteracting topological defects caused by vacuum quantum fluctuations.

  19. All One-loop Maximally Helicity Violating Gluonic Amplitudes in QCD

    SciTech Connect

    Berger, Carola F.; Bern, Zvi; Dixon, Lance J.; Forde, Darren; Kosower, David A.

    2006-07-05

    We use on-shell recursion relations to compute analytically the one-loop corrections to maximally-helicity-violating n-gluon amplitudes in QCD. The cut-containing parts have been computed previously; our work supplies the remaining rational parts for these amplitudes, which contain two gluons of negative helicity and the rest positive, in an arbitrary color ordering. We also present formulae specific to the six-gluon cases, with helicities (-+-+++) and (-++-++), as well as numerical results for six, seven, and eight gluons. Our construction of the n-gluon amplitudes illustrates the relatively modest growth in complexity of the on-shell-recursive calculation as the number of external legs increases. These amplitudes add to the growing body of one-loop amplitudes known for all n, which are useful for studies of general properties of amplitudes, including their twistor-space structure.

  20. The complete one-loop dilatation operator of planar real β-deformed = 4 SYM theory

    NASA Astrophysics Data System (ADS)

    Fokken, Jan; Sieg, Christoph; Wilhelm, Matthias

    2014-07-01

    We determine the missing finite-size corrections to the asymptotic one-loop dilatation operator of the real β-deformed = 4 SYM theory for the gauge groups U( N) and SU( N) in the 't Hooft limit. In the SU( N) case, the absence of the U(1) field components leads to a new kind of finite-size effect, which we call prewrapping. We classify which states are potentially affected by prewrapping at generic loop orders and comment on the necessity to include it into the integrability-based description. As a further result, we identify classes of n-point correlation functions which at all loop orders in the planar theory are given by the values of their undeformed counterparts. Finally, we determine the superconformal multiplet structure and one-loop anomalous dimensions of all single-trace states with classical scaling dimension Δ0 ≤ 4.5.

  1. Package-X: A Mathematica package for the analytic calculation of one-loop integrals

    NASA Astrophysics Data System (ADS)

    Patel, Hiren H.

    2015-12-01

    Package-X, a Mathematica package for the analytic computation of one-loop integrals dimensionally regulated near 4 spacetime dimensions is described. Package-X computes arbitrarily high rank tensor integrals with up to three propagators, and gives compact expressions of UV divergent, IR divergent, and finite parts for any kinematic configuration involving real-valued external invariants and internal masses. Output expressions can be readily evaluated numerically and manipulated symbolically with built-in Mathematica functions. Emphasis is on evaluation speed, on readability of results, and especially on user-friendliness. Also included is a routine to compute traces of products of Dirac matrices, and a collection of projectors to facilitate the computation of fermion form factors at one-loop. The package is intended to be used both as a research tool and as an educational tool.

  2. One-loop vacuum polarization at m α7 order for the two-center problem

    NASA Astrophysics Data System (ADS)

    Karr, J.-Ph.; Hilico, L.; Korobov, Vladimir I.

    2014-12-01

    We present calculations of the one-loop vacuum polarization contribution (Uehling potential) for the two-center problem in the nonrelativistic quantum electrodynamics formalism. The cases of hydrogen molecular ions (Z1=Z2=1 ) and antiprotonic helium (Z1=2 , Z2=-1 ) are considered. Numerical results for the vacuum polarization contribution at m α7 order for the fundamental transitions (v =0 ,L =0 ) →(v'=1 ,L'=0 ) in H2+ and HD+ are presented.

  3. One-Loop Multi-Parton Amplitudes with a Vector Boson for the LHC

    SciTech Connect

    Berger, C.F.; Bern, Z.; Dixon, L.J.; Cordero, F.Febres; Forde, D.; Ita, H.; Kosower, D.A.; Maitre, D.; /SLAC

    2008-08-11

    In this talk, we present the first, numerically stable, results for the one-loop amplitudes needed for computing W; Z + 3 jet cross sections at the LHC to next-to-leading order in the QCD coupling. We implemented these processes in BlackHat, an automated program based on on-shell methods. These methods scale very well with increasing numbers of external partons, and are applicable to a wide variety of problems of phenomenological interest at the LHC.

  4. Supergravitons from one loop perturbative N=4 super Yang-Mills theory

    SciTech Connect

    Janik, Romuald A.; Trzetrzelewski, Maciej

    2008-04-15

    We determine the partition function of (1/16)BPS operators in N=4 super Yang-Mills (SYM) at weak coupling at the one-loop level in the planar limit. This partition function is significantly different from the one computed at zero coupling. We find that it coincides precisely with the partition function of a gas of (1/16)BPS supergravitons in AdS{sub 5}xS{sup 5}.

  5. One-loop effects of extra dimensions on the WW{gamma} and WWZ vertices

    SciTech Connect

    Flores-Tlalpa, A.; Novales-Sanchez, H.; Toscano, J. J.; Montano, J.; Ramirez-Zavaleta, F.

    2011-01-01

    The one-loop contribution of the excited Kaluza-Klein (KK) modes of the SU{sub L}(2) gauge group on the off-shell W{sup -}W{sup +}{gamma} and W{sup -}W{sup +}Z vertices is calculated in the context of a pure Yang-Mills theory in five dimensions and its phenomenological implications discussed. The use of a gauge-fixing procedure for the excited KK modes that is covariant under the standard gauge transformations of the SU{sub L}(2) group is stressed. A gauge-fixing term and the Faddeev-Popov ghost sector for the KK gauge modes that are separately invariant under the standard gauge transformations of SU{sub L}(2) are presented. It is shown that the one-loop contributions of the KK modes to the off-shell W{sup -}W{sup +}{gamma} and W{sup -}W{sup +}Z vertices are free of ultraviolet divergences and well-behaved at high energies. It is found that for a size of the fifth dimension of R{sup -1{approx}}1 TeV, the one-loop contribution of the KK modes to these vertices is about 1 order of magnitude lower than the corresponding standard model radiative correction. This contribution is similar to the one estimated for new gauge bosons contributions in other contexts. Tree-level effects on these vertices induced by operators of higher canonical dimension are also investigated. It is found that these effects are lower than those generated at the one-loop order by the KK gauge modes.

  6. Heavy Higgs decays into sfermions in the complex MSSM: a full one-loop analysis

    NASA Astrophysics Data System (ADS)

    Heinemeyer, S.; Schappacher, C.

    2015-05-01

    For the search for additional Higgs bosons in the Minimal Supersymmetric Standard Model (MSSM) as well as for future precision analyses in the Higgs sector a precise knowledge of their decay properties is mandatory. We evaluate all two-body decay modes of the heavy Higgs bosons into sfermions in the MSSM with complex parameters (cMSSM). The evaluation is based on a full one-loop calculation of all decay channels, also including hard QED and QCD radiation. The dependence of the heavy Higgs bosons on the relevant cMSSM parameters is analyzed numerically. We find sizable contributions to many partial decay widths. They are roughly of of the tree-level results, but can go up to or higher. The size of the electroweak one-loop corrections can be as large as the QCD corrections. The full one-loop contributions are important for the correct interpretation of heavy Higgs-boson search results at the LHC and, if kinematically allowed, at a future linear collider. The evaluation of the branching ratios of the heavy Higgs bosons will be implemented into the Fortran code FeynHiggs.

  7. Massive basketball diagram for a thermal scalar field theory

    NASA Astrophysics Data System (ADS)

    Andersen, Jens O.; Braaten, Eric; Strickland, Michael

    2000-08-01

    The ``basketball diagram'' is a three-loop vacuum diagram for a scalar field theory that cannot be expressed in terms of one-loop diagrams. We calculate this diagram for a massive scalar field at nonzero temperature, reducing it to expressions involving three-dimensional integrals that can be easily evaluated numerically. We use this result to calculate the free energy for a massive scalar field with a φ4 interaction to three-loop order.

  8. Capturing the Fused-Pentagon C74 by Stepwise Chlorination.

    PubMed

    Gao, Cong-Li; Abella, Laura; Tan, Yuan-Zhi; Wu, Xin-Zhou; Rodríguez-Fortea, Antonio; Poblet, Josep M; Xie, Su-Yuan; Huang, Rong-Bin; Zheng, Lan-Sun

    2016-07-18

    As a bridge to connect medium-sized fullerenes, fused-pentagon C74 is still missing heretofore. Of 14 246 possible isomers, the first fused-pentagon C74 with the Fowler-Manolopoulos code of 14 049 was stabilized as C74Cl10 in the chlorine-involving carbon arc. The structure of C74Cl10 was identified by X-ray crystallography. The stabilization of pristine fused-pentagon C74 by stepwise chlorination was clarified in both theoretical simulation with density functional theory calculations and experimental fragmentation with multistage mass spectrometry. PMID:27341488

  9. Expansion of the one-loop effective action in covariant derivatives

    SciTech Connect

    Zuk, J.A.

    1986-06-15

    With an approach based on the heat-kernel representation, we show how to construct the expansion of the one-loop effective action in powers of covariant derivatives D/sub ..mu../ whenever it can be expressed in terms of an operator determinant of the form det(-D/sup 2/+V), where V is some positive Hermitian matrix-valued function. We present general expressions for the contributions to the effective Lagrangian in two and four covariant derivatives for four Euclidean space-time dimensions.

  10. One-loop perturbative unitarity and the Higgs-boson mass: A new approach

    NASA Astrophysics Data System (ADS)

    Durand, Loyal; Johnson, James M.; Lopez, Jorge L.

    1990-03-01

    We reexamine the unitarity constraints on the high-energy scattering of longitudinal W 's and Z's and Higgs bosons in the standard model including one-loop corrections, and make an Argand-diagram analysis of the j=0 scattering amplitudes. We find that the theory is approximately unitary and weakly interacting at O(λ2) for Higgs-boson couplings λ<λc=1.5-2 (equivalent to MH<350-400 GeV), but that O(λ3) or higher corrections must be included to restore perturbative unitarity for larger values of λ or MH.

  11. A FDR-Preserving Field Theory for Interacting Brownian Particles: One-Loop Theory and MCT

    SciTech Connect

    Kim, Bongsoo; Kawasaki, Kyozi

    2008-02-21

    We develop a field theoretical treatment of a model of interacting Brownian particles. We pay particlular attention to the requirement of the time reversal (TR) invariance and the flucutation-dissipation relationship (FDR). Previous field theoretical formulations were found to be inconsistent with this requirement. The method used in the present formulation is a modified version of the auxilliary field method due originally to Andreanov, Biroli and Lefevre (ABL). We recover the correct diffusion law when the interaction is dropped as well as the standard mode coupling equation in the one-loop order calculation for interacting Brownian particle systems.

  12. One loop graviton self-energy in a locally de Sitter background

    SciTech Connect

    tSAMIS, n.c. |; Woodard, R.P.

    1996-02-01

    The graviton tadpole has recently been computed at two loops in a locally de Sitter background. We apply intermediate results of this work to exhibit the graviton self-energy at one loop. This quantity is interesting both to check the accuracy of the first calculation and to understand the relaxation effect it reveals. In the former context we show that the self-energy obeys the appropriate Ward identity. We also show that its flat space limit agrees with the flat space result obtained by Capper in what should be the same gauge. 15 refs., 4 figs., 10 tabs.

  13. Noncommutative Maxwell-Chern-Simons theory: One-loop dispersion relation analysis

    NASA Astrophysics Data System (ADS)

    Ghasemkhani, M.; Bufalo, R.

    2016-04-01

    In this paper, we study the three-dimensional noncommutative Maxwell-Chern-Simons theory. In the present analysis, a complete account for the gauge field two-point function renormalizability is presented and physical significant quantities are carefully established. The respective form factor expressions from the gauge field self-energy are computed at one-loop order. More importantly, an analysis of the gauge field dispersion relation, in search of possible noncommutative anomalies and infrared finiteness, is performed for three special cases, with particular interest in the highly noncommutative limit.

  14. Integrand reduction of one-loop scattering amplitudes through Laurent series expansion

    NASA Astrophysics Data System (ADS)

    Mastrolia, Pierpaolo; Mirabella, Edoardo; Peraro, Tiziano

    2012-06-01

    We present a semi-analytic method for the integrand reduction of one-loop amplitudes, based on the systematic application of the Laurent expansions to the integrand-decomposition. In the asymptotic limit, the coefficients of the master integrals are the solutions of a diagonal system of equations, properly corrected by counterterms whose parametric form is known a priori. The Laurent expansion of the integrand is implemented through polynomial division. The extension of the integrand-reduction to the case of numerators with rank larger than the number of propagators is discussed as well.

  15. VIEW SOUTH TOWARD MOVEABLE FIELD LEVEL SEATS. NOTE RETRACTABLE PENTAGONAL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW SOUTH TOWARD MOVEABLE FIELD LEVEL SEATS. NOTE RETRACTABLE PENTAGONAL LIGHT RING GONDOLA SUSPENDED FROM ROOF CUPOLA. SKY LIGHTS PAINTED OVER TO REDUCE GLARE FOR BASEBALL OUTFIELDERS. - Houston Astrodome, 8400 Kirby Drive, Houston, Harris County, TX

  16. Pentagon packing models for "all-pentamer" virus structures.

    PubMed Central

    Tarnai, T; Gáspár, Z; Szalai, L

    1995-01-01

    A connection is made between 1) the observed structures of virus capsids whose capsomers are all pentamers and 2) the mathematical problem of determination of the largest size of a given number of equal regular spherical pentagons that can be packed on the surface of the unit sphere without overlapping. It is found that papillomaviruses provide the conjectured solution to the spherical pentagon packing problem for 72 pentagons. Thus, a study of some virus structures has given additional insight into a mathematical problem. At the same time this mathematical problem enables prediction of an octahedral form of papillomavirus particles consisting of 24 pentamers. It is also found that the various tubular and spherical "all-pentamer" virus structures identified so far can be represented by closet-packing arrangements of equal morphological units composed of equal regular pentagons on a cylinder and on a sphere. PMID:8527676

  17. 70. AERIAL VIEW OF ROUTE 110 WITH PENTAGON AND PARKING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    70. AERIAL VIEW OF ROUTE 110 WITH PENTAGON AND PARKING AREA LOOKING SOUTHEAST.(EXPRESSWAY V.S. PARKWAY) - George Washington Memorial Parkway, Along Potomac River from McLean to Mount Vernon, VA, Mount Vernon, Fairfax County, VA

  18. Symmetry breaking and restoration for interacting scalar and gauge fields in Lifshitz type theories

    NASA Astrophysics Data System (ADS)

    Farakos, K.; Metaxas, D.

    2012-05-01

    We consider the one-loop effective potential at zero and finite temperature in field theories with anisotropic space-time scaling, with critical exponent z = 2, including both scalar and gauge fields. Depending on the relative strength of the coupling constants for the gauge and scalar interactions, we find that there is a symmetry breaking term induced at one loop at zero temperature and we find symmetry restoration through a first-order phase transition at high temperature.

  19. A one-loop test for construction of 4D N = 4 SYM from 2D SYM via fuzzy-sphere geometry

    NASA Astrophysics Data System (ADS)

    Matsuura, So; Sugino, Fumihiko

    2016-04-01

    As a perturbative check of the construction of 4D N=4 supersymmetric Yang-Mills theory (SYM) from mass-deformed N=(8,8) SYM on the 2D lattice, the one-loop effective action for scalar kinetic terms is computed in N=4 U(k) SYM on R^2 × (fuzzy S^2), which is obtained by expanding 2D N=(8,8) U(N) SYM with mass deformation around its fuzzy-sphere classical solution. The radius of the fuzzy sphere is proportional to the inverse of the mass. We consider two successive limits: (1) decompactify the fuzzy sphere to a noncommutative (Moyal) plane and (2) turn off the noncommutativity of the Moyal plane. It is straightforward at the classical level to obtain the ordinary N=4 SYM on R^4 in the limits, while it is nontrivial at the quantum level. The one-loop effective action for the SU(k) sector of the gauge group U(k) coincides with that of the ordinary 4D N=4 SYM in the above limits. Although a "noncommutative anomaly" appears in the overall U(1) sector of the U(k) gauge group, this can be expected to be a gauge artifact not affecting gauge-invariant observables.

  20. Higgs decays into charginos and neutralinos in the complex MSSM: a full one-loop analysis

    NASA Astrophysics Data System (ADS)

    Heinemeyer, S.; Schappacher, C.

    2015-05-01

    For the search for additional Higgs bosons in the minimal supersymmetric standard model (MSSM) as well as for future precision analyses in the Higgs sector a precise knowledge of their decay properties is mandatory. We evaluate all two-body decay modes of the Higgs bosons into charginos and neutralinos in the MSSM with complex parameters (cMSSM). The evaluation is based on a full one-loop calculation of all decay channels, also including hard QED radiation. We restricted ourselves to a version of our renormalization scheme which is valid for and to simplify the analysis, even though we are able to switch to other parameter regions. The dependence of the Higgs boson predictions on the relevant cMSSM parameters is analyzed numerically. We find sizable contributions to many partial decay widths. They are roughly of 10 % of the tree-level results, but they can go up to 20 % or higher. The full one-loop contributions are important for the correct interpretation of heavy Higgs boson search results at the LHC and, if kinematically allowed, at a future linear collider. There are plans to implement the evaluation of the branching ratios of the Higgs bosons into the Fortran code FeynHiggs, together with an automated choice of the renormalization scheme valid for the full cMSSM parameter space.

  1. Functionalization of pentagon-pentagon edges of fullerenes by cyclic polysulfides: A DFT study

    NASA Astrophysics Data System (ADS)

    Anafcheh, Maryam; Khodadadi, Zahra; Ektefa, Fatemeh; Ghafouri, Reza

    2016-05-01

    We have performed a computational study to investigate the cyclosulfurization of the pentagon-pentagon (p-p) junctions in the non-IPR fullerenes C60(D3) and C70(C2v), and also Stone-Wales defective C60 fullerene. Our results indicate the exothermic character of cyclosulfurization processes which can be related to the increase of pyramidalization angle (spherical excesses) and p characters of natural hybrid orbitals of C atoms at the p-p junctions. In fact these lead to the structural strain relief and stability of the cyclosulfurization derivatives of the non-IPR fullerenes. Moreover, the cyclosulfurization reaction of p-p bonds on the C70(C2v) is more energetically favorable than that of C60(D3), due to the higher curvature of carbon sites and the larger values of the p characters of natural hybrid orbitals in the C70(C2v). On the other hand, localization of the excess electrons on the C atoms at the p-p junctions leads to the low tendency of the charged non-IPR fullerenes to cyclosulfurization process. The desulfurization pathway of the exohedral derivatives of C70(C2v) indicates that it is energetically unfavorable for the functionalized fullerenes to break into individual fullerene and sulfur molecules. HOMO-LUMO gaps almost are independent of the number of pentathiepin rings while sensitive to the type of parent fullerene.

  2. Hartree approximation to the one loop quantum gravitational correction to the graviton mode function on de Sitter

    SciTech Connect

    Mora, P.J.; Woodard, R.P.; Tsamis, N.C. E-mail: tsamis@physics.uoc.gr

    2013-10-01

    We use the Hartree approximation to the Einstein equation on de Sitter background to solve for the one loop correction to the graviton mode function. This should give a reasonable approximation to how the ensemble of inflationary gravitons affects a single external graviton. At late times we find that the one loop correction to the plane wave mode function u(η,k) goes like GH{sup 2}ln (a)/a{sup 2}, where a is the inflationary scale factor. One consequence is that the one loop corrections to the ''electric'' components of the linearized Weyl tensor grow compared to the tree order result.

  3. Impacts of biasing schemes in the one-loop integrated perturbation theory

    NASA Astrophysics Data System (ADS)

    Matsubara, Takahiko; Desjacques, Vincent

    2016-06-01

    The impact of biasing schemes on the clustering of tracers of the large-scale structure is analytically studied in the weakly nonlinear regime. For this purpose, we use the one-loop approximation of the integrated perturbation theory together with the renormalized bias functions of various, physically motivated Lagrangian bias schemes. These include the halo, peaks, and excursion set peaks model, for which we derive useful formulas for the evaluation of their renormalized bias functions. The shapes of the power spectra and correlation functions are affected by the different bias models at the level of a few percent on weakly nonlinear scales. These effects are studied quantitatively both in real and redshift space. The amplitude of the scale-dependent bias in the presence of primordial non-Gaussianity also depends on the details of the bias models. If left unaccounted for, these theoretical uncertainties could affect the robustness of the cosmological constraints extracted from galaxy clustering data.

  4. Complete spectrum of long operators in Script N = 4 SYM at one loop

    NASA Astrophysics Data System (ADS)

    Beisert, Niklas; Kazakov, Vladimir A.; Sakai, Kazuhiro; Zarembo, Konstantin

    2005-07-01

    We construct the complete spectral curve for an arbitrary local operator, including fermions and covariant derivatives, of one-loop Script N = 4 gauge theory in the thermodynamic limit. This curve perfectly reproduces the Frolov-Tseytlin limit of the full spectral curve of classical strings on AdS5 × S5 derived in [64]. To complete the comparison we introduce stacks, novel bound states of roots of different flavors which arise in the thermodynamic limit of the corresponding Bethe ansatz equations. We furthermore show the equivalence of various types of Bethe equations for the underlying fraktur sfraktur u(2,2|4) superalgebra, in particular of the type ``Beauty'' and ``Beast''.

  5. One-loop superstring six-point amplitudes and anomalies in pure spinor superspace

    NASA Astrophysics Data System (ADS)

    Mafra, Carlos R.; Schlotterer, Oliver

    2016-04-01

    We present the massless six-point one-loop amplitudes in the open and closed superstring using BRST cohomology arguments from the pure spinor formalism. The hexagon gauge anomaly is traced back to a class of kinematic factors in pure spinor superspace which were recently introduced as BRST pseudo-invariants. This complements previous work where BRST invariance arguments were used to derive the non-anomalous part of the amplitude. The associated worldsheet functions are non-singular and demonstrated to yield total derivatives on moduli space upon gauge variation. These cohomology considerations yield an efficient organizing principle for closed-string amplitudes that match expectations from S-duality in the low-energy limit.

  6. Bloch-Nordsieck thermometers: one-loop exponentiation in finite temperature QED

    NASA Astrophysics Data System (ADS)

    Gupta, Sourendu; Indumathi, D.; Mathews, Prakash; Ravindran, V.

    1996-02-01

    We study the scattering of hard external particles in a heat bath in a real-time formalism for finite temperature QED. We investigate the distribution of the 4-momentum difference of initial and final hard particles in a fully covariant manner when the scale of the process, Q, is much larger than the temperature, T. Our computations are valid for all T subject to this constraint. We exponentiate the leading infra-red term at one-loop order through a resummation of soft (thermal) photon emissions and absorptions. For T > 0, we find that tensor structures arise which are not present at T = 0. These cant' thermal signatures. As a result, external particles can serve as thermometers introduced into the heat bath. We investigate the phase space origin of log( Q/ m) and log ( Q/ T) teens.

  7. Towards one-loop SYM amplitudes from the pure spinor BRST cohomology

    NASA Astrophysics Data System (ADS)

    Mafra, Carlos R.; Schlotterer, Oliver

    2015-02-01

    In this paper, we outline a method to compute supersymmetric one-loop integrands in ten-dimensional SYM theory. It relies on the constructive interplay between their cubic-graph organization and BRST invariance of the underlying pure spinor superstring description. The five- and six-point amplitudes are presented in a manifestly local form where the kinematic dependence is furnished by BRST-covariant expressions in pure spinor superspace. At five points, the local kinematic numerators are shown to satisfy the BCJ duality between color and kinematics leading to supergravity amplitudes as a byproduct. At six points, the sources of the hexagon anomaly are identified in superspace as systematic obstructions to BRST invariance. Our results are expected to reproduce any integrated SYM amplitude in dimensions $D< 8$.

  8. Integrated perturbation theory and one-loop power spectra of biased tracers

    NASA Astrophysics Data System (ADS)

    Matsubara, Takahiko

    2014-08-01

    General and explicit predictions from the integrated perturbation theory (iPT) for power spectra and correlation functions of biased tracers are derived and presented in the one-loop approximation. The iPT is a general framework of the nonlinear perturbation theory of cosmological density fields in the presence of nonlocal bias, redshift-space distortions, and primordial non-Gaussianity. Analytic formulas of auto and cross power spectra of nonlocally biased tracers in both real and redshift spaces are derived and the results are comprehensively summarized. The main difference from previous formulas derived by the present author is to include the effects of generally nonlocal Lagrangian bias and primordial non-Gaussianity, and the derivation method of the new formula is fundamentally different from the previous one. Relations to recent work on improved methods of nonlinear perturbation theory in the literature are clarified and discussed.

  9. The one-loop matter bispectrum in the Effective Field Theory of Large Scale Structures

    DOE PAGESBeta

    Angulo, Raul E.; Foreman, Simon; Schmittfull, Marcel; Senatore, Leonardo

    2015-10-14

    With this study, given the importance of future large scale structure surveys for delivering new cosmological information, it is crucial to reliably predict their observables. The Effective Field Theory of Large Scale Structures (EFTofLSS) provides a manifestly convergent perturbative scheme to compute the clustering of dark matter in the weakly nonlinear regime in an expansion in k/kNL, where k is the wavenumber of interest and kNL is the wavenumber associated to the nonlinear scale. It has been recently shown that the EFTofLSS matches to 1% level the dark matter power spectrum at redshift zero up to k ≃ 0.3 hmore » Mpc–1 and k ≃ 0.6 h Mpc–1 at one and two loops respectively, using only one counterterm that is fit to data. Similar results have been obtained for the momentum power spectrum at one loop. This is a remarkable improvement with respect to former analytical techniques. Here we study the prediction for the equal-time dark matter bispectrum at one loop. We find that at this order it is sufficient to consider the same counterterm that was measured in the power spectrum. Without any remaining free parameter, and in a cosmology for which kNL is smaller than in the previously considered cases (σ8=0.9), we find that the prediction from the EFTofLSS agrees very well with N-body simulations up to k ≃ 0.25 h Mpc–1, given the accuracy of the measurements, which is of order a few percent at the highest k's of interest. While the fit is very good on average up to k ≃ 0.25 h Mpc–1, the fit performs slightly worse on equilateral configurations, in agreement with expectations that for a given maximum k, equilateral triangles are the most nonlinear.« less

  10. The one-loop matter bispectrum in the Effective Field Theory of Large Scale Structures

    SciTech Connect

    Angulo, Raul E.; Foreman, Simon; Schmittfull, Marcel; Senatore, Leonardo

    2015-10-14

    With this study, given the importance of future large scale structure surveys for delivering new cosmological information, it is crucial to reliably predict their observables. The Effective Field Theory of Large Scale Structures (EFTofLSS) provides a manifestly convergent perturbative scheme to compute the clustering of dark matter in the weakly nonlinear regime in an expansion in k/kNL, where k is the wavenumber of interest and kNL is the wavenumber associated to the nonlinear scale. It has been recently shown that the EFTofLSS matches to 1% level the dark matter power spectrum at redshift zero up to k ≃ 0.3 h Mpc–1 and k ≃ 0.6 h Mpc–1 at one and two loops respectively, using only one counterterm that is fit to data. Similar results have been obtained for the momentum power spectrum at one loop. This is a remarkable improvement with respect to former analytical techniques. Here we study the prediction for the equal-time dark matter bispectrum at one loop. We find that at this order it is sufficient to consider the same counterterm that was measured in the power spectrum. Without any remaining free parameter, and in a cosmology for which kNL is smaller than in the previously considered cases (σ8=0.9), we find that the prediction from the EFTofLSS agrees very well with N-body simulations up to k ≃ 0.25 h Mpc–1, given the accuracy of the measurements, which is of order a few percent at the highest k's of interest. While the fit is very good on average up to k ≃ 0.25 h Mpc–1, the fit performs slightly worse on equilateral configurations, in agreement with expectations that for a given maximum k, equilateral triangles are the most nonlinear.

  11. One-loop Electroweak Radiative Corrections for Polarized Møller Scattering

    NASA Astrophysics Data System (ADS)

    Barkanova, Svetlana; Aleksejevs, Aleksandrs; Ilyichev, Alexander; Kolomensky, Yury; Zykunov, Vladimir

    2011-04-01

    Møller scattering measurements are a clean, powerful probe of new physics effects. However, before physics of interest can be extracted from the experimental data, radiative corrections must be taken into account very carefully. Using two different approaches, we perform updated and detailed calculations of the complete one-loop set of electroweak radiative corrections to parity violating electron-electron scattering asymmetry at low energies relevant for the ultra-precise 11 GeV MOLLER experiment planned at JLab. Although contributions from some of the self-energies and vertex diagrams calculated in the two approaches can differ significantly, our full gauge-invariant set still guarantees that the total relative weak corrections are in excellent agreement for the two methods of calculation. Our numerical results are presented for a range of experimental cuts and the relative importance of various contributions is analyzed. We also provide very compact expressions analytically free from non-physical parameters and show them to be valid for fast yet accurate estimations.

  12. Scalar explanation of diphoton excess at LHC

    NASA Astrophysics Data System (ADS)

    Han, Huayong; Wang, Shaoming; Zheng, Sibo

    2016-06-01

    Inspired by the diphoton signal excess observed in the latest data of 13 TeV LHC, we consider either a 750 GeV real scalar or pseudo-scalar responsible for this anomaly. We propose a concrete vector-like quark model, in which the vector-like fermion pairs directly couple to this scalar via Yukawa interaction. For this setting the scalar is mainly produced via gluon fusion, then decays at the one-loop level to SM diboson channels gg , γγ , ZZ , WW. We show that for the vector-like fermion pairs with exotic electric charges, such model can account for the diphoton excess and is consistent with the data of 8 TeV LHC simultaneously in the context of perturbative analysis.

  13. Two aspects of one loop structure: Unitarity delay in the Standard Model and modular invariance in string theory

    SciTech Connect

    Ahn, C.

    1989-08-01

    We study two aspects of one loop structures in quantum field theories which describe two different areas of particle physics: the one loop unitarity behavior of the Standard Model of electroweak interactions and modular invariance of string model theory. Loop expansion has its importance in that it contains quantum fluctuations due to all physical states in the theory. Therefore, by studying the various models to one loop, we can understand how the contents of the theory can contribute to physically measurable quantities and how the consistency at quantum level restricts the physical states of the theory, as well. In the first half of the thesis, we study one loop corrections to the process {ital e}{sup +}{ital e}{sup {minus}} {yields} {ital W}{sup +}{ital W}{sup {minus}}. In this process, there is a delicate unitarity-saving cancellation between s-channel and t-channel tree level Feynman diagrams. If the one loop contribution due to heavy particles corrects the channels asymmetrically, the cancellation, hence unitarity, will be delayed up to the mass scale of these heavy particles. We refer to this phenomena as the unitarity delay effect. Due to this effect, cross section below these mass scales can have significant radiative corrections which may provide an appropriate window through which we can see the high energy structure of the Standard Model from relatively low energy experiments. In the second half, we will show how quantum consistency can restrict the physical states in string theory. 53 refs., 13 figs.

  14. Trace anomaly of dilaton-coupled scalars in two dimensions

    NASA Astrophysics Data System (ADS)

    Bousso, Raphael; Hawking, Stephen

    1997-12-01

    Conformal scalar fields coupled to the dilaton appear naturally in two-dimensional models of black hole evaporation. We show that their trace anomaly is (1/24π)[R-6(∇φ)2-2□φ]. It follows that a Russo-Susskind-Thorlacius-type counterterm appears naturally in the one-loop effective action.

  15. The Pentagon's Military Analyst Program

    ERIC Educational Resources Information Center

    Valeri, Andy

    2014-01-01

    This article provides an investigatory overview of the Pentagon's military analyst program, what it is, how it was implemented, and how it constitutes a form of propaganda. A technical analysis of the program is applied using the theoretical framework of the propaganda model first developed by Noam Chomsky and Edward S. Herman. Definitions…

  16. Pentagonal monolayer crystals of carbon, boron nitride, and silver azide

    SciTech Connect

    Yagmurcukardes, M. Senger, R. T.; Sahin, H.; Kang, J.; Torun, E.; Peeters, F. M.

    2015-09-14

    In this study, we present a theoretical investigation of structural, electronic, and mechanical properties of pentagonal monolayers of carbon (p-graphene), boron nitride (p-B{sub 2}N{sub 4} and p-B{sub 4}N{sub 2}), and silver azide (p-AgN{sub 3}) by performing state-of-the-art first principles calculations. Our total energy calculations suggest feasible formation of monolayer crystal structures composed entirely of pentagons. In addition, electronic band dispersion calculations indicate that while p-graphene and p-AgN{sub 3} are semiconductors with indirect bandgaps, p-BN structures display metallic behavior. We also investigate the mechanical properties (in-plane stiffness and the Poisson's ratio) of four different pentagonal structures under uniaxial strain. p-graphene is found to have the highest stiffness value and the corresponding Poisson's ratio is found to be negative. Similarly, p-B{sub 2}N{sub 4} and p-B{sub 4}N{sub 2} have negative Poisson's ratio values. On the other hand, the p-AgN{sub 3} has a large and positive Poisson's ratio. In dynamical stability tests based on calculated phonon spectra of these pentagonal monolayers, we find that only p-graphene and p-B{sub 2}N{sub 4} are stable, but p-AgN{sub 3} and p-B{sub 4}N{sub 2} are vulnerable against vibrational excitations.

  17. Galois Symmetries of Bethe Parameters for the Heisenberg Pentagon

    NASA Astrophysics Data System (ADS)

    Banaszak, G.; Lulek, B.; Lulek, T.; Milewski, J.; Szydło, B.

    2013-04-01

    In this paper the field generated by the Bethe parameters related to the XXX model for the Heisenberg pentagon is considered. For the interior of the Brillouin zone, the Galois group of the Bethe number field over the rationals is determined. This Galois group is recognized as the group of arithmetic symmetries of the Bethe parameters.

  18. Spectral Signatures of the Pentagonal Water Cluster in Bacteriorhodopsin

    SciTech Connect

    Baer, Marcel; Mathias, Gerald; Kuo, I-F W.; Tobias, Douglas J.; Mundy, Christopher J.; Marx, Dominik

    2008-12-22

    We utilize QM/MM methodology with different size QM regions to elucidate the spectral fingerprint of the pentagonal water cluster in Bacteriorhodopsin. This work was supported by the U.S. Department of Energy's (DOE) Office of Basic Energy Sciences, Chemical Sciences program. The Pacific Northwest National Laboratory is operated by Battelle for DOE.

  19. A small-world and scale-free network generated by Sierpinski Pentagon

    NASA Astrophysics Data System (ADS)

    Chen, Jin; Le, Anbo; Wang, Qin; Xi, Lifeng

    2016-05-01

    The Sierpinski Pentagon is used to construct evolving networks, whose nodes are all solid regular pentagons in the construction of the Sierpinski Pentagon up to the stage t and any two nodes are neighbors if and only if the intersection of corresponding pentagons is non-empty and non-singleton. We show that such networks have the small-world and scale-free effects, but are not fractal scaling.

  20. Single pentagon in a hexagonal carbon lattice revealed by scanning tunneling microscopy

    SciTech Connect

    An, B.; Fukuyama, S.; Yokogawa, K.; Yoshimura, M.; Egashira, M.; Korai, Y.; Mochida, I.

    2001-06-04

    The electronic structure of a single pentagon in a hexagonal carbon lattice has been revealed on an atomic scale by scanning tunneling microscopy. The pentagon is located at the apex of the conical protuberance of the graphitic particle. The enhanced charge density localized at each carbon atom in the pentagon is identified, and the ringlike pattern of the ({radical}3{times}{radical}3)R30{degree} superstructure of graphite is clearly observed around the pentagon. {copyright} 2001 American Institute of Physics.

  1. Involution-dependent constants and the cancellation of divergences in the one-loop open-string amplitude

    SciTech Connect

    Nagao, G.

    1988-07-15

    We recalculate the bosonic one-loop open-string scattering amplitude using the results of the bosonic one-loop closed-string amplitude. The results show explicitly how the cancellation of divergences depends upon a set of involution-dependent constants which relate the torus to the cylinder and Moebius strip. Such a set of involution-dependent constants exists at each loop level and thus provides a means with which to study the cancellation of divergences and the connection between the world sheet and internal symmetries.

  2. 3-point off-shell vertex in scalar QED in arbitrary gauge and dimension

    SciTech Connect

    Bashir, A.; Concha-Sanchez, Y.; Delbourgo, R.

    2007-09-15

    We calculate the complete one-loop off-shell three-point scalar-photon vertex in arbitrary gauge and dimension for scalar quantum electrodynamics. Explicit results are presented for the particular cases of dimensions 3 and 4 both for massive and massless scalars. We then propose nonperturbative forms of this vertex that coincide with the perturbative answer to order e{sup 2}.

  3. One-loop renormalization of the NMSSM in SloopS: The neutralino-chargino and sfermion sectors

    NASA Astrophysics Data System (ADS)

    Bélanger, G.; Bizouard, V.; Boudjema, F.; Chalons, G.

    2016-06-01

    We have completed the one-loop renormalisation of the Next-to-Minimal Supersymmetric Standard Model (NMSSM) allowing for and comparing between different renormalisation schemes. A special attention is paid to on-shell schemes. We study a variety of these schemes based on alternative choices of the physical input parameters. In this paper we present our approach to the renormalization of the NMSSM and report on our results for the neutralino-chargino and sfermion sectors. We will borrow some results from our study of the Higgs sector whose full discussion is left for a separate publication. We have implemented the setup for all the sectors of the NMSSM within SloopS, a code for the automatic computation of one-loop corrections initially developed for the standard model and the MSSM. Among the many applications that allows the code, we present here the one-loop corrections to neutralino masses and to partial widths of neutralinos and charginos into final states with one gauge boson. One-loop electroweak and QCD corrections to the partial widths of third generation sfermions into a fermion and a chargino or a neutralino are also computed.

  4. Massive basketball diagram for a thermal scalar field theory

    SciTech Connect

    Andersen, Jens O.; Braaten, Eric; Strickland, Michael

    2000-08-15

    The ''basketball diagram'' is a three-loop vacuum diagram for a scalar field theory that cannot be expressed in terms of one-loop diagrams. We calculate this diagram for a massive scalar field at nonzero temperature, reducing it to expressions involving three-dimensional integrals that can be easily evaluated numerically. We use this result to calculate the free energy for a massive scalar field with a {phi}{sup 4} interaction to three-loop order. (c) 2000 The American Physical Society.

  5. Noncommutative scalar field minimally coupled to nonsymmetric gravity

    SciTech Connect

    Kouadik, S.; Sefai, D.

    2012-06-27

    We construct a non-commutative non symmetric gravity minimally coupled model (the star product only couples matter). We introduce the action for the system considered namely a non-commutative scalar field propagating in a nontrivial gravitational background. We expand the action in powers of the anti-symmetric field and the graviton to second order adopting the assumption that the scalar is weekly coupled to the graviton. We compute the one loop radiative corrections to the self-energy of a scalar particle.

  6. Magnetic Frustration in an Iron-Based Cairo Pentagonal Lattice

    NASA Astrophysics Data System (ADS)

    Ressouche, E.; Simonet, V.; Canals, B.; Gospodinov, M.; Skumryev, V.

    2009-12-01

    The Fe3+ lattice in the Bi2Fe4O9 compound is found to materialize the first analogue of a magnetic pentagonal lattice. Because of its odd number of bonds per elemental brick, this lattice, subject to first neighbor antiferromagnetic interactions, is prone to geometric frustration. The Bi2Fe4O9 magnetic properties have been investigated by macroscopic magnetic measurements and neutron diffraction. The observed noncollinear magnetic arrangement is related to the one stabilized on a perfect tiling as obtained from a mean field analysis with direct space magnetic configuration calculations. The peculiarity of this structure arises from the complex connectivity of the pentagonal lattice, a novel feature compared to the well-known case of triangle-based lattices.

  7. Gamma-ray lines and one-loop continuum from s-channel dark matter annihilations

    NASA Astrophysics Data System (ADS)

    Jackson, C. B.; Servant, Géraldine; Shaughnessy, Gabe; Tait, Tim M. P.; Taoso, Marco

    2013-07-01

    The era of indirect detection searches for dark matter has begun, with the sensitivities of gamma-ray detectors now approaching the parameter space relevant for weakly interacting massive particles. In particular, gamma ray lines would be smoking gun signatures of dark matter annihilation, although they are typically suppressed compared to the continuum. In this paper, we pay particular attention to the 1-loop continuum generated together with the gamma-ray lines and investigate under which conditions a dark matter model can naturally lead to a line signal that is relatively enhanced. We study generic classes of models in which DM is a fermion that annihilates through an s-channel mediator which is either a vector or scalar and identify the coupling and mass conditions under which large line signals occur. We focus on the ``forbidden channel mechanism" advocated a few years ago in the ``Higgs in space" scenario for which tree level annihilation is kinematically forbidden today. Detailed calculations of all 1-loop annihilation channels are provided. We single out very simple models with a large line over continuum ratio and present general predictions for a large range of WIMP masses that are relevant not only for Fermi and Hess II but also for the next generation of telescopes such as CTA and Gamma-400. Constraints from the relic abundance, direct detection and collider bounds are also discussed.

  8. Gamma-ray lines and one-loop continuum from s-channel dark matter annihilations

    SciTech Connect

    Jackson, C.B.; Servant, Géraldine; Shaughnessy, Gabe; Tait, Tim M.P.; Taoso, Marco E-mail: chris@uta.edu E-mail: ttait@uci.edu

    2013-07-01

    The era of indirect detection searches for dark matter has begun, with the sensitivities of gamma-ray detectors now approaching the parameter space relevant for weakly interacting massive particles. In particular, gamma ray lines would be smoking gun signatures of dark matter annihilation, although they are typically suppressed compared to the continuum. In this paper, we pay particular attention to the 1-loop continuum generated together with the gamma-ray lines and investigate under which conditions a dark matter model can naturally lead to a line signal that is relatively enhanced. We study generic classes of models in which DM is a fermion that annihilates through an s-channel mediator which is either a vector or scalar and identify the coupling and mass conditions under which large line signals occur. We focus on the ''forbidden channel mechanism'' advocated a few years ago in the ''Higgs in space'' scenario for which tree level annihilation is kinematically forbidden today. Detailed calculations of all 1-loop annihilation channels are provided. We single out very simple models with a large line over continuum ratio and present general predictions for a large range of WIMP masses that are relevant not only for Fermi and Hess II but also for the next generation of telescopes such as CTA and Gamma-400. Constraints from the relic abundance, direct detection and collider bounds are also discussed.

  9. Controlled synthesis of pentagonal gold nanotubes at room temperature.

    PubMed

    Bi, Yingpu; Lu, Gongxuan

    2008-07-01

    Large quantities of pentagonal gold nanotubes have been synthesized by reducing chloroauric acid with silver nanowires in an aqueous solution of hexadecyltrimethylammonium bromide (CTAB) at room temperature. These gold nanotubes possess perfect structures, smooth surfaces, highly crystalline walls, and similar cross-sections to that of the silver template. In this process, the CTAB participation was found to be crucial for shape-controlled synthesis of pentagonal gold nanotubes. In the absence of CTAB, loose and hollow gold structures were routinely generated, while bundled gold nanotubes with rough surfaces were obtained by replacing the CTAB with poly(vinyl pyrrolidone) (PVP). The possible formation mechanism of pentagonal gold nanotubes has also been discussed on the basis of various growth stages studied by field-emission scanning electron microscopy (FE-SEM) images. In addition, the catalytic properties of these hollow nanostructures for hydrogen generation reaction from HCHO solution have also been investigated. They showed higher activity than that of spherical gold nanoparticles. PMID:21828702

  10. Equation for one-loop divergences in two dimensions and its application to higher-spin fields

    NASA Astrophysics Data System (ADS)

    Popova, H. P.; Stepanyantz, K. V.

    2016-06-01

    We derive a simple formula for one-loop logarithmic divergences on the background of a two-dimensional curved space-time for theories in which the second variation of the action is a nonminimal second-order operator with small nonminimal terms. In particular, this formula allows calculating terms that are integrals of total derivatives. As an application of the result, we obtain one-loop divergences for higher-spin fields on a constant-curvature background in a nonminimal gauge that depends on two parameters. By an explicit calculation, we demonstrate that with the considered accuracy, the result is gauge independent and, moreover, spin independent for spins s ≥ 3.

  11. Minding one's P's and Q's: From the one loop effective action in quantum field theory to classical transport theory

    SciTech Connect

    Jalilian-Marian, Jamal; Jeon, Sangyong; Venugopalan, Raju; Wirstam, Jens

    2000-08-15

    The one loop effective action in quantum field theory can be expressed as a quantum mechanical path integral over world lines, with internal symmetries represented by Grassmanian variables. In this paper, we develop a real time, many body, world line formalism for the one loop effective action. In particular, we study hot QCD and obtain the classical transport equations which, as Litim and Manuel have shown, reduce in the appropriate limit to the non-Abelian Boltzmann-Langevin equation first obtained by Boedeker. In the Vlasov limit, the classical kinetic equations are those that correspond to the hard thermal loop effective action. We also discuss the imaginary time world line formalism for a hot {phi}{sup 4} theory, and elucidate its relation to classical transport theory. (c) 2000 The American Physical Society.

  12. One-Loop Factorization for Inclusive Hadron Production in p-A Collisions in the Saturation Formalism

    NASA Astrophysics Data System (ADS)

    Chirilli, Giovanni A.; Xiao, Bo-Wen; Yuan, Feng

    2012-03-01

    We demonstrate the QCD factorization for inclusive hadron production in p-A collisions in the saturation formalism at one-loop order, with explicit calculation of both real and virtual gluon radiation diagrams. In particular, we find that the cross section can be written into a factorization form in the coordinate space at the next-to-leading order, while the naive form of the convolution in the transverse momentum space does not hold. The collinear divergences associated with the incoming parton distribution of the nucleon and the outgoing fragmentation function of the final-state hadron, as well as the rapidity divergence with small-x dipole gluon distribution of the nucleus are factorized into the splittings of the associated parton distribution and fragmentation functions and the energy evolution of the dipole gluon distribution function. The hard coefficient function is evaluated at one-loop order, and contains no divergence.

  13. One-loop amplitudes in Script N = 4 super Yang-Mills and anomalous dual conformal symmetry

    NASA Astrophysics Data System (ADS)

    Brandhuber, Andreas; Heslop, Paul; Travaglini, Gabriele

    2009-08-01

    We discuss what predictions can be made for one-loop superamplitudes in maximally supersymmetric Yang-Mills theory by using anomalous dual conformal symmetry. We show that the anomaly coefficient is a specific combination of two-mass hard and one-mass supercoefficients which appears in the supersymmetric on-shell recursion relations and equals the corresponding tree-level superamplitude. We discuss further novel relations among supercoefficients imposed by the remaining non-anomalous part of the symmetry. In particular, we find that all one-loop supercoefficients, except the four-mass box coefficients, can be expressed as linear combinations of three-mass box coefficients and a particular symmetric combination of two-mass hard coefficients. We check that our equations are explicitly satisfied in the case of one-loop n-point MHV and NMHV amplitudes. As a bonus, we prove the covariance of the NMHV superamplitudes at an arbitrary number of points, extending previous results at n <= 9.

  14. Liquid Crystalline Networks Composed of Pentagonal, Square, and Triangular Cylinders

    NASA Astrophysics Data System (ADS)

    Chen, Bin; Zeng, Xiangbing; Baumeister, Ute; Ungar, Goran; Tschierske, Carsten

    2005-01-01

    T-shaped molecules are designed in such a way that they self-organize into nanoscale liquid crystalline honeycombs based on polygons with any chosen number of sides. One of the phases reported here is a periodic organization of identical pentagonal cylinders; the other one is a structure composed of square-shaped and triangular cylinders in the ratio 2:1. These two different packing motifs represent duals of the same topological class. The generalization of the concept applied here allows the prediction of a whole range of unusual complex liquid crystalline phases.

  15. HFOLD - A program package for calculating two-body MSSM Higgs decays at full one-loop level.

    PubMed

    Frisch, W; Eberl, H; Hluchá, H

    2011-10-01

    HFOLD (Higgs Full One Loop Decays) is a Fortran program package for calculating all MSSM Higgs two-body decay widths and the corresponding branching ratios at full one-loop level. The package is done in the SUSY Parameter Analysis convention and supports the SUSY Les Houches Accord input and output format. PROGRAM SUMMARY: Program title: HFOLD Catalogue identifier: AEJG_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEJG_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 340 621 No. of bytes in distributed program, including test data, etc.: 1 760 051 Distribution format: tar.gz Programming language: Fortran 77 Computer: Workstation, PC Operating system: Linux RAM: 524 288 000 Bytes Classification: 11.1 External routines: LoopTools 2.2 (http://www.feynarts.de/looptools/), SLHALib 2.2 (http://www.feynarts.de/slha/). The LoopTools code is included in the distribution package. Nature of problem: A future high-energy e+e- linear collider will be the best environment for the precise measurements of masses, cross sections, branching ratios, etc. Experimental accuracies are expected at the per-cent down to the per-mile level. These must be matched from the theoretical side. Therefore higher order calculations are mandatory. Solution method: This program package calculates all MSSM Higgs two-body decay widths and the corresponding branching ratios at full one-loop level. The renormalization is done in the DR scheme following the SUSY Parameter Analysis convention. The program supports the SUSY Les Houches Accord input and output format. Running time: The example provided takes only a few seconds to run. PMID:21969735

  16. The complete one-loop BMN S-matrix in AdS 3 × S 3 × T 4

    NASA Astrophysics Data System (ADS)

    Sundin, Per; Wulff, Linus

    2016-06-01

    We compute the full one-loop 2-particle S-matrix for excitations of the type IIB AdS 3 × S 3 × T 4 BMN string. The S-matrix is found to respect the expected symmetries and the phases are consistent with the crossing equations. By analyzing how the relevant integrals scale with the IR regulator we show that scattering of massless bosons is trivial at two loops. Based on our results we argue that the additional su(2) S-matrix appearing in the massless sector in the exact solution should trivialize.

  17. Neutral Higgs boson production at e^+e^- colliders in the complex MSSM: a full one-loop analysis

    NASA Astrophysics Data System (ADS)

    Heinemeyer, S.; Schappacher, C.

    2016-04-01

    For the search for additional Higgs bosons in the Minimal Supersymmetric Standard Model (MSSM) as well as for future precision analyses in the Higgs sector precise knowledge of their production properties is mandatory. We evaluate the cross sections for the neutral Higgs boson production at e^+e^- colliders in the MSSM with complex parameters (cMSSM). The evaluation is based on a full one-loop calculation of the production mechanism e^+e^- → h_i Z, h_i γ , h_i h_j (i,j = 1,2,3), including soft and hard QED radiation. The dependence of the Higgs boson production cross sections on the relevant cMSSM parameters is analyzed numerically. We find sizable contributions to many cross sections. They are, depending on the production channel, roughly of 10-20 % of the tree-level results, but can go up to 50 % or higher. The full one-loop contributions are important for a future linear e^+e^- collider such as the ILC or CLIC. There are plans to implement the evaluation of the Higgs boson production cross sections into the code FeynHiggs.

  18. Revealing the interactions between pentagon-octagon-pentagon defect graphene and organic donor/acceptor molecules: a theoretical study.

    PubMed

    Li, Jie-Wei; Liu, Yu-Yu; Xie, Ling-Hai; Shang, Jing-Zhi; Qian, Yan; Yi, Ming-Dong; Yu, Ting; Huang, Wei

    2015-02-21

    Defect engineering and the non-covalent interaction strategy allow for dramatically tuning the optoelectronic features of graphene. Herein, we theoretically investigated the intrinsic mechanism of non-covalent interactions between pentagon-octagon-pentagon (5-8-5) defect graphene (DG) and absorbed molecules, tetrathiafulvalene (TTF), perfluoronaphthalene (FNa), tetracyanoquinodimethane (TCNQ) and 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ), through geometry, distance, interaction energy, Mulliken charge distribution, terahertz frequency vibration, visualization of the interactions, charge density difference, electronic transition behaviour, band structure and density of state. All the calculations were performed using density functional theory including a dispersion correction (DFT-D). The calculated results indicate that the cyano- (CN) group (electron withdraw group) in TCNQ and F4TCNQ, rather than the F group, gain the electron from DG effectively and exhibit much stronger interactions via wavefunction overlap with DG, leading to a short non-covalent interaction distance, a large interaction energy and a red-shift of out-of-plane terahertz frequency vibration, changing the bands near the Fermi level and enhancing the infrared (IR) light absorption significantly. The enhancement of such IR absorbance offering a broader absorption (from 300 to 1200 nm) will benefit light harvesting in potential applications of solar energy conversion. PMID:25559269

  19. Landau pole in the Standard Model with weakly interacting scalar fields

    NASA Astrophysics Data System (ADS)

    Hamada, Yuta; Kawana, Kiyoharu; Tsumura, Koji

    2015-07-01

    We consider the Standard Model with a new scalar field X which is an nX representation of the SU (2)L with a hypercharge YX. The renormalization group running effects on the new scalar quartic coupling constants are evaluated. Even if we set the scalar quartic coupling constants to be zero at the scale of the new scalar field, the coupling constants are induced by the one-loop effect of the weak gauge bosons. Once non-vanishing couplings are generated, the couplings rapidly increase by renormalization group effect of the quartic coupling constant itself. As a result, the Landau pole appears below Planck scale if nX ≥ 4. We find that the scale of the obtained Landau pole is much lower than that evaluated by solving the one-loop beta function of the gauge coupling constants.

  20. Theoretical Prediction of Hydrogen Separation Performance of Two-Dimensional Carbon Network of Fused Pentagon.

    PubMed

    Zhu, Lei; Xue, Qingzhong; Li, Xiaofang; Jin, Yakang; Zheng, Haixia; Wu, Tiantian; Guo, Qikai

    2015-12-30

    Using the van-der-Waals-corrected density functional theory (DFT) and molecular dynamic (MD) simulations, we theoretically predict the H2 separation performance of a new two-dimensional sp(2) carbon allotropes-fused pentagon network. The DFT calculations demonstrate that the fused pentagon network with proper pore sizes presents a surmountable energy barrier (0.18 eV) for H2 molecule passing through. Furthermore, the fused pentagon network shows an exceptionally high selectivity for H2/gas (CO, CH4, CO2, N2, et al.) at 300 and 450 K. Besides, using MD simulations we demonstrate that the fused pentagon network exhibits a H2 permeance of 4 × 10(7) GPU at 450 K, which is much higher than the value (20 GPU) in the current industrial applications. With high selectivity and excellent permeability, the fused pentagon network should be an excellent candidate for H2 separation. PMID:26632974

  1. Origin of kinetic instability of fullerenes that violate the isolated pentagon rule.

    PubMed

    Aihara, Jun-ichi

    2015-03-26

    The isolated pentagon rule (IPR) holds without exceptions for neutral fullerene molecules. Unlike those in non-IPR fullerenes, 5/5 bonds (i.e., π-bonds shared by two pentagons) in many planar polycyclic π-systems are kinetically rather stable with large positive bond resonance energies (BREs), where BRE is a graph-theoretically defined index of kinetic stability. Geometric conditions were explored for designing planar polycyclic π-systems with unstable 5/5 bonds. We then found that the kinetic instability of non-IPR fullerenes stems from the coexistence of pentalene substructures and nearby disjoint pentagons. Proper arrangements of fused pentagons and disjoint pentagons make the 5/5 bonds highly reactive with large negative BREs. PMID:25746678

  2. One-Loop β Functions for Yukawa Couplings in the Electroweak-Scale Right-Handed Neutrino Model

    NASA Astrophysics Data System (ADS)

    Nhu Le, Nguyen; Quang Hung, Pham

    2014-09-01

    Fermions in the model of electroweak-scale right-handed neutrinos (EWRH) with masses of the order of 300 GeV or more could result in dynamical electroweak symmetry breaking by forming condensates through the exchange of a fundamental Higgs scalar doublet or triplet. These condensates are dynamically studied within the framework of the Schwinger- Dyson equation. With the electroweak symmetry broken by condensates, the fully worked-out model of EWRH in which there are two doublets and two triplets, one of which is composite and the others being the original fundamental scalar doublet and triplet could be suitable for recent LHC discovery of the 125 GeV scalar particle.

  3. Absence of cosmological constant problem in special relativistic field theory of gravity: one-loop renormalization group

    NASA Astrophysics Data System (ADS)

    Carballo-Rubio, Raúl; Barceló, Carlos; Garay, Luis J.

    2015-04-01

    There exists a nonlinear theory of gravity which is not structurally equivalent to general relativity and that, in the non-interacting limit, describes a free massless particle with helicity ±2. We have recently shown that this theory can be understood as the result of self-coupling, in complete parallelism to the well-known case of general relativity. This special relativistic field theory of gravity exhibits a decoupling of vacuum zero-point energies of matter and passes all the known experimental tests in gravitation. It is explicitly demonstrated that there is no flow of the effective cosmological constant under the action of the renormalization group at one-loop level, while simple symmetry arguments show that this would continue to be true for higher-loop corrections. The important lesson is that just mild local assumptions concerning the nature of the particle mediating the gravitational interactions are enough to motivate theories which are free of the cosmological constant problem.

  4. Continuum behavior of lattice QED, discretized with one-sided lattice differences, in one-loop order

    SciTech Connect

    Sadooghi, N.; Rothe, H.J.

    1997-06-01

    A lattice action for QED is considered, where the derivatives in the Dirac operator are replaced by one-sided lattice differences. A systematic expansion in the lattice spacing of the one-loop contribution to the fermion self-energy, vacuum polarization tensor, and vertex function is carried out for an arbitrary choice of one-sided lattice differences. It is shown that only the vacuum polarization tensor possesses the correct continuum limit, while the fermion self-energy and vertex function receive noncovariant contributions. A lattice action, discretized with a fixed choice of one-sided lattice differences, therefore, does not define a renormalizable field theory. The noncovariant contributions can, however, be eliminated by averaging the expression over all possible choices of one-sided lattice differences. {copyright} {ital 1997} {ital The American Physical Society}

  5. Regular scalar collapse

    NASA Astrophysics Data System (ADS)

    Lasukov, V. V.

    2012-06-01

    It is shown that negative Scalars can claim to be the object referred to as black holes, therefore observation of black holes means observation of Scalars. In contrast to blackholes, negative Scalars contain no singularity inside. Negative Scalars can be observed from the effect of generation of ordinary matter by the Lemaître primordial atom.

  6. One-loop stress-tensor renormalization in curved background: The relation between ζ-function and point-splitting approaches, and an improved point-splitting procedure

    NASA Astrophysics Data System (ADS)

    Moretti, Valter

    1999-08-01

    We conclude the rigorous analysis of a previous paper [V. Moretti, Commun. Math. Phys. 201, 327 (1999)] concerning the relation between the (Euclidean) point-splitting approach and the local ζ-function procedure to renormalize physical quantities at one-loop in (Euclidean) Quantum Field Theory in curved space-time. The case of the stress tensor is now considered in general D-dimensional closed manifolds for positive scalar operators -Δ+V(x). Results obtained formally in previous works [in the case D=4 and V(x)=ξR(x)+m2] are rigorously proven and generalized. It is also proven that, in static Euclidean manifolds, the method is compatible with Lorentzian-time analytic continuations. It is proven that the result of the ζ-function procedure is the same obtained from an improved version of the point-splitting method which uses a particular choice of the term w0(x,y) in the Hadamard expansion of the Green's function, given in terms of heat-kernel coefficients. This version of the point-splitting procedure works for any value of the field mass m. If D is even, the result is affected by an arbitrary one-parameter class of (conserved in absence of external source) symmetric tensors, dependent on the geometry locally, and it gives rise to the general correct trace expression containing the renormalized field fluctuations as well as the conformal anomaly term. Furthermore, it is proven that, in the case D=4 and V(x)=ξR(x)+m2, the given procedure reduces to the Euclidean version of Wald's improved point-splitting procedure provided the arbitrary mass scale present in the ζ-function is chosen opportunely. It is finally argued that the found point-splitting method should work generally, also dropping the hypothesis of a closed manifold, and not depending on the ζ-function procedure. This fact is indeed checked in the Euclidean section of Minkowski space-time for A=-Δ+m2 where the method gives rise to the correct Minkowski stress tensor for m2⩾0 automatically.

  7. golem95: A numerical program to calculate one-loop tensor integrals with up to six external legs

    NASA Astrophysics Data System (ADS)

    Binoth, T.; Guillet, J.-Ph.; Heinrich, G.; Pilon, E.; Reiter, T.

    2009-11-01

    We present a program for the numerical evaluation of form factors entering the calculation of one-loop amplitudes with up to six external legs. The program is written in Fortran95 and performs the reduction to a certain set of basis integrals numerically, using a formalism where inverse Gram determinants can be avoided. It can be used to calculate one-loop amplitudes with massless internal particles in a fast and numerically stable way. Catalogue identifier: AEEO_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEEO_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 50 105 No. of bytes in distributed program, including test data, etc.: 241 657 Distribution format: tar.gz Programming language: Fortran95 Computer: Any computer with a Fortran95 compiler Operating system: Linux, Unix RAM: RAM used per form factor is insignificant, even for a rank six six-point form factor Classification: 4.4, 11.1 External routines: Perl programming language (http://www.perl.com/) Nature of problem: Evaluation of one-loop multi-leg tensor integrals occurring in the calculation of next-to-leading order corrections to scattering amplitudes in elementary particle physics. Solution method: Tensor integrals are represented in terms of form factors and a set of basic building blocks ("basis integrals"). The reduction to the basis integrals is

  8. Antenna of adjustable bandwidth based on a pentagonal array

    NASA Astrophysics Data System (ADS)

    Tecpoyotl-Torres, M.; Vera-Dimas, J. G.; Cabello Ruiz, R.; García-García, O.; Escobedo-Alatorre, J.; Sanchez-Mondragon, J.; Torres-Cisneros, M.; Varona, J.; Vargas-Bernal, R.

    2011-09-01

    Antenna characteristics are chosen according to the features determined by the systems where they will be used. While some systems require a very narrow bandwidth, others may operate with a much wider bandwidth. Some techniques used for increasing the bandwidth of a given antenna have considered mechanical adjustment of the air layer thickness, with the consequent change on the effective permittivity and performance. Some other systems consider a suitable choice of feeding techniques and impedance matching network. However, approaches for reducing the bandwidth have not received the same level of attention. Narrow bandwidth antennas are of particular interest in security and surveillance systems. In this work we present a technique, based on the design of a pentagonal antenna array, which allows for adjusting the bandwidth in either direction. The array is formed by an inner patch designed at the desired operating frequency of the system and a gap coupled external ring centered at a different frequency (lower or very near the operating frequency), which determines the potential bandwidth increment or decrement. The feed point is located on the inner patch. As a proof-of-concept, this work offers a tuning range that goes from -40% of the center frequency up to +50% of the center operating frequency of the patch antenna. The single patch antenna of this work was designed and simulated at an operating frequency of 4.9 GHz on RT/Duroid 5880.

  9. Pentagone internalises glypicans to fine-tune multiple signalling pathways

    PubMed Central

    Norman, Mark; Vuilleumier, Robin; Springhorn, Alexander; Gawlik, Jennifer; Pyrowolakis, George

    2016-01-01

    Tight regulation of signalling activity is crucial for proper tissue patterning and growth. Here we investigate the function of Pentagone (Pent), a secreted protein that acts in a regulatory feedback during establishment and maintenance of BMP/Dpp morphogen signalling during Drosophila wing development. We show that Pent internalises the Dpp co-receptors, the glypicans Dally and Dally-like protein (Dlp), and propose that this internalisation is important in the establishment of a long range Dpp gradient. Pent-induced endocytosis and degradation of glypicans requires dynamin- and Rab5, but not clathrin or active BMP signalling. Thus, Pent modifies the ability of cells to trap and transduce BMP by fine-tuning the levels of the BMP reception system at the plasma membrane. In addition, and in accordance with the role of glypicans in multiple signalling pathways, we establish a requirement of Pent for Wg signalling. Our data propose a novel mechanism by which morphogen signalling is regulated. DOI: http://dx.doi.org/10.7554/eLife.13301.001 PMID:27269283

  10. Modelling rumors: the no plane Pentagon French hoax case

    NASA Astrophysics Data System (ADS)

    Galam, Serge

    2003-03-01

    The recent astonishing wide adhesion of French people to the rumor claiming ‘No plane did crash on the Pentagon on September 11’, is given a generic explanation in terms of a model of minority opinion spreading. Using a majority rule reaction-diffusion dynamics, a rumor is shown to invade for sure a social group provided it fulfills simultaneously two criteria. First it must initiate with a support beyond some critical threshold which however, turns out to be always very low. Then it has to be consistent with some larger collective social paradigm of the group. Otherwise it just dies out. Both conditions were satisfied in the French case with the associated book sold at more than 200 000 copies in just a few days. The rumor was stopped by the firm stand of most newspaper editors stating it is nonsense. Such an incredible social dynamics is shown to result naturally from an open and free public debate among friends and colleagues. Each one searching for the truth sincerely on a free will basis and without individual biases. The polarization process appears also to be very quick in agreement with reality. It is a very strong anti-democratic reversal of opinion although made quite democratically. The model may apply to a large range of rumors.

  11. Hexagon and pentagon identities for the Z sub 3 Potts model

    SciTech Connect

    Ryang, S. )

    1991-04-15

    Investigating the transformation properties of the conformal blocks in the {ital Z}{sub 3} Potts model we derive some braid matrices. From the obtained braid matrices we explicitly show how the hexagon and pentagon identities are satisfied.

  12. Dynamic criticality far from equilibrium: One-loop flow of Burgers-Kardar-Parisi-Zhang systems with broken Galilean invariance.

    PubMed

    Strack, Philipp

    2015-03-01

    Burgers-Kardar-Parisi-Zhang (KPZ) scaling has recently (re-) surfaced in a variety of physical contexts, ranging from anharmonic chains to quantum systems such as open superfluids, in which a variety of random forces may be encountered and/or engineered. Motivated by these developments, we here provide a generalization of the KPZ universality class to situations with long-ranged temporal correlations in the noise, which purposefully break the Galilean invariance that is central to the conventional KPZ solution. We compute the phase diagram and critical exponents of the KPZ equation with 1/f noise (KPZ1/f) in spatial dimensions 1≤d<4 using the dynamic renormalization group with a frequency cutoff technique in a one-loop truncation. Distinct features of KPZ1/f are (i) a generically scale-invariant, rough phase at high noise levels that violates fluctuation-dissipation relations and exhibits hyperthermal statistics even in d=1, (ii) a fine-tuned roughening transition at which the flow fulfills an emergent thermal-like fluctuation-dissipation relation, that separates the rough phase from (iii) a massive phase in 1

  13. A diagrammatic kinetic theory of density fluctuations in simple liquids in the overdamped limit. II. The one-loop approximation

    PubMed Central

    Pilkiewicz, Kevin R.; Andersen, Hans C.

    2014-01-01

    A diagrammatic kinetic theory of density fluctuations in simple dense liquids at long times, described in Paper I, is applied to a high density Lennard-Jones liquid to calculate various equilibrium time correlation functions. The calculation starts from the general theory and makes two approximations. (1) The general diagrammatic expression for an irreducible memory kernel is approximated using a one-loop approximation. (2) The generalized Enskog projected propagator, which is required for the calculation, is approximated using a simple kinetic model for the hard sphere memory function. The coherent intermediate scattering function (CISF), the longitudinal current correlation function (LCCF), the transverse current correlation function (TCCF), the incoherent intermediate scattering function (IISF), and the incoherent longitudinal current correlation function are calculated and compared with simulation results for the Lennard-Jones liquid at high density. The approximate theoretical results are in good agreement with the simulation data for the IISF for all wave vectors studied and for the CISF and LCCF for large wave vector. The approximate results are in poor agreement with the simulation data for the CISF, LCCF, and TCCF for small wave vectors because these functions are strongly affected by hydrodynamic fluctuations at small wave vector that are not well described by the simple kinetic model used. The possible implications of this approach for the study of liquids are discussed.

  14. One-loop omega-potential of quantum fields with ellipsoid constant-energy surface dispersion law

    NASA Astrophysics Data System (ADS)

    Kazinski, P. O.; Shipulya, M. A.

    2011-10-01

    Rapidly convergent expansions of a one-loop contribution to the partition function of quantum fields with ellipsoid constant-energy surface dispersion law are derived. The omega-potential is naturally decomposed into three parts: the quasiclassical contribution, the contribution from the branch cut of the dispersion law, and the oscillating part. The low- and high-temperature expansions of the quasiclassical part are obtained. An explicit expression and a relation of the contribution from the cut with the Casimir term and vacuum energy are established. The oscillating part is represented in the form of the Chowla-Selberg expansion of the Epstein zeta function. Various resummations of this expansion are considered. The general procedure developed is then applied to two models: massless particles in a box both at zero and nonzero chemical potential, and electrons in a thin metal film. Rapidly convergent expansions of the partition function and average particle number are obtained for these models. In particular, the oscillations of the chemical potential of conduction electrons in graphene and a thin metal film due to a variation of size of the crystal are described.

  15. Generic scalar potentials in geometric scalar gravity

    NASA Astrophysics Data System (ADS)

    Kan, Nahomi; Shiraishi, Kiyoshi

    2016-06-01

    We discuss a generic form of the scalar potential appearing in the geometric scalar theory of gravity. We find the conditions on the potential by considering weak and strong gravity. The modified black hole solutions are obtained for generic potentials and the inverse problems on a black hole and on a spherical body (`pseudo-gravastar') are investigated.

  16. One-loop divergences in non-Abelian supersymmetric theories regularized by BRST-invariant version of the higher derivative regularization

    NASA Astrophysics Data System (ADS)

    Aleshin, S. S.; Kazantsev, A. E.; Skoptsov, M. B.; Stepanyantz, K. V.

    2016-05-01

    We consider a general non-Abelian renormalizable {N} = 1 supersymmetric gauge theory, regularized by higher covariant derivatives without breaking the BRST invariance, and calculate one-loop divergences for a general form of higher derivative regulator and of the gauge fixing term. It is demonstrated that the momentum integrals giving the one-loop β-function are integrals of double total derivatives independently of a particular choice of the higher derivative term. Evaluating them we reproduce the well-known result for the one-loop β-function. Also we find that the three-point ghost vertices with a single line of the quantum gauge superfield are not renormalized in the considered approximation.

  17. Constructing scalar-photon three point vertex in massless quenched scalar QED

    NASA Astrophysics Data System (ADS)

    Fernández-Rangel, L. Albino; Bashir, Adnan; Gutiérrez-Guerrero, L. X.; Concha-Sánchez, Y.

    2016-03-01

    Nonperturbative studies of Schwinger-Dyson equations require their infinite, coupled tower to be truncated in order to reduce them to a practically solvable set. In this connection, a physically acceptable Ansatz for the three point vertex is the most favorite choice. Scalar quantum electrodynamics (sQED) provides a simple and neat platform to address this problem. The most general form of the three point scalar-photon vertex can be expressed in terms of only two independent form factors, a longitudinal and a transverse one. Ball and Chiu have demonstrated that the longitudinal vertex is fixed by requiring the Ward-Fradkin-Green-Takahashi identity while the transverse vertex remains undetermined. In massless quenched sQED, we construct the transverse part of the nonperturbative scalar-photon vertex. This construction (i) ensures multiplicative renormalizability of the scalar propagator in keeping with the Landau-Khalatnikov-Fradkin transformations, (ii) has the same transformation properties as the bare vertex under charge conjugation, parity and time reversal, (iii) has no kinematic singularities and (iv) reproduces the one-loop asymptotic result in the weak coupling regime of the theory.

  18. Design of modified pentagonal patch antenna on defective ground for Wi-Max/WLAN application

    NASA Astrophysics Data System (ADS)

    Rawat, Sanyog; Sharma, K. K.

    2016-04-01

    This paper presents the design and performance of a modified pentagonal patch antenna with defective ground plane. A pentagonal slot is inserted in the pentagonal patch and slot loaded ground through optimized dimensions is used in the antenna to resonate it at dual frequency. The geometry operates at two resonant frequencies (2.5 GHz and 5.58 GHz) and offers impedance bandwidth of 864 MHz and 554 MHz in the two bands of interest. The proposed antenna covers the lower band (2.45 to 2.484/2.495 to 2.695 GHz) and upper band (5.15 to 5.825 GHz/5.25 to 5.85 GHz) allocated for Wi-Max and WLAN communication systems.

  19. Electron diffraction analysis of the pentagonal arrangement of grains found in CVD pure Ni films

    SciTech Connect

    Campbell, A.N.; Carr, M.J.; VanderSande, J.B.

    1986-01-01

    The structure of each crystal in the pentagon is fcc, as verified by diffraction patterns from individual grains. It is suggested that the large pentagonal regions observed were nucleated by small decahedral clusters of Ni atoms during the early stages of the deposition. However, for grains as large as those shown the body centered orthorhombic structure is not stable; at some point during the growth process the crystal structure reverted to the energetically preferred fcc. The relative orientation between the individual crystals, having been established by the decahedral nucleus, was preserved during growth. The 7.5/sup 0/ mismatch was taken up evenly around the pentagon by the formation of dislocations and/or secondary twins at the boundaries.

  20. Enhancing immunomodulation on innate immunity by shape transition among RNA triangle, square and pentagon nanovehicles

    PubMed Central

    Khisamutdinov, Emil F.; Li, Hui; Jasinski, Daniel L.; Chen, Jiao; Fu, Jian; Guo, Peixuan

    2014-01-01

    Modulation of immune response is important in cancer immunotherapy, vaccine adjuvant development and inflammatory or immune disease therapy. Here we report the development of new immunomodulators via control of shape transition among RNA triangle, square and pentagon. Changing one RNA strand in polygons automatically induced the stretching of the interior angle from 60° to 90° or 108°, resulting in self-assembly of elegant RNA triangles, squares and pentagons. When immunological adjuvants were incorporated, their immunomodulation effect for cytokine TNF-α and IL-6 induction was greatly enhanced in vitro and in animals up to 100-fold, while RNA polygon controls induced unnoticeable effect. The RNA nanoparticles were delivered to macrophages specifically. The degree of immunostimulation greatly depended on the size, shape and number of the payload per nanoparticles. Stronger immune response was observed when the number of adjuvants per polygon was increased, demonstrating the advantage of shape transition from triangle to pentagon. PMID:25092921

  1. Comparison of aerodynamic characteristics of pentagonal and hexagonal shaped bridge decks

    NASA Astrophysics Data System (ADS)

    Haque, Md. Naimul; Katsuchi, Hiroshi; Yamada, Hitoshi; Nishio, Mayuko

    2016-07-01

    Aerodynamics of the long-span bridge deck should be well understood for an efficient design of the bridge system. For practical bridges various deck shapes are being recommended and adopted, yet not all of their aerodynamic behaviors are well interpreted. In the present study, a numerical investigation was carried out to explore the aerodynamic characteristics of pentagonal and hexagonal shaped bridge decks. A relative comparison of steady state aerodynamic responses was made and the flow field was critically analyzed for better understanding the aerodynamic responses. It was found that the hexagonal shaped bridge deck has better aerodynamic characteristics as compared to the pentagonal shaped bridge deck.

  2. Scalar Gravitational Waves

    NASA Astrophysics Data System (ADS)

    Mottola, Emil

    2016-03-01

    General Relativity receives quantum corrections relevant at macroscopic distance scales and near event horizons. These arise from the conformal scalar degree of freedom in the extended effective field theory (EFT) of gravity generated by the trace anomaly of massless quantum fields in curved space. Linearized around flat space this quantum scalar degree of freedom combines with the conformal part of the metric and predicts the existence of scalar spin-0 ``breather'' propagating gravitational waves in addition to the transverse tensor spin-2 waves of classical General Relativity. Estimates of the expected strength of scalar gravitational radiation from compact astrophysical sources are given.

  3. Electroweak baryogenesis in a scalar-assisted vectorlike fermion model

    NASA Astrophysics Data System (ADS)

    Xiao, Ming-Lei; Yu, Jiang-Hao

    2016-07-01

    We extend the standard model to a scalar-assisted vectorlike fermion model to realize electroweak baryogenesis. The extended Cabibbo-Kobayashi-Maskawa matrix, due to the mixing among the vectorlike quark and the standard model quarks, provides additional sources of the C P violation. Together with the enhancement from a large vectorlike quark mass, a large enough baryon-to-photon ratio could be obtained. The strongly first-order phase transition could be realized via the potential barrier which separates the broken minimum and the symmetric minimum in the scalar potential. We investigate in detail the one loop temperature-dependent effective potential and perform a random parameter scan to study the allowed parameter region that satisfies the strongly first order phase transition criteria vc≥Tc. Several distinct patterns of phase transition are classified and discussed. Among these patterns, a large trilinear mass term between the Higgs boson and the scalar is preferred, for it controls the width of the potential barrier. Our results indicate large quartic scalar couplings and a moderate mixing angle between the Higgs boson and the new scalar. This parameter region could be further explored at the Run 2 LHC.

  4. Effects of a real singlet scalar on Veltman condition

    NASA Astrophysics Data System (ADS)

    Karahan, Canan Nurhan; Korutlu, Beste

    2014-05-01

    We revisit the fine-tuning problem in the Standard Model (SM) and show the modification in the Veltman condition by virtue of a minimally-extended particle spectrum with one real SM gauge singlet scalar field. We demand the new scalar to interact with the SM fields through Higgs portal only, and the new singlet to acquire a vacuum expectation value, resulting in a mixing with the CP-even neutral component of the Higgs doublet in the SM. The experimental bounds on the mixing angle are determined by the observed best-fit signal strength σ/σ. While, the one-loop radiative corrections to the Higgs mass squared, computed with an ultraviolet cut-off scale Λ, come with a negative coefficient, the quantum corrections to the singlet mass squared acquire both positive and negative values depending on the parameter space chosen, which if positive might be eliminated by introducing singlet or doublet vector-like fermions. However, based upon the fact that there is mixing between the scalars, when transformed into the physical states, the tree-level coupling of the Higgs field to the vector-like fermions worsens the Higgs mass hierarchy problem. Therefore, the common attempt to introduce vector-like fermions to cancel the divergences in the new scalar mass might not be a solution, if there is mixing between the scalars.

  5. On mass shell renormalization of one loop radiative corrections in e/sup +/e/sup -/ yields W/sup +/W/sup -/

    SciTech Connect

    Kalyniak, P.; Sundaresan, M.K. . Dept. of Physics)

    1988-01-01

    In this paper, the one loop radiative corrections for the process e/sup +/e/sup -/ {yields} W/sup +/W/sup -/ are re-examined adopting the on-mass shell subtraction scheme. The main purpose of the paper is to present the details of this procedure. A complete computer program for the calculation of the radiative corrections based on this scheme is being developed to analyze the experimental data.

  6. How does particle shape affect the near jamming properties of granular materials? Pentagons vs. disks

    NASA Astrophysics Data System (ADS)

    Zhao, Yiqiu; Bares, Jonathan; Behringer, Bob

    Understanding the role of particle shape in system-scale properties is a fundamental challenge in granular physics. We investigated the difference between the response of systems made of pentagons vs. more traditional disks. We performed isotropic compression experiments on 2D photoelastic pentagons and disks near the jamming transition. These experiments show qualitative and quantitative differences in the macroscopic responses of the two systems, such as shifts in the packing fraction at jamming onset and differences in the contact number evolution. Some of these differences are due to a reduction of packing order and the appearance of side-side contacts for the pentatons. We also examined the stress relaxation and dynamical heterogeneity of pentagon particles by performing cyclic compression to allow the system explore phase diagram. We contrast disk and pentagon evolution using four-point-susceptibility and G2 techniques. Work supported by NSF-DMR1206351, DMS1248071, NASA NNX15AD38G, and the W.M. Keck Foundation.

  7. From Pentagon to Triangle: A Cross-Cultural Investigation of an Implicit Theory of Giftedness.

    ERIC Educational Resources Information Center

    Zhang, Li-fang; Hui, Sammy King-fai

    2002-01-01

    This study examined use of Sternberg and Zhang's (1995) pentagonal implicit theory of giftedness by 189 preservice teachers in China. In making judgments about giftedness, study participants considered three of the models' five criteria: excellence, productivity, and value (but not rarity and demonstrability). Results are compared to similar…

  8. A geometric formulation of Higgs Effective Field Theory: Measuring the curvature of scalar field space

    NASA Astrophysics Data System (ADS)

    Alonso, Rodrigo; Jenkins, Elizabeth E.; Manohar, Aneesh V.

    2016-03-01

    A geometric formulation of Higgs Effective Field Theory (HEFT) is presented. Experimental observables are given in terms of geometric invariants of the scalar sigma model sector such as the curvature of the scalar field manifold M. We show how the curvature can be measured experimentally via Higgs cross-sections, WL scattering, and the S parameter. The one-loop action of HEFT is given in terms of geometric invariants of M. The distinction between the Standard Model (SM) and HEFT is whether M is flat or curved, and the curvature is a signal of the scale of new physics.

  9. Inflationary universe from higher derivative quantum gravity coupled with scalar electrodynamics

    NASA Astrophysics Data System (ADS)

    Myrzakulov, R.; Odintsov, S. D.; Sebastiani, L.

    2016-06-01

    We study inflation for a quantum scalar electrodynamics model in curved space-time and for higher-derivative quantum gravity (QG) coupled with scalar electrodynamics. The corresponding renormalization-group (RG) improved potential is evaluated for both theories in Jordan frame where non-minimal scalar-gravitational coupling sector is explicitly kept. The role of one-loop quantum corrections is investigated by showing how these corrections enter in the expressions for the slow-roll parameters, the spectral index and the tensor-to-scalar ratio and how they influence the bound of the Hubble parameter at the beginning of the primordial acceleration. We demonstrate that the viable inflation maybe successfully realized, so that it turns out to be consistent with last Planck and BICEP2/Keck Array data.

  10. Scalar Contribution to the Graviton Self-Energy During Inflation

    SciTech Connect

    Park, Sohyun

    2012-01-01

    We use dimensional regularization to evaluate the one loop contribution to the graviton self-energy from a massless, minimally coupled scalar on a locally de Sitter background. For noncoincident points our result agrees with the stress tensor correlators obtained recently by Perez-Nadal, Roura and Verdaguer. We absorb the ultraviolet divergences using the R2 and C2 counterterms first derived by ’t Hooft and Veltman, and we take the D = 4 limit of the finite remainder. The renormalized result is expressed as the sum of two transverse, 4th order differential operators acting on nonlocal, de Sitter invariant structure functions. In this form it can be used to quantum-correct the linearized Einstein equations so that one can study how the inflationary production of infrared scalars affects the propagation of dynamical gravitons and the force of gravity. We have seen that they have no effect on the propagation of dynamical gravitons. Our computation motivates a conjecture for the first correction to the vacuum state wave functional of gravitons. We comment as well on performing the same analysis for the more interesting contribution from inflationary gravitons, and on inferring one loop corrections to the force of gravity.

  11. SFOLD — A program package for calculating two-body sfermion decays at full one-loop level in the MSSM

    NASA Astrophysics Data System (ADS)

    Hluchá, H.; Eberl, H.; Frisch, W.

    2012-10-01

    SFOLD (Sfermion Full One-Loop Decays) is a Fortran program package for calculating all sfermion two-body decay widths and the corresponding branching ratios at full one-loop level within the MSSM. The package adopts the SUSY Parameter Analysis convention and supports the SUSY Les Houches Accord input and output format. With the SFOLD package we found non-negligible electroweak corrections in bosonic decays of b˜,t˜ and τ˜. Program summaryProgram title: SFOLD Catalogue identifier: AEMZ_v1_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEMZ_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU General Public License, version 3 No. of lines in distributed program, including test data, etc.: 263346 No. of bytes in distributed program, including test data, etc.: 1481697 Distribution format: tar.gz Programming language: Fortran 77. Computer: Workstation, PC. Operating system: Linux. RAM: approx. 500 Mbytes Classification: 11.1. External routines: LoopTools 2.6 (http://www.feynarts.de/looptools/), SLHALib 2.2 (http://www.feynarts.de/slha/) Nature of problem: If the MSSM is realized in nature, LHC will produce supersymmetric particles copiously. The best environment for a precise determination of the model parameters would be a high energy e+e- linear collider. Experimental accuracies are expected at the per-cent down to the per-mill level. These must be matched from the theoretical side. Therefore loop calculations are mandatory. Solution method: This program package calculates all sfermion two-body decay widths and the corresponding branching ratios at full one-loop level within the MSSM. The renormalization is done in the DR¯ scheme following the SUSY Parameter Analysis convention. The program supports the SUSY Les Houches Accord input and output format. Running time: The test provided just takes a few seconds to run.

  12. Factorization for radiative heavy quarkonium decays into scalar Glueball

    NASA Astrophysics Data System (ADS)

    Zhu, Ruilin

    2015-09-01

    We establish the factorization formula for scalar Glueball production through radiative decays of vector states of heavy quarkonia, e.g. J/ ψ, ψ(2 S) and Υ( nS), where the Glueball mass is much less than the parent heavy quarkonium mass. The factorization is demonstrated explicitly at one-loop level through the next-to-leading order (NLO) corrections to the hard kernel, the non-relativistic QCD (NRQCD) long-distance matrix elements (LDMEs) of the heavy quarkonium, and the light-cone distribution amplitude (LCDA) of scalar Glueball. The factorization provides a comprehensive theoretical approach to investigate Glueball production in the radiative decays of vector states of heavy quarkonia and determine the physic nature of Glueball. We discuss the scale evolution equation of LCDA for scalar Glueball. In the end, we extract the value of the decay constant of Scalar Glueball from Lattice QCD calculation and analyze the mixing effect among f 0(1370), f 0(1500) and f 0(1710).

  13. One-loop corrections to the perturbative unitarity bounds in the CP-conserving two-Higgs doublet model with a softly broken {{Z}}_2 symmetry

    NASA Astrophysics Data System (ADS)

    Grinstein, Benjamín; Murphy, Christopher W.; Uttayarat, Patipan

    2016-06-01

    We compute all of the one-loop corrections that are enhanced, O( λ i λ j /16 π 2), in the limit s ≫ | λ i | v 2 ≫ M W 2 , s ≫ m 12 2 to all the 2 → 2 longitudinal vector boson and Higgs boson scattering amplitudes in the CP -conserving two-Higgs doublet model with a softly broken {{Z}}_2 symmetry. In the two simplified scenarios we study, the typical bound we find is | λ i ( s)| ⪷ 4.

  14. Constraint on R-parity violating MSSM at the one-loop level from CP-odd N-N interaction

    SciTech Connect

    Yamanaka, Nodoka; Sato, Toru; Kubota, Takahiro

    2011-10-21

    Minimal supersymmetric standard model with R-parity violation (RPVMSSM) contributes to the P-, CP-odd four-quark interaction. The P-, CP-odd four-quark interaction is constrained by the new {sup 199}Hg EDM experimental data. It is then possible to constrain R-parity violating (RPV) couplings from the {sup 199}Hg EDM data. In this talk, we analyze the RPV contribution to the P-, CP-odd four-quark interaction at the one-loop level to give constraints on RPV parameters.

  15. One-loop corrections to the perturbative unitarity bounds in the CP-conserving two-Higgs doublet model with a softly broken {mathbb{Z}}_2 symmetry

    NASA Astrophysics Data System (ADS)

    Grinstein, Benjamín; Murphy, Christopher W.; Uttayarat, Patipan

    2016-06-01

    We compute all of the one-loop corrections that are enhanced, O( λ i λ j /16 π 2), in the limit s ≫ | λ i | v 2 ≫ M W 2 , s ≫ m 12 2 to all the 2 → 2 longitudinal vector boson and Higgs boson scattering amplitudes in the CP -conserving two-Higgs doublet model with a softly broken {mathbb{Z}}_2 symmetry. In the two simplified scenarios we study, the typical bound we find is | λ i ( s)| ⪷ 4.

  16. The trace anomaly and massless scalar degrees of freedom

    SciTech Connect

    Gianotti, Maurizio; Mottola, Emil

    2008-01-01

    The trace anomaly of quantum fields in electromagnetic or gravitational backgrounds implies the existence of massless scalar poles in physical amplitudes involving the stress-energy tensor. Considering first the axial anomaly and using QED as an example, we compute the full one-loop triangle amplitude of the fermionic stress tensor with two current vertices, {open_square}T{sup {mu}{nu}}J{sup {alpha}}J{sup {beta}}, and exhibit the scalar pole in this amplitude associated with the trace anomaly, in the limit of zero electron mass m{yields}0. To emphasize the infrared aspect of the anomaly, we use a dispersive approach and show that this amplitude and the existence of the massless scalar pole is determined completely by its ultraviolet finite terms, together with the requirements of Poincare invariance of the vacuum, Bose symmetry under interchange of J{sup {alpha}} and J{sup {beta}}, and vector current and stress-tensor conservation. We derive a sum rule for the appropriate positive spectral function corresponding to the discontinuity of the triangle amplitude, showing that it becomes proportional to {delta}(k{sup 2}) and therefore contains a massless scalar intermediate state in the conformal limit of zero electron mass. The effective action corresponding to the trace of the triangle amplitude can be expressed in local form by the introduction of two scalar auxiliary fields which satisfy massless wave equations. These massless scalar degrees of freedom couple to classical sources, contribute to gravitational scattering processes, and can have long range gravitational effects.

  17. Spontaneous Scalarization of Massive Fields

    NASA Astrophysics Data System (ADS)

    Ramazanoglu, Fethi M.; Pretorius, Frans

    2014-03-01

    Spontaneous scalarization is a phenomenon in certain scalar-tensor theories where large deviations from general relativity can be observed inside compact stars, while the known observational bounds can also be satisfied far away. This scenario has been investigated for massless scalars and binary neutron stars using numerical relativity, but the parameter space for such theories have been severely restricted by recent observations. Here, we present our results on the spontaneous scalarization of massive scalars. We simulate cases with different equations of state and scalar field parameters, and comment on the detectability of the scalar field effects from the gravitational wave signal.

  18. Multi-disclination configurations in pentagonal microcrystals and two-dimensional carbon structures

    NASA Astrophysics Data System (ADS)

    Yasnikov, I. S.; Kolesnikova, A. L.; Romanov, A. E.

    2016-06-01

    A mechanism of decrease in the elastic (latent) energy of a solid containing disclination defects by introducing multi-disclination configurations of opposite sign has been considered. The relation of the proposed model with relaxation modifications of microcrystals with pentagonal symmetry, as well as with the structure of two-dimensional carbon films, has been discussed. An approach to the prediction of new carbon structures inherently containing multi-disclination configurations with screening has been demonstrated.

  19. Evolution of Pentagonal Nano- and Micro-Objects in Temperature Fields

    NASA Astrophysics Data System (ADS)

    Dorogov, M. V.; Vikarchuk, A. A.; Romanov, A. E.

    2015-10-01

    The effect of temperature and annealing atmosphere on the structure and morphology of small icosahedral copper particles and filamentary pentagonal crystals has been investigated. Particles and filamentary crystals were obtained by electrodeposition of metal, and their structure and morphology were investigated by electron microscopy and x-ray diffraction. It has been shown that during annealing, whiskers are formed on the surface of the particles together with porous and "flake" structures, and cavities are formed inside them.

  20. Structure of force networks in tapped particulate systems of disks and pentagons. I. Clusters and loops

    NASA Astrophysics Data System (ADS)

    Pugnaloni, Luis A.; Carlevaro, C. Manuel; Kramár, M.; Mischaikow, K.; Kondic, L.

    2016-06-01

    The force network of a granular assembly, defined by the contact network and the corresponding contact forces, carries valuable information about the state of the packing. Simple analysis of these networks based on the distribution of force strengths is rather insensitive to the changes in preparation protocols or to the types of particles. In this and the companion paper [Kondic et al., Phys. Rev. E 93, 062903 (2016), 10.1103/PhysRevE.93.062903], we consider two-dimensional simulations of tapped systems built from frictional disks and pentagons, and study the structure of the force networks of granular packings by considering network's topology as force thresholds are varied. We show that the number of clusters and loops observed in the force networks as a function of the force threshold are markedly different for disks and pentagons if the tangential contact forces are considered, whereas they are surprisingly similar for the network defined by the normal forces. In particular, the results indicate that, overall, the force network is more heterogeneous for disks than for pentagons. Such differences in network properties are expected to lead to different macroscale response of the considered systems, despite the fact that averaged measures (such as force probability density function) do not show any obvious differences. Additionally, we show that the states obtained by tapping with different intensities that display similar packing fraction are difficult to distinguish based on simple topological invariants.

  1. Structure of force networks in tapped particulate systems of disks and pentagons. I. Clusters and loops.

    PubMed

    Pugnaloni, Luis A; Carlevaro, C Manuel; Kramár, M; Mischaikow, K; Kondic, L

    2016-06-01

    The force network of a granular assembly, defined by the contact network and the corresponding contact forces, carries valuable information about the state of the packing. Simple analysis of these networks based on the distribution of force strengths is rather insensitive to the changes in preparation protocols or to the types of particles. In this and the companion paper [Kondic et al., Phys. Rev. E 93, 062903 (2016)10.1103/PhysRevE.93.062903], we consider two-dimensional simulations of tapped systems built from frictional disks and pentagons, and study the structure of the force networks of granular packings by considering network's topology as force thresholds are varied. We show that the number of clusters and loops observed in the force networks as a function of the force threshold are markedly different for disks and pentagons if the tangential contact forces are considered, whereas they are surprisingly similar for the network defined by the normal forces. In particular, the results indicate that, overall, the force network is more heterogeneous for disks than for pentagons. Such differences in network properties are expected to lead to different macroscale response of the considered systems, despite the fact that averaged measures (such as force probability density function) do not show any obvious differences. Additionally, we show that the states obtained by tapping with different intensities that display similar packing fraction are difficult to distinguish based on simple topological invariants. PMID:27415342

  2. Regarding the scalar mesons

    SciTech Connect

    Liu Yunhu; Shao Jianxin; Wang Xiaogang; Zhang Ziying; Li Demin

    2008-02-01

    Based on the main assumption that the D{sub sJ}(2860) belongs to the 2{sup 3}P{sub 0} qq multiplet, the masses of the scalar meson nonet are estimated in the framework of the relativistic independent quark model, Regge phenomenology, and meson-meson mixing. We suggest that the a{sub 0}(1005), K{sub 0}*(1062), f{sub 0}(1103), and f{sub 0}(564) constitute the ground scalar meson nonet; it is supposed that these states would likely correspond to the observed states a{sub 0}(980), {kappa}(900), f{sub 0}(980), and f{sub 0}(600)/{sigma}, respectively. Also a{sub 0}(1516), K{sub 0}*(1669), f{sub 0}(1788), and f{sub 0}(1284) constitute the first radial scalar meson nonet, it is supposed that these states would likely correspond to the observed states a{sub 0}(1450), K{sub 0}*(1430), f{sub 0}(1710), and f{sub 0}(1370), respectively. The scalar state f{sub 0}(1500) may be a good candidate for the ground scalar glueball. The agreement between the present findings and those given by other different approaches is satisfactory.

  3. Radiative corrections to the Higgs boson couplings in the model with an additional real singlet scalar field

    NASA Astrophysics Data System (ADS)

    Kanemura, Shinya; Kikuchi, Mariko; Yagyu, Kei

    2016-06-01

    We calculate renormalized Higgs boson couplings with gauge bosons and fermions at the one-loop level in the model with an additional isospin singlet real scalar field. These coupling constants can deviate from the predictions in the standard model due to tree-level mixing effects and one-loop contributions of the extra neutral scalar boson. We investigate how they can be significant under the theoretical constraints from perturbative unitarity and vacuum stability and also the condition of avoiding the wrong vacuum. Furthermore, comparing with the predictions in the Type I two Higgs doublet model, we numerically demonstrate how the singlet extension model can be distinguished and identified by using precision measurements of the Higgs boson couplings at future collider experiments.

  4. Does one need the O({epsilon})- and O({epsilon}{sup 2})-terms of one-loop amplitudes in a next-to-next-to-leading order calculation ?

    SciTech Connect

    Weinzierl, Stefan

    2011-10-01

    This article discusses the occurrence of one-loop amplitudes within a next-to-next-to-leading-order calculation. In a next-to-next-to-leading-order calculation, the one-loop amplitude enters squared and one would therefore naively expect that the O({epsilon})- and O({epsilon}{sup 2})-terms of the one-loop amplitudes are required. I show that the calculation of these terms can be avoided if a method is known, which computes the O({epsilon}{sup 0})-terms of the finite remainder function of the two-loop amplitude.

  5. Scalar-vector bootstrap

    NASA Astrophysics Data System (ADS)

    Rejon-Barrera, Fernando; Robbins, Daniel

    2016-01-01

    We work out all of the details required for implementation of the conformal bootstrap program applied to the four-point function of two scalars and two vectors in an abstract conformal field theory in arbitrary dimension. This includes a review of which tensor structures make appearances, a construction of the projectors onto the required mixed symmetry representations, and a computation of the conformal blocks for all possible operators which can be exchanged. These blocks are presented as differential operators acting upon the previously known scalar conformal blocks. Finally, we set up the bootstrap equations which implement crossing symmetry. Special attention is given to the case of conserved vectors, where several simplifications occur.

  6. Closed star product on noncommutative ℝ 3 and scalar field dynamics

    NASA Astrophysics Data System (ADS)

    Jurić, Tajron; Poulain, Timothé; Wallet, Jean-Christophe

    2016-05-01

    We consider the noncommutative space ℝ θ 3 , a deformation of ℝ 3 for which the star product is closed for the trace functional. We study one-loop IR and UV properties of the 2-point function for real and complex noncommutative scalar field theories with quartic interactions and Laplacian on ℝ 3 as kinetic operator. We find that the 2-point functions for these noncommutative scalar field theories have no IR singularities in the external momenta, indicating the absence of UV/IR mixing. We also find that the 2-point functions are UV finite with the deformation parameter θ playing the role of a natural UV cut-off. The possible origin of the absence of UV/IR mixing in noncommutative scalar field theories on ℝ θ 3 as well as on ℝ λ 3 , another deformation of ℝ 3, is discussed.

  7. Quaternion scalar field

    SciTech Connect

    De Leo, S. ); Rotelli, P. )

    1992-01-15

    We discuss the extension of a version of {ital quaternion} quantum mechanics to field theory and in particular to the simplest example, the free scalar field. A previous difficulty with the conservation of four-momentum for the anomalous'' bosonic particles is resolved.

  8. Triangle and concave pentagon electrodes for an improved broadband frequency response of stripline beam position monitors

    NASA Astrophysics Data System (ADS)

    Shobuda, Yoshihiro; Chin, Yong Ho; Takata, Koji; Toyama, Takeshi; Nakamura, Keigo

    2016-02-01

    The frequency domain performance of a stripline beam position monitor depends largely on the longitudinal shape of its electrode. Some shapes other than a conventional rectangle have been proposed and tested. To attain a good impedance matching along the electrode, they need to be precisely bent down toward their downstream in proportion to their width. This is a considerable task, and a failure to comply with it will result in a large distortion of the frequency-domain transfer function from the ideal one due to unwanted signal reflections. In this report, we first propose a triangle electrode for easy fabrication and setup: it only requires that a triangularly cut flat electrode will be placed in a chamber while being obliquely inclined toward the downstream port. Theoretical and simulation results show that the simple triangle electrode has a remarkably flatter frequency response than the rectangle one. The frequency response, in particular at high frequencies, can be further improved by attaching an "apron" plate, perpendicular to the upstream edge of the electrode. The overshooting of the frequency response at low frequency can be eliminated by replacing the straight sidelines of the triangle by three-point polylines (with a result that the triangle is transformed to a concave pentagon). The concave pentagon electrode needs to be bent only once at the middle point of the polylines for a good impedance matching and thus its fabrication and setup remain to be easy. Rf measurements for the various electrode shapes have been carried out. We found that the concave pentagon electrode achieves a wide and flat frequency response up to about 4 GHz for the J-PARC Main Ring (MR).

  9. Regional significance of Mississippian rocks at Pentagon Mountain, Lewis and Clark Range, northwestern Montana

    SciTech Connect

    Nichols, K.M.

    1985-05-01

    Pentagon Mountain exposes one of the best of the few sections of Mississippian rocks in the Lewis and Clark Range of northwestern Montana. This section consists of 225 m (738 ft) of marine carbonate rocks from which conodonts, ranging in age from earliest Osagean to early Meramecian, have been identified. Its stratigraphic base is well exposed, but the top has been eroded. Five units are recognized in this sequence, in ascending order: (1) phosphatized coarsely crinoidal and spiculitic wackestone, (2) dolomitic lime mudstone or wackestone, thinly interbedded with spiculitic biogenic chert, (3) partly dolomitized lime bioclastic wackestone showing much pressure-solution compaction, (4) partly dolomitized lime bioclastic packstone or wackestone, also showing much pressure-solution compaction, and (5) dolomitic mudstone. The Mississippian sequence at Pentagon Mountain can be readily correlated lithologically, across the Lewis thrust system with Mississippian rocks that crop out to the east in the Sawtooth Range. This implies either that Mississippian units were originally widespread or that the magnitude of thrusting between the Mississippian rocks in the Lewis and Clark Range and those in the Sawtooth Range was insignificant. However, Mississippian rocks at Pentagon Mountain exhibit extreme pressure-solution compaction, which suggests greater stratigraphic or structural burial of these rocks than their Mississippian counterparts in the Sawtooth Range. Secondary dolomite is pervasive in the lower part of the Mississippian section in the Lewis and Clark Range, and spectacular solution breccias locally disrupt the base of the section. These breccias and the adjacent dolomite are probably related, as both are thought to result from the passage of fluids through these rocks during Laramide uplift and/or post Laramide erosion and extension.

  10. Two-dimensional interlocked pentagonal bilayer ice: how do water molecules form a hydrogen bonding network?

    PubMed

    Zhu, Weiduo; Zhao, Wen-Hui; Wang, Lu; Yin, Di; Jia, Min; Yang, Jinlong; Zeng, Xiao Cheng; Yuan, Lan-Feng

    2016-06-01

    The plethora of ice structures observed both in bulk and under nanoscale confinement reflects the extraordinary ability of water molecules to form diverse forms of hydrogen bonding networks. An ideal hydrogen bonding network of water should satisfy three requirements: (1) four hydrogen bonds connected with every water molecule, (2) nearly linear hydrogen bonds, and (3) tetrahedral configuration for the four hydrogen bonds around an O atom. However, under nanoscale confinement, some of the three requirements have to be unmet, and the selection of the specific requirement(s) leads to different types of hydrogen bonding structures. According to molecular dynamics (MD) simulations for water confined between two smooth hydrophobic walls, we obtain a phase diagram of three two-dimensional (2D) crystalline structures and a bilayer liquid. A new 2D bilayer ice is found and named the interlocked pentagonal bilayer ice (IPBI), because its side view comprises interlocked pentagonal channels. The basic motif in the top view of IPBI is a large hexagon composed of four small pentagons, resembling the top view of a previously reported "coffin" bilayer ice [Johnston, et al., J. Chem. Phys., 2010, 133, 154516]. First-principles optimizations suggest that both bilayer ices are stable. However, there are fundamental differences between the two bilayer structures due to the difference in the selection among the three requirements. The IPBI sacrifices the linearity of hydrogen bonds to retain locally tetrahedral configurations of the hydrogen bonds, whereas the coffin structure does the opposite. The tradeoff between the conditions of an ideal hydrogen bonding network can serve as a generic guidance to understand the rich phase behaviors of nanoconfined water. PMID:27063210

  11. Multi-disclinational description of pentagonal particles with subsurface layer free of twin boundaries

    NASA Astrophysics Data System (ADS)

    Yasnikov, I. S.; Kolesnikova, A. L.; Romanov, A. E.

    2015-09-01

    We present the results on the modelling of structural changes in pentagonal small particles (PSPs) during their growth. We prove that after a certain critical size it becomes energetically favourable for a PSP to form a subsurface layer free of twin boundaries (TBs), which are only typical structural elements for smaller size PSPs. In this layer, the low-angle dislocation boundaries (DBs) are formed. Our calculations of the energy stored in the transformed PSP are based on the disclination model of a PSP, in which the TB junctions, as well as TB-DB junctions are treated as wedge disclinations.

  12. More about scalar gravity

    NASA Astrophysics Data System (ADS)

    Bittencourt, E.; Moschella, U.; Novello, M.; Toniato, J. D.

    2016-06-01

    We discuss a class of models for gravity based on a scalar field. The models include and generalize the old approach by Nordström which predated and, in some ways, inspired general relativity. The class include also a model that we have recently introduced and discussed in terms of its cosmological aspects (GSG). We present here a complete characterization of the Schwarschild geometry as a vacuum solution of GSG and sketch a discussion of the first post-Newtonian approximation.

  13. Conformal scalar field wormholes

    NASA Technical Reports Server (NTRS)

    Halliwell, Jonathan J.; Laflamme, Raymond

    1989-01-01

    The Euclidian Einstein equations with a cosmological constant and a conformally coupled scalar field are solved, taking the metric to be of the Robertson-Walker type. In the case Lambda = 0, solutions are found which represent a wormhole connecting two asymptotically flat Euclidian regions. In the case Lambda greater than 0, the solutions represent tunneling from a small Tolman-like universe to a large Robertson-Walker universe.

  14. Imploding scalar fields

    SciTech Connect

    Roberts, M.D.

    1996-09-01

    Static spherically symmetric uncoupled scalar space{endash}times have no event horizon and a divergent Kretschmann singularity at the origin of the coordinates. The singularity is always present so that nonstatic solutions have been sought to see if the singularities can develop from an initially singular free space{endash}time. In flat space{endash}time the Klein{endash}Gordon equation {D`Alembertian}{var_phi}=0 has the nonstatic spherically symmetric solution {var_phi}={sigma}({ital v})/{ital r}, where {sigma}({ital v}) is a once differentiable function of the null coordinate {ital v}. In particular, the function {sigma}({ital v}) can be taken to be initially zero and then grow, thus producing a singularity in the scalar field. A similar situation occurs when the scalar field is coupled to gravity via Einstein{close_quote}s equations; the solution also develops a divergent Kretschmann invariant singularity, but it has no overall energy. To overcome this, Bekenstein{close_quote}s theorems are applied to give two corresponding conformally coupled solutions. One of these has positive ADM mass and has the following properties: (i) it develops a Kretschmann invariant singularity, (ii) it has no event horizon, (iii) it has a well-defined source, (iv) it has well-defined junction condition to Minkowski space{endash}time, and (v) it is asymptotically flat with positive overall energy. This paper presents this solution and several other nonstatic scalar solutions. The properties of these solutions which are studied are limited to the following three: (i) whether the solution can be joined to Minkowski space{endash}time, (ii) whether the solution is asymptotically flat, (iii) and, if so, what the solutions{close_quote} Bondi and ADM masses are. {copyright} {ital 1996 American Institute of Physics.}

  15. Scalar multi-wormholes

    NASA Astrophysics Data System (ADS)

    Egorov, A. I.; Kashargin, P. E.; Sushkov, Sergey V.

    2016-09-01

    In 1921 Bach and Weyl derived the method of superposition to construct new axially symmetric vacuum solutions of general relativity. In this paper we extend the Bach–Weyl approach to non-vacuum configurations with massless scalar fields. Considering a phantom scalar field with the negative kinetic energy, we construct a multi-wormhole solution describing an axially symmetric superposition of N wormholes. The solution found is static, everywhere regular and has no event horizons. These features drastically tell the multi-wormhole configuration from other axially symmetric vacuum solutions which inevitably contain gravitationally inert singular structures, such as ‘struts’ and ‘membranes’, that keep the two bodies apart making a stable configuration. However, the multi-wormholes are static without any singular struts. Instead, the stationarity of the multi-wormhole configuration is provided by the phantom scalar field with the negative kinetic energy. Anther unusual property is that the multi-wormhole spacetime has a complicated topological structure. Namely, in the spacetime there exist 2 N asymptotically flat regions connected by throats.

  16. Revisiting scalar glueballs

    NASA Astrophysics Data System (ADS)

    Cheng, Hai-Yang; Chua, Chun-Khiang; Liu, Keh-Fei

    2015-11-01

    It is commonly believed that the lowest-lying scalar glueball lies somewhere in the isosinglet scalar mesons f0(1370 ) , f0(1500 ) and f0(1710 ) denoted generically by f0. In this work we consider lattice calculations and experimental data to infer the glue and q q ¯ components of f0. These include the calculations of the scalar glueball masses in quenched and unquenched lattice QCD, measurements of the radiative decays J /ψ →γ f0 , the ratio of f0 decays to π π , K K ¯ and η η , the ratio of J /ψ decays to f0(1710 )ω and f0(1710 )ϕ , the f0 contributions to Bs→J /ψ π+π- , and the near mass degeneracy of a0(1450 ) and K0*(1430 ) . All analyses suggest the prominent glueball nature of f0(1710 ) and the flavor octet structure of f0(1500 ).

  17. Medical surveillance of search dogs deployed to the World Trade Center and Pentagon: 2001-2006.

    PubMed

    Otto, Cynthia M; Downend, Amanda B; Moore, George E; Daggy, Joanne K; Ranivand, D Lauren; Reetz, Jennifer A; Fitzgerald, Scott D

    2010-09-01

    In response to the terrorist attacks of September 11, 2001, at the World Trade Center and Pentagon, almost 50,000 rescue workers and approximately 300 search and rescue dogs participated in rescue and recovery operations. The dogs were exposed to the same hazards as the human workers, but did not have any of the personal protective gear. This prospective double cohort observational study compared annual medical history, blood biochemical and hematologic results, and thoracic radiographic findings in 95 search and rescue dogs that responded to the terrorist attacks at the World Trade Center or the Pentagon on September 11, 2001, to a control group of 55 search and rescue dogs that were not involved in the 9/11 response. Compared to controls, the deployed search dogs demonstrated mild changes in blood work and a higher incidence of radiographic cardiac abnormalities. Species differences may explain the lack of pulmonary findings in the dogs. These dogs may provide early evidence of nonpulmonary complications of the 9/11 response. Continued surveillance of all responders is warranted. PMID:20873528

  18. Structure of force networks in tapped particulate systems of disks and pentagons. II. Persistence analysis

    NASA Astrophysics Data System (ADS)

    Kondic, L.; Kramár, M.; Pugnaloni, Luis A.; Carlevaro, C. Manuel; Mischaikow, K.

    2016-06-01

    In the companion paper [Pugnaloni et al., Phys. Rev. E 93, 062902 (2016), 10.1103/PhysRevE.93.062902], we use classical measures based on force probability density functions (PDFs), as well as Betti numbers (quantifying the number of components, related to force chains, and loops), to describe the force networks in tapped systems of disks and pentagons. In the present work, we focus on the use of persistence analysis, which allows us to describe these networks in much more detail. This approach allows us not only to describe but also to quantify the differences between the force networks in different realizations of a system, in different parts of the considered domain, or in different systems. We show that persistence analysis clearly distinguishes the systems that are very difficult or impossible to differentiate using other means. One important finding is that the differences in force networks between disks and pentagons are most apparent when loops are considered: the quantities describing properties of the loops may differ significantly even if other measures (properties of components, Betti numbers, force PDFs, or the stress tensor) do not distinguish clearly or at all the investigated systems.

  19. Structure of force networks in tapped particulate systems of disks and pentagons. II. Persistence analysis.

    PubMed

    Kondic, L; Kramár, M; Pugnaloni, Luis A; Carlevaro, C Manuel; Mischaikow, K

    2016-06-01

    In the companion paper [Pugnaloni et al., Phys. Rev. E 93, 062902 (2016)10.1103/PhysRevE.93.062902], we use classical measures based on force probability density functions (PDFs), as well as Betti numbers (quantifying the number of components, related to force chains, and loops), to describe the force networks in tapped systems of disks and pentagons. In the present work, we focus on the use of persistence analysis, which allows us to describe these networks in much more detail. This approach allows us not only to describe but also to quantify the differences between the force networks in different realizations of a system, in different parts of the considered domain, or in different systems. We show that persistence analysis clearly distinguishes the systems that are very difficult or impossible to differentiate using other means. One important finding is that the differences in force networks between disks and pentagons are most apparent when loops are considered: the quantities describing properties of the loops may differ significantly even if other measures (properties of components, Betti numbers, force PDFs, or the stress tensor) do not distinguish clearly or at all the investigated systems. PMID:27415343

  20. Complete one-loop MSSM predictions for B{sup 0}{yields}l{sup +}l{sup '-} at the Tevatron and LHC

    SciTech Connect

    Dedes, Athanasios; Rosiek, Janusz; Tanedo, Philip

    2009-03-01

    During the last few years the Tevatron has dramatically improved the bounds on rare B-meson decays into two leptons. In the case of B{sub s}{sup 0}{yields}{mu}{sup +}{mu}{sup -}, the current bound is only 10 times greater than the standard model expectation. Sensitivity to this decay is one of the benchmark goals for LHCb performance and physics. The Higgs penguin dominates this rate in the region of large tan{beta} of the minimal supersymmetric standard model. This is not necessarily the case in the region of low tan{beta}, since box and Z-penguin diagrams may contribute at a comparable rate. In this article, we compute the complete one-loop minimal supersymmetric standard model contribution to B{sub s,d}{sup 0}{yields}l{sup +}l{sup '-} for l, l{sup '}=e, {mu}. We study the predictions for general values of tan{beta} with arbitrary flavor mixing parameters. We discuss the possibility of both enhancing and suppressing the branching ratios relative to their standard model expectations. In particular, we find that there are 'cancellation regions' in parameter space where the branching ratio is suppressed well below the standard model expectation, making it effectively invisible to the LHC.

  1. Perturbative unitarity and high-energy W+/-L,ZL,H scattering. One-loop corrections and the Higgs-boson coupling

    NASA Astrophysics Data System (ADS)

    Durand, Loyal; Johnson, James M.; Lopez, Jorge L.

    1992-05-01

    We reexamine the unitarity constraints on the high-energy scattering of longitudinally polarized W's and Z's and Higgs bosons in the standard model including one-loop corrections. Using an Argand diagram analysis, we find that the j=0 scattering amplitudes are approximately unitary and weakly interacting at order λ2 for Higgs-boson couplings λ(s,M2H)<~2, but that corrections of order λ3 or higher must be included to restore perturbative unitarity for larger values of λ. We show also that two-loop [O(λ3)] corrections cannot extend the range of validity of perturbation theory beyond λ~=2.2. An analysis of inelastic 2-->4 scattering in the W+/-L,ZL, H system gives an independent but weaker limit λ(s,M2H)<~5. The limit λ(s,M2H)<2 translates to a physical-Higgs-boson mass MH<~400 GeV if the bound is to hold up to energies of a few TeV, or MH<~160 GeV in perturbatively unified theories with a mass scale of order 1015 GeV. For masses much larger than these bounds, low-order perturbation theory fails and the Higgs sector of the standard model becomes effectively strongly interacting.

  2. The formation of pentagon-heptagon pair defect by the reconstruction og vacancy defects in carbon nanotube

    SciTech Connect

    Lee, G.D.; Wang, C.Z.; Yoon, E.; Hwang, N.M.; Ho, K.M.

    2008-01-29

    The reconstruction process of vacancy hole in carbon nanotube is investigated by tight-binding molecular dynamics simulations and by ab initio total energy calculations. In the molecular dynamics simulation, a vacancy hole is found to reconstruct into two separated pentagon-heptagon pair defects. As the result of reconstruction, the radius of the carbon nanotube is reduced and the chirality of the tube is partly changed. During the vacancy hole healing process, the formation of pentagonal and heptagonal rings is proceeded by the subsequent Stone-Wales.

  3. Quantum scalar corrections to the gravitational potentials on de Sitter background

    NASA Astrophysics Data System (ADS)

    Park, Sohyun; Prokopec, Tomislav; Woodard, R. P.

    2016-01-01

    We employ the graviton self-energy induced by a massless, minimally coupled (MMC) scalar on de Sitter background to compute the quantum corrections to the gravitational potentials of a static point particle with a mass M . The Schwinger-Keldysh formalism is used to derive real and causal effective field equations. When evaluated at the one-loop order, the gravitational potentials exhibit a secular decrease in the observed gravitational coupling G. This can also be interpreted as a (time dependent) anti-screening of the mass M.

  4. Geometric scalar theory of gravity

    SciTech Connect

    Novello, M.; Bittencourt, E.; Goulart, E.; Salim, J.M.; Toniato, J.D.; Moschella, U. E-mail: eduhsb@cbpf.br E-mail: egoulart@cbpf.br E-mail: toniato@cbpf.br

    2013-06-01

    We present a geometric scalar theory of gravity. Our proposal will be described using the ''background field method'' introduced by Gupta, Feynman, Deser and others as a field theory formulation of general relativity. We analyze previous criticisms against scalar gravity and show how the present proposal avoids these difficulties. This concerns not only the theoretical complaints but also those related to observations. In particular, we show that the widespread belief of the conjecture that the source of scalar gravity must be the trace of the energy-momentum tensor — which is one of the main difficulties to couple gravity with electromagnetic phenomenon in previous models — does not apply to our geometric scalar theory. From the very beginning this is not a special relativistic scalar gravity. The adjective ''geometric'' pinpoints its similarity with general relativity: this is a metric theory of gravity. Some consequences of this new scalar theory are explored.

  5. A model of whisker crystal growth from a pentagonal small particle

    NASA Astrophysics Data System (ADS)

    Romanov, A. E.; Dorogin, L. M.; Kolesnikova, A. L.; Kink, I.; Yasnikov, I. S.; Vikarchuk, A. A.

    2014-02-01

    We present a physical model of growth of whisker crystals from metal pentagonal small particles (PSPs). The model is based upon the notions of nucleation and slippage of prismatic dislocation loops in the elastic field of disclination defects that are inherent in PSPs. In the framework of this model, the escape of interstitial dislocation loops at the PSP surface leads to an increase in the whisker length relative to the base, while incorporation of the vacancy-type loops is accompanied by their accumulation on the internal surface. The model is illustrated by calculations that show a gain in the total PSP energy as a result of the formation of a pair of prismatic dislocation loops with opposite signs.

  6. Performance and Maqasid al-Shari'ah's Pentagon-Shaped Ethical Measurement.

    PubMed

    Bedoui, Houssem Eddine; Mansour, Walid

    2015-06-01

    Business performance is traditionally viewed from the one-dimensional financial angle. This paper develops a new approach that links performance to the ethical vision of Islam based on maqasid al-shari'ah (i.e., the objectives of Islamic law). The approach involves a Pentagon-shaped performance scheme structure via five pillars, namely wealth, posterity, intellect, faith, and human self. Such a scheme ensures that any firm or organization can ethically contribute to the promotion of human welfare, prevent corruption, and enhance social and economic stability and not merely maximize its own performance in terms of its financial return. A quantitative measure of ethical performance is developed. It surprisingly shows that a firm or organization following only the financial aspect at the expense of the others performs poorly. This paper discusses further the practical instances of the quantitative measurement of the ethical aspects of the system taken at an aggregate level. PMID:24898420

  7. Reagan's energy war: can deregulation and the Pentagon save the nuclear industry

    SciTech Connect

    Feeney, A.

    1981-11-01

    Mr. Feeney feels that Administration energy policies claiming to protect democracy and reduce government interference will transfer money and political control from the people to the energy corporations and the Pentagon. Critics deplore the hard-path approach of downgrading conservation and solar energy in favor of nuclear energy, which some see as setting the stage for a nuclear war in this decade. They see the plan to abolish DOE as providing an opportunity to bail out the nuclear industry, bury environmental and alternative energy research, and block regulations. Critics question why Reagan's devotion to the free market is not applied to the nuclear industry, although they disagree on the linkage with nuclear weapons of new fuel cycle proposals and the use of national security to solve the waste disposal problem by nationalizing and militarizing the fuel cycle. (DCK)

  8. Endohedrally stabilized C70 isomer with fused pentagons characterized by crystallography.

    PubMed

    Feng, Lai; Zhang, Meirong; Hao, Yajuan; Tang, Qiangqiang; Chen, Ning; Slanina, Zdeněk; Uhlík, Filip

    2016-05-10

    Besides the conventional D5h(8149)-C70 fullerene, there are a large number of C70 isomers that violate the isolated pentagon rule (IPR). However, these non-IPR C70 fullerenes have been less investigated owing to their low stabilities or high reactivities. In this study, we report for the first time the X-ray structure of an unconventional endohedral C70 fullerene, Sc2O@C2(7892)-C70. The combined study of geometrical analysis and computation further reveals the ionic and covalent interactions between the cluster and the cage, both of which contribute to the stabilization of this non-IPR C70 fullerene. In addition, a close structural relationship between the non-IPR C2(7892)-C70 and the IPR D5h(8149)-C70 has been demonstrated, which might provide an alternative explanation of the formation of non-IPR fullerenes. PMID:27090070

  9. The Regioselectivity of Bingel-Hirsch Cycloadditions on Isolated Pentagon Rule Endohedral Metallofullerenes.

    PubMed

    Garcia-Borràs, Marc; Cerón, Maira R; Osuna, Sílvia; Izquierdo, Marta; Luis, Josep M; Echegoyen, Luis; Solà, Miquel

    2016-02-12

    In this work, the Bingel-Hirsch addition of diethylbromomalonate to all non-equivalent bonds of Sc3N@D3h -C78 was studied using density functional theory calculations. The regioselectivities observed computationally allowed the proposal of a set of rules, the predictive aromaticity criteria (PAC), to identify the most reactive bonds of a given endohedral metallofullerene based on a simple evaluation of the cage structure. The predictions based on the PAC are fully confirmed by both the computational and experimental exploration of the Bingel-Hirsch reaction of Sc3N@D5h -C80, thus indicating that these rules are rather general and applicable to other isolated pentagon rule endohedral metallofullerenes. PMID:26765333

  10. A dislocation model for the pentagon-heptagon pair in zigzag single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Wang, Shao Feng; Zhang, Hui Li; Zhi Wu, Xiao

    2010-06-01

    The pentagon-heptagon (5/7) pair in a zigzag single-walled carbon nanotube (SWCNT) is described as a dislocation by the modified Peierls-Nabarro (P-N) theory. The theory takes discrete effects, size effects and curvature effects into account. The bonds variation and shape distortion caused by 5/7 pair have been evaluated. It is found that the neck bond (shared bond) becomes longer while the shoulder bonds become shorter comparing with the one of the hexagons. The results show that the zigzag chain across the center of the 5/7 pair will bend slightly in the axis direction towards the heptagon, and the tube will be flattened where the 5/7 pair is located because of the appearance of the internal stress and nonzero curvature.

  11. Two-dimensional pentagonal crystals and possible spin-polarized Dirac dispersion relations

    SciTech Connect

    Tang, Chi-Pui; Xiong, Shi-Jie Shi, Wu-Jun; Cao, Jie

    2014-03-21

    Based on first-principles calculations we show that the two-dimensional pentagonal (pt) structures, the compositions of pt-BN{sub 2}, pt-C, and pt-Fe{sub 2}S, are stable. As a common feature, they are composed of 3 components: 2 stretched honeycomb sublattices and 1 square sublattice, conferring flexibility of tailoring the properties peculiar to the graphene. Although the Dirac dispersion relation is removed in metallic pt-BN{sub 2} and insulating pt-C due to the hybridization of two honeycomb sublattices, it survives in pt-Fe{sub 2}S because of the suppression of such hybridization between different spins. As a result, in the dispersion relation of pt-Fe{sub 2}S spin-polarized and anisotropic Dirac cones occur. We suggest that such type of dispersion relation can be used to produce spin-filter effect by applying electric bias in a specific direction.

  12. Highly tapered pentagonal bipyramidal Au microcrystals with high index faceted corrugation: Synthesis and optical properties

    NASA Astrophysics Data System (ADS)

    Mettela, Gangaiah; Boya, Radha; Singh, Danveer; Kumar, G. V. Pavan; Kulkarni, G. U.

    2013-05-01

    Focusing light at sub-wavelength region opens up interesting applications in optical sensing and imaging beyond the diffraction limit. In the past, tapered Au wires with carved gratings have been employed to achieve nanofocusing. The fabrication process however, is expensive and the obtained wires are polycrystalline with high surface roughness. A chemical synthetic method overcoming these hurdles should be an attractive alternative. Here, we report a method to chemically synthesize Au microcrystals (~10 μm) bearing pentagonal bipyramidal morphology with surface corrugations assignable to high index planes. The method is a single step solid state synthesis at a temperature amenable to common substrates. The microcrystals are tapered at both ends forming sharp tips (~55 nm). Individual microcrystals have been used as pick and probe SERS substrates for a dye embedded in a polymer matrix. The unique geometry of the microcrystal also enables light propagation across its length.

  13. Is Julian Assange an International Version of Daniel Ellsberg and WikiLeaks the Modern Equivalent of the Pentagon Papers?

    ERIC Educational Resources Information Center

    Freivogel, William H.

    2011-01-01

    History has placed the stamp of approval on the publication of the Pentagon Papers, the top-secret history of the Vietnam War. If WikiLeaks editor-in-chief Julian Assange is another Daniel Ellsberg, then it is possible the website's disclosures will be viewed over time as similarly in the public interest. A classroom discussion on the release of…

  14. Flexible structural and electronic properties of a pentagonal B2C monolayer via external strain: a computational investigation.

    PubMed

    Li, Fengyu; Tu, Kaixiong; Zhang, Haijun; Chen, Zhongfang

    2015-10-01

    Inspired by the recent theoretical finding that penta-graphene, composed entirely of carbon pentagons, is dynamically and mechanically stable [Proc. Natl. Acad. Sci. U. S. A., 2015, 112, 2372-2377], we computationally designed a new two-dimensional (2D) inorganic material, a pentagonal B2C monolayer (penta-B2C), in which each pentagon contains three boron and two carbon atoms, the C atom is four-coordinated with four B atoms, and all the B atoms are three-coordinated with two C atoms and one B atom, forming a buckled 2D network. The pentagonal B2C monolayer is semiconducting with a wide indirect band gap of 2.28 eV from HSE calculations. The absence of imaginary modes in its phonon spectrum, and the high melting point predicted by molecular dynamics (MD) simulations indicate its good stability. Interestingly, the buckled structure could be stretched to planar under 15% biaxial tensile strain, and the band gap will be strikingly reduced to 0.06 eV. The semiconducting properties of penta-B2C could also be switched to those of a metallic semiconductor under certain biaxial strains, while uniaxial strains could only tune the band gaps without changing the semiconducting characteristics. PMID:26315808

  15. On the distribution of scalar k for elliptic scalar multiplication

    NASA Astrophysics Data System (ADS)

    Ajeena, Ruma Kareem K.; Kamarulhaili, Hailiza

    2015-10-01

    In this study, we introduce the probability distribution of the elliptic curve scalar multiplication through finding the probability distribution of the secret key, namely, the scalar k of the scalar multiplication kP of a point P which has a large prime order n lying on elliptic curve group E(Fp) over a finite prime field Fp. To determine this distribution of k, we use the integer sub-decomposition (ISD) approach that inspired from Gallant, Lambert and Vanstone (GLV) idea. In ISD approach, the distribution of the values of scalars k lie outside the range ±√{n } on the interval [1, n - 1]. This distribution determines the successful rate to compute a scalar multiplication kP, on ISD approach, in comparison with the original GLV method. The conception of the ISD approach depends on the sub- decomposition of the scalar k to compute the scalar multiplication kP which uses efficiently computable endomorphisms Ψ1 and Ψ2 of elliptic curve E over Fp. The ISD sub-decomposition can be defined by k P =k11P +k12ψ1(P )+k21P +k22ψ2(P ), with max{ | k11 | ,| k12 | } and max{ | k21 | ,| k22 | } ≤C √{n }, for some explicit constant C > 0. Furthermore, this study compares between the GLV and ISD approaches on the basis of the probability distribution of the scalar k in the interval [1, n - 1], where n is a large prime number.

  16. Chiral symmetry restoration and scalar-pseudoscalar partners in QCD

    NASA Astrophysics Data System (ADS)

    Gómez Nicola, A.; Ruiz de Elvira, J.; Torres Andrés, R.

    2013-10-01

    We describe scalar-pseudoscalar partner degeneration at the QCD chiral transition in terms of the dominant low-energy physical states for the light quark sector. First, we obtain within model-independent one-loop chiral perturbation theory that the QCD pseudoscalar susceptibility is proportional to the quark condensate at low T. Next, we show that this chiral-restoring behavior for χP is compatible with recent lattice results for screening masses and gives rise to degeneration between the scalar and pseudoscalar susceptibilities (χS,χP) around the transition point, consistently with an O(4)-like current restoration pattern. This scenario is clearly confirmed by lattice data when we compare χS(T) with the quark condensate, expected to scale as χP(T). Finally, we show that saturating χS with the σ/f0(500) broad resonance observed in pion scattering and including its finite temperature dependence, allows us to describe the peak structure of χS(T) in lattice data and the associated critical temperature. This is carried out within a unitarized chiral perturbation theory scheme which generates the resonant state dynamically and is also consistent with partner degeneration.

  17. Spontaneous scalarization with massive fields

    NASA Astrophysics Data System (ADS)

    Ramazanoǧlu, Fethi M.; Pretorius, Frans

    2016-03-01

    We study the effect of a mass term in the spontaneous scalarization of neutron stars, for a wide range of scalar field parameters and neutron star equations of state. Even though massless scalars have been the focus of interest in spontaneous scalarization so far, recent observations of binary systems rule out most of their interesting parameter space. We point out that adding a mass term to the scalar field potential is a natural extension to the model that avoids these observational bounds if the Compton wavelength of the scalar is small compared to the binary separation. Our model is formally similar to the asymmetron scenario recently introduced in application to cosmology, though here we are interested in consequences for neutron stars and thus consider a mass term that does not modify the geometry on cosmological scales. We review the allowed values for the mass and scalarization parameters in the theory given current binary system observations and black hole spin measurements. We show that within the allowed ranges, spontaneous scalarization can have nonperturbative, strong effects that may lead to observable signatures in binary neutron star or black hole-neutron star mergers, or even in isolated neutron stars.

  18. Ultrarelativistic boost with scalar field

    NASA Astrophysics Data System (ADS)

    Svítek, O.; Tahamtan, T.

    2016-02-01

    We present the ultrarelativistic boost of the general global monopole solution which is parametrized by mass and deficit solid angle. The problem is addressed from two different perspectives. In the first one the primary object for performing the boost is the metric tensor while in the second one the energy momentum tensor is used. Since the solution is sourced by a triplet of scalar fields that effectively vanish in the boosting limit we investigate the behavior of a scalar field in a simpler setup. Namely, we perform the boosting study of the spherically symmetric solution with a free scalar field given by Janis, Newman and Winicour. The scalar field is again vanishing in the limit pointing to a broader pattern of scalar field behaviour during an ultrarelativistic boost in highly symmetric situations.

  19. Electroweak Baryogenesis and Colored Scalars

    SciTech Connect

    Cohen, Timothy; Pierce, Aaron; /Michigan U., MCTP

    2012-02-15

    We consider the 2-loop finite temperature effective potential for a Standard Model-like Higgs boson, allowing Higgs boson couplings to additional scalars. If the scalars transform under color, they contribute 2-loop diagrams to the effective potential that include gluons. These 2-loop effects are perhaps stronger than previously appreciated. For a Higgs boson mass of 115 GeV, they can increase the strength of the phase transition by as much as a factor of 3.5. It is this effect that is responsible for the survival of the tenuous electroweak baryogenesis window of the Minimal Supersymmetric Standard Model. We further illuminate the importance of these 2-loop diagrams by contrasting models with colored scalars to models with singlet scalars. We conclude that baryogenesis favors models with light colored scalars. This motivates searches for pair-produced di-jet resonances or jet(s) + = E{sub T}.

  20. Scalar-tensor theories with an external scalar

    NASA Astrophysics Data System (ADS)

    Chauvineau, Bertrand; Rodrigues, Davi C.; Fabris, Júlio C.

    2016-06-01

    Scalar-tensor (ST) gravity is considered in the case where the scalar is an external field. We show that general relativity (GR) and usual ST gravity are particular cases of the external scalar-tensor (EST) gravity. It is shown with a particular cosmological example that it is possible to join a part of a GR solution to a part of a ST one such that the complete solution neither belongs to GR nor to ST, but fully satisfies the EST field equations. We argue that external fields may effectively work as a type of screening mechanism for ST theories.

  1. Are stealth scalar fields stable?

    SciTech Connect

    Faraoni, Valerio; Moreno, Andres F. Zambrano

    2010-06-15

    Nongravitating (stealth) scalar fields associated with Minkowski space in scalar-tensor gravity are examined. Analytical solutions for both nonminimally coupled scalar field theory and for Brans-Dicke gravity are studied and their stability with respect to tensor perturbations is assessed using a covariant and gauge-invariant formalism developed for alternative gravity. For Brans-Dicke solutions, the stability with respect to homogeneous perturbations is also studied. There are regions of parameter space corresponding to stability and other regions corresponding to instability.

  2. Symmetry inheritance of scalar fields

    NASA Astrophysics Data System (ADS)

    Smolić, Ivica

    2015-07-01

    Matter fields do not necessarily have to share the symmetries with the spacetime they live in. When this happens, we speak of the symmetry inheritance of fields. In this paper we classify the obstructions of symmetry inheritance by the scalar fields, both real and complex, and look more closely at the special cases of stationary and axially symmetric spacetimes. Since the symmetry noninheritance is present in the scalar fields of boson stars and may enable the existence of the black hole scalar hair, our results narrow the possible classes of such solutions. Finally, we define and analyse the symmetry noninheritance contributions to the Komar mass and angular momentum of the black hole scalar hair.

  3. Gravitational scalar-tensor theory

    NASA Astrophysics Data System (ADS)

    Naruko, Atsushi; Yoshida, Daisuke; Mukohyama, Shinji

    2016-05-01

    We consider a new form of gravity theories in which the action is written in terms of the Ricci scalar and its first and second derivatives. Despite the higher derivative nature of the action, the theory is ghost-free under an appropriate choice of the functional form of the Lagrangian. This model possesses 2 + 2 physical degrees of freedom, namely 2 scalar degrees and 2 tensor degrees. We exhaust all such theories with the Lagrangian of the form f(R,{({{\

  4. Scalar graviton as dark matter

    SciTech Connect

    Pirogov, Yu. F.

    2015-06-15

    The basics of the theory of unimodular bimode gravity built on the principles of unimodular gauge invariance/relativity and general covariance are exposed. Besides the massless tensor graviton of General Relativity, the theory includes an (almost) massless scalar graviton treated as the gravitational dark matter. A spherically symmetric vacuum solution describing the coherent scalar-graviton field for the soft-core dark halos, with the asymptotically flat rotation curves, is demonstrated as an example.

  5. Copper Mediated Hydrothermal Synthesis of Ultra Long Pentagonally Twinned Palladium Nanowires

    NASA Astrophysics Data System (ADS)

    Hanson, Jennifer

    Palladium nanowires (Pd NWs) have attracted considerable attention due to applications in hydrogen sensing and heterogeneous catalysis. Several methods have been reported for the synthesis of Pd NWs including using chemical vapor transport, electrodeposition in porous membranes, electron beam lithography, and colloidal self-assembly; however, it has been challenging to produce large quantities. Hydrothermal methods have been reported recently for the production of high yields of Pd NWs using palladium (II) chloride as a metal precursor, deionized water as the solvent, and polyvinylpyrrolidone for the NW capping agent. Reported prior methods have not been reproducible. With the introduction of trace amounts of Copper (II) ions synthesis is possible and aspect ratios of >500 have been obtained. It is likely that the deionized water used in the synthesis contained trace amounts of copper from metal pipes, thus leading to the synthesis of PdNWs. Copper ions have been shown to act as effective oxygen scavengers during the aqueous synthesis and we postulate that oxidative etching of multiply pentagonally twinned palladium seeds must be avoided in order to achieve high yields of palladium nanowires. This research focuses on the trace addition of copper ions and improvement of the Pd NW synthesis.

  6. Migrations of pentagon-heptagon defects in hexagonal boron nitride monolayer: the first-principles study.

    PubMed

    Wang, J; Li, S N; Liu, J B

    2015-04-16

    The first-principles calculations are employed to study the migrations of pentagon-heptagon (5-7) defects in hexagonal boron nitride monolayer (h-BN). A type of grain boundaries, consisted of 5-7 defects, is constructed on the basis of experimental observations. With the absorption of a pair of atoms, one 5-7 defect in the grain boundary migrates apart by one unit cell and afterward migrates again through the bond rotation. It is also found that the two migrations could be replaced by one single step when the pair of absorbed atoms is located at another specific site in the same heptagon. Energy barriers and reaction paths for the migrations of 5-7 defects in h-BN by the bond rotation are theoretically investigated by the standard nudged elastic band method and the generalized solid-state nudged elastic band method. To elucidate the difference between the bond rotation process of the 5-7 defects with N-N bonds and those with B-B bonds, a couple of typical 21.7° grain boundaries with either N-N or B-B bonds are investigated. It is shown that the energy barrier of the migration of defects with N-N bonds is lower than that with B-B bonds in this type of grain boundaries. PMID:25811102

  7. Translation symmetry breakdown in low-dimensional lattices of pentagonal rings.

    PubMed

    Avramov, Paul; Demin, Victor; Luo, Ming; Choi, Cheol Ho; Sorokin, Pavel B; Yakobson, Boris; Chernozatonskii, Leonid

    2015-11-19

    The mechanism of translation symmetry breakdown in newly proposed low-dimensional carbon pentagon-constituted nanostructures (e.g., pentagraphene) with multiple sp(2)/sp(3) sublattices was studied by GGA DFT, DFTB, and model potential approaches. It was found that finite nanoclusters suffer strong uniform unit cell bending followed by breaking of crystalline lattice linear translation invariance caused by structural mechanical stress. It was shown that 2D sp(2)/sp(3) nanostructures are correlated transition states between two symmetrically equivalent bent structures. At DFT level of theory the distortion energy of the flakes (7.5 × 10(-2) eV/atom) is much higher the energy of dynamical stabilization of graphene. Strong mechanical stress prevents stabilization of the nanoclusters on any type of supports by either van der Waals or covalent bonding and should lead to formation of pentatubes, nanorings, or nanofoams rather than infinite nanoribbons or nanosheets. Formation of two-layered pentagraphene structures leads to compensation of the stress and stabilization of flat finite pentaflakes. PMID:26582476

  8. Energetic analysis of pentagon road intermediates of C{sub 60}-buckminsterfullerene formation

    SciTech Connect

    Bates, K.R.; Scuseria, G.E.

    1997-04-17

    We report an energetic analysis of the principal intermediates of the pentagon road (PR) scheme for formation of C{sub 60}-Buckminsterfullerene. All calculations were initially performed using the tight-binding semiempirical method. For selected cases, more rigorous 3-21G/HF and 3-21G/B3LYP calculations were carried out. The first part of this study includes an energetic comparison between the 30-, 40-, and 50-atom PR intermediates and a representative group of 30-, 40-, and 50-atom carbon clusters. While C{sub 30} PR is higher in energy than a large variety of graphene sheets and fullerenes, C{sub 40} PR and C{sub 50} PR are considerably lower in energy than many other isomers; only fullerenes are more stable. Additionally, we examine a plausible mechanism by which C{sub 50} PR rearranges to form a C{sub 50} cage with D{sub 5h} symmetry. Because of its large energy barrier, this process is unlikely to affect the C{sub 60} growth mechanism. 17 refs., 9 figs., 3 tabs.

  9. A geometric constraint, the head-to-tail exclusion rule, may be the basis for the isolated-pentagon rule in fullerenes with more than 60 vertices

    PubMed Central

    Schein, Stan; Friedrich, Tara

    2008-01-01

    Carbon atoms self-assemble into the famous soccer-ball shaped Buckminsterfullerene (C60), the smallest fullerene cage that obeys the isolated-pentagon rule (IPR). Carbon atoms self-assemble into larger (n > 60 vertices) empty cages as well—but only the few that obey the IPR—and at least 1 small fullerene (n ≤ 60) with adjacent pentagons. Clathrin protein also self-assembles into small fullerene cages with adjacent pentagons, but just a few of those. We asked why carbon atoms and clathrin proteins self-assembled into just those IPR and small cage isomers. In answer, we described a geometric constraint—the head-to-tail exclusion rule—that permits self-assembly of just the following fullerene cages: among the 5,769 possible small cages (n ≤ 60 vertices) with adjacent pentagons, only 15; the soccer ball (n = 60); and among the 216,739 large cages with 60 < n ≤ 84 vertices, only the 50 IPR ones. The last finding was a complete surprise. Here, by showing that the largest permitted fullerene with adjacent pentagons is one with 60 vertices and a ring of interleaved hexagons and pentagon pairs, we prove that for all n > 60, the head-to-tail exclusion rule permits only (and all) fullerene cages and nanotubes that obey the IPR. We therefore suggest that self-assembly that obeys the IPR may be explained by the head-to-tail exclusion rule, a geometric constraint. PMID:19050075

  10. One-loop corrections to h → boverline{b} and h → τ overline{τ} decays in the Standard Model dimension-6 EFT: four-fermion operators and the large- m t limit

    NASA Astrophysics Data System (ADS)

    Gauld, Rhorry; Pecjak, Benjamin D.; Scott, Darren J.

    2016-05-01

    We calculate a set of one-loop corrections to h → boverline{b} and h → τ overline{τ} decays in the dimension-6 Standard Model effective field theory (SMEFT). In particular, working in the limit of vanishing gauge couplings, we calculate directly in the broken phase of the theory all large logarithmic corrections and in addition the finite corrections in the large- m t limit. Moreover, we give exact results for one-loop contributions from four-fermion operators. We obtain these corrections within an extension of the widely used on-shell renormalisation scheme appropriate for SMEFT calculations, and show explicitly how UV divergent bare amplitudes from a total of 21 different SMEFT operators are rendered finite within this scheme. As a by-product of the calculation, we also compute to one-loop order the logarithmically enhanced and finite large- m t corrections to muon decay in the limit of vanishing gauge couplings, which is necessary to implement the G F input parameter scheme within the SMEFT.

  11. Color Sextet Scalars in Early LHC Experiments

    SciTech Connect

    Berger, Edmond L.; Cao Qinghong; Chen, Chuan-Ren; Shaughnessy, Gabe; Zhang Hao

    2010-10-29

    We explore the potential for discovery of an exotic color sextet scalar in same-sign top quark pair production in early running at the LHC. We present the first phenomenological analysis at colliders of color sextet scalars with full top quark spin correlations included. We demonstrate that one can measure the scalar mass, the top quark polarization, and confirm the scalar resonance with 1 fb{sup -1} of integrated luminosity. The top quark polarization can distinguish gauge triplet and singlet scalars.

  12. C₇₄ endohedral metallofullerenes violating the isolated pentagon rule: a density functional theory study.

    PubMed

    Zheng, Hong; Zhao, Xiang; Ren, Ting; Wang, Wei-Wei

    2012-08-01

    Precise studies on M(2)@C(74) (M = Sc, La) series by means of DFT methods have disclosed that certain non-IPR isomers are more stable than the IPR structure. M(2)@C(2)(13295)-C(74) and M(2)@C(2)(13333)-C(74), both of which have two pentagon adjacencies (PA), present excellent thermodynamic stability with very small energy differences. Statistical mechanics calculations on the M(2)@C(74) series reveal that M(2)@C(2)(13295)-C(74) and M(2)@C(2)(13333)-C(74) are quite favoured by entropy effects below 3000 K. Sc(2)@C(74) and La(2)@C(74) series are found to have similar electronic transfer but different electronic structures due to the distinct properties of scandium and lanthanum elements according to Natural Bond Orbital (NBO) analysis in conjunction with orbital interaction diagrams. Investigations of bonding energies reflect quite different influences of the two types of metal atoms to C(74) metallo-fullerenes. Further examinations on C(74) metallo-fullerenes uncover significant stabilization effects of metal atoms acting on PA fragments. Geometrical structures of certain non-IPR cages (from C(72) to C(76)), which exhibit splendid stabilities when encapsulating metallo-clusters, are found to be related by Stone-Wales transformation and C(2) addition. Furthermore, IR spectra and (13)C NMR spectra of M(2)@C(2)(13295)-C(74) and M(2)@C(2)(13333)-C(74) have been simulated to assist further experimental characterization. PMID:22695730

  13. The emergence of scalar meanings

    PubMed Central

    Etxeberria, Urtzi; Irurtzun, Aritz

    2015-01-01

    This paper analyzes the emergence of scalar additive meanings. We show that in Basque the same particle ere can obtain both the “simple additive” reading (akin to English too) and the “scalar additive” reading (akin to English even) but we argue that we do not have to distinguish two types of ere. We provide evidence, by means of a production and a perception experiment, that the reading is disambiguated by means of prosody (the placement of nuclear stress), which is a correlate of focus. We argue that the scalarity effect is generated by the combination of two presuppositions (a focus-induced one and a lexical one) and the assertion of the sentence. PMID:25745405

  14. Scalar transport by planktonic swarms

    NASA Astrophysics Data System (ADS)

    Martinez-Ortiz, Monica; Dabiri, John O.

    2012-11-01

    Nutrient and energy transport in the ocean is primarily governed by the action of physical phenomena. In previous studies it has been suggested that aquatic fauna may significantly contribute to this process through the action of the induced drift mechanism. In this investigation, the role of planktonic swarms as ecosystem engineers is assessed through the analysis of scalar transport within a stratified water column. The vertical migration of Artemia salina is controlled via luminescent signals on the top and bottom of the column. The scalar transport of fluorescent dye is visualized and quantified through planar laser induced fluorescence (PLIF). Preliminary results show that the vertical movement of these organisms enhances scalar transport relative to control cases in which only buoyancy forces and diffusion are present. Funded by the BSF program (2011553).

  15. Optimizing elliptic curve scalar multiplication for small scalars

    NASA Astrophysics Data System (ADS)

    Giorgi, Pascal; Imbert, Laurent; Izard, Thomas

    2009-08-01

    On an elliptic curve, the multiplication of a point P by a scalar k is defined by a series of operations over the field of definition of the curve E, usually a finite field Fq. The computational cost of [k]P = P + P + ...+ P (k times) is therefore expressed as the number of field operations (additions, multiplications, inversions). Scalar multiplication is usually computed using variants of the binary algorithm (double-and-add, NAF, wNAF, etc). If s is a small integer, optimized formula for [s]P can be used within a s-ary algorithm or with double-base methods with bases 2 and s. Optimized formulas exists for very small scalars (s <= 5). However, the exponential growth of the number of field operations makes it a very difficult task when s > 5. We present a generic method to automate transformations of formulas for elliptic curves over prime fields in various systems of coordinates. Our method uses a directed acyclic graph structure to find possible common subexpressions appearing in the formula and several arithmetic transformations. It produces efficient formulas to compute [s]P for a large set of small scalars s. In particular, we present a faster formula for [5]P in Jacobian coordinates. Moreover, our program can produce code for various mathematical software (Magma) and libraries (PACE).

  16. Scalar fields and particle accelerators

    NASA Astrophysics Data System (ADS)

    Sultana, Joseph; Bose, Benjamin

    2015-06-01

    The phenomenon discovered in 2009 by Bañados, Silk and West where particle collisions can achieve arbitrary high center-of-mass (c.m.) energies close to the event horizon of an extreme Kerr black hole, has generated a lot of interest. Although rotation seemed to be an essential requirement, it was later shown that arbitrary high energies can also be achieved for collisions between radially moving particles near the horizon of the electrically charged extreme Reissner-Nordström black hole. Recently Patil and Joshi claimed that instead of spinning up the black hole one can also crank up the c.m. energy of particle collisions by "charging up" a static black hole with a massless scalar field. In this regard they showed that infinite energies can be attained in the vicinity of the naked singularity of the Janis-Newman-Wincour (JNW) spacetime, which contains a massless scalar field that also becomes infinite at the position of the curvature singularity. In this study we show that Patil and Joshi's claim does not apply for other static black hole systems endowed with a massless scalar field. In particular we consider the well-known Bekenstein black hole and the recently discovered Martínez-Troncoso-Zanelli black hole, and show that the expression of the c.m. energy for particle collisions near the event horizons of these black holes is no different than the corresponding case with vanishing scalar field represented by the Schwarzschild solution. Moreover by studying the motion of scalar test charges that interact with the background scalar field in these black hole spacetimes we show that the resulting c.m. energies are even smaller than in the case of free particles. This shows that the infinite energies obtained by Patil and Joshi may not be due to the fact that the black hole contains a massless scalar field, but may be instead related to the geometry of the naked singularity in the JNW spacetime. An analogous case of infinite c.m. energy in the vicinity of a naked

  17. Scalar limitations of diffractive optical elements

    NASA Technical Reports Server (NTRS)

    Johnson, Eric G.; Hochmuth, Diane; Moharam, M. G.; Pommet, Drew

    1993-01-01

    In this paper, scalar limitations of diffractive optic components are investigated using coupled wave analyses. Results are presented for linear phase gratings and fanout devices. In addition, a parametric curve is given which correlates feature size with scalar performance.

  18. Bianchi I in scalar and scalar-tensor cosmologies

    NASA Astrophysics Data System (ADS)

    Belinchón, José

    2012-08-01

    We study how the constants G and Λ may vary in different theoretical models (general relativity (GR) with a perfect fluid, scalar cosmological models (SM) ("quintessence") with and without interacting scalar and matter fields and three scalar-tensor theories (STT) with a dynamical Λ) in order to explain some observational results. We apply the program outlined in section II to study the Bianchi I models, under the self-similarity hypothesis. We put special emphasis on calculating exact power-law solutions which allow us to compare the different models. In all the studied cases we conclude that the solutions are isotropic and noninflationary. We also arrive at the conclusion that in the GR model with time-varying constants, Λ vanishes while G is constant. In the SM all the solutions are massless i.e. the potential vanishes and all the interacting models are inconsistent from the thermodynamical point of view. The solutions obtained in the STT collapse to the perfect fluid one obtained in the GR model where G is a true constant and Λ vanishes as in the GR and SM frameworks.

  19. Symmetry-Supported Magnetic Blocking at 20 K in Pentagonal Bipyramidal Dy(III) Single-Ion Magnets.

    PubMed

    Chen, Yan-Cong; Liu, Jun-Liang; Ungur, Liviu; Liu, Jiang; Li, Quan-Wen; Wang, Long-Fei; Ni, Zhao-Ping; Chibotaru, Liviu F; Chen, Xiao-Ming; Tong, Ming-Liang

    2016-03-01

    Single-molecule magnets (SMMs) that can be trapped in one of the bistable magnetic states separated by an energy barrier are among the most promising candidates for high-density information storage, quantum processing, and spintronics. To date, a considerable series of achievements have been made. However, the presence of fast quantum tunnelling of magnetization (QTM) in most SMMs, especially in single-ion magnets (SIMs), provides a rapid relaxation route and often sets up a limit for the relaxation time. Here, we pursue the pentagonal bipyramidal symmetry to suppress the QTM and present pentagonal bipyramidal Dy(III) SIMs [Dy(Cy3PO)2(H2O)5]Cl3·(Cy3PO)·H2O·EtOH (1) and [Dy(Cy3PO)2(H2O)5]Br3·2(Cy3PO)·2H2O·2EtOH (2), (Cy3PO = tricyclohexyl phosphine oxide). Magnetic characterizations reveal their fascinating SMM properties with high energy barriers as 472(7) K for 1 and 543(2) K for 2, along with a record magnetic hysteresis temperature up to 20 K for 2. These results, combined with the ab initio calculations, offer an illuminating insight into the vast possibility and potential of what the symmetry rules can achieve in molecular magnetism. PMID:26883386

  20. Signatures from scalar dark matter with a vector-like quark mediator

    NASA Astrophysics Data System (ADS)

    Giacchino, Federica; Ibarra, Alejandro; Lopez Honorez, Laura; Tytgat, Michel H. G.; Wild, Sebastian

    2016-02-01

    We present a comprehensive study of a model where the dark matter is composed of a singlet real scalar that couples to the Standard Model predominantly via a Yukawa interaction with a light quark and a colored vector-like fermion. A distinctive feature of this scenario is that thermal freeze-out in the early universe may be driven by annihilation both into gluon pairs at one-loop (gg) and by virtual internal Bremsstrahlung of a gluon (qbar q g). Such a dark matter candidate may also be tested through direct and indirect detection and at the LHC; viable candidates have either a mass nearly degenerate with that of the fermionic mediator or a mass above about 2 TeV.

  1. Constrained inflaton due to a complex scalar

    NASA Astrophysics Data System (ADS)

    Budhi, Romy H. S.; Kashiwase, Shoichi; Suematsu, Daijiro

    2015-09-01

    We reexamine inflation due to a constrained inflaton in the model of a complex scalar. Inflaton evolves along a spiral-like valley of special scalar potential in the scalar field space just like single field inflation. Sub-Planckian inflaton can induce sufficient e-foldings because of a long slow-roll path. In a special limit, the scalar spectral index and the tensor-to-scalar ratio has equivalent expressions to the inflation with monomial potential varphin. The favorable values for them could be obtained by varying parameters in the potential. This model could be embedded in a certain radiative neutrino mass model

  2. Constrained inflaton due to a complex scalar

    SciTech Connect

    Budhi, Romy H. S.; Kashiwase, Shoichi; Suematsu, Daijiro

    2015-09-14

    We reexamine inflation due to a constrained inflaton in the model of a complex scalar. Inflaton evolves along a spiral-like valley of special scalar potential in the scalar field space just like single field inflation. Sub-Planckian inflaton can induce sufficient e-foldings because of a long slow-roll path. In a special limit, the scalar spectral index and the tensor-to-scalar ratio has equivalent expressions to the inflation with monomial potential φ{sup n}. The favorable values for them could be obtained by varying parameters in the potential. This model could be embedded in a certain radiative neutrino mass model.

  3. Variations on Slavnov's scalar product

    NASA Astrophysics Data System (ADS)

    Foda, O.; Wheeler, M.

    2012-10-01

    We consider the rational six-vertex model on an L× L lattice with domain wall boundary conditions and restrict N parallel-line rapidities, N ≤ L/2, to satisfy length- L XXX spin-1/2 chain Bethe equations. We show that the partition function is an ( L - 2 N )- parameter extension of Slavnov's scalar product of a Bethe eigenstate and a generic state, with N magnons each, on a length- L XXX spin-1/2 chain. Decoupling the extra parameters, we obtain a third determinant expression for the scalar product, where the first is due to Slavnov [1], and the second is due to Kostov and Matsuo [2]. We show that the new determinant is Casoratian, and consequently that tree-level {N}=4 SYM structure constants that are known to be determinants, remain determinants at 1-loop level.

  4. Scalar top study: Detector optimization

    SciTech Connect

    Milstene, C.; Sopczak, A.; /Lancaster U.

    2006-09-01

    A vertex detector concept of the Linear Collider Flavor Identification (LCFI) collaboration, which studies pixel detectors for heavy quark flavor identification, has been implemented in simulations for c-quark tagging in scalar top studies. The production and decay of scalar top quarks (stops) is particularly interesting for the development of the vertex detector as only two c-quarks and missing energy (from undetected neutralinos) are produced for light stops. Previous studies investigated the vertex detector design in scenarios with large mass differences between stop and neutralino, corresponding to large visible energy in the detector. In this study we investigate the tagging performance dependence on the vertex detector design in a scenario with small visible energy for the International Linear Collider (ILC).

  5. The search for scalar mesons

    NASA Astrophysics Data System (ADS)

    Pennington, M. R.

    1989-04-01

    The search for I=0 0++ mesons is described. We highlight the crucial role played by the states in the 1 GeV region. An analysis program that with unimpeachable data would produce definitive results on these is outlined and shown with present data to provide prima facie evidence for dynamics beyond that of the quark model. We briefly speculate on the current status of the lowest mass scalar mesons and discuss how experiment can resolve the unanswered issues.

  6. Analysis of Doppler Lidar Data Acquired During the Pentagon Shield Field Campaign

    SciTech Connect

    Newsom, Rob K.

    2011-04-14

    Observations from two coherent Doppler lidars deployed during the Pentagon Shield field campaign are analyzed in conjunction with other sensors to characterize the overall boundary-layer structure, and identify the dominant flow characteristics during the entire two-week field campaign. Convective boundary layer (CBL) heights and cloud base heights (CBH) are estimated from an analysis of the lidar signal-to-noise-ratio (SNR), and mean wind profiles are computed using a modified velocity-azimuth-display (VAD) algorithm. Three-dimensional wind field retrievals are computed from coordinated overlapping volume scans, and the results are analyzed by visualizing the flow in horizontal and vertical cross sections. The VAD winds show that southerly flows dominate during the two-week field campaign. Low-level jets (LLJ) were evident on all but two of the nights during the field campaign. The LLJs tended to form a couple hours after sunset and reach maximum strength between 03 and 07 UTC. The surface friction velocities show distinct local maxima during four nights when strong LLJs formed. Estimates of the convective boundary layer height and residual layer height are obtained through an analysis of the vertical gradient of the lidar signal-to-noise-ratio (SNR). Strong minimum in the SNR gradient often develops just above the surface after sunrise. This minimum is associated with the developing CBL, and increases rapidly during the early portion of the daytime period. On several days, this minimum continues to increase until about sunset. Secondary minima in the SNR gradient were also observed at higher altitudes, and are believed to be remnants of the CBL height from previous days, i.e. the residual layer height. The dual-Doppler analysis technique used in this study makes use of hourly averaged radial velocity data to produce three-dimensional grids of the horizontal velocity components, and the horizontal velocity variance. Visualization of horizontal and vertical cross

  7. Scalar meson f{sub 0}(980) in heavy-meson decays.

    SciTech Connect

    El-Bennich, B.; Leitner, O.; Dedonder, J.-P.; Loiseau, B.; Physics; Lab. de Physique Nucleaire et de Hautes Energies; Lab. Nazionali di Frascati

    2009-04-01

    A phenomenological analysis of the scalar meson f{sub 0}(980) is performed that relies on the quasi-two-body decays D and D{sub s} {yields} f{sub 0}(980)P, with P = {pi}, K. The two-body branching ratios are deduced from experimental data on D or D{sub s} {yields} {pi}{pi}{pi}, K{sup -} K{pi} and from the f{sub 0}(980) {yields} {pi}{sup +}{pi}{sup -} and f{sub 0}(980) {yields} K{sup +}K{sup -} branching fractions. Within a covariant quark model, the scalar form factors for the transitions D and D{sub s} {yields} f{sub 0}(980) are computed. The weak D decay amplitudes, in which these form factors enter, are obtained in the naive factorization approach assuming a q{bar q} state for the scalar and pseudoscalar mesons. They allow to extract information on the f{sub 0}(980) wave function in terms of u{bar u}, d{bar d}, and s{bar s} pairs as well as on the mixing angle between the strange and nonstrange components. The weak transition form factors are modeled by the one-loop triangular diagram using two different relativistic approaches: covariant light-front dynamics and dispersion relations. We use the information found on the f{sub 0}(980) structure to evaluate the scalar and vector form factors in the transitions D and D{sub s} {yields} f{sub 0}(980), as well as to make predictions for B and B{sub s} {yields} f{sub 0}(980), for the entire kinematically allowed momentum range of q{sup 2}.

  8. GaN nanowires with pentagon shape cross-section by ammonia-source molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Lin, Yong; Leung, Benjamin; Li, Qiming; Figiel, Jeffrey. J.; Wang, George T.

    2015-10-01

    Ammonia-based molecular beam epitaxy (NH3-MBE) was used to grow catalyst-assisted GaN nanowires on (1 1 bar 02) r-plane sapphire substrates. Dislocation free [ 11 2 bar 0 ] oriented nanowires are formed with pentagon shape cross-section, instead of the usual triangular shape facet configuration. Specifically, the cross-section is the result of the additional two nonpolar { 10 1 bar 0 } side facets, which appear due to a decrease in relative growth rate of the { 10 1 bar 0 } facets to the { 10 1 bar 1 } and { 10 1 bar 1 } facets under the growth regime in NH3-MBE. Compared to GaN nanowires grown by Ni-catalyzed metal-organic chemical vapor deposition, the NH3-MBE grown GaN nanowires show more than an order of magnitude increase in band-edge to yellow luminescence intensity ratio, as measured by cathodoluminescence, indicating improved microstructural and optical properties.

  9. A Stable Pentagonal Bipyramidal Dy(III) Single-Ion Magnet with a Record Magnetization Reversal Barrier over 1000 K.

    PubMed

    Liu, Jiang; Chen, Yan-Cong; Liu, Jun-Liang; Vieru, Veacheslav; Ungur, Liviu; Jia, Jian-Hua; Chibotaru, Liviu F; Lan, Yanhua; Wernsdorfer, Wolfgang; Gao, Song; Chen, Xiao-Ming; Tong, Ming-Liang

    2016-04-27

    Single-molecule magnets (SMMs) with a large spin reversal barrier have been recognized to exhibit slow magnetic relaxation that can lead to a magnetic hysteresis loop. Synthesis of highly stable SMMs with both large energy barriers and significantly slow relaxation times is challenging. Here, we report two highly stable and neutral Dy(III) classical coordination compounds with pentagonal bipyramidal local geometry that exhibit SMM behavior. Weak intermolecular interactions in the undiluted single crystals are first observed for mononuclear lanthanide SMMs by micro-SQUID measurements. The investigation of magnetic relaxation reveals the thermally activated quantum tunneling of magnetization through the third excited Kramers doublet, owing to the increased axial magnetic anisotropy and weaker transverse magnetic anisotropy. As a result, pronounced magnetic hysteresis loops up to 14 K are observed, and the effective energy barrier (Ueff = 1025 K) for relaxation of magnetization reached a breakthrough among the SMMs. PMID:27054904

  10. Fused Dibenzo[a,m]rubicene: A New Bowl-Shaped Subunit of C70 Containing Two Pentagons.

    PubMed

    Liu, Junzhi; Osella, Silvio; Ma, Ji; Berger, Reinhard; Beljonne, David; Schollmeyer, Dieter; Feng, Xinliang; Müllen, Klaus

    2016-07-13

    Total synthetic approaches of fullerenes are the holy grail for organic chemistry. So far, the main attempts have focused on the synthesis of the buckminsterfullerene C60. In contrast, access to subunits of the homologue C70 remains challenging. Here, we demonstrate an efficient bottom-up strategy toward a novel bowl-shaped polycyclic aromatic hydrocarbons (PAH) C34 with two pentagons. This PAH represents a subunit for C70 and of other higher fullerenes. The bowl-shaped structure was unambiguously determined by X-ray crystallography. A bowl-to-bowl inversion for a C70 fragment in solution was investigated by dynamic NMR analysis, showing a bowl-to-bowl inversion energy (ΔG(⧧)) of 16.7 kcal mol(-1), which is further corroborated by DFT calculations. PMID:27355697

  11. Entropic quantization of scalar fields

    SciTech Connect

    Ipek, Selman; Caticha, Ariel

    2015-01-13

    Entropic Dynamics is an information-based framework that seeks to derive the laws of physics as an application of the methods of entropic inference. The dynamics is derived by maximizing an entropy subject to constraints that represent the physically relevant information that the motion is continuous and non-dissipative. Here we focus on the quantum theory of scalar fields. We provide an entropic derivation of Hamiltonian dynamics and using concepts from information geometry derive the standard quantum field theory in the Schrödinger representation.

  12. Entropic quantization of scalar fields

    NASA Astrophysics Data System (ADS)

    Ipek, Selman; Caticha, Ariel

    2015-01-01

    Entropic Dynamics is an information-based framework that seeks to derive the laws of physics as an application of the methods of entropic inference. The dynamics is derived by maximizing an entropy subject to constraints that represent the physically relevant information that the motion is continuous and non-dissipative. Here we focus on the quantum theory of scalar fields. We provide an entropic derivation of Hamiltonian dynamics and using concepts from information geometry derive the standard quantum field theory in the Schrödinger representation.

  13. Slowly rotating neutron stars in scalar-tensor theories with a massive scalar field

    NASA Astrophysics Data System (ADS)

    Yazadjiev, Stoytcho S.; Doneva, Daniela D.; Popchev, Dimitar

    2016-04-01

    In the scalar-tensor theories with a massive scalar field, the coupling constants, and the coupling functions in general, which are observationally allowed, can differ significantly from those in the massless case. This fact naturally implies that the scalar-tensor neutron stars with a massive scalar field can have rather different structure and properties in comparison with their counterparts in the massless case and in general relativity. In the present paper, we study slowly rotating neutron stars in scalar-tensor theories with a massive gravitational scalar. Two examples of scalar-tensor theories are examined—the first example is the massive Brans-Dicke theory and the second one is a massive scalar-tensor theory indistinguishable from general relativity in the weak-field limit. In the latter case, we study the effect of the scalar field mass on the spontaneous scalarization of neutron stars. Our numerical results show that the inclusion of a mass term for the scalar field indeed changes the picture drastically compared to the massless case. It turns out that mass, radius, and moment of inertia for neutron stars in massive scalar-tensor theories can differ drastically from the pure general relativistic solutions if sufficiently large masses of the scalar field are considered.

  14. A realizable EDQNM model for anisotropic scalars

    NASA Astrophysics Data System (ADS)

    Collins, Lance; Ulitsky, Mark

    1999-11-01

    As noted in the previous talk and abstract, the direct application of the edqnm formalism to two scalars with different diffusivities leads to a scalar covariance spectrum that violates the Cauchy-Schwartz inequality. This can be remedied by eliminating the explicit dependence of the eddy damping time scales on the molecular diffusivities, which can be shown to be unphysical at short times. Here we present an extension of this idea to anisotropic scalars. Anisotropy in this case results from uniform mean gradients of the scalar concentration in one direction. The approach we take is similar to the one described in Herr, Wang and Collins (Phys. Fluids 8:1588, 1996), except we substitute the modified eddy damping coefficients derived earlier for the isotropic scalar. The resulting edqnm model yields a realizable covariance spectrum for all times and for all combinations of the scalar diffusivities we considered. Several example calculations will be presented.

  15. High-level ab-initio calculations for the four low-lying families of minima of (H2O)20: II. Spectroscopic signatures of the dodecahedron, fused cubes, face-sharing pentagonal prisms, and edge-sharing pentagonal prisms hydrogen bonding networks

    SciTech Connect

    Fanourgakis, Georgios S.; Apra, Edoardo; De Jong, Wibe A.; Xantheas, Sotiris S.

    2005-04-01

    We report the first harmonic vibrational spectra for each of the lowest lying isomers within the four major families of minima of (H{sub 2}O){sub 20}, namely the dodecahedron, fused cubes, face-sharing pentagonal prisms and edge-sharing pentagonal prisms. These were obtained at the second-order Moeller-Plesset perturbation level of theory (MP2) with the augmented correlation consistent basis set of double zeta quality (aug-cc-pVDZ) at the corresponding minimum energy geometries. The computed infrared (IR) spectra are the first ones obtained from first principles for these clusters. They were found to contain spectral features, which can be directly mapped onto the distinctive spectroscopic signatures of their constituent tetramer, pentamer and octamer fragments. The dodecahedron spectra show the richest structure in the OH stretching region and are associated with the most red-shifted OH vibrations with respect to the monomer. The lowest lying face-sharing pentagonal prism isomer displays intense IR active vibrations that are red-shifted by {approx}600 cm{sup -1} with respect to the water monomer. The zero-point energy corrected MP2/CBS (complete basis set) limit binding energies (D{sub 0}) for the four isomers are -163.1 kcal/mol (face-sharing pentagonal prism), -160.1 kcal/mol (edgesharing pentagonal prism), -157.5 kcal/mol (fused cubes) and -148.1 kcal/mol (dodecahedron).

  16. Schwarzschild Black Holes can Wear Scalar Wigs

    NASA Astrophysics Data System (ADS)

    Barranco, Juan; Bernal, Argelia; Degollado, Juan Carlos; Diez-Tejedor, Alberto; Megevand, Miguel; Alcubierre, Miguel; Núñez, Darío; Sarbach, Olivier

    2012-08-01

    We study the evolution of a massive scalar field surrounding a Schwarzschild black hole and find configurations that can survive for arbitrarily long times, provided the black hole or the scalar field mass is small enough. In particular, both ultralight scalar field dark matter around supermassive black holes and axionlike scalar fields around primordial black holes can survive for cosmological times. Moreover, these results are quite generic in the sense that fairly arbitrary initial data evolve, at late times, as a combination of those long-lived configurations.

  17. Visualization of scalar topology for structural enhancement

    SciTech Connect

    Bajaj, C.L.; Pascucci, V.; Schikore, D.R.

    1998-09-22

    Scalar fields arise in every scientific application. Existing scalar visualization techniques require that the user infer the global scalar structure from what is frequently an insufficient display of information. We present a visualization technique which numerically detects the structure at all scales, removing from the user the responsibility of extracting information implicit in the data, and presenting the structure explicitly for analysis. We further demonstrate how scalar topology detection proves useful for correct visualization and image processing applications such as image co-registration, isocontouring, and mesh compression.

  18. Schwarzschild black holes can wear scalar wigs.

    PubMed

    Barranco, Juan; Bernal, Argelia; Degollado, Juan Carlos; Diez-Tejedor, Alberto; Megevand, Miguel; Alcubierre, Miguel; Núñez, Darío; Sarbach, Olivier

    2012-08-24

    We study the evolution of a massive scalar field surrounding a Schwarzschild black hole and find configurations that can survive for arbitrarily long times, provided the black hole or the scalar field mass is small enough. In particular, both ultralight scalar field dark matter around supermassive black holes and axionlike scalar fields around primordial black holes can survive for cosmological times. Moreover, these results are quite generic in the sense that fairly arbitrary initial data evolve, at late times, as a combination of those long-lived configurations. PMID:23002734

  19. Cosmology with many light scalar fields: Stochastic inflation and loop corrections

    NASA Astrophysics Data System (ADS)

    Adshead, Peter; Easther, Richard; Lim, Eugene A.

    2009-03-01

    We explore the consequences of the existence of a very large number of light scalar degrees of freedom in the early universe. We distinguish between participator and spectator fields. The former have a small mass, and can contribute to the inflationary dynamics; the latter are either strictly massless or have a negligible VEV. In N-flation and generic assisted inflation scenarios, inflation is a cooperative phenomenon driven by N participator fields, none of which could drive inflation on its own. We review upper bounds on N, as a function of the inflationary Hubble scale H. We then consider stochastic and eternal inflation in models with N participator fields showing that individual fields may evolve stochastically while the whole ensemble behaves deterministically, and that a wide range of eternal inflationary scenarios are possible in this regime. We then compute one-loop quantum corrections to the inflationary power spectrum. These are largest with N spectator fields and a single participator field, and the resulting bound on N is always weaker than those obtained in other ways. We find that loop corrections to the N-flation power spectrum do not scale with N, and thus place no upper bound on the number of participator fields. This result also implies that, at least to leading order, the theory behaves like a composite single scalar field. In order to perform this calculation, we address a number of issues associated with loop calculations in the Schwinger-Keldysh “in-in” formalism.

  20. Naturalness in a type II seesaw model and implications for physical scalars

    NASA Astrophysics Data System (ADS)

    Chabab, M.; Peyranère, M. C.; Rahili, L.

    2016-06-01

    In this paper, we consider a minimal extension to the standard model by a scalar triplet field with hypercharge Y =2 . This model relies on the seesaw mechanism which provides a consistent explication of neutrino mass generation. We show from naturalness considerations that the Veltman condition is modified by virtue of the additional scalar charged states and that quadratic divergencies at one loop can be driven to zero within the allowed parameter space of the model; the latter is severely constrained by unitarity and boundedness from below, and it is consistent with the di-photon Higgs decay data of the LHC. Furthermore, we analyze the naturalness condition effects to the masses of heavy Higgs bosons H0, A0, H± and H±±, providing a drastic reduction of the ranges of variation of mH± and mH±± with an upper bounds at 288 and 351 GeV, respectively, while predicting almost a degeneracy for the other neutral Higgs bosons H0, A0 at about 207 GeV.

  1. Scalar Potential Model of light

    NASA Astrophysics Data System (ADS)

    Hodge, John

    2008-04-01

    Some observations of light are inconsistent with a wave--like model. Other observations of light are inconsistent with a particle--like model. A model of light is proposed wherein Newton's and Democritus's speculations are combined with the cosmological scalar potential model (SPM). The SPM was tested by confrontation with observations of galaxy HI rotation curves (RCs), asymmetric RCs, redshift, discrete redshift, galaxy central mass, and central velocity dispersion; and with observations of the Pioneer Anomaly. The resulting model of light will be tested by numerical simulation of a photon behaving in a wave-like manner such as diffusion, interference, reflection, spectrography, and the Afshar experiment. Although the SPM light model requires more work, early results are beginning to emerge that suggest possible tests because a few predictions are inconsistent with both the current particle and wave models of light and that suggest a re-interpretation of the equations of quantum mechanics.

  2. Psycholinguistic and Neurolinguistic Investigations of Scalar Implicature

    ERIC Educational Resources Information Center

    Politzer-Ahles, Stephen

    2013-01-01

    The present study examines the representation and composition of meaning in scalar implicatures. Scalar implicature is the phenomenon whereby the use of a less informative term (e.g., "some") is inferred to mean the negation of a more informative term (e.g., to mean "not all"). The experiments reported here investigate how the…

  3. A note on perfect scalar fields

    NASA Astrophysics Data System (ADS)

    Unnikrishnan, Sanil; Sriramkumar, L.

    2010-05-01

    We derive a condition on the Lagrangian density describing a generic, single, noncanonical scalar field, by demanding that the intrinsic, nonadiabatic pressure perturbation associated with the scalar field vanishes identically. Based on the analogy with perfect fluids, we refer to such fields as perfect scalar fields. It is common knowledge that models that depend only on the kinetic energy of the scalar field (often referred to as pure kinetic models) possess no nonadiabatic pressure perturbation. While we are able to construct models that seemingly depend on the scalar field and also do not contain any nonadiabatic pressure perturbation, we find that all such models that we construct allow a redefinition of the field under which they reduce to pure kinetic models. We show that, if a perfect scalar field drives inflation, then, in such situations, the first slow roll parameter will always be a monotonically decreasing function of time. We point out that this behavior implies that these scalar fields cannot lead to features in the inflationary, scalar perturbation spectrum.

  4. Cross Sections From Scalar Field Theory

    NASA Technical Reports Server (NTRS)

    Norbury, John W.; Dick, Frank; Norman, Ryan B.; Nasto, Rachel

    2008-01-01

    A one pion exchange scalar model is used to calculate differential and total cross sections for pion production through nucleon- nucleon collisions. The collisions involve intermediate delta particle production and decay to nucleons and a pion. The model provides the basic theoretical framework for scalar field theory and can be applied to particle production processes where the effects of spin can be neglected.

  5. A note on perfect scalar fields

    SciTech Connect

    Unnikrishnan, Sanil; Sriramkumar, L.

    2010-05-15

    We derive a condition on the Lagrangian density describing a generic, single, noncanonical scalar field, by demanding that the intrinsic, nonadiabatic pressure perturbation associated with the scalar field vanishes identically. Based on the analogy with perfect fluids, we refer to such fields as perfect scalar fields. It is common knowledge that models that depend only on the kinetic energy of the scalar field (often referred to as pure kinetic models) possess no nonadiabatic pressure perturbation. While we are able to construct models that seemingly depend on the scalar field and also do not contain any nonadiabatic pressure perturbation, we find that all such models that we construct allow a redefinition of the field under which they reduce to pure kinetic models. We show that, if a perfect scalar field drives inflation, then, in such situations, the first slow roll parameter will always be a monotonically decreasing function of time. We point out that this behavior implies that these scalar fields cannot lead to features in the inflationary, scalar perturbation spectrum.

  6. Synthesis and characterization of uranyl chromate sheet compounds containing edge-sharing dimers of uranyl pentagonal bipyramids

    SciTech Connect

    Unruh, Daniel K.; Baranay, Michelle; Pressprich, Laura; Stoffer, Megan; Burns, Peter C.

    2012-02-15

    Eight uranyl chromates have been crystallized from aqueous solution and characterized: Mg(H{sub 2}O){sub 6}[(UO{sub 2}){sub 2}(CrO{sub 4}){sub 2}(OH){sub 2}](H{sub 2}O){sub 3} (1), (NH{sub 4}){sub 2}[(UO{sub 2}){sub 2}(CrO{sub 4}){sub 2}(OH){sub 2}](H{sub 2}O){sub 3}, Rb{sub 2}[(UO{sub 2}){sub 2}(CrO{sub 4}){sub 2}(OH){sub 2}](H{sub 2}O){sub 3} (3), Cs[(UO{sub 2})(CrO{sub 4})(OH)]H{sub 2}O (4), Rb[(UO{sub 2})(CrO{sub 4})(OH)]H{sub 2}O (5) Co(H{sub 2}O){sub 4}(Co(H{sub 2}O){sub 6}){sub 2}[(UO{sub 2}){sub 4}(CrO{sub 4}){sub 6}(OH){sub 2}](H{sub 2}O){sub 4} (6), Li{sub 2}[(UO{sub 2}){sub 2}(CrO{sub 4}){sub 3}](H{sub 2}O){sub 7} (7), and Zn(H{sub 2}O){sub 6}[(UO{sub 2}){sub 2}(CrO{sub 4}){sub 3}](H{sub 2}O){sub 3} (8). The structural units of 1 through 8 each consist of a sheet of uranyl pentagonal bipyramids and (Cr(VI)O{sub 4}){sup 2-} tetrahedra. In each case two uranyl pentagonal bipyramids share an equatorial edge, giving a dimer that is linked into the sheet through vertex sharing with (Cr(VI)O{sub 4}){sup 2-} tetrahedra. The sheets are based upon three distinct sheet anion topologies, and the sheets based on a given anion topology can differ in the orientations of the non-bridging O atoms of (CrO{sub 4}){sup 2-} tetrahedra. The interlayers of these compounds contain either monovalent or divalent cations, as well as H{sub 2}O groups that are either bonded to the interlayer cation or are held in place by H bonding only. We explore the relationships between sheet topologies and interlayer configuration in these compounds. - Graphical abstract: Eight uranyl chromate compounds containing sheet structural units built from uranyl pentagonal bipyramids and (CrO{sub 4}){sup 2-} tetrahedra are reported. Relationships between sheet topologies and interstitial constituents is examined. Highlights: Black-Right-Pointing-Pointer Eight uranyl Cr(VI) compounds with sheet structural units are reported. Black-Right-Pointing-Pointer Relationships between the topology of the uranyl

  7. Viable dark matter via radiative symmetry breaking in a scalar singlet Higgs portal extension of the standard model.

    PubMed

    Steele, T G; Wang, Zhi-Wei; Contreras, D; Mann, R B

    2014-05-01

    We consider the generation of dark matter mass via radiative electroweak symmetry breaking in an extension of the conformal standard model containing a singlet scalar field with a Higgs portal interaction. Generating the mass from a sequential process of radiative electroweak symmetry breaking followed by a conventional Higgs mechanism can account for less than 35% of the cosmological dark matter abundance for dark matter mass M(s)>80 GeV. However, in a dynamical approach where both Higgs and scalar singlet masses are generated via radiative electroweak symmetry breaking, we obtain much higher levels of dark matter abundance. At one-loop level we find abundances of 10%-100% with 106 GeVscalar-singlet self-coupling, providing a natural explanation for the astrophysical observations that place upper bounds on dark matter self-interaction. The predictions in all three approaches are within the M(s)>80 GeV detection region of the next generation XENON experiment. PMID:24836235

  8. Static weak dipole moments of the τ lepton via renormalizable scalar leptoquark interactions

    NASA Astrophysics Data System (ADS)

    Bolaños, A.; Moyotl, A.; Tavares-Velasco, G.

    2014-03-01

    The weak dipole moments of elementary fermions are calculated at the one-loop level in the framework of a renormalizable scalar leptoquark model that forbids baryon number violating processes and so is free from the strong constraints arising from experimental data. In this model there are two scalar leptoquarks accommodated in a SUL(2)×UY(1) doublet: One of these leptoquarks is nonchiral and has electric charge of 5/3e, whereas the other one is chiral and has electric charge 2/3e. In particular, a nonchiral leptoquark contributes to the weak properties of an up fermion via a chirality-flipping term proportional to the mass of the virtual fermion, and can also induce a nonzero weak electric dipole moment provided that the leptoquark couplings are complex. The numerical analysis is focused on the weak properties of the τ lepton since they offer good prospects for experimental study. The constraints on leptoquark couplings are briefly discussed for a nonchiral leptoquark with nondiagonal couplings to the second and third fermion generations, a third-generation nonchiral leptoquark, and a third-generation chiral leptoquark. It is found that although the chirality-flipping term can enhance the weak properties of the τ lepton via the top quark contribution, such an enhancement would be offset by the strong constraints on the leptoquark couplings. So, the contribution of scalar leptoquarks to the weak magnetic dipole moment of the τ lepton are smaller than the standard model (SM) contributions but can be of similar size to those arising in some SM extensions. A nonchiral leptoquark can also give contributions to the weak electric dipole moment larger than the SM one but well below the experimental limit. We also discuss the case of the off-shell weak dipole moments and, for completeness, analyze the behavior of the τ electromagnetic properties.

  9. Refining inflation using non-canonical scalars

    SciTech Connect

    Unnikrishnan, Sanil; Sahni, Varun; Toporensky, Aleksey E-mail: varun@iucaa.ernet.in

    2012-08-01

    This paper revisits the Inflationary scenario within the framework of scalar field models possessing a non-canonical kinetic term. We obtain closed form solutions for all essential quantities associated with chaotic inflation including slow roll parameters, scalar and tensor power spectra, spectral indices, the tensor-to-scalar ratio, etc. We also examine the Hamilton-Jacobi equation and demonstrate the existence of an inflationary attractor. Our results highlight the fact that non-canonical scalars can significantly improve the viability of inflationary models. They accomplish this by decreasing the tensor-to-scalar ratio while simultaneously increasing the value of the scalar spectral index, thereby redeeming models which are incompatible with the cosmic microwave background (CMB) in their canonical version. For instance, the non-canonical version of the chaotic inflationary potential, V(φ) ∼ λφ{sup 4}, is found to agree with observations for values of λ as large as unity! The exponential potential can also provide a reasonable fit to CMB observations. A central result of this paper is that steep potentials (such as V∝φ{sup −n}) usually associated with dark energy, can drive inflation in the non-canonical setting. Interestingly, non-canonical scalars violate the consistency relation r = −8n{sub T}, which emerges as a smoking gun test for this class of models.

  10. First-principles theory of Si(110)-(16 × 2) surface reconstruction for unveiling origin of pentagonal scanning tunneling microscopy images

    NASA Astrophysics Data System (ADS)

    Yamasaki, Takahiro; Kato, Koichi; Uda, Tsuyoshi; Yamamoto, Takenori; Ohno, Takahisa

    2016-03-01

    The origin of the scanning tunneling microscopy (STM) zigzag chain structures composed of pairs of pentagons on the Si(110)-(16 × 2) surface is unveiled through the first-principles calculation method. Stable Si(110) surface structures, on both flat and stepped surfaces, have been discovered. The energy gain of the stable step structure is larger than those of previously proposed models by 5.0 eV/(16 × 2) cell or more. The structure consists of buckled tetramers, heptagonal rings, tetragonal rings, and threefold-coordinated Si atoms, but no pentagonal rings. It reproduces the experimental STM images only when frequent flip-floppings of the buckled tetramers at room temperature are considered.

  11. GaN nanowires with pentagon shape cross-section by ammonia-source molecular beam epitaxy

    DOE PAGESBeta

    Lin, Yong; Leung, Benjamin; Li, Qiming; Figiel, Jeffrey J.; Wang, George T.

    2015-07-14

    In this study, ammonia-based molecular beam epitaxy (NH3-MBE) was used to grow catalyst-assisted GaN nanowires on (11¯02) r-plane sapphire substrates. Dislocation free [112¯0] oriented nanowires are formed with pentagon shape cross-section, instead of the usual triangular shape facet configuration. Specifically, the cross-section is the result of the additional two nonpolar {101¯0} side facets, which appear due to a decrease in relative growth rate of the {101¯0} facets to the {101¯1} and {101¯1} facets under the growth regime in NH3-MBE. Compared to GaN nanowires grown by Ni-catalyzed metal–organic chemical vapor deposition, the NH3-MBE grown GaN nanowires show more than an ordermore » of magnitude increase in band-edge to yellow luminescence intensity ratio, as measured by cathodoluminescence, indicating improved microstructural and optical properties.« less

  12. GaN nanowires with pentagon shape cross-section by ammonia-source molecular beam epitaxy

    SciTech Connect

    Lin, Yong; Leung, Benjamin; Li, Qiming; Figiel, Jeffrey J.; Wang, George T.

    2015-07-14

    In this study, ammonia-based molecular beam epitaxy (NH3-MBE) was used to grow catalyst-assisted GaN nanowires on (11¯02) r-plane sapphire substrates. Dislocation free [112¯0] oriented nanowires are formed with pentagon shape cross-section, instead of the usual triangular shape facet configuration. Specifically, the cross-section is the result of the additional two nonpolar {101¯0} side facets, which appear due to a decrease in relative growth rate of the {101¯0} facets to the {101¯1} and {101¯1} facets under the growth regime in NH3-MBE. Compared to GaN nanowires grown by Ni-catalyzed metal–organic chemical vapor deposition, the NH3-MBE grown GaN nanowires show more than an order of magnitude increase in band-edge to yellow luminescence intensity ratio, as measured by cathodoluminescence, indicating improved microstructural and optical properties.

  13. Static scalar field solutions in symmetric gravity

    NASA Astrophysics Data System (ADS)

    Hossenfelder, S.

    2016-09-01

    We study an extension of general relativity with a second metric and an exchange symmetry between the two metrics. Such an extension might help to address some of the outstanding problems with general relativity, for example the smallness of the cosmological constant. We here derive a family of exact solutions for this theory. In this two-parameter family of solutions the gravitational field is sourced by a time-independent massless scalar field. We find that the only limit in which the scalar field entirely vanishes is flat space. The regular Schwarzschild-solution is left with a scalar field hidden in the second metric’s sector.

  14. Bifurcation of tracked scalar waves

    SciTech Connect

    Glimm, J.; Grove, J.; Lindquist, B.; McBryan, O.A.; Tryggvason, G.

    1986-05-01

    The dynamic evolution of tracked waves by a front-tracking algorithm may lead on either numerical or physical grounds to intersections of the waves. The correct resolution of these intersections is described locally by the solution of Riemann problems and requires a bifurcation of the topology defined by the tracked waves. An algorithm is described which is appropriate for the resolution of scalar tracked waves, such as material discontinuities, contact dicontinuities in gas dynamics, or constituent concetration waves including oil-water banks in oil reservoirs Even here the algorithm is not fully general, and the resolution of the intersections of an arbitrary set of curves in the plane for the above range of physical problems remains unsolved. However with the assumption that the set of intersections to be resolved is a small perturbation (resulting for example from a small time step in an evolution) of a valid, non-intersecting front, the algorithm seems to be general. In any case examples will be presented that show that complicated interfaces can be generated automatically from simple ones through successive bifurcations. 15 refs., 9 figs.

  15. Searching for the Scalar Glueball

    SciTech Connect

    Ochs, Wolfgang

    2008-08-31

    Existence of gluonic resonances is among the early expectations of QCD. Today, QCD calculations predict the lightest glueball to be a scalar state with mass within a range of about 900-1700 MeV but there is no consensus about its experimental evidence. In a re-analysis of the phase shifts for {pi}{pi} scattering up to 1800 MeV where such states should show up we find the broad resonance f{sub 0}(600)/{sigma} contributing to the full mass range and the narrow f{sub 0}(980) and f{sub 0}(1500) but no evidence for f{sub 0}(1370). Phenomenological arguments for the broad state to be a glueball are recalled. It is argued that the large radiative width of f{sub 0}(600)/{sigma} reported recently is not in contradiction to this hypothesis but is mainly due to {pi}{pi}-rescattering. The small 'direct' radiative component is consistent with QCD sum rule predictions for the light glueball.

  16. Identification of a scalar glueball.

    PubMed

    Albaladejo, M; Oller, J A

    2008-12-19

    We perform a coupled channel study of the meson-meson S waves with isospin (I) 0 and 1/2 up to 2 GeV. A new approach is derived that allows one to include the many channels pipi, KK[over ], etaeta, sigmasigma, etaeta; eta; eta; , rhorho, omegaomega, omegavarphi, varphivarphi, a(1)pi, and pipi with still few free parameters. It follows that coupled channel dynamics is strong and cannot be neglected in order to study resonance properties in the region 1.4-1.6 GeV. All the resonances with masses below 2 GeV and I=0 and 1/2 are generated. We identify the f(0)(1710) and an important contribution to the f (0)(1500) as an unmixed glueball. This is based on an accurate agreement of our results with predictions of lattice QCD and the chiral suppression of the coupling of a scalar glueball to q[over ]q. Another pole, mainly corresponding to the f_{0}(1370), is a pure octet state. PMID:19113698

  17. Intermediate inflation driven by DBI scalar field

    NASA Astrophysics Data System (ADS)

    Nazavari, N.; Mohammadi, A.; Ossoulian, Z.; Saaidi, Kh.

    2016-06-01

    Picking out a DBI scalar field as inflation, the slow-rolling inflationary scenario is studied by attributing an exponential time function to scale factor, known as intermediate inflation. The perturbation parameters of the model are estimated numerically for two different cases, and the final result is compared with Planck data. The diagram of tensor-to-scalar ratio r versus scalar spectra index ns is illustrated, and it is found that they are within an acceptable range as suggested by Planck. In addition, the acquired values for amplitude of scalar perturbation reveal the ability of the model to depict a good picture of the Universe in one of its earliest stages. As a further argument, the non-Gaussianity is investigated, displaying that the model prediction stands in a 68% C.L. regime according to the latest Planck data.

  18. Subfemtotesla scalar atomic magnetometry using multipass cells.

    PubMed

    Sheng, D; Li, S; Dural, N; Romalis, M V

    2013-04-19

    Scalar atomic magnetometers have many attractive features but their sensitivity has been relatively poor. We describe a Rb scalar gradiometer using two multipass optical cells. We use a pump-probe measurement scheme to suppress spin-exchange relaxation and two probe pulses to find the spin precession zero crossing times with a resolution of 1 psec. We realize a magnetic field sensitivity of 0.54 fT/Hz(1/2), which improves by an order of magnitude the best scalar magnetometer sensitivity and exceeds, for example, the quantum limit set by the spin-exchange collisions for a scalar magnetometer with the same measurement volume operating in a continuous regime. PMID:23679590

  19. Subfemtotesla Scalar Atomic Magnetometry Using Multipass Cells

    NASA Astrophysics Data System (ADS)

    Sheng, D.; Li, S.; Dural, N.; Romalis, M. V.

    2013-04-01

    Scalar atomic magnetometers have many attractive features but their sensitivity has been relatively poor. We describe a Rb scalar gradiometer using two multipass optical cells. We use a pump-probe measurement scheme to suppress spin-exchange relaxation and two probe pulses to find the spin precession zero crossing times with a resolution of 1 psec. We realize a magnetic field sensitivity of 0.54fT/Hz1/2, which improves by an order of magnitude the best scalar magnetometer sensitivity and exceeds, for example, the quantum limit set by the spin-exchange collisions for a scalar magnetometer with the same measurement volume operating in a continuous regime.

  20. Inflation in anisotropic scalar-tensor theories

    NASA Technical Reports Server (NTRS)

    Pimentel, Luis O.; Stein-Schabes, Jaime

    1988-01-01

    The existence of an inflationary phase in anisotropic Scalar-Tensor Theories is investigated by means of a conformal transformation that allows us to rewrite these theories as gravity minimally coupled to a scalar field with a nontrivial potential. The explicit form of the potential is then used and the No Hair Theorem concludes that there is an inflationary phase in all open or flat anisotropic spacetimes in these theories. Several examples are constructed where the effect becomes manifest.

  1. Releasing scalar fields: cosmological simulations of scalar-tensor theories for gravity beyond the static approximation.

    PubMed

    Llinares, Claudio; Mota, David F

    2013-04-19

    Several extensions of general relativity and high energy physics include scalar fields as extra degrees of freedom. In the search for predictions in the nonlinear regime of cosmological evolution, the community makes use of numerical simulations in which the quasistatic limit is assumed when solving the equation of motion of the scalar field. In this Letter, we propose a method to solve the full equations of motion for scalar degrees of freedom coupled to matter. We run cosmological simulations which track the full time and space evolution of the scalar field, and find striking differences with respect to the commonly used quasistatic approximation. This novel procedure reveals new physical properties of the scalar field and uncovers concealed astrophysical phenomena which were hidden in the old approach. PMID:23679591

  2. Inflation as AN Attractor in Scalar Cosmology

    NASA Astrophysics Data System (ADS)

    Kim, Hyeong-Chan

    2013-06-01

    We study an inflation mechanism based on attractor properties in cosmological evolutions of a spatially flat Friedmann-Robertson-Walker spacetime based on the Einstein-scalar field theory. We find a new way to get the Hamilton-Jacobi equation solving the field equations. The equation relates a solution "generating function" with the scalar potential. We analyze its stability and find a later time attractor which describes a Universe approaching to an eternal-de Sitter inflation driven by the potential energy, V0>0. The attractor exists when the potential is regular and does not have a linear and quadratic terms of the field. When the potential has a mass term, the attractor exists if the scalar field is in a symmetric phase and is weakly coupled, λ<9V0/16. We also find that the attractor property is intact under small modifications of the potential. If the scalar field has a positive mass-squared or is strongly coupled, there exists a quasi-attractor. However, the quasi-attractor property disappears if the potential is modified. On the whole, the appearance of the eternal inflation is not rare in scalar cosmology in the presence of an attractor.

  3. Scalar transport in plane mixing layers

    NASA Astrophysics Data System (ADS)

    Vanormelingen, J.; Van den Bulck, E.

    This paper describes the application of the Eulerian, single-point, single-time joint-scalar probability density function (PDF) equation for predicting the scalar transport in mixing layer with a high-speed and a low-speed stream. A finite-volume procedure is applied to obtain the velocity field with the k-ɛ closure being used to describe turbulent transport. The scalar field is represented through the modelled evolution equation for the scalar PDF and is solved using a Monte Carlo simulation. The PDF equation employs gradient transport modelling to represent the turbulent diffusion, and the molecular mixing term is modelled by the LMSE closure. There is no source term for chemical reaction as only an inert mixing layer is considered here. The experimental shear layer data published by Batt is used to validate the computational results despite the fact that comparisons between experiments and computational results are difficult because of the high sensitivity of the shear layer to initial conditions and free stream turbulence phenomena. However, the bimodal shape of the RMS scalar fluctuation as was measured by Batt can be reproduced with this model, whereas standard gradient diffusion calculations do not predict the dip in this profile. In this work for the first time an explanation is given for this phenomenon and the importance of a micromixing model is stressed. Also it is shown that the prediction of the PDF shape by the LMSE model is very satisfactory.

  4. Can dark matter be a scalar field?

    NASA Astrophysics Data System (ADS)

    Jesus, J. F.; Pereira, S. H.; Malatrasi, J. L. G.; Andrade-Oliveira, F.

    2016-08-01

    In this paper we study a real scalar field as a possible candidate to explain the dark matter in the universe. In the context of a free scalar field with quadratic potential, we have used Union 2.1 SN Ia observational data jointly with a Planck prior over the dark matter density parameter to set a lower limit on the dark matter mass as m>=0.12H0‑1 eV (c=hbar=1). For the recent value of the Hubble constant indicated by the Hubble Space Telescope, namely H0=73±1.8 km s‑1Mpc‑1, this leads to m>=1.56×10‑33 eV at 99.7% c.l. Such value is much smaller than m~ 10‑22 eV previously estimated for some models. Nevertheless, it is still in agreement with them once we have not found evidences for a upper limit on the scalar field dark matter mass from SN Ia analysis. In practice, it confirms free real scalar field as a viable candidate for dark matter in agreement with previous studies in the context of density perturbations, which include scalar field self interaction.

  5. Exploring scalar field dynamics with Gaussian processes

    SciTech Connect

    Nair, Remya; Jhingan, Sanjay; Jain, Deepak E-mail: sanjay.jhingan@gmail.com

    2014-01-01

    The origin of the accelerated expansion of the Universe remains an unsolved mystery in Cosmology. In this work we consider a spatially flat Friedmann-Robertson-Walker (FRW) Universe with non-relativistic matter and a single scalar field contributing to the energy density of the Universe. Properties of this scalar field, like potential, kinetic energy, equation of state etc. are reconstructed from Supernovae and BAO data using Gaussian processes. We also reconstruct energy conditions and kinematic variables of expansion, such as the jerk and the slow roll parameter. We find that the reconstructed scalar field variables and the kinematic quantities are consistent with a flat ΛCDM Universe. Further, we find that the null energy condition is satisfied for the redshift range of the Supernovae data considered in the paper, but the strong energy condition is violated.

  6. Extended scalar-tensor theories of gravity

    NASA Astrophysics Data System (ADS)

    Crisostomi, Marco; Koyama, Kazuya; Tasinato, Gianmassimo

    2016-04-01

    We study new consistent scalar-tensor theories of gravity recently introduced by Langlois and Noui with potentially interesting cosmological applications. We derive the conditions for the existence of a primary constraint that prevents the propagation of an additional dangerous mode associated with higher order equations of motion. We then classify the most general, consistent scalar-tensor theories that are at most quadratic in the second derivatives of the scalar field. In addition, we investigate the possible connection between these theories and (beyond) Horndeski through conformal and disformal transformations. Finally, we point out that these theories can be associated with new operators in the effective field theory of dark energy, which might open up new possibilities to test dark energy models in future surveys.

  7. Recent progress on light scalar mesons

    SciTech Connect

    Peláez, J. R.

    2014-07-23

    This is a brief account of the recent developments on the determination of the mass and widths of the much debated scalar mesons, paying particular attention to the causes of major revision of the σ or f{sub 0}(500) meson in the last edition of the Review of Particle Physics, which has finally acknowledged that the situation concerning the mass and width of this controversial state has been settled, although this was already well-known to scalar meson practitioners for about a decade. I will briefly comment on the dispersive approach, followed by several groups, which seems to have been the most decisive in support of the existence and precise determinations of scalar meson properties.

  8. The Neural Computation of Scalar Implicature

    PubMed Central

    Hartshorne, Joshua K.; Snedeker, Jesse; Azar, Stephanie Yen-Mun Liem; Kim, Albert E.

    2014-01-01

    Language comprehension involves not only constructing the literal meaning of a sentence but also going beyond the literal meaning to infer what was meant but not said. One widely-studied test case is scalar implicature: The inference that, e.g., Sally ate some of the cookies implies she did not eat all of them. Research is mixed on whether this is due to a rote, grammaticalized procedure or instead a complex, contextualized inference. We find that in sentences like If Sally ate some of the cookies, then the rest are on the counter, that the rest triggers a late, sustained positivity relative to Sally ate some of the cookies, and the rest are on the counter. This is consistent with behavioral results and linguistic theory suggesting that the former sentence does not trigger a scalar implicature. This motivates a view on which scalar implicature is contextualized but dependent on grammatical structure. PMID:25914890

  9. Composite scalar dark matter from vector-like SU(2) confinement

    NASA Astrophysics Data System (ADS)

    Pasechnik, Roman; Beylin, Vitaly; Kuksa, Vladimir; Vereshkov, Grigory

    2016-03-01

    A toy-model with SU(2)TC dynamics confined at high scales ΛTC ≫ 100GeV enables to construct Dirac UV completion from the original chiral multiplets predicting a vector-like nature of their weak interactions consistent with electroweak precision tests. In this work, we investigate a potential of the lightest scalar baryon-like (T-baryon) state B0 = UD with mass mB ≳ 1TeV predicted by the simplest two-flavor vector-like confinement model as a dark matter (DM) candidate. We show that two different scenarios with the T-baryon relic abundance formation before and after the electroweak (EW) phase transition epoch lead to symmetric (or mixed) and asymmetric DM, respectively. Such a DM candidate evades existing direct DM detection constraints since its vector coupling to Z boson absents at tree level, while one-loop gauge boson mediated contribution is shown to be vanishingly small close to the threshold. The dominating spin-independent (SI) T-baryon-nucleon scattering goes via tree-level Higgs boson exchange in the t-channel. The corresponding bound on the effective T-baryon-Higgs coupling has been extracted from the recent LUX data and turns out to be consistent with naive expectations from the light technipion case mπ˜ ≪ ΛTC. The latter provides the most stringent phenomenological constraint on strongly-coupled SU(2)TC dynamics so far. Future prospects for direct and indirect scalar T-baryon DM searches in astrophysics as well as in collider measurements have been discussed.

  10. On causality in polymer scalar field theory

    NASA Astrophysics Data System (ADS)

    García-Chung, Angel A.; Morales-Técotl, Hugo A.

    2011-10-01

    The properties of spacetime corresponding to a proposed quantum gravity theory might modify the high energy behavior of quantum fields. Motivated by loop quantum gravity, recently, Hossain et al [1] have considered a polymer field algebra that replaces the standard canonical one in order to calculate the propagator of a real scalar field in flat spacetime. This propagator features Lorentz violations. Motivated by the relation between Lorentz invariance and causality in standard Quantum Field Theory, in this work we investigate the causality behavior of the polymer scalar field.

  11. Scalar operators in solid-state NMR

    SciTech Connect

    Sun, Boqin

    1991-11-01

    Selectivity and resolution of solid-state NMR spectra are determined by dispersion of local magnetic fields originating from relaxation effects and orientation-dependent resonant frequencies of spin nuclei. Theoretically, the orientation-dependent resonant frequencies can be represented by a set of irreducible tensors. Among these tensors, only zero rank tensors (scalar operators) are capable of providing high resolution NMR spectra. This thesis presents a series of new developments in high resolution solid-state NMR concerning the reconstruction of various scalar operators motion in solid C{sub 60} is analyzed.

  12. Halos of unified dark matter scalar field

    SciTech Connect

    Bertacca, Daniele; Bartolo, Nicola; Matarrese, Sabino E-mail: nicola.bartolo@pd.infn.it

    2008-05-15

    We investigate the static and spherically symmetric solutions of Einstein's equations for a scalar field with a non-canonical kinetic term, assumed to provide both the dark matter and dark energy components of the Universe. In particular, we give a prescription to obtain solutions (dark halos) whose rotation curve v{sub c}(r) is in good agreement with observational data. We show that there exist suitable scalar field Lagrangians that allow us to describe the cosmological background evolution and the static solutions with a single dark fluid.

  13. A Search for Scalar Chameleons with ADMX

    SciTech Connect

    Rybka, G.; Hotz, M.; Rosenberg, L.J.; Asztalos, S.J.; Carosi, G.; Hagmann, C.; Kinion, D.; van Bibber, K.; Hoskins, J.; Martin, C.; Sikivie, P.; Tanner, D.B.; Bradley, R.; Clarke, J.

    2010-04-26

    Scalar fields with a"chameleon" property, in which the effective particle mass is a function of its local environment, are common to many theories beyond the standard model and could be responsible for dark energy. If these fields couple weakly to the photon, they could be detectable through the afterglow effect of photon-chameleon-photon transitions. The ADMX experiment was used in the first chameleon search with a microwave cavity to set a new limit on scalar chameleon-photon coupling beta_gamma excluding values between 2x109 and 5x1014 for effective chameleon masses between 1.9510 and 1:9525 micro eV.

  14. Astrophysical constraints on scalar field models

    SciTech Connect

    Bertolami, O.; Paramos, J.

    2005-01-15

    We use stellar structure dynamics arguments to extract bounds on the relevant parameters of two scalar field models: the putative scalar field mediator of a fifth force with a Yukawa potential and the new variable mass particle models. We also analyze the impact of a constant solar inbound acceleration, such as the one reported by the Pioneer anomaly, on stellar astrophysics. We consider the polytropic gas model to estimate the effect of these models on the hydrostatic equilibrium equation and fundamental quantities such as the central temperature. The current bound on the solar luminosity is used to constrain the relevant parameters of each model.

  15. Initial scalar magnetic anomaly map from Magsat

    NASA Technical Reports Server (NTRS)

    Langel, R. A.; Phillips, J. D.; Horner, R. J.

    1982-01-01

    Magsat data acquired during the November 1979-June 1980 mission was used to derive a scalar magnetic anomaly map covering +50 to -50 deg geographic latitude, and the separation of anomaly fields from core and external fields was accomplished by techniques developed for POGO satellite data. Except in the Atlantic and Pacific at latitudes south of -15 deg, comparison of the Magsat map with its POGO data-derived counterpart shows basic anomaly patterns to be reproducible, and higher resolution due to Magsat's lower measurement altitude. Color-coded scalar anomaly maps are presented for both satellites.

  16. Scalar discrete nonlinear multipoint boundary value problems

    NASA Astrophysics Data System (ADS)

    Rodriguez, Jesus; Taylor, Padraic

    2007-06-01

    In this paper we provide sufficient conditions for the existence of solutions to scalar discrete nonlinear multipoint boundary value problems. By allowing more general boundary conditions and by imposing less restrictions on the nonlinearities, we obtain results that extend previous work in the area of discrete boundary value problems [Debra L. Etheridge, Jesus Rodriguez, Periodic solutions of nonlinear discrete-time systems, Appl. Anal. 62 (1996) 119-137; Debra L. Etheridge, Jesus Rodriguez, Scalar discrete nonlinear two-point boundary value problems, J. Difference Equ. Appl. 4 (1998) 127-144].

  17. The scalar glueball mass in Regge phenomenology

    SciTech Connect

    Burakovsky, L.

    1998-12-01

    The author shows that linear Regge trajectories for mesons and glueballs, and the cubic mass spectrum associated with them, determine a relation between the masses of the {rho} meson and the scalar glueball, M(0{sup ++}) = 3/{radical}2 M({rho}), which implies M(0{sup ++}) = 1620 {+-} 10 MeV. He also discusses a relation between the masses of the scalar and tensor glueballs, M(2{sup ++}) = {radical}2 M(0{sup ++}), which implies M(2{sup ++}) = 2290 {+-} 15 MeV.

  18. Scalar-Pseudoscalar scattering and pseudoscalar resonances

    SciTech Connect

    Albaladejo, M.; Oller, J. A.; Roca, L.

    2011-05-23

    The interactions between the f{sub 0}(980) and a{sub 0}(980) scalar resonances and the lightest pseudoscalar mesons are studied. We first obtain the interacting kernels, without including any ad hoc free parameter, because the lightest scalar resonances are dynamically generated. These kernels are unitarized, giving the final amplitudes, which generate pseudoscalar resonances, associated with the K(1460), {pi}(1300), {pi}(1800), {eta}(1475) and X(1835). We also consider the exotic channels with I = 3/2 and I{sup G} = 1{sup +} quantum numbers. The former could be also resonant in agreement with a previous prediction.

  19. An improved mixing model providing joint statistics of scalar and scalar dissipation

    SciTech Connect

    Meyer, Daniel W.; Jenny, Patrick

    2008-11-15

    For the calculation of nonpremixed turbulent flames with thin reaction zones the joint probability density function (PDF) of the mixture fraction and its dissipation rate plays an important role. The corresponding PDF transport equation involves a mixing model for the closure of the molecular mixing term. Here, the parameterized scalar profile (PSP) mixing model is extended to provide the required joint statistics. Model predictions are validated using direct numerical simulation (DNS) data of a passive scalar mixing in a statistically homogeneous turbulent flow. Comparisons between the DNS and the model predictions are provided, which involve different initial scalar-field lengthscales. (author)

  20. Scalar Mesons in B-decays

    SciTech Connect

    Minkowski, Peter; Ochs, Wolfgang

    2006-02-11

    We summarize some persistent problems in scalar spectroscopy and discuss what could be learned here from charmless B-decays. Recent experimental results are discussed in comparison with theoretical expectations: a simple model based on penguin dominance leads to various symmetry relations in good agreement with recent data; a factorisation approach yields absolute predictions of rates.

  1. Scalar field radiation from dilatonic black holes

    NASA Astrophysics Data System (ADS)

    Gohar, H.; Saifullah, K.

    2012-12-01

    We study radiation of scalar particles from charged dilaton black holes. The Hamilton-Jacobi method has been used to work out the tunneling probability of outgoing particles from the event horizon of dilaton black holes. For this purpose we use WKB approximation to solve the charged Klein-Gordon equation. The procedure gives Hawking temperature for these black holes as well.

  2. Kerr black holes with scalar hair.

    PubMed

    Herdeiro, Carlos A R; Radu, Eugen

    2014-06-01

    We present a family of solutions of Einstein's gravity minimally coupled to a complex, massive scalar field, describing asymptotically flat, spinning black holes with scalar hair and a regular horizon. These hairy black holes (HBHs) are supported by rotation and have no static limit. Besides mass M and angular momentum J, they carry a conserved, continuous Noether charge Q measuring the scalar hair. HBHs branch off from the Kerr metric at the threshold of the superradiant instability and reduce to spinning boson stars in the limit of vanishing horizon area. They overlap with Kerr black holes for a set of (M, J) values. A single Killing vector field preserves the solutions, tangent to the null geodesic generators of the event horizon. HBHs can exhibit sharp physical differences when compared to the Kerr solution, such as J/M^{2}>1, a quadrupole moment larger than J^{2}/M, and a larger orbital angular velocity at the innermost stable circular orbit. Families of HBHs connected to the Kerr geometry should exist in scalar (and other) models with more general self-interactions. PMID:24949750

  3. Dissipation element analysis of turbulent scalar fields

    NASA Astrophysics Data System (ADS)

    Wang, Lipo; Peters, Norbert

    2008-12-01

    Dissipation element analysis is a new approach for studying turbulent scalar fields. Gradient trajectories starting from each material point in a scalar field \\phi'(\\vec{x},t) in ascending directions will inevitably reach a maximal and a minimal point. The ensemble of material points sharing the same pair ending points is named a dissipation element. Dissipation elements can be parameterized by the length scale l and the scalar difference Δphi ', which are defined as the straight line connecting the two extremal points and the scalar difference at these points, respectively. The decomposition of a turbulent field into dissipation elements is space-filling. This allows us to reconstruct certain statistical quantities of fine scale turbulence which cannot be obtained otherwise. The marginal probability density function (PDF) of the length scale distribution based on a Poisson random cutting-reconnection process shows satisfactory agreement with the direct numerical simulation (DNS) results. In order to obtain the further information that is needed for the modeling of scalar mixing in turbulence, such as the marginal PDF of the length of elements and all conditional moments as well as their scaling exponents, there is a need to model the joint PDF of l and Δphi ' as well. A compensation-defect model is put forward in this work to show the dependence of Δphi ' on l. The agreement between the model prediction and DNS results is satisfactory, which may provide another explanation of the Kolmogorov scaling and help to improve turbulent mixing models. Furthermore, intermittency and cliff structure can also be related to and explained from the joint PDF.

  4. Brane solutions sourced by a scalar with vanishing potential and classification of scalar branes

    NASA Astrophysics Data System (ADS)

    Cadoni, Mariano; Franzin, Edgardo; Serra, Matteo

    2016-01-01

    We derive exact brane solutions of minimally coupled Einstein-Maxwell-scalar gravity in d + 2 dimensions with a vanishing scalar potential and we show that these solutions are conformal to the Lifshitz spacetime whose dual QFT is characterized by hyperscaling violation. These solutions, together with the AdS brane and the domain wall sourced by an exponential potential, give the complete list of scalar branes sourced by a generic potential having simple (scale-covariant) scaling symmetries not involving Galilean boosts. This allows us to give a classification of both simple and interpolating brane solution of minimally coupled Einstein-Maxwell-scalar gravity having no Schrödinger isometries, which may be very useful for holographic applications.

  5. Intersecting pentagons as surrogate for identifying the use of mini mental state examination in assessment of dementia in a largely illiterate population

    PubMed Central

    Raina, SK; Maria, A; Chander, V; Raina, S

    2015-01-01

    Background and Rationale: The mini-mental state evaluation (MMSE) is often used to identify patients with dementia. One component of the MMSE is the intersecting pentagon copying (IPC) test, which may be difficult to be used in an illiterate population. Materials and Methods: A post hoc analysis on an elderly population (60 years and above) from Himachal Pradesh was carried out. The data of only 1,513 elderly individuals out of a total of 2,000 participants with a score of more than 26 (nondemented) out of a possible score of 30 on cognitive battery available were used. The scores on the IPC were evaluated and their association with some demographic variables was also assessed. Results: Illiterate participants, female participants, those with greater age, and the rural/tribal population groups faced the most difficulty in drawing the intersecting pentagons and even greater difficulty in drawing them correctly. Discussion: The IPC presents challenges for people who are illiterate and the scoring method needs to be addressed and changed particularly when the test is used in largely illiterate populations. PMID:26440395

  6. Synthesis and structure of K{sub 10}Tl{sub 7}: The first binary trielide containing naked pentagonal bipyramidal Tl{sub 7} clusters

    SciTech Connect

    Kaskel, S.; Corbett, J.D.

    2000-02-21

    The title compound is synthesized by direct fusion of the elements at 400 C followed by annealing at 330 C, quenching to room temperature, and subsequent annealing at 120 and 100 C for days to weeks. The compound crystallizes in the monoclinic space group P2{sub 1}/c (No. 14), with Z = 4, a = 10.132(1){angstrom}, b = 22.323(2){angstrom}, c = 13.376(1){angstrom}, and {beta} = 93.14(1){degree}, and consists of Tl{sub 7}{sup 7{minus}} clusters embedded in a matrix of potassium ions. The cluster is an axially compressed pentagonal bipyramid close to D{sub 5h} symmetry. The apex-apex bond distance (3.462(1){angstrom}) is little longer than the bonds in the pentagonal waist (3.183(1)--3.247(1){angstrom}). Structurally the compound is not electron-precise: K{sub 10}Tl{sub 7} has three extra electrons per Tl{sub 7} cluster and is Pauli paramagnetic ({chi}{sub 300} = 2.25 x 10{sup {minus}4} emu/mol).

  7. Transport Of Passive Scalars In A Turbulent Channel Flow

    NASA Technical Reports Server (NTRS)

    Kim, John; Moin, Parviz

    1990-01-01

    Computer simulation of transport of passive scalars in turbulent channel flow described in report. Shows flow structures and statistical properties. As used here, "passive scalars" means scalar quantities like fluctuations in temperature or concentrations of contaminants that do not disturb flow appreciably. Examples include transport of heat in heat exchangers, gas turbines, and nuclear reactors and dispersal of pollution in atmosphere.

  8. Highly compact neutron stars in scalar-tensor theories of gravity: Spontaneous scalarization versus gravitational collapse

    NASA Astrophysics Data System (ADS)

    Mendes, Raissa F. P.; Ortiz, Néstor

    2016-06-01

    Scalar-tensor theories of gravity are extensions of general relativity (GR) including an extra, nonminimally coupled scalar degree of freedom. A wide class of these theories, albeit indistinguishable from GR in the weak field regime, predicts a radically different phenomenology for neutron stars, due to a nonperturbative, strong-field effect referred to as spontaneous scalarization. This effect is known to occur in theories where the effective linear coupling β0 between the scalar and matter fields is sufficiently negative, i.e. β0≲-4.35 , and has been strongly constrained by pulsar timing observations. In the test-field approximation, spontaneous scalarization manifests itself as a tachyonic-like instability. Recently, it was argued that, in theories where β0>0 , a similar instability would be triggered by sufficiently compact neutron stars obeying realistic equations of state. In this work we investigate the end state of this instability for some representative coupling functions with β0>0 . This is done both through an energy balance analysis of the existing equilibrium configurations, and by numerically determining the nonlinear Cauchy development of unstable initial data. We find that, contrary to the β0<0 case, the final state of the instability is highly sensitive to the details of the coupling function, varying from gravitational collapse to spontaneous scalarization. In particular, we show, for the first time, that spontaneous scalarization can happen in theories with β0>0 , which could give rise to novel astrophysical tests of the theory of gravity.

  9. Stellar oscillations in scalar-tensor theory of gravity

    SciTech Connect

    Sotani, Hajime; Kokkotas, Kostas D.

    2005-06-15

    We derive the perturbation equations for relativistic stars in scalar-tensor theories of gravity and study the corresponding oscillation spectrum. We show that the frequency of the emitted gravitational waves is shifted proportionally to the scalar field strength. Scalar waves which might be produced from such oscillations can be a unique probe for the theory, but their detectability is questionable if the radiated energy is small. However, we show that there is no need for a direct observation of scalar waves: The shift in the gravitational wave spectrum could unambiguously signal the presence of a scalar field.

  10. Creation of the universe with a stealth scalar field

    NASA Astrophysics Data System (ADS)

    Maeda, Hideki; Maeda, Kei-ichi

    2012-12-01

    The stealth scalar field is a nontrivial configuration without any backreaction to geometry, which is characteristic for nonminimally coupled scalar fields. Studying the creation probability of the de Sitter universe with a stealth scalar field by Hartle and Hawking’s semiclassical method, we show that the effect of the stealth field can be significant. For the class of scalar fields we consider, creation with a stealth field is possible for a discrete value of the coupling constant, and its creation probability is always less than that with a trivial scalar field. However, those creation rates can be almost the same depending on the parameters of the theory.

  11. Scalar field cosmologies with inverted potentials

    NASA Astrophysics Data System (ADS)

    Boisseau, B.; Giacomini, H.; Polarski, D.

    2015-10-01

    Regular bouncing solutions in the framework of a scalar-tensor gravity model were found in a recent work. We reconsider the problem in the Einstein frame (EF) in the present work. Singularities arising at the limit of physical viability of the model in the Jordan frame (JF) are either of the Big Bang or of the Big Crunch type in the EF. As a result we obtain integrable scalar field cosmological models in general relativity (GR) with inverted double-well potentials unbounded from below which possess solutions regular in the future, tending to a de Sitter space, and starting with a Big Bang. The existence of the two fixed points for the field dynamics at late times found earlier in the JF becomes transparent in the EF.

  12. Scalar waves in a wormhole geometry

    SciTech Connect

    Kar, S.; Sahdev, D. ); Bhawal, B. )

    1994-01-15

    The reflection and transmission of massless scalar waves in the curved background geometry of a typical Lorentzian wormhole (in 2+1 and 3+1 dimensions) are discussed. Using the exact solutions which involve modified Mathieu (in 2+1 dimensions) and radial oblate spheroidal (in 3+1 dimensions) functions, explicit analytic expressions are obtained for the reflection and transmission coefficients at specific values of the quantity [omega][ital b][sub 0] ([omega] being the energy of the scalar wave and [ital b][sub 0] the throat radius of the wormhole). It is found that both near-perfect reflection as well as transmission are possible for specific choices of certain parameters.

  13. Continuity of scalar fields with logarithmic correlations

    NASA Astrophysics Data System (ADS)

    Rajeev, S. G.; Ranken, Evan

    2015-08-01

    We apply select ideas from the modern theory of stochastic processes in order to study the continuity/roughness of scalar quantum fields. A scalar field with logarithmic correlations (such as a massless field in 1 +1 spacetime dimensions) has the mildest of singularities, making it a logical starting point. Instead of the usual inner product of the field with a smooth function, we introduce a moving average on an interval which allows us to obtain explicit results and has a simple physical interpretation. Using the mathematical work of Dudley, we prove that the averaged random process is in fact continuous, and give a precise modulus of continuity bounding the short-distance variation.

  14. Compton scattering vertex for massive scalar QED

    SciTech Connect

    Bashir, A.; Concha-Sanchez, Y.; Delbourgo, R.; Tejeda-Yeomans, M. E.

    2009-08-15

    We investigate the Compton scattering vertex of charged scalars and photons in scalar quantum electrodynamics (SQED). We carry out its nonperturbative construction consistent with Ward-Fradkin-Green-Takahashi identity which relates 3-point vertices to the 4-point ones. There is an undetermined part which is transverse to one or both the external photons, and needs to be evaluated through perturbation theory. We present in detail how the transverse part at the 1-loop order can be evaluated for completely general kinematics of momenta involved in covariant gauges and dimensions. This involves the calculation of genuine 4-point functions with three massive propagators, the most nontrivial integrals reported in this paper. We also discuss possible applications of our results.

  15. Swarm's Absolute Scalar Magnetometer metrological performances

    NASA Astrophysics Data System (ADS)

    Leger, J.; Fratter, I.; Bertrand, F.; Jager, T.; Morales, S.

    2012-12-01

    The Absolute Scalar Magnetometer (ASM) has been developed for the ESA Earth Observation Swarm mission, planned for launch in November 2012. As its Overhauser magnetometers forerunners flown on Oersted and Champ satellites, it will deliver high resolution scalar measurements for the in-flight calibration of the Vector Field Magnetometer manufactured by the Danish Technical University. Latest results of the ground tests carried out to fully characterize all parameters that may affect its accuracy, both at instrument and satellite level, will be presented. In addition to its baseline function, the ASM can be operated either at a much higher sampling rate (burst mode at 250 Hz) or in a dual mode where it also delivers vector field measurements as a by-product. The calibration procedure and the relevant vector performances will be discussed.

  16. Scalar entrainment in the mixing layer

    NASA Technical Reports Server (NTRS)

    Sandham, N. D.; Mungal, M. G.; Broadwell, J. E.; Reynolds, W. C.

    1988-01-01

    New definitions of entrainment and mixing based on the passive scalar field in the plane mixing layer are proposed. The definitions distinguish clearly between three fluid states: (1) unmixed fluid, (2) fluid engulfed in the mixing layer, trapped between two scalar contours, and (3) mixed fluid. The difference betwen (2) and (3) is the amount of fluid which has been engulfed during the pairing process, but has not yet mixed. Trends are identified from direct numerical simulations and extensions to high Reynolds number mixing layers are made in terms of the Broadwell-Breidenthal mixing model. In the limit of high Peclet number (Pe = ReSc) it is speculated that engulfed fluid rises in steps associated with pairings, introducing unmixed fluid into the large scale structures, where it is eventually mixed at the Kolmogorov scale. From this viewpoint, pairing is a prerequisite for mixing in the turbulent plane mixing layer.

  17. Anisotropic inflation from charged scalar fields

    SciTech Connect

    Emami, Razieh; Firouzjahi, Hassan; Movahed, S.M. Sadegh; Zarei, Moslem E-mail: firouz@ipm.ir E-mail: m.zarei@cc.iut.ac.ir

    2011-02-01

    We consider models of inflation with U(1) gauge fields and charged scalar fields including symmetry breaking potential, chaotic inflation and hybrid inflation. We show that there exist attractor solutions where the anisotropies produced during inflation becomes comparable to the slow-roll parameters. In the models where the inflaton field is a charged scalar field the gauge field becomes highly oscillatory at the end of inflation ending inflation quickly. Furthermore, in charged hybrid inflation the onset of waterfall phase transition at the end of inflation is affected significantly by the evolution of the background gauge field. Rapid oscillations of the gauge field and its coupling to inflaton can have interesting effects on preheating and non-Gaussianities.

  18. Antimatter signals of singlet scalar dark matter

    SciTech Connect

    Goudelis, A.; Mambrini, Y.; Yaguna, C. E-mail: yann.mambrini@th.u-psud.fr

    2009-12-01

    We consider the singlet scalar model of dark matter and study the expected antiproton and positron signals from dark matter annihilations. The regions of the viable parameter space of the model that are excluded by present data are determined, as well as those regions that will be probed by the forthcoming experiment AMS-02. In all cases, different propagation models are investigated, and the possible enhancement due to dark matter substructures is analyzed. We find that the antiproton signal is more easily detectable than the positron one over the whole parameter space. For a typical propagation model and without any boost factor, AMS-02 will be able to probe –via antiprotons– the singlet model of dark matter up to masses of 600 GeV. Antiprotons constitute, therefore, a promising signal to constraint or detect the singlet scalar model.

  19. Noncommutative scalar fields from symplectic deformation

    SciTech Connect

    Daoud, M.; Hamama, A.

    2008-02-15

    This paper is concerned with the quantum theory of noncommutative scalar fields in two dimensional space-time. It is shown that the noncommutativity originates from the the deformation of symplectic structures. The quantization is performed and the modes expansions of the fields, in the presence of an electromagnetic background, are derived. The Hamiltonian of the theory is given and the degeneracies lifting, induced by the deformation, is also discussed.

  20. Scalar waves in the Witten bubble spacetime

    SciTech Connect

    Bhawal, B. Raman Research Institute, Bangalore ); Vishveshwara, C.V. )

    1990-09-15

    Massless scalar waves in the Witten bubble spacetime are studied. The timelike and angular parts of the separated Klein-Gordon equation are written in terms of hyperbolic harmonics characterized by the generalized frequency {omega}. The radial equation is cast into the Schroedinger form. The above mathematical formulation is applied to study the scattering problem, the bound states, and the corresponding stability criteria. The results confirm the concept of a bubble wall as a perfectly reflecting expanding sphere.

  1. Robinson-Trautman solution with scalar hair

    NASA Astrophysics Data System (ADS)

    Tahamtan, T.; Svítek, O.

    2015-05-01

    The explicit Robinson-Trautman solution with a minimally coupled free scalar field is derived and analyzed. It is shown that this solution contains curvature singularity, which is initially naked but later enveloped by the horizon. We use the quasilocal horizon definition and prove its existence in later retarded times using sub- and supersolution method combined with growth estimates. We show that the solution is generally of algebraic type II but reduces to type D in spherical symmetry.

  2. Gravitational collapse of a scalar field

    SciTech Connect

    Maithreyan, T.

    1985-01-01

    A self-similar collapse of massless scalar waves is considered, and the Einstein field equations in classical general relativity are solved to obtain the metric for the collapse. These scalar waves satisfy the massless wave equation and the energy momentum tensor associated with them is derived from their Lagrangian density. The collapse begins at t = 0 before which spacetime is flat, empty spacetime described by the Minkowski metric. Self similarity assumes that a homothetic Killing vector exists for the collapse, which satisfies the corresponding homothetic Killing equation. The solution obtained contains a constant c/sup 2/ whose value determines the nature of the collapse and the kind of singularity formed by the collapsing scalar waves. The three different cases are outlined and the corresponding Penrose diagrams are given. The apparent horizons, defined by Hawking as the limit of the trapped surfaces surrounding the singularity, are calculated for each case. A quantum correction is given for the above classical picture using the method developed originally by Hawking, to study particle creation by a black hole.

  3. FESDIF -- Finite Element Scalar Diffraction theory code

    SciTech Connect

    Kraus, H.G.

    1992-09-01

    This document describes the theory and use of a powerful scalar diffraction theory based computer code for calculation of intensity fields due to diffraction of optical waves by two-dimensional planar apertures and lenses. This code is called FESDIF (Finite Element Scalar Diffraction). It is based upon both Fraunhofer and Kirchhoff scalar diffraction theories. Simplified routines for circular apertures are included. However, the real power of the code comes from its basis in finite element methods. These methods allow the diffracting aperture to be virtually any geometric shape, including the various secondary aperture obstructions present in telescope systems. Aperture functions, with virtually any phase and amplitude variations, are allowed in the aperture openings. Step change aperture functions are accommodated. The incident waves are considered to be monochromatic. Plane waves, spherical waves, or Gaussian laser beams may be incident upon the apertures. Both area and line integral transformations were developed for the finite element based diffraction transformations. There is some loss of aperture function generality in the line integral transformations which are typically many times more computationally efficient than the area integral transformations when applicable to a particular problem.

  4. Scalar-vector quantization of medical images.

    PubMed

    Mohsenian, N; Shahri, H; Nasrabadi, N M

    1996-01-01

    A new coding scheme based on the scalar-vector quantizer (SVQ) is developed for compression of medical images. The SVQ is a fixed rate encoder and its rate-distortion performance is close to that of optimal entropy-constrained scalar quantizers (ECSQs) for memoryless sources. The use of a fixed-rate quantizer is expected to eliminate some of the complexity of using variable-length scalar quantizers. When transmission of images over noisy channels is considered, our coding scheme does not suffer from error propagation that is typical of coding schemes using variable-length codes. For a set of magnetic resonance (MR) images, coding results obtained from SVQ and ECSQ at low bit rates are indistinguishable. Furthermore, our encoded images are perceptually indistinguishable from the original when displayed on a monitor. This makes our SVQ-based coder an attractive compression scheme for picture archiving and communication systems (PACS). PACS are currently under study for use in an all-digital radiology environment in hospitals, where reliable transmission, storage, and high fidelity reconstruction of images are desired. PMID:18285124

  5. Age Crises, Scalar Fields, and the Apocalypse

    NASA Astrophysics Data System (ADS)

    Jackson, J. C.

    Recent observations suggest that Hubble's constant is large, to the extent that the oldest stars appear to have ages which are greater than the Hubble time, and that the Hubble expansion is slowing down, so that according to conventional cosmology the age of the Universe is less than the Hubble time. The concepts of weak and strong age crises (respectively t0<1/H0 but longer than the age inferred from some lower limit on q0, and t0>1/H0 and q0>0) are introduced. These observations are reconciled in models which are dynamically dominated by a homogeneous scalar field, corresponding to an ultra-light boson whose Compton wavelength is of the same order as the Hubble radius. Two such models are considered, an open one with vacuum energy comprising a conventional cosmological term and a scalar field component, and a flat one with a scalar component only, aimed respectively at weak and strong age crises. Both models suggest that anti-gravity plays a significant role in the evolution of the Universe.

  6. Scalar meson spectroscopy with lattice staggered fermions

    SciTech Connect

    Bernard, Claude; DeTar, Carleton; Fu Ziwen; Prelovsek, Sasa

    2007-11-01

    With sufficiently light up and down quarks the isovector (a{sub 0}) and isosinglet (f{sub 0}) scalar meson propagators are dominated at large distance by two-meson states. In the staggered-fermion formulation of lattice quantum chromodynamics, taste-symmetry breaking causes a proliferation of two-meson states that further complicates the analysis of these channels. Many of them are unphysical artifacts of the lattice approximation. They are expected to disappear in the continuum limit. The staggered-fermion fourth-root procedure has its purported counterpart in rooted staggered chiral perturbation theory (rS{chi}PT). Fortunately, the rooted theory provides a strict framework that permits the analysis of scalar meson correlators in terms of only a small number of low-energy couplings. Thus the analysis of the point-to-point scalar meson correlators in this context gives a useful consistency check of the fourth-root procedure and its proposed chiral realization. Through numerical simulation we have measured correlators for both the a{sub 0} and f{sub 0} channels in the 'Asqtad' improved staggered-fermion formulation in a lattice ensemble with lattice spacing a=0.12 fm. We analyze those correlators in the context of rS{chi}PT and obtain values of the low-energy chiral couplings that are reasonably consistent with previous determinations.

  7. Searches for scalar top and scalar bottom quarks at LEP2

    NASA Astrophysics Data System (ADS)

    ALEPH Collaboration; Barate, R.; Buskulic, D.; Decamp, D.; Ghez, P.; Goy, C.; Lees, J.-P.; Lucotte, A.; Minard, M.-N.; Nief, J.-Y.; Pietrzyk, B.; Casado, M. P.; Chmeissani, M.; Comas, P.; Crespo, J. M.; Delfino, M.; Fernandez, E.; Fernandez-Bosman, M.; Garrido, Ll.; Juste, A.; Martinez, M.; Merino, G.; Miquel, R.; Mir, Ll. M.; Padilla, C.; Park, I. C.; Pascual, A.; Perlas, J. A.; Riu, I.; Sanchez, F.; Teubert, F.; Colaleo, A.; Creanza, D.; de Palma, M.; Gelao, G.; Iaselli, G.; Maggi, G.; Maggi, M.; Marinelli, N.; Nuzzo, S.; Ranieri, A.; Raso, G.; Ruggieri, F.; Selvaggi, G.; Silvestris, L.; Tempesta, P.; Tricomi, A.; Zito, G.; Huang, X.; Lin, J.; Ouyang, Q.; Wang, T.; Xie, Y.; Xu, R.; Xue, S.; Zhang, J.; Zhang, L.; Zhao, W.; Abbaneo, D.; Alemany, R.; Bazarko, A. O.; Becker, U.; Bright-Thomas, P.; Cattaneo, M.; Cerutti, F.; Dissertori, G.; Drevermann, H.; Forty, R. W.; Frank, M.; Hagelberg, R.; Hansen, J. B.; Harvey, J.; Janot, P.; Jost, B.; Kneringer, E.; Knobloch, J.; Lehraus, I.; Mato, P.; Minten, A.; Moneta, L.; Pacheco, A.; Pusztaszeri, J.-F.; Ranjard, F.; Rizzo, G.; Rolandi, L.; Rousseau, D.; Schlatter, D.; Schmitt, M.; Schneider, O.; Tejessy, W.; Tomalin, I. R.; Wachsmuth, H.; Wagner, A.; Ajaltouni, Z.; Barrès, A.; Boyer, C.; Falvard, A.; Ferdi, C.; Gay, P.; Guicheney, C.; Henrard, P.; Jousset, J.; Michel, B.; Monteil, S.; Montret, J.-C.; Pallin, D.; Perret, P.; Podlyski, F.; Proriol, J.; Rosnet, P.; Rossignol, J.-M.; Fearnley, T.; Hansen, J. D.; Hansen, J. R.; Hansen, P. H.; Nilsson, B. S.; Rensch, B.; Wäänänen, A.; Daskalakis, G.; Kyriakis, A.; Markou, C.; Simopoulou, E.; Vayaki, A.; Blondel, A.; Brient, J. C.; Machefert, F.; Rougé, A.; Rumpf, M.; Valassi, A.; Videau, H.; Focardi, E.; Parrini, G.; Zachariadou, K.; Cavanaugh, R.; Corden, M.; Georgiopoulos, C.; Huehn, T.; Jaffe, D. E.; Antonelli, A.; Bencivenni, G.; Bologna, G.; Bossi, F.; Campana, P.; Capon, G.; Casper, D.; Chiarella, V.; Felici, G.; Laurelli, P.; Mannocchi, G.; Murtas, F.; Murtas, G. P.; Passalacqua, L.; Pepe-Altarelli, M.; Curtis, L.; Dorris, S. J.; Halley, A. W.; Knowles, I. G.; Lynch, J. G.; O'Shea, V.; Raine, C.; Scarr, J. M.; Smith, K.; Teixeira-Dias, P.; Thompson, A. S.; Thomson, E.; Thomson, F.; Turnbull, R. M.; Buchmüller, O.; Dhamotharan, S.; Geweniger, C.; Graefe, G.; Hanke, P.; Hansper, G.; Hepp, V.; Kluge, E. E.; Putzer, A.; Sommer, J.; Tittel, K.; Werner, S.; Wunsch, M.; Beuselinck, R.; Binnie, D. M.; Cameron, W.; Dornan, P. J.; Girone, M.; Goodsir, S.; Martin, E. B.; Morawitz, P.; Moutoussi, A.; Nash, J.; Sedgbeer, J. K.; Spagnolo, P.; Stacey, A. M.; Williams, M. D.; Ghete, V. M.; Girtler, P.; Kuhn, D.; Rudolph, G.; Betteridge, A. P.; Bowdery, C. K.; Colrain, P.; Crawford, G.; Finch, A. J.; Foster, F.; Hughes, G.; Jones, R. W. L.; Sloan, T.; Whelan, E. P.; Williams, M. I.; Hoffmann, C.; Jakobs, K.; Kleinknecht, K.; Quast, G.; Renk, B.; Rohne, E.; Sander, H.-G.; van Gemmeren, P.; Zeitnitz, C.; Aubert, J. J.; Benchouk, C.; Bonissent, A.; Bujosa, G.; Carr, J.; Coyle, P.; Diaconu, C.; Ealet, A.; Fouchez, D.; Konstantinidis, N.; Leroy, O.; Motsch, F.; Payre, P.; Talby, M.; Sadouki, A.; Thulasidas, M.; Tilquin, A.; Trabelsi, K.; Aleppo, M.; Antonelli, M.; Ragusa, F.; Berlich, R.; Blum, W.; Büscher, V.; Dietl, H.; Ganis, G.; Gotzhein, C.; Kroha, H.; Lütjens, G.; Lutz, G.; Männer, W.; Moser, H.-G.; Richter, R.; Rosado-Schlosser, A.; Schael, S.; Settles, R.; Seywerd, H.; St. Denis, R.; Stenzel, H.; Wiedenmann, W.; Wolf, G.; Boucrot, J.; Callot, O.; Chen, S.; Cordier, A.; Davier, M.; Duflot, L.; Grivaz, J.-F.; Heusse, Ph.; Höcker, A.; Jacholkowska, A.; Jacquet, M.; Kim, D. W.; Le Diberder, F.; Lefrançois, J.; Lutz, A.-M.; Nikolic, I.; Schune, M.-H.; Serin, L.; Simion, S.; Tournefier, E.; Veillet, J.-J.; Videau, I.; Zerwas, D.; Azzurri, P.; Bagliesi, G.; Bettarini, S.; Bozzi, C.; Calderini, G.; Ciulli, V.; dell'Orso, R.; Fantechi, R.; Ferrante, I.; Giassi, A.; Gregorio, A.; Ligabue, F.; Lusiani, A.; Marrocchesi, P. S.; Messineo, A.; Palla, F.; Sanguinetti, G.; Sciabà, A.; Sguazzoni, G.; Steinberger, J.; Tenchini, R.; Vannini, C.; Venturi, A.; Verdini, P. G.; Blair, G. A.; Bryant, L. M.; Chambers, J. T.; Gao, Y.; Green, M. G.; Medcalf, T.; Perrodo, P.; Strong, J. A.; von Wimmersperg-Toeller, J. H.; Botterill, D. R.; Clifft, R. W.; Edgecock, T. R.; Haywood, S.; Maley, P.; Norton, P. R.; Thompson, J. C.; Wright, A. E.; Bloch-Devaux, B.; Colas, P.; Fabbro, B.; Kozanecki, W.; Lançon, E.; Lemaire, M. C.; Locci, E.; Perez, P.; Rander, J.; Renardy, J.-F.; Rosowsky, A.; Roussarie, A.; Schuller, J.-P.; Schwindling, J.; Trabelsi, A.; Vallage, B.; Black, S. N.; Dann, J. H.; Kim, H. Y.; Litke, A. M.; McNeil, M. A.; Taylor, G.; Booth, C. N.; Boswell, R.; Brew, C. A. J.; Cartwright, S.; Combley, F.; Kelly, M. S.; Lehto, M.; Newton, W. M.; Reeve, J.; Thompson, L. F.; Affholderbach, K.; Böhrer, A.; Brandt, S.; Cowan, G.; Foss, J.; Grupen, C.; Lutters, G.; Saraiva, P.; Smolik, L.; Stephan, F.; Apollonio, M.; Bosisio, L.; della Marina, R.; Giannini, G.; Gobbo, B.; Musolino, G.; Putz, J.; Rothberg, J.; Wasserbaech, S.; Williams, R. W.; Armstrong, S. R.; Charles, E.; Elmer, P.; Ferguson, D. P. S.; González, S.; Greening, T. C.; Hayes, O. J.; Hu, H.; Jin, S.; McNamara, P. A., III; Nachtman, J. M.; Nielsen, J.; Orejudos, W.; Pan, Y. B.; Saadi, Y.; Scott, I. J.; Walsh, J.; Wu, Sau Lan; Wu, X.; Yamartino, J. M.; Zobernig, G.

    1997-11-01

    Searches for scalar top and bottom quarks have been performed with data collected by the ALEPH detector at LEP. The data sample consists of 21.7 pb-1 taken at sqrt(s) = 161, 170, and 172 GeV and 5.7 pb-1 taken at sqrt(s) = 130 and 136 GeV. No evidence for scalar top quarks or scalar bottom quarks was found in the channels t~-->cχ, t~-->blν~, and b~-->bχ. For the channel t~-->cχ a limit of 67 GeV/c2has been set on the scalar top quark mass, independent of the mixing angle between the supersymmetric partners of the left and right-handed states of the top quark. This limit assumes a mass difference between the t~ and the χ of at least 10 GeV/c2. For the channel t~-->blν~ the mixing-angle independent scalar top limit is 70 GeV/c2, assuming a mass difference between the t~ and the ν~ of at least 10 GeV/c2. For the channel b~-->bχ, a limit of 73 GeV/c2has been set on the mass of the supersymmetric partner of the left-handed state of the bottom quark. This limit is valid if the mass difference between the b~ and the χ is at least 10 GeV/c2.

  8. Infrared detection of (H2O)20 isomers of exceptional stability: A drop-like and a face-sharing pentagonal prism cluster

    DOE PAGESBeta

    Pradzynski, Christoph C.; Dierking, Christoph W.; Zurheide, Florian; Forck, Richard M.; Buck, Udo; Zeuch, Thomas; Xantheas, Sotiris S.

    2014-09-01

    Water clusters containing fully coordinated water molecules are model systems that mimic the local environment of the condensed phase. Present knowledge about the water cluster size regime in which the transition from the allsurface to the fully solvated water molecules occurs is mainly based on theoretical predictions in lieu of the absence of precisely size resolved experimental measurements. Here, we report size and isomer selective infrared (IR) spectra of (H2O)20 clusters tagged with a sodium atom by employing IR excitation modulated photoionization spectroscopy. The observed absorption patterns in the OH stretching ”fingerprint” region are consistent with the theoretically predicted spectramore » of two structurally distinct isomers: A drop-like cluster with a fully coordinated (interior) water and an edge-sharing pentagonal prism cluster in which all atoms are on the surface. The observed isomers show exceptional stability and are predicted to be nearly isoenergetic.« less

  9. Workshop on models to estimate military system probability of effect (P/sub E/) due to incident radiofrequency energy: Volume 2, Proceedings: The Pentagon

    SciTech Connect

    Chesser, N.J.

    1988-01-01

    The material which follows summarizes the presentations and discussion which took place during a workshop held at the Pentagon in June 1988. The first five sections are summaries of individual presentations, not strictly in the order in which they were given, but rather divided into five topic areas and arranged within those areas in the order in which they were presented: Introduction; Proposed Approaches to P/sub K/; Methods from SDI LTH; Lessons from the EMP/EMI/EMC Community; HPM Testing Methodology. Where appropriate, comments made during those presentations are noted within curly brackets /l brace/.../r brace/. Section Six summarizes the observations made and issues raised during the working session on the afternoon of the second day.

  10. Simple Method for Constructing RNA Triangle, Square, Pentagon by Tuning Interior RNA 3WJ Angle from 60° to 90° or 108°.

    PubMed

    Khisamutdinov, Emil F; Bui, My Nguyen Hoan; Jasinski, Daniel; Zhao, Zhengyi; Cui, Zheng; Guo, Peixuan

    2015-01-01

    Precise shape control of architectures at the nanometer scale is an intriguing but extremely challenging facet. RNA has recently emerged as a unique material and thermostable building block for use in nanoparticle construction. Here, we describe a simple method from design to synthesis of RNA triangle, square, and pentagon by stretching RNA 3WJ native angle from 60° to 90° and 108°, using the three-way junction (3WJ) of the pRNA from bacteriophage phi29 dsDNA packaging motor. These methods for the construction of elegant polygons can be applied to other RNA building blocks including the utilization and application of RNA 4-way, 5-way, and other multi-way junctions. PMID:25967062

  11. Comparison of geometric, electronic, and vibrational properties for all pentagon/hexagon-bearing isomers of fullerenes C38, C40, and C42

    NASA Astrophysics Data System (ADS)

    Małolepsza, Edyta; Lee, Yuan-Pern; Witek, Henryk A.; Irle, Stephan; Lin, Chun-Fu; Hsieh, Horng-Ming

    The self-consistent-charge density-functional tight-binding (SCC-DFTB) method is employed for computing geometric, electronic, and vibrational properties for various topological isomers of small fullerenes. We consider all pentagon/hexagon-bearing isomers of C38, C40, and C42 as the second part of a larger effort to catalogue the CC distance distributions, valence CCC angle distributions, electronic densities of states (DOSs), vibrational densities of states (VDOSs), and infrared (IR) and Raman spectra for fullerenes C20=C180 [analogous data for C20=C36 were published previously in Małolepsza et al., J Phys Chem A, 2007, 111, 6649]. Common features among the fullerenes are identified and properties characteristic for each specific fullerene cage size are discussed.

  12. (An)Isotropic models in scalar and scalar-tensor cosmologies

    NASA Astrophysics Data System (ADS)

    Belinchón, José Antonio

    2012-04-01

    We study how the constants G and Λ may vary in different theoretical models (general relativity with a perfect fluid, scalar cosmological models ("quintessence") with and without interacting scalar and matter fields and a scalar-tensor model with a dynamical Λ) in order to explain some observational results. We apply the program outlined in section II to study three different geometries which generalize the FRW ones, which are Bianchi V, VII0 and IX, under the self-similarity hypothesis. We put special emphasis on calculating exact power-law solutions which allow us to compare the different models. In all the studied cases we arrive at the conclusion that the solutions are isotropic and noninflationary while the cosmological constant behaves as a positive decreasing time function (in agreement with the current observations) and the gravitational constant behaves as a growing time function.

  13. Synthesis, structure and magnetic ordering of the mullite-type Bi2Fe(4-x)CrxO9 solid solutions with a frustrated pentagonal Cairo lattice.

    PubMed

    Rozova, M G; Grigoriev, V V; Bobrikov, I A; Filimonov, D S; Zakharov, K V; Volkova, O S; Vasiliev, A N; Antipov, E V; Tsirlin, A A; Abakumov, A M

    2016-01-21

    Highly homogeneous mullite-type solid solutions Bi2Fe(4-x)CrxO9 (x = 0.5, 1, 1.2) were synthesized using a soft chemistry technique followed by a solid-state reaction in Ar. The crystal structure of Bi2Fe3CrO9 was investigated using X-ray and neutron powder diffraction, transmission electron microscopy and (57)Fe Mössbauer spectroscopy (S.G. Pbam, a = 7.95579(9) Å, b = 8.39145(9) Å, c = 5.98242(7) Å, RF(X-ray) = 0.022, RF(neutron) = 0.057). The ab planes in the structure are tessellated with distorted pentagonal loops built up by three tetrahedrally coordinated Fe sites and two octahedrally coordinated Fe/Cr sites, linked together in the ab plane by corner-sharing forming a pentagonal Cairo lattice. Magnetic susceptibility measurements and powder neutron diffraction show that the compounds order antiferromagnetically (AFM) with the Néel temperatures decreasing upon increasing the Cr content from TN ∼ 250 K for x = 0 to TN ∼ 155 K for x = 1.2. The magnetic structure of Bi2Fe3CrO9 at T = 30 K is characterized by a propagation vector k = (1/2,1/2,1/2). The tetrahedrally coordinated Fe cations form singlet pairs within dimers of corner-sharing tetrahedra, but spins on the neighboring dimers are nearly orthogonal. The octahedrally coordinated (Fe,Cr) cations form antiferromagnetic up-up-down-down chains along c, while the spin arrangement in the ab plane is nearly orthogonal between nearest neighbors and collinear between second neighbors. The resulting magnetic structure is remarkably different from the one in pure Bi2Fe4O9 and features several types of spin correlations even on crystallographically equivalent exchange that may be caused by the simultaneous presence of Fe and Cr on the octahedral site. PMID:26661379

  14. On the power law of passive scalars in turbulence

    NASA Astrophysics Data System (ADS)

    Gotoh, Toshiyuki; Watanabe, Takeshi

    2015-11-01

    It has long been considered that the moments of the scalar increment with separation distance r obey power law with scaling exponents in the inertial convective range and the exponents are insensitive to variation of pumping of scalar fluctuations at large scales, thus the scaling exponents are universal. We examine the scaling behavior of the moments of increments of passive scalars 1 and 2 by using DNS up to the grid points of 40963. They are simultaneously convected by the same isotropic steady turbulence atRλ = 805 , but excited by two different methods. Scalar 1 is excited by the random scalar injection which is isotropic, Gaussian and white in time at law wavenumber band, while Scalar 2 is excited by the uniform mean scalar gradient. It is found that the local scaling exponents of the scalar 1 has a logarithmic correction, meaning that the moments of the scalar 1 do not obey simple power law. On the other hand, the moments of the scalar 2 is found to obey the well developed power law with exponents consistent with those in the literature. Physical reasons for the difference are explored. Grants-in-Aid for Scientific Research 15H02218 and 26420106, NIFS14KNSS050, HPCI project hp150088 and hp140024, JHPCN project jh150012.

  15. Astrophysical effects of scalar dark matter miniclusters

    NASA Astrophysics Data System (ADS)

    Zurek, Kathryn M.; Hogan, Craig J.; Quinn, Thomas R.

    2007-02-01

    We model the formation, evolution and astrophysical effects of dark compact Scalar Miniclusters (“ScaMs”). These objects arise when a scalar field, with an axion-like or Higgs-like potential, undergoes a second-order phase transition below the QCD scale. Such a scalar field may couple too weakly to the standard model to be detectable directly through particle interactions, but may still be detectable by gravitational effects, such as lensing and baryon accretion by large, gravitationally bound miniclusters. The masses of these objects are shown to be constrained by the Lyα power spectrum to be less than ˜104M⊙, but they may be as light as classical axion miniclusters, of the order of 10-12M⊙. We simulate the formation and nonlinear gravitational collapse of these objects around matter-radiation equality using an N-body code, estimate their gravitational lensing properties, and assess the feasibility of studying them using current and future lensing experiments. Future MACHO-type variability surveys of many background sources can reveal either high-amplification, strong-lensing events, or measure density profiles directly via weak-lensing variability, depending on ScaM parameters and survey depth. However, ScaMs, due to their low internal densities, are unlikely to be responsible for apparent MACHO events already detected in the Galactic halo. As a result, in the entire window between 10-7M⊙ and 102M⊙ covered by the galactic scale lensing experiments, ScaMs may in fact compose all the dark matter. A simple estimate is made of parameters that would give rise to early structure formation; in principle, early stellar collapse could be triggered by ScaMs as early as recombination, and significantly affect cosmic reionization.

  16. Scalar wave diffraction from a circular aperture

    SciTech Connect

    Cerjan, C.

    1995-01-25

    The scalar wave theory is used to evaluate the expected diffraction patterns from a circular aperture. The standard far-field Kirchhoff approximation is compared to the exact result expressed in terms of oblate spheroidal harmonics. Deviations from an expanding spherical wave are calculated for circular aperture radius and the incident beam wavelength using suggested values for a recently proposed point diffractin interferometer. The Kirchhoff approximation is increasingly reliable in the far-field limit as the aperture radius is increased, although significant errors in amplitude and phase persist.

  17. Scalar-field theory of dark matter

    NASA Astrophysics Data System (ADS)

    Huang, Kerson; Xiong, Chi; Zhao, Xiaofei

    2014-05-01

    We develop a theory of dark matter based on a previously proposed picture, in which a complex vacuum scalar field makes the universe a superfluid, with the energy density of the superfluid giving rise to dark energy, and variations from vacuum density giving rise to dark matter. We formulate a nonlinear Klein-Gordon equation to describe the superfluid, treating galaxies as external sources. We study the response of the superfluid to the galaxies, in particular, the emergence of the dark-matter galactic halo, contortions during galaxy collisions and the creation of vortices due to galactic rotation.

  18. Casimir effect for massive scalar field

    NASA Astrophysics Data System (ADS)

    Mobassem, S.

    2014-10-01

    The energy-momentum tensor is used to introduce the Casimir force of the massive scalar field acting on a nonpenetrating surface. This expression can be used to evaluate the vacuum force by employing the appropriate field operators. To simplify our formalism, we also relate the vacuum force expression to the imaginary part of the Green function via the fluctuation-dissipation theorem and Kubo's formula. This allows one to evaluate the vacuum force without resorting to the process of field quantization. These two approaches are used to calculate the attractive force between two nonpenetrating plates. Special attention is paid to the generalization of the formalism to D+1 spacetime dimensions.

  19. Scalar mesons and polarizability of the nucleon

    SciTech Connect

    Schumacher, Martin

    2008-08-31

    It is shown that the scalar mesons {sigma}, f{sub 0}(980) and a{sub 0}(980) as t-channel exchanges quantitatively solve the problem of diamagnetism and give an explanation of the large missing part of the electric polarizability {alpha} showing up when only the pion cloud is taken into account. The electric polarizability of the proton {alpha}{sub p} confirms a two-photon width of the {sigma} meson of {gamma}{sub {sigma}}{sub {gamma}}{sub {gamma}} = (2.58{+-}0.26) keV.

  20. Global integrability of cosmological scalar fields

    NASA Astrophysics Data System (ADS)

    Maciejewski, Andrzej J.; Przybylska, Maria; Stachowiak, Tomasz; Szydłowski, Marek

    2008-11-01

    We investigate the Liouvillian integrability of Hamiltonian systems describing a universe filled with a scalar field (possibly complex). The tool used is the differential Galois group approach, as introduced by Morales-Ruiz and Ramis. The main result is that the generic systems with minimal coupling are non-integrable, although there still exist some values of parameters for which integrability remains undecided; the conformally coupled systems are only integrable in four known cases. We also draw a connection with the chaos present in such cosmological models, and the issues of the integrability restricted to the real domain.

  1. Induced gravity I: real scalar field

    NASA Astrophysics Data System (ADS)

    Einhorn, Martin B.; Jones, D. R. Timothy

    2016-01-01

    We show that classically scale invariant gravity coupled to a single scalar field can undergo dimensional transmutation and generate an effective Einstein-Hilbert action for gravity, coupled to a massive dilaton. The same theory has an ultraviolet fixed point for coupling constant ratios such that all couplings are asymptotically free. However the catchment basin of this fixed point does not include regions of coupling constant parameter space compatible with locally stable dimensional transmutation. In a companion paper, we will explore whether this more desirable outcome does obtain in more complicated theories with non-Abelian gauge interactions.

  2. Scalar Potential Model of photon diffraction

    NASA Astrophysics Data System (ADS)

    Hodge, John

    2011-04-01

    Some observations of light are inconsistent with a wave-like model. Other observations of light are inconsistent with a traditional particle-like model. A single model of light has remained a mystery. Newton's speculations, Democritus's speculations, the Bohm interpretation, and the fractal philosophy are combined with the cosmological Scalar Potential Model (SPM). The resulting model of photon structure and dynamics is tested by a toy computer experiment. The simulations included light from a distance and Young's experiment. The patterns on the screens showed diffraction wave patterns fit by the Fresnel equation. The model is consistent with the Afshar experiment and with the concepts of Bohmian mechanics.

  3. Scalar field collapse with negative cosmological constant

    NASA Astrophysics Data System (ADS)

    Baier, R.; Nishimura, H.; Stricker, S. A.

    2015-07-01

    The formation of black holes or naked singularities is studied in a model in which a homogeneous time-dependent scalar field with an exponential potential couples to four-dimensional gravity with negative cosmological constant. An analytic solution is derived and its consequences are discussed. The model depends only on one free parameter, which determines the equation of state and decides the fate of the spacetime. Without fine tuning the value of this parameter the collapse ends in a generic formation of a black hole or a naked singularity. The latter case violates the cosmic censorship conjecture.

  4. Modeling dynamical scalarization with a resummed post-Newtonian expansion

    NASA Astrophysics Data System (ADS)

    Sennett, Noah; Buonanno, Alessandra

    2016-06-01

    Despite stringent constraints set by astrophysical observations, there remain viable scalar-tensor theories that could be distinguished from general relativity with gravitational-wave detectors. A promising signal predicted in these alternative theories is dynamical scalarization, which can dramatically affect the evolution of neutron-star binaries near merger. Motivated by the successful treatment of spontaneous scalarization, we develop a formalism that partially resums the post-Newtonian expansion to capture dynamical scalarization in a mathematically consistent manner. We calculate the post-Newtonian order corrections to the equations of motion and scalar mass of a binary system. Through comparison with quasiequilibrium configuration calculations, we verify that this new approximation scheme can accurately predict the onset and magnitude of dynamical scalarization.

  5. Study of Several Potentials as Scalar Field Dark Matter Candidates

    SciTech Connect

    Matos, Tonatiuh; Vazquez-Gonzalez, Alberto; Magan a, Juan

    2008-12-04

    In this work we study several scalar field potentials as a plausible candidate to be the dark matter in the universe. The main idea is the following; if the scalar field is an ultralight boson particle, it condensates like a Bose-Einstein system at very early times and forms the basic structure of the Universe. Real scalar fields collapse in equilibrium configurations which oscillate in space-time (oscillatons). The cosmological behavior of the field equations are solved using the dynamical system formalism. We use the current cosmological parameters as constraints for the free parameters of the scalar field potentials. We are able to reproduce very well the cosmological predictions of the standard {lambda}CDM model with some scalar field potentials. Therefore, scalar field dark matter seems to be a good alternative to be the nature of the dark matter of the universe.

  6. Quantum tunneling from scalar fields in rotating black strings

    NASA Astrophysics Data System (ADS)

    Gohar, H.; Saifullah, K.

    2013-08-01

    Using the Hamilton-Jacobi method of quantum tunneling and complex path integration, we study Hawking radiation of scalar particles from rotating black strings. We discuss tunneling of both charged and uncharged scalar particles from the event horizons. For this purpose, we use the Klein-Gordon equation and find the tunneling probability of outgoing scalar particles. The procedure gives Hawking temperature for rotating charged black strings as well.

  7. Black holes with surrounding matter in scalar-tensor theories.

    PubMed

    Cardoso, Vitor; Carucci, Isabella P; Pani, Paolo; Sotiriou, Thomas P

    2013-09-13

    We uncover two mechanisms that can render Kerr black holes unstable in scalar-tensor gravity, both associated with the presence of matter in the vicinity of the black hole and the fact that this introduces an effective mass for the scalar. Our results highlight the importance of understanding the structure of spacetime in realistic, astrophysical black holes in scalar-tensor theories. PMID:24074068

  8. B meson decays into charmless pseudoscalar scalar mesons

    SciTech Connect

    Delepine, D.; Lucio M, J. L.; Ramirez, Carlos A.; Mendoza S, J. A.

    2007-06-19

    The nonleptonic weak decays of meson B into a scalar and pseudoscalar meson are studied. The scalar mesons under consideration are {sigma} (or f0(600)), f0(980), a0(980) and K{sub 0}{sup *}(1430). We calculate the Branching ratios in the Naive Factorization approximation. Scalars are assumed to be qq-bar bounded sates, but an estimation can be obtained in the case they are four bounded states.

  9. Scalar dissipation rate statistics in turbulent swirling jets

    NASA Astrophysics Data System (ADS)

    Stetsyuk, V.; Soulopoulos, N.; Hardalupas, Y.; Taylor, A. M. K. P.

    2016-07-01

    The scalar dissipation rate statistics were measured in an isothermal flow formed by discharging a central jet in an annular stream of swirling air flow. This is a typical geometry used in swirl-stabilised burners, where the central jet is the fuel. The flow Reynolds number was 29 000, based on the area-averaged velocity of 8.46 m/s at the exit and the diameter of 50.8 mm. The scalar dissipation rate and its statistics were computed from two-dimensional imaging of the mixture fraction fields obtained with planar laser induced fluorescence of acetone. Three swirl numbers, S, of 0.3, 0.58, and 1.07 of the annular swirling stream were considered. The influence of the swirl number on scalar mixing, unconditional, and conditional scalar dissipation rate statistics were quantified. A procedure, based on a Wiener filter approach, was used to de-noise the raw mixture fraction images. The filtering errors on the scalar dissipation rate measurements were up to 15%, depending on downstream positions from the burner exit. The maximum of instantaneous scalar dissipation rate was found to be up to 35 s-1, while the mean dissipation rate was 10 times smaller. The probability density functions of the logarithm of the scalar dissipation rate fluctuations were found to be slightly negatively skewed at low swirl numbers and almost symmetrical when the swirl number increased. The assumption of statistical independence between the scalar and its dissipation rate was valid for higher swirl numbers at locations with low scalar fluctuations and less valid for low swirl numbers. The deviations from the assumption of statistical independence were quantified. The conditional mean of the scalar dissipation rate, the standard deviation of the scalar dissipation rate fluctuations, the weighted probability of occurrence of the mean conditional scalar dissipation rate, and the conditional probability are reported.

  10. Scalar self-interactions loosen constraints from fifth force searches

    SciTech Connect

    Gubser, Steven S.; Khoury, Justin

    2004-11-15

    The mass of a scalar field mediating a fifth force is tightly constrained by experiments. We show, however, that adding a quartic self-interaction for such a scalar makes most tests much less constraining: the nonlinear equation of motion masks the coupling of the scalar to matter through the chameleon mechanism. We discuss consequences for fifth force experiments. In particular, we find that, with quartic coupling of order unity, a gravitational strength interaction with matter is allowed by current constraints. We show that our chameleon scalar field results in experimental signatures that could be detected through modest improvements of current laboratory set-ups.

  11. Inert scalar doublet asymmetry as origin of dark matter

    NASA Astrophysics Data System (ADS)

    Dhen, Mikaël; Hambye, Thomas

    2015-10-01

    In the inert scalar doublet framework, we analyze what would be the effect of a B -L asymmetry that could have been produced at high temperature in the thermal bath of the Universe. We show that unless the "λ5" scalar interaction is tiny, this asymmetry is automatically reprocessed in part into an inert scalar asymmetry that could be at the origin of dark matter today. Along this scenario, the inert mass scale lies in the few-TeV range, and direct detection constraints require that the inert scalar particles decay into a lighter dark matter particle which, as the inert doublet, is odd under a Z2 symmetry.

  12. Charged scalar perturbations around a regular magnetic black hole

    NASA Astrophysics Data System (ADS)

    Huang, Yang; Liu, Dao-Jun

    2016-05-01

    We study charged scalar perturbations in the background of a regular magnetic black hole. In this case, the charged scalar perturbation does not result in superradiance. By using a careful time-domain analysis, we show that the charge of the scalar field can change the real part of the quasinormal frequency, but has little impact on the imaginary part of the quasinormal frequency and the behavior of the late-time tail. Therefore, the regular magnetic black hole may be stable under the perturbations of a charged scalar field at the linear level.

  13. Inflationary solutions in the nonminimally coupled scalar field theory

    NASA Astrophysics Data System (ADS)

    Koh, Seoktae; Kim, Sang Pyo; Song, Doo Jong

    2005-08-01

    We study analytically and numerically the inflationary solutions for various type scalar potentials in the nonminimally coupled scalar field theory. The Hamilton-Jacobi equation is used to deal with nonlinear evolutions of inhomogeneous spacetimes and the long-wavelength approximation is employed to find the homogeneous solutions during an inflation period. The constraints that lead to a sufficient number of e-folds, a necessary condition for inflation, are found for the nonminimal coupling constant and initial conditions of the scalar field for inflation potentials. In particular, we numerically find an inflationary solution in the new inflation model of a nonminimal scalar field.

  14. Stability of gravitating charged-scalar solitons in a cavity

    NASA Astrophysics Data System (ADS)

    Ponglertsakul, Supakchai; Dolan, Sam R.; Winstanley, Elizabeth

    2016-07-01

    We present new regular solutions of Einstein-charged-scalar-field theory in a cavity. The system is enclosed inside a reflecting mirrorlike boundary, on which the scalar field vanishes. The mirror is placed at the zero of the scalar field closest to the origin, and inside this boundary our solutions are regular. We study the stability of these solitons under linear, spherically symmetric perturbations of the metric, scalar and electromagnetic fields. If the radius of the mirror is sufficiently large, we present numerical evidence for the stability of the solitons. For small mirror radius, some of the solitons are unstable. We discuss the physical interpretation of this instability.

  15. Black hole hair in generalized scalar-tensor gravity.

    PubMed

    Sotiriou, Thomas P; Zhou, Shuang-Yong

    2014-06-27

    The most general action for a scalar field coupled to gravity that leads to second-order field equations for both the metric and the scalar--Horndeski's theory--is considered, with the extra assumption that the scalar satisfies shift symmetry. We show that in such theories, the scalar field is forced to have a nontrivial configuration in black hole spacetimes, unless one carefully tunes away a linear coupling with the Gauss-Bonnet invariant. Hence, black holes for generic theories in this class will have hair. This contradicts a recent no-hair theorem which seems to have overlooked the presence of this coupling. PMID:25014801

  16. Duality linking standard and tachyon scalar field cosmologies

    SciTech Connect

    Avelino, P. P.; Bazeia, D.; Losano, L.; Oliveira, J. C. R. E.; Pavan, A. B.

    2010-09-15

    In this work we investigate the duality linking standard and tachyon scalar field homogeneous and isotropic cosmologies in N+1 dimensions. We determine the transformation between standard and tachyon scalar fields and between their associated potentials, corresponding to the same background evolution. We show that, in general, the duality is broken at a perturbative level, when deviations from a homogeneous and isotropic background are taken into account. However, we find that for slow-rolling fields the duality is still preserved at a linear level. We illustrate our results with specific examples of cosmological relevance, where the correspondence between scalar and tachyon scalar field models can be calculated explicitly.

  17. Searching for Chameleon-Like Scalar Fields

    NASA Astrophysics Data System (ADS)

    Levshakov, S. A.; Molaro, P.; Kozlov, M. G.; Lapinov, A. V.; Henkel, Ch.; Reimersi, D.; Sakai, T.; Agafonova, I. I.

    Using the 32-m Medicina, 45-m Nobeyama, and 100-m Effelsberg telescopes we found a statistically significant velocity offset ΔV ≈ 27 ± 3 m s - 1 (1σ) between the inversion transition in NH3(1,1) and low-J rotational transitions in N2H + (1-0) and HC3N(2-1) arising in cold and dense molecular cores in the Milky Way. Systematic shifts of the line centers caused by turbulent motions and velocity gradients, possible non-thermal hyperfine structure populations, pressure and optical depth effects are shown to be lower than or about 1 m s - 1 and thus can be neglected in the total error budget. The reproducibility of ΔV at the same facility (Effelsberg telescope) on a year-to-year basis is found to be very good. Since the frequencies of the inversion and rotational transitions have different sensitivities to variations in μ ≡ m e / m p, the revealed non-zero ΔV may imply that μ changes when measured at high (terrestrial) and low (interstellar) matter densities as predicted by chameleon-like scalar field models - candidates to the dark energy carrier. Thus we are testing whether scalar field models have chameleon-type interactions with ordinary matter. The measured velocity offset corresponds to the ratio Δμ / μ ≡ (μspace - μlab) / μlab of (26 ± 3) ×10 - 9 (1σ).

  18. Scalar field theory on noncommutative Snyder spacetime

    SciTech Connect

    Battisti, Marco Valerio; Meljanac, Stjepan

    2010-07-15

    We construct a scalar field theory on the Snyder noncommutative space-time. The symmetry underlying the Snyder geometry is deformed at the co-algebraic level only, while its Poincare algebra is undeformed. The Lorentz sector is undeformed at both the algebraic and co-algebraic level, but the coproduct for momenta (defining the star product) is non-coassociative. The Snyder-deformed Poincare group is described by a non-coassociative Hopf algebra. The definition of the interacting theory in terms of a nonassociative star product is thus questionable. We avoid the nonassociativity by the use of a space-time picture based on the concept of the realization of a noncommutative geometry. The two main results we obtain are (i) the generic (namely, for any realization) construction of the co-algebraic sector underlying the Snyder geometry and (ii) the definition of a nonambiguous self-interacting scalar field theory on this space-time. The first-order correction terms of the corresponding Lagrangian are explicitly computed. The possibility to derive Noether charges for the Snyder space-time is also discussed.

  19. Emergence of Lorentzian signature and scalar gravity

    SciTech Connect

    Girelli, F.; Liberati, S.; Sindoni, L.

    2009-02-15

    In recent years, a growing momentum has been gained by the emergent gravity framework. Within the latter, the very concepts of geometry and gravitational interaction are not seen as elementary aspects of nature but rather as collective phenomena associated to the dynamics of more fundamental objects. In this paper we want to further explore this possibility by proposing a model of emergent Lorentzian signature and scalar gravity. Assuming that the dynamics of the fundamental objects can give rise in first place to a Riemannian manifold and a set of scalar fields we show how time (in the sense of hyperbolic equations) can emerge as a property of perturbations dynamics around some specific class of solutions of the field equations. Moreover, we show that these perturbations can give rise to a spin-0 gravity via a suitable redefinition of the fields that identifies the relevant degrees of freedom. In particular, we find that our model gives rise to Nordstroem gravity. Since this theory is invariant under general coordinate transformations, this also shows how diffeomorphism invariance (albeit of a weaker form than the one of general relativity) can emerge from much simpler systems.

  20. Modelling Scalar Skewness in Cloudy Boundary Layers

    NASA Astrophysics Data System (ADS)

    Mironov, Dmitrii; Machulskaya, Ekaterina; Naumann, Ann Kristin; Seifert, Axel; Mellado, Juan Pedro

    2015-04-01

    Following the pioneering work of Sommeria and Deardorff (1977), statistical cloud schemes are widely used in numerical weather prediction (NWP) and climate models to parameterize the effect of shallow clouds on turbulent mixing and radiation fluxes. Statistical cloud schemes compute the cloud fraction, the amount of cloud condensate and the effect clouds on the buoyancy flux in a given atmospheric-model grid box. This is done with due regard for the sub-grid scale (SGS) fluctuations of temperature and humidity (and possibly the vertical velocity), thus providing an important coupling between cloudiness and the SGS mixing processes. The shape of the PDF of fluctuating fields is assumed, whereas the PDF moments should be provided to the cloud scheme as an input. For non-precipitation clouds, the mixing schemes are usually formulated in terms of quasi-conservative variable, e.g. the liquid (total) water potential temperature and the total water specific humidity. Then, the cloud schemes are conveniently cast in terms of the linearized saturation deficit, referred to as the "s" variable (Mellor 1977), that accounts for the combined effect of the two scalars. If a simple two-parameter single-Gaussian PDF is used, the only "turbulence" parameter to be provided to the cloud scheme is the variance of s. The single-Gaussian PDF ignores the skewed nature of SGS motions and fails to describe many important regimes, e.g. shallow cumuli. A number of more flexible skewed PDFs have been proposed to date. A three-parameter PDF, based on a double-Gaussian distribution and diagnostic relations between some PDF parameters derived from LES and observational data (Naumann et al. 2013), appears to be a good compromise between physical realism and computational economy. A crucial point is that the cloud schemes using non-Gaussian PDFs require the scalar skewness as an input. Using rather mild non-restrictive assumptions, we develop a transport equation for the s-variable triple

  1. General Relativity, Scalar Fields and Cosmic Strings.

    NASA Astrophysics Data System (ADS)

    Burd, Adrian Benedict

    1987-09-01

    Available from UMI in association with The British Library. This thesis is divided into three, essentially self-contained, parts. In the first part we examine the structure of classical three-dimensional space-times. Here, we review and extend what is known about the gravitational theories in these models. We investigate the non-existence of a Newtonian limit to the relativistic theories showing that in the presence of certain matter terms, Newtonian gravity can be obtained as a suitable weak-field limit. We present a number of new, exact static and non-static solutions to the equations of three-dimensional general relativity with scalar field and perfect fluid sources. We comment on the relationship between the stiff perfect fluid and the scalar field. Motivated by the Kaluza-Klein procedure of dimensional reduction we find some exact scalar field solutions which have analogues in four-dimensions. We also present classification schemes based on the group of motions of homogeneous space-times and on the Cotton -York tensor. The description of the general cosmological solution in the vicinity of the singularity is given in terms of the number of arbitrary spatial functions independently specified on a space-like hypersurface. We also study a series approximation to the space-time in the vicinity of the cosmological singularity. Some conjectures are made concerning the space-time singularities. We present two exact cosmological solutions containing self-interacting scalar fields. The models exhibit an inflationary behaviour. We also present an anisotropic cosmological model. The second part of the thesis contains a study of certain cosmological models which have self-interacting scalar fields obeying an exponential potential. We use the techniques of phase portrait analysis to study the N-dimensional cosmological models as well as certain anisotropic models. The latter involves the analysis of a three-dimensional system of equations and we review the relevant theory

  2. A new scalar resonance at 750 GeV: towards a proof of concept in favor of strongly interacting theories

    NASA Astrophysics Data System (ADS)

    Son, Minho; Urbano, Alfredo

    2016-05-01

    We interpret the recently observed excess in the diphoton invariant mass as a new spin-0 resonant particle. On theoretical grounds, an interesting question is whether this new scalar resonance belongs to a strongly coupled sector or a well-defined weakly coupled theory. A possible UV-completion that has been widely considered in literature is based on the existence of new vector-like fermions whose loop contributions — Yukawa-coupled to the new resonance — explain the observed signal rate. The large total width preliminarily suggested by data seems to favor a large Yukawa coupling, at the border of a healthy perturbative definition. This potential problem can be fixed by introducing multiple vector-like fermions or large electric charges, bringing back the theory to a weakly coupled regime. However, this solution risks to be only a low-energy mirage: large multiplicity or electric charge can dangerously reintroduce the strong regime by modifying the renormalization group running of the dimensionless couplings. This issue is also tightly related to the (in)stability of the scalar potential. First, we study — in the theoretical setup described above — the parametric behavior of the diphoton signal rate, total width, and one-loop β functions. Then, we numerically solve the renormalization group equations, taking into account the observed diphoton signal rate and total width, to investigate the fate of the weakly coupled theory. We find that — with the only exception of few fine-tuned directions — weakly coupled interpretations of the excess are brought back to a strongly coupled regime if the running is taken into account.

  3. Singlet scalar resonances and the diphoton excess

    NASA Astrophysics Data System (ADS)

    McDermott, Samuel D.; Meade, Patrick; Ramani, Harikrishnan

    2016-04-01

    ATLAS and CMS recently released the first results of searches for diphoton resonances in 13 TeV data, revealing a modest excess at an invariant mass of approximately 750 GeV. We find that it is generically possible that a singlet scalar resonance is the origin of the excess while avoiding all other constraints. We highlight some of the implications of this model and how compatible it is with certain features of the experimental results. In particular, we find that the very large total width of the excess is difficult to explain with loop-level decays alone, pointing to other interesting bounds and signals if this feature of the data persists. Finally we comment on the robust Zγ signature that will always accompany the model we investigate.

  4. Gastric cryptosporidiosis in freshwater angelfish (Pterophyllum scalare).

    PubMed

    Murphy, Brian G; Bradway, Daniel; Walsh, Timothy; Sanders, George E; Snekvik, Kevin

    2009-09-01

    A freshwater angelfish (Pterophyllum scalare) hatchery experienced variable levels of emaciation, poor growth rates, swollen coelomic cavities, anorexia, listlessness, and increased mortality within their fish. Multiple chemotherapeutic trials had been attempted without success. In affected fish, large numbers of protozoa were identified both histologically and ultrastructurally associated with the gastric mucosa. The youngest cohort of parasitized fish was the most severely affected and demonstrated the greatest morbidity and mortality. The protozoa were morphologically most consistent with Cryptosporidium. All of the protozoan life stages were identified ultrastructurally and protozoal genomic DNA was isolated from parasitized tissue viscera and sequenced. Histological, ultrastructural, genetic, and phylogenetic analyses confirmed this protozoal organism to be a novel species of Cryptosporidium. PMID:19737774

  5. The bifurcation of tracked scalar waves

    SciTech Connect

    Glimm, J.; Grove, J.; Lindquist, B.; McBryan, O.A.; Tryggvason, G.

    1988-01-01

    The dynamic evolution of tracked waves by a front-tracking algorithm may lead on either numerical or physical grounds to intersections. The correct resolution of these intersections is described locally by the solution of Riemann problems and requires a bifurcation of the topology defined by the tracked waves. Here the authors describe an algorithm that is appropriate for the resolution of scalar tracked waves, such as material discontinuities, contact discontinuities in gas dynamics, or constituent concentration waves including oil-water banks in oil reservoirs. Although the algorithm is not fully general, it seems to be adequate provided the front to be untangled is a small perturbation (resulting for example from a single time step in an evolution) of a valid, nonintersecting front. Examples are presented that show that complicated interfaces can be generated automatically from simple ones through successive bifurcations.

  6. Gastric cryptosporidiosis in freshwater angelfish (Pterophyllum scalare)

    USGS Publications Warehouse

    Murphy, B.G.; Bradway, D.; Walsh, T.; Sanders, G.E.; Snekvik, K.

    2009-01-01

    A freshwater angelfish (Pterophyllum scalare) hatchery experienced variable levels of emaciation, poor growth rates, swollen coelomic cavities, anorexia, listlessness, and increased mortality within their fish. Multiple chemotherapeutic trials had been attempted without success. In affected fish, large numbers of protozoa were identified both histologically and ultrastructurally associated with the gastric mucosa. The youngest cohort of parasitized fish was the most severely affected and demonstrated the greatest morbidity and mortality. The protozoa were morphologically most consistent with Cryptosporidium. All of the protozoan life stages were identified ultrastructurally and protozoal genomic DNA was isolated from parasitized tissue viscera and sequenced. Histological, ultrastructural, genetic, and phylogenetic analyses confirmed this protozoal organism to be a novel species of Cryptosporidium.

  7. Scalar mixing in the supersonic shear layer

    NASA Technical Reports Server (NTRS)

    Clemens, N. T.; Mungal, M. G.; Hanson, R. K.; Paul, P. H.

    1991-01-01

    Experiments were conducted in a two-stream planar mixing layer facility at convective Mach numbers of 0.28 and 0.62. Mie scattering from condensed alcohol droplets and planar laser-induced fluorescence (PLIF) of nitric oxide were used for flow visualization in both the side and plan views. The PLIF signals were approximately proportional to mixture fraction and were used to generate statistical quantities. Visualizations using both the Mie scattering and PLIF indicate the structure is essentially two-dimensional at Mc = 0.28 and three-dimensional at Mc = 0.62. Perspective renderings of side view images show the structures are streamwise ramped at Mc = 0.28 and cross-stream ramped at Mc = 0.62. This difference appears to be associated with decreasing streamwise structure spacings at the higher Mc condition. The statistical analysis suggests that with increasing compressibility, the scalar fluctuations are smaller, and the fraction of mixed fluid is higher.

  8. Scalar modes of the relic gravitons

    NASA Astrophysics Data System (ADS)

    Giovannini, Massimo

    2015-01-01

    In conformally flat background geometries the long-wavelength gravitons can be described in the fluid approximation and they induce scalar fluctuations both during inflation and in the subsequent radiation-dominated epoch. While this effect is minute and suppressed for a de Sitter stage of expansion, the fluctuations of the energy-momentum pseudotensor of the graviton fluid lead to curvature perturbations that increase with time all along the post-inflationary evolution. An explicit calculation of these effects is presented for a standard thermal history and it is shown that the growth of the curvature perturbations caused by the long-wavelength modes is approximately compensated by the slope of the power spectra of the energy density, pressure and anisotropic stress of the relic gravitons.

  9. Scalar dark matter: direct vs. indirect detection

    NASA Astrophysics Data System (ADS)

    Duerr, Michael; Pérez, Pavel Fileviez; Smirnov, Juri

    2016-06-01

    We revisit the simplest model for dark matter. In this context the dark matter candidate is a real scalar field which interacts with the Standard Model particles through the Higgs portal. We discuss the relic density constraints as well as the predictions for direct and indirect detection. The final state radiation processes are investigated in order to understand the visibility of the gamma lines from dark matter annihilation. We find two regions where one could observe the gamma lines at gamma-ray telescopes. We point out that the region where the dark matter mass is between 92 and 300 GeV can be tested in the near future at direct and indirect detection experiments.

  10. Electromagnetic fields with vanishing scalar invariants

    NASA Astrophysics Data System (ADS)

    Ortaggio, Marcello; Pravda, Vojtěch

    2016-06-01

    We determine the class of p-forms {\\boldsymbol{F}} that possess vanishing scalar invariants (VSIs) at arbitrary order in an n-dimensional spacetime. Namely, we prove that {\\boldsymbol{F}} is a VSI if and only if if it is of type N, its multiple null direction {\\boldsymbol{\\ell }} is ‘degenerate Kundt’, and {\\pounds }{\\boldsymbol{\\ell }}{\\boldsymbol{F}}=0. The result is theory-independent. Next, we discuss the special case of Maxwell fields, both at the level of test fields and of the full Einstein-Maxwell equations. These describe electromagnetic non-expanding waves propagating in various Kundt spacetimes. We further point out that a subset of these solutions possesses a universal property, i.e. they also solve (virtually) any generalized (non-linear and with higher derivatives) electrodynamics, possibly also coupled to Einstein’s gravity.

  11. Visualization of Scalar Adaptive Mesh Refinement Data

    SciTech Connect

    VACET; Weber, Gunther; Weber, Gunther H.; Beckner, Vince E.; Childs, Hank; Ligocki, Terry J.; Miller, Mark C.; Van Straalen, Brian; Bethel, E. Wes

    2007-12-06

    Adaptive Mesh Refinement (AMR) is a highly effective computation method for simulations that span a large range of spatiotemporal scales, such as astrophysical simulations, which must accommodate ranges from interstellar to sub-planetary. Most mainstream visualization tools still lack support for AMR grids as a first class data type and AMR code teams use custom built applications for AMR visualization. The Department of Energy's (DOE's) Science Discovery through Advanced Computing (SciDAC) Visualization and Analytics Center for Enabling Technologies (VACET) is currently working on extending VisIt, which is an open source visualization tool that accommodates AMR as a first-class data type. These efforts will bridge the gap between general-purpose visualization applications and highly specialized AMR visual analysis applications. Here, we give an overview of the state of the art in AMR scalar data visualization research.

  12. A broad-band scalar vortex coronagraph

    NASA Astrophysics Data System (ADS)

    Errmann, R.; Minardi, S.; Pertsch, T.

    2013-10-01

    Broad-band coronagraphy with deep nulling and small inner working angle has the potential of delivering images and spectra of exoplanets and other faint objects. In recent years, many coronagraphic schemes have been proposed, the most promising being the optical vortex phase mask coronagraphs. In this paper, a new scheme of broad-band optical scalar vortex coronagraph is proposed and characterized experimentally in the laboratory. Our setup employs a pair of computer-generated phase gratings (one of them containing a singularity) to control the chromatic dispersion of phase plates and achieves a constant peak-to-peak attenuation below 1 × 10-3 over a bandwidth of 120 nm centred at 700 nm. An inner working angle of ˜λ/D is demonstrated along with a raw contrast of 11.5 mag at 2λ/D.

  13. A broadband scalar optical vortex coronagraph

    NASA Astrophysics Data System (ADS)

    Errmann, Ronnie; Minardi, Stefano; Pertsch, Thomas

    2014-07-01

    In recent years, new coronagraphic schemes have been proposed, the most promising being the optical vortex phase mask coronagraphs. In our work, a new scheme of broadband optical scalar vortex coronagraph is proposed and characterized experimentally in the laboratory. Our setup employs a pair of computer generated phase gratings (one of them containing a singularity) to control the chromatic dispersion of phase plates and achieves a constant peak-to-peak attenuation below 1:1000 over a bandwidth of 120 nm centered at 700 nm. An inner working angle of λ/D is demonstrated along with a raw contrast of 11.5magnitudes at 2λ/D. A more compact setup achieves a peak-to-peak attenuation below 1:1000 over a bandwidth of 60 nm with the other results remaining the same.

  14. Scalar Dark Matter From Theory Space

    SciTech Connect

    Birkedal-Hansen, Andreas; Wacker, Jay G.

    2003-12-26

    The scalar dark matter candidate in a prototypical theory space little Higgs model is investigated. We review all details of the model pertinent to a relic density calculation. We perform a thermal relic density calculation including couplings to the gauge and Higgs sectors of the model. We find two regions of parameter space that give acceptable dark matter abundances. The first region has a dark matter candidate with a mass {Omicron}(100 GeV), the second region has a candidate with a mass greater than {Omicron}(500 GeV). The dark matter candidate in either region is an admixture of an SU(2) triplet and an SU(2) singlet, thereby constituting a possible WIMP (weakly interacting massive particle).

  15. Search for scalar top and bottom quarks at the Tevatron

    SciTech Connect

    Calfayan, Philippe

    2008-11-23

    This document reviews recent results on the search for scalar top and scalar bottom quarks in pp-bar collisions at {radical}(s) = 1.96 TeV. The analyses presented are based on data samples with integrated luminosities from 1.0 to 1.9 fb{sup -1} recorded at the Tevatron with the D0 and CDF detectors.

  16. Renormalization group analysis in nonrelativistic QCD for colored scalars

    SciTech Connect

    Hoang, Andre H.; Ruiz-Femenia, Pedro

    2006-01-01

    The velocity nonrelativistic QCD Lagrangian for colored heavy scalar fields in the fundamental representation of QCD and the renormalization group analysis of the corresponding operators are presented. The results are an important ingredient for renormalization group improved computations of scalar-antiscalar bound state energies and production rates at next-to-next-to-leading-logarithmic (NNLL) order.

  17. Relativistic stars in scalar-tensor theories with disformal coupling

    NASA Astrophysics Data System (ADS)

    Minamitsuji, Masato; Silva, Hector O.

    2016-06-01

    We present a general formulation to analyze the structure of slowly rotating relativistic stars in a broad class of scalar-tensor theories with disformal coupling to matter. Our approach includes theories with generalized kinetic terms, generic scalar field potentials and contains theories with conformal coupling as particular limits. In order to investigate how the disformal coupling affects the structure of relativistic stars, we propose a minimal model of a massless scalar-tensor theory and investigate in detail how the disformal coupling affects the spontaneous scalarization of slowly rotating neutron stars. We show that for negative values of the disformal coupling parameter between the scalar field and matter, scalarization can be suppressed, while for large positive values of the disformal coupling parameter stellar models cannot be obtained. This allows us to put a mild upper bound on this parameter. We also show that these properties can be qualitatively understood by linearizing the scalar field equation of motion in the background of a general-relativistic incompressible star. To address the intrinsic degeneracy between uncertainties in the equation of state of neutron stars and gravitational theory, we also show the existence of universal equation-of-state-independent relations between the moment of inertia and compactness of neutron stars in this theory. We show that in a certain range of the theory's parameter space the universal relation largely deviates from that of general relativity, allowing, in principle, to probe the existence of spontaneous scalarization with future observations.

  18. Emission of scalar particles from cylindrical black holes

    NASA Astrophysics Data System (ADS)

    Gohar, H.; Saifullah, K.

    2013-01-01

    We study quantum tunneling of scalar particles from black strings. For this purpose we apply WKB approximation and Hamilton-Jacobi method to solve the Klein-Gordon equation for outgoing trajectories. We find the tunneling probability of outgoing charged and uncharged scalars from the event horizon of black strings, and hence the Hawking temperature for these black configurations.

  19. Bose-Einstein condensates from scalar field dark matter

    SciTech Connect

    Urena-Lopez, L. Arturo

    2010-12-07

    We review the properties of astrophysical and cosmological relevance that may arise from the bosonic nature of scalar field dark matter models. The key property is the formation of Bose-Einstein condensates, but we also consider the presence of non-empty excited states that may be relevant for the description of scalar field galaxy halos and the properties of rotation curves.

  20. On relation between scalar interfaces and vorticity in inviscid flows

    NASA Astrophysics Data System (ADS)

    Ramesh, O. N.; Patwardhan, Saurabh

    2013-11-01

    A great variety of applications like pollutant mixing in the atmosphere, mixing of reactants in combustion highlight the importance of passive scalar dynamics in fluid flows. The other dynamically important variable in the study of fluid flow is the vorticity. Vorticity though, unlike a passive scalar, does affect the fluid motion. The dynamics of scalar (linear) and vorticity (non-linear) are governed by the equations which inherently have different characteristics. This paper addresses the question of the faithfulness of representation of vorticity by scalar marker and the motivation for this comes from the experiment of Head and Bandyopadhyay (1981) which showed the existence of coherent vortices by using smoke flow visualization in a turbulent boundary layer. We will show analytically in regions where the molecular diffusion effects are negligible, the vorticity and scalar gradients are orthogonal to each other. The iso- surface of scalar follows the vorticity in an inviscid situation. Also, we will demonstrate that in the case of unsteady burgers vortex and vortex shedding behind a finite circular cylinder, the scalar gradient is orthogonal to vorticity and inner product of vorticity and scalar gradients is zero in regions away from the wall.

  1. Scalar field dark matter: behavior around black holes

    SciTech Connect

    Cruz-Osorio, Alejandro; Guzmán, F. Siddhartha; Lora-Clavijo, Fabio D. E-mail: guzman@ifm.umich.mx

    2011-06-01

    We present the numerical evolution of a massive test scalar fields around a Schwarzschild space-time. We proceed by using hyperboloidal slices that approach future null infinity, which is the boundary of scalar fields, and also demand the slices to penetrate the event horizon of the black hole. This approach allows the scalar field to be accreted by the black hole and to escape toward future null infinity. We track the evolution of the energy density of the scalar field, which determines the rate at which the scalar field is being diluted. We find polynomial decay of the energy density of the scalar field, and use it to estimate the rate of dilution of the field in time. Our findings imply that the energy density of the scalar field decreases even five orders of magnitude in time scales smaller than a year. This implies that if a supermassive black hole is the Schwarzschild solution, then scalar field dark matter would be diluted extremely fast.

  2. LIPSS results for photons coupling to light neutral scalar bosons

    SciTech Connect

    Andrei Afanasev; Oliver K. Baker; Kevin Beard; George Biallas; James Boyce; Minarni Minarni; Roopchan Ramdon; Michelle D. Shinn; Penny Slocum

    2008-06-01

    The LIPSS search for a light neutral scalar boson coupling to optical photons is reported. The search covers a region of parameter space of approximately 1.0 meV and coupling strength greater than 10^-6 GeV^-1. The LIPSS results show no evidence for scalar coupling in this region of parameter space.

  3. Scalar Field Theories with Polynomial Shift Symmetries

    NASA Astrophysics Data System (ADS)

    Griffin, Tom; Grosvenor, Kevin T.; Hořava, Petr; Yan, Ziqi

    2015-12-01

    We continue our study of naturalness in nonrelativistic QFTs of the Lifshitz type, focusing on scalar fields that can play the role of Nambu-Goldstone (NG) modes associated with spontaneous symmetry breaking. Such systems allow for an extension of the constant shift symmetry to a shift by a polynomial of degree P in spatial coordinates. These "polynomial shift symmetries" in turn protect the technical naturalness of modes with a higher-order dispersion relation, and lead to a refinement of the proposed classification of infrared Gaussian fixed points available to describe NG modes in nonrelativistic theories. Generic interactions in such theories break the polynomial shift symmetry explicitly to the constant shift. It is thus natural to ask: Given a Gaussian fixed point with polynomial shift symmetry of degree P, what are the lowest-dimension operators that preserve this symmetry, and deform the theory into a self-interacting scalar field theory with the shift symmetry of degree P? To answer this (essentially cohomological) question, we develop a new graph-theoretical technique, and use it to prove several classification theorems. First, in the special case of P = 1 (essentially equivalent to Galileons), we reproduce the known Galileon N-point invariants, and find their novel interpretation in terms of graph theory, as an equal-weight sum over all labeled trees with N vertices. Then we extend the classification to P > 1 and find a whole host of new invariants, including those that represent the most relevant (or least irrelevant) deformations of the corresponding Gaussian fixed points, and we study their uniqueness.

  4. Scalar triplet flavored leptogenesis: a systematic approach

    SciTech Connect

    Sierra, D. Aristizabal; Dhen, Mikaël; Hambye, Thomas E-mail: mikadhen@ulb.ac.be

    2014-08-01

    Type-II seesaw is a simple scenario in which Majorana neutrino masses are generated by the exchange of a heavy scalar electroweak triplet. When endowed with additional heavy fields, such as right-handed neutrinos or extra triplets, it also provides a compelling framework for baryogenesis via leptogenesis. We derive in this context the full network of Boltzmann equations for studying leptogenesis in the flavored regime. To this end we determine the relations which hold among the chemical potentials of the various particle species in the thermal bath. This takes into account the standard model Yukawa interactions of both leptons and quarks as well as sphaleron processes which, depending on the temperature, may be classified as faster or slower than the Universe Hubble expansion. We find that when leptogenesis is enabled by the presence of an extra triplet, lepton flavor effects allow the production of the B-L asymmetry through lepton number conserving CP asymmetries. This scenario becomes dominant as soon as the triplets couple more to leptons than to standard model scalar doublets. In this case, the way the B-L asymmetry is created through flavor effects is novel: instead of invoking the effect of L-violating inverse decays faster than the Hubble rate, it involves the effect of L-violating decays slower than the Hubble rate. We also analyze the more general situation where lepton number violating CP asymmetries are present and actively participate in the generation of the B-L asymmetry, pointing out that as long as L-violating triplet decays are still in thermal equilibrium when the triplet gauge scattering processes decouple, flavor effects can be striking, allowing to avoid all washout suppression effects from seesaw interactions. In this case the amount of B-L asymmetry produced is limited only by a universal gauge suppression effect, which nevertheless goes away for large triplet decay rates.

  5. Involvement of prefrontal cortex in scalar implicatures: evidence from magnetoencephalography

    PubMed Central

    Politzer-Ahles, Stephen; Gwilliams, Laura

    2015-01-01

    The present study investigated the neural correlates of the realisation of scalar inferences, i.e., the interpretation of some as meaning some but not all. We used magnetoencephalography, which has high temporal resolution, to measure neural activity while participants heard stories that included the scalar inference trigger some in contexts that either provide strong cues for a scalar inference or provide weaker cues. The middle portion of the lateral prefrontal cortex (Brodmann area 46) showed an increased response to some in contexts with fewer cues to the inference, suggesting that this condition elicited greater effort. While the results are not predicted by traditional all-or-nothing accounts of scalar inferencing that assume the process is always automatic or always effortful, they are consistent with more recent gradient accounts which predict that the speed and effort of scalar inferences is strongly modulated by numerous contextual factors. PMID:26247054

  6. Cosmological model with gravitational, electromagnetic, and scalar waves

    SciTech Connect

    Charach, C.; Malin, S.

    1980-06-15

    Following Gowdy, Berger, and Misner we construct a new exact solution of the Einstein--Maxwell--massless-scalar-field equations which corresponds to an inhomogeneous closed universe filled with scalar, gravitational, and electromagnetic waves. It is obtained as a result of homogeneity breaking in the corresponding Bianchi type-I universe. The combined effect of the scalar and vector fields on the dynamics of the evolution process and the interactions between the fields involved are systematically investigated. The structure of the initial singularity is studied in detail in both the homogeneous and inhomogeneous cases. The final stage of evolution is studied and interpreted in terms of the quanta of scalar, gravitational, and electromagnetic fields. Possible extensions of the present model to the conformally coupled scalar field and the Abelian solutions of the Yang-Mills field equations are pointed out.

  7. Interacting scalar radiation and dark matter in cosmology

    NASA Astrophysics Data System (ADS)

    Tang, Yong

    2016-06-01

    We investigate possible cosmological effects of interacting scalar radiation and dark matter. After its decoupling, scalar radiation can stream freely as neutrinos or self-interact strongly as perfect fluid, highly depending on the magnitude of its self-couplings. We obtain the general and novel structure for self-scattering rate and compare it with the expansion rate of our Universe. If its trilinear/cubic coupling is non-zero, scalar radiation can be eventually treated as perfect fluid. Possible effects on CMB are also discussed. When this scalar also mediates interaction among dark matter particles, the linear matter power spectrum for large scale structure can be modified differently from other models. We propose to use Debye shielding to avoid the singularity appearing in the scattering between scalar radiation and dark matter.

  8. Interactive Reference Point Procedure Based on the Conic Scalarizing Function

    PubMed Central

    2014-01-01

    In multiobjective optimization methods, multiple conflicting objectives are typically converted into a single objective optimization problem with the help of scalarizing functions. The conic scalarizing function is a general characterization of Benson proper efficient solutions of non-convex multiobjective problems in terms of saddle points of scalar Lagrangian functions. This approach preserves convexity. The conic scalarizing function, as a part of a posteriori or a priori methods, has successfully been applied to several real-life problems. In this paper, we propose a conic scalarizing function based interactive reference point procedure where the decision maker actively takes part in the solution process and directs the search according to her or his preferences. An algorithmic framework for the interactive solution of multiple objective optimization problems is presented and is utilized for solving some illustrative examples. PMID:24723795

  9. New Isolated-Pentagon-Rule and Skeletally Transformed Isomers of C100 Fullerene Identified by Structure Elucidation of their Chloro Derivatives.

    PubMed

    Wang, Song; Yang, Shangfeng; Kemnitz, Erhard; Troyanov, Sergey I

    2016-03-01

    High-temperature chlorination of C100 fullerene followed by X-ray structure determination of the chloro derivatives enabled the identification of three isomers of C100 from the fullerene soot, specifically numbers 18, 425, and 417, which obey the isolated pentagon rule (IPR). Among them, isomers C1-C100 (425) and C2-C100 (18) afforded C1-C100 (425)Cl22 and C2-C100 (18)Cl28/30 compounds, respectively, which retain their IPR cage connectivities. In contrast, isomer C2v -C100 (417) gives Cs -C100 (417)Cl28 which undergoes a skeletal transformation by the loss of a C2  fragment, resulting in the formation of a nonclassical (NC) C1-C98 (NC)Cl26 with a heptagon in the carbon cage. Most probably, two nonclassical C1-C100 (NC)Cl18/22 chloro derivatives originate from the IPR isomer C1-C100 (382), although both C1-C100 (344) and even nonclassical C1-C100 (NC) can be also considered as the starting isomers. PMID:26848074

  10. Scalar Dissipation Modeling for Passive and Active Scalars: a priori Study Using Direct Numerical Simulation

    NASA Technical Reports Server (NTRS)

    Selle, L. C.; Bellan, Josette

    2006-01-01

    Transitional databases from Direct Numerical Simulation (DNS) of three-dimensional mixing layers for single-phase flows and two-phase flows with evaporation are analyzed and used to examine the typical hypothesis that the scalar dissipation Probability Distribution Function (PDF) may be modeled as a Gaussian. The databases encompass a single-component fuel and four multicomponent fuels, two initial Reynolds numbers (Re), two mass loadings for two-phase flows and two free-stream gas temperatures. Using the DNS calculated moments of the scalar-dissipation PDF, it is shown, consistent with existing experimental information on single-phase flows, that the Gaussian is a modest approximation of the DNS-extracted PDF, particularly poor in the range of the high scalar-dissipation values, which are significant for turbulent reaction rate modeling in non-premixed flows using flamelet models. With the same DNS calculated moments of the scalar-dissipation PDF and making a change of variables, a model of this PDF is proposed in the form of the (beta)-PDF which is shown to approximate much better the DNS-extracted PDF, particularly in the regime of the high scalar-dissipation values. Several types of statistical measures are calculated over the ensemble of the fourteen databases. For each statistical measure, the proposed (beta)-PDF model is shown to be much superior to the Gaussian in approximating the DNS-extracted PDF. Additionally, the agreement between the DNS-extracted PDF and the (beta)-PDF even improves when the comparison is performed for higher initial Re layers, whereas the comparison with the Gaussian is independent of the initial Re values. For two-phase flows, the comparison between the DNS-extracted PDF and the (beta)-PDF also improves with increasing free-stream gas temperature and mass loading. The higher fidelity approximation of the DNS-extracted PDF by the (beta)-PDF with increasing Re, gas temperature and mass loading bodes well for turbulent reaction rate

  11. One-loop chiral perturbation theory with two fermion representations

    NASA Astrophysics Data System (ADS)

    DeGrand, Thomas; Golterman, Maarten; Neil, Ethan T.; Shamir, Yigal

    2016-07-01

    We develop chiral perturbation theory for chirally broken theories with fermions in two different representations of the gauge group. Any such theory has a nonanomalous singlet U (1 )A symmetry, yielding an additional Nambu-Goldstone boson when spontaneously broken. We calculate the next-to-leading order corrections for the pseudoscalar masses and decay constants, which include the singlet Nambu-Goldstone boson, as well as for the two condensates. The results can be generalized to more than two representations.

  12. Phenomenological aspects of heterotic orbifold models at one loop

    SciTech Connect

    Birkedal-Hansen, A.; Binetruy, P.; Mambrini, Y.; Nelson, B.

    2003-08-05

    We provide a detailed study of the phenomenology of orbifold compactifications of the heterotic string within the context of supergravity effective theories. Our investigation focuses on those models where the soft Lagrangian is dominated by loop contributions to the various soft supersymmetry breaking parameters. Such models typically predict non-universal soft masses and are thus significantly different from minimal supergravity and other universal models. We consider the pattern of masses that are governed by these soft terms and investigate the implications of certain indirect constraints on supersymmetric models, such as flavor-changing neutral currents, the anomalous magnetic moment of the muon and the density of thermal relic neutralinos. These string-motivated models show novel behavior that interpolates between the phenomenology of unified supergravity models and models dominated by the superconformal anomaly.

  13. Passive scalars in turbulent channel flow at high Reynolds number

    NASA Astrophysics Data System (ADS)

    Pirozzoli, Sergio; Bernardini, Matteo; Orlandi, Paolo

    2015-11-01

    We study passive scalars in turbulent plane channels at computationally high Reynolds number, which allows to observe previously unnoticed effects. The mean scalar profiles are found to obey a generalized logarithmic law which includes a linear correction term in the whole lower half-channel, and they follow a universal parabolic defect profile in the core region. This is consistent with recent findings regarding the mean velocity profiles in channel flow. The scalar variances also exhibit a near universal parabolic distribution in the core flow, and hints of a sizeable log layer, unlike the velocity variances. The energy spectra highlight the formation of large scalar-bearing eddies spanning each half-channel, which are caused by production excess over dissipation, and which are clearly visible in the flow visualizations. Close correspondence of the velocity and scalar eddies is observed, the main difference being that the latter have more convoluted interfaces, which translates into higher scalar dissipation. Another notable Reynolds number effect is the decreased correlation of the scalar field with the vertical velocity field, which is traced to the reduced effectiveness of ejection events. We acknowledge that the results reported in this paper have been achieved using the PRACE Research Infrastructure resource FERMI based at CINECA, Casalecchio di Reno, Italy.

  14. Self-accelerating solutions of scalar-tensor gravity

    SciTech Connect

    Barenboim, Gabriela; Lykken, Joseph D E-mail: lykken@fnal.gov

    2008-03-15

    Scalar-tensor gravity is the simplest and best understood modification of general relativity, consisting of a real scalar field coupled directly to the Ricci scalar curvature. Models of this type have self-accelerating solutions. In an example inspired by string dilaton couplings, scalar-tensor gravity coupled to ordinary matter exhibits a de Sitter type expansion, even in the presence of a negative cosmological constant whose magnitude exceeds that of the matter density. This unusual behavior does not require phantoms, ghosts or other exotic sources. More generally, we show that any expansion history can be interpreted as arising partly or entirely from scalar-tensor gravity. To distinguish any quintessence or inflation model from its scalar-tensor variants, we use the fact that scalar-tensor models imply deviations of the post-Newtonian parameters of general relativity and time variation of Newton's gravitational coupling G. We emphasize that next-generation probes of modified GR and the time variation of G are an essential complement to dark energy probes based on luminosity-distance measurements.

  15. Reaction enhancement of initially distant scalars by Lagrangian coherent structures

    SciTech Connect

    Pratt, Kenneth R. Crimaldi, John P.; Meiss, James D.

    2015-03-15

    Turbulent fluid flows have long been recognized as a superior means of diluting initial concentrations of scalars due to rapid stirring. Conversely, experiments have shown that the structures responsible for this rapid dilution can also aggregate initially distant reactive scalars and thereby greatly enhance reaction rates. Indeed, chaotic flows not only enhance dilution by shearing and stretching but also organize initially distant scalars along transiently attracting regions in the flow. To show the robustness of this phenomenon, a hierarchical set of three numerical flows is used: the periodic wake downstream of a stationary cylinder, a chaotic double gyre flow, and a chaotic, aperiodic flow consisting of interacting Taylor vortices. We demonstrate that Lagrangian coherent structures (LCS), as identified by ridges in finite time Lyapunov exponents, are directly responsible for this coalescence of reactive scalar filaments. When highly concentrated filaments coalesce, reaction rates can be orders of magnitude greater than would be predicted in a well-mixed system. This is further supported by an idealized, analytical model that was developed to quantify the competing effects of scalar dilution and coalescence. Chaotic flows, known for their ability to efficiently dilute scalars, therefore have the competing effect of organizing initially distant scalars along the LCS at timescales shorter than that required for dilution, resulting in reaction enhancement.

  16. Scalar fluctuations in turbulent combustion - An experimental study

    NASA Astrophysics Data System (ADS)

    Ballal, D. R.; Chen, T. H.; Yaney, P. P.

    1986-01-01

    Temperature and velocity fluctuations data were gathered for turbulent premixed combustion to evaluate a model for scalar transport and scalar dissipation. The data were collected using laser Raman spectroscopy and laser Doppler anemometry with a premixed CH4-air flame from a Bunsen burner. Mean temperature profiles were generated and the pdf's temperature fluctuations were calculated. A wrinkled laminar flame structure was noted in the reaction zone, where the scalar field was anisotropic and where the temperature fluctuations exhibited peak values. The Bray, Moss and Libby model (1985) was successful in predicting the temperature fluctuation intensity and the dissipation ratios, the latter reaching peak values in the flame tip region.

  17. Charged scalar perturbations around Garfinkle-Horowitz-Strominger black holes

    NASA Astrophysics Data System (ADS)

    Zhang, Cheng-Yong; Zhang, Shao-Jun; Wang, Bin

    2015-10-01

    We examine the stability of the Garfinkle-Horowitz-Strominger (GHS) black hole under charged scalar perturbations. Employing the appropriate numerical methods, we show that the GHS black hole is always stable against charged scalar perturbations. This is different from the results obtained in the de Sitter and anti-de Sitter black holes. Furthermore, we argue that in the GHS black hole background there is no amplification of the incident charged scalar wave to cause the superradiance, so that the superradiant instability cannot exist in this spacetime.

  18. Generalized cosmic Chaplygin gas inspired intermediate standard scalar field inflation

    NASA Astrophysics Data System (ADS)

    Jawad, Abdul; Rani, Shamaila; Mohsaneen, Sidra

    2016-08-01

    We study the warm intermediate inflationary regime in the presence of generalized cosmic Chaplygin gas and an inflaton decay rate proportional to the temperature. For this purpose, we consider standard scalar field model during weak and strong dissipative regimes. We explore inflationary parameters like spectral index, scalar and tensor power spectra, tensor to scalar ratio and decay rate in order to compare the present model with recent observational data. The physical behavior of inflationary parameters is presented and found that all the results are agreed with recent observational data such as WMAP7, WMAP9 and Planck 2015.

  19. Study of Scalar Mesons and Related Radiative Decays

    SciTech Connect

    Deirdre Black; Masayasu Harada; Joseph Schechter

    2002-06-01

    After a brief review of the puzzling light scalar meson sector of QCD, a brief summary will be given of a paper concerning radiative decays involving the light scalars. There, a simple vector meson dominance model is constructed in an initial attempt to relate a large number of the radiative decays involving a putative scalar nonet to each other. As an application it is illustrated why a{sub 0}(980)-f{sub 0}(980) mixing is not expected to greatly alter the f{sub 0}/a{sub 0} production ratio for radiative {phi} decays.

  20. Fundamental scalar fields and the dark side of the universe

    NASA Astrophysics Data System (ADS)

    Mychelkin, Eduard G.; Makukov, Maxim A.

    2015-11-01

    Starting with geometrical premises, we infer the existence of fundamental cosmological scalar fields. We then consider physically relevant situations in which spacetime metric is induced by one or, in general, by two scalar fields, in accord with the Papapetrou algorithm. The first of these fields, identified with dark energy (DE), has exceedingly small but finite (subquantum) Hubble mass scale ( ≈ 10-33 eV), and might be represented as a neutral superposition of quasi-static electric fields. The second field is identified with dark matter (DM) as an effectively scalar conglomerate composed of primordial neutrinos and antineutrinos in a special tachyonic state.

  1. Analysis and modeling of subgrid scalar mixing using numerical data

    NASA Technical Reports Server (NTRS)

    Girimaji, Sharath S.; Zhou, YE

    1995-01-01

    Direct numerical simulations (DNS) of passive scalar mixing in isotropic turbulence is used to study, analyze and, subsequently, model the role of small (subgrid) scales in the mixing process. In particular, we attempt to model the dissipation of the large scale (supergrid) scalar fluctuations caused by the subgrid scales by decomposing it into two parts: (1) the effect due to the interaction among the subgrid scales; and (2) the effect due to interaction between the supergrid and the subgrid scales. Model comparisons with DNS data show good agreement. This model is expected to be useful in the large eddy simulations of scalar mixing and reaction.

  2. Generalized gravitational entropy of interacting scalar field and Maxwell field

    NASA Astrophysics Data System (ADS)

    Huang, Wung-Hong

    2014-12-01

    The generalized gravitational entropy proposed recently by Lewkowycz and Maldacena is extended to the interacting real scalar field and Maxwell field system. Using the BTZ geometry we first investigate the case of free real scalar field and then show a possible way to calculate the entropy of the interacting scalar field. Next, we investigate the Maxwell field system. We exactly solve the wave equation and calculate the analytic value of the generalized gravitational entropy. We also use the Einstein equation to find the effect of backreaction of the Maxwell field on the area of horizon. The associated modified area law is consistent with the generalized gravitational entropy.

  3. Observational constraints in scalar tensor theory with tachyonic potential

    SciTech Connect

    Farajollahi, Hossein; Salehi, Amin; Shahabi, Asieh E-mail: a.salehi@guilan.ac.ir

    2011-10-01

    We study the dynamics of the scalar tensor cosmological model in the presence of tachyon field. In an alternative approach, in two exponential and power law form of the scalar field functions in the model, field equations are solved by simultaneously best fitting the model parameters with the most recent observational data. This approach gives us an observationally verified interpretation of the dynamics of the universe. We then discuss the best fitted of equation of state parameter, the statefinder parameters and the reconstructed scalar field in the model.

  4. Noninertial effects on the quantum dynamics of scalar bosons

    NASA Astrophysics Data System (ADS)

    Castro, Luis B.

    2016-02-01

    The noninertial effect of rotating frames on the quantum dynamics of scalar bosons embedded in the background of a cosmic string is considered. In this work, scalar bosons are described by the Duffin-Kemmer-Petiau (DKP) formalism. Considering the DKP oscillator in this background the combined effects of a rotating frames and cosmic string on the equation of motion, energy spectrum, and DKP spinor are analyzed and discussed in detail. Additionally, the effect of rotating frames on the scalar bosons' localization is studied.

  5. Hyperbolicity of scalar-tensor theories of gravity

    SciTech Connect

    Salgado, Marcelo; Martinez del Rio, David; Alcubierre, Miguel; Nunez, Dario

    2008-05-15

    Two first order strongly hyperbolic formulations of scalar-tensor theories of gravity allowing nonminimal couplings (Jordan frame) are presented along the lines of the 3+1 decomposition of spacetime. One is based on the Bona-Masso formulation, while the other one employs a conformal decomposition similar to that of Baumgarte-Shapiro-Shibata-Nakamura. A modified Bona-Masso slicing condition adapted to the scalar-tensor theory is proposed for the analysis. This study confirms that the scalar-tensor theory has a well-posed Cauchy problem even when formulated in the Jordan frame.

  6. Scalar/Vector potential formulation for compressible viscous unsteady flows

    NASA Technical Reports Server (NTRS)

    Morino, L.

    1985-01-01

    A scalar/vector potential formulation for unsteady viscous compressible flows is presented. The scalar/vector potential formulation is based on the classical Helmholtz decomposition of any vector field into the sum of an irrotational and a solenoidal field. The formulation is derived from fundamental principles of mechanics and thermodynamics. The governing equations for the scalar potential and vector potential are obtained, without restrictive assumptions on either the equation of state or the constitutive relations or the stress tensor and the heat flux vector.

  7. Einstein static universe in scalar-fluid theories

    NASA Astrophysics Data System (ADS)

    Böhmer, Christian G.; Tamanini, Nicola; Wright, Matthew

    2015-12-01

    A new Lagrangian framework has recently been proposed to describe interactions between relativistic perfect fluids and scalar fields. In this paper we investigate the Einstein static universe in this new class of theories, which have been named scalar-fluid theories. The stability of the static solutions to both homogeneous and inhomogeneous perturbations is analyzed deriving the relevant cosmological perturbation equations at the linear order. We can find several configurations corresponding to an Einstein static universes which are stable against inhomogeneous perturbations, but unstable against homogeneous perturbations. This shows the possible applications of scalar-fluid theories to the inflationary emergent universe scenario.

  8. Synergy among ocean scalars usign their turbulent singularity structure

    NASA Astrophysics Data System (ADS)

    Turiel, A.; Umbert, M.; Olmedo, E.; Gonzalez-Gambau, V.; Martínez, J.; Ballabrera, J.

    2014-12-01

    Despite of the differences in the equations governing the dynamics of different ocean scalars (as SSH, SST, SSS, chlorophyll concentration, or sea roughness), visual inspection of remote sensing maps of these different ocean scalars reveals the existence of many common features. They always correspond with dynamic structures of the oceanic flow, such as eddies, filaments or upwelling areas. That consistent correspondence may be explained by the action of flow advection, which stretches and shears scalars along the most energetic streamlines. Horizontal advection does not only shape structures in scalars. Eddy transport and filament advection carry long away water masses with relatively homogeneous scalar properties, especially at areas of large Eddy Kinetic Energy. The signature of those water masses can be recognised as specific functional relations among the variables when joint histograms are computed. The repeated observation of particular arrangements of values of scalars allows identifying those water masses, similarly to what oceanographers do with T-S diagrams of vertical profiles. But processes at surface are more energetic than in the water column; hence, the value of scalars evolve very fast and there is not a permanent rule linking them, although for a given period one such relation may hold for a specific region.The introduction of singularity analysis has meant a significant advancement in the description and understanding of the dynamic relations at ocean surface. Using singularity analysis, the Singularity Exponents (SE) of any scalar field can be calculated. SE are dimensionless variables linked to the structure of the underlying surface flow and not to the specific properties of the scalar from which they are derived. It has been shown that SE from different remote sensing scalars have very close values. This correspondence can be used to increase the signal to noise ratio of a given scalar, and even to extrapolate it into data gaps, using a

  9. MAGSAT scalar anomaly map of South America

    NASA Technical Reports Server (NTRS)

    Ridgway, J. R.; Hinze, W. J.; Braile, L. W.

    1985-01-01

    A scalar magnetic anomaly map was prepared for South America and adjacent marine areas directly from original MAGSAT orbits. The preparation of the map poses special problems, notably in the separation of external field and crustal anomalies, and in the reduction of data to a common altitude. External fields are manifested in a long-wavelength ring current effect, a medium-wavelength equatorial electrojet, and short-wavelength noise. The noise is reduced by selecting profiles from quiet periods, and since the electrojet is confined primarily to dusk profiles, its effect is minimized by drawing the data set from dawn profiles only. The ring current is corrected through the use of the standard ring current equation, augmented by further filtering with a Butterworth bandpass filter. Under the assumption that the time-variant ring current is best removed when a replication of redundant profiles is achieved, a test set of 25 groups of 3 nearly coincident orbits per group is set up for filtering with a range of long-wavelength cutoffs to determine which cutoff best replicates the residual profiles. Altitude differences are then normalized by an inversion of the profile data onto a grid of equivalent point dipoles, and recalculated at an altitude of 350 km. The resulting map, when compared to the 2 deg averaged map, shows more coherent anomalies, with notable differences in the region affected by the electrojet.

  10. A search for third generation scalar leptoquarks

    SciTech Connect

    Zatserklyaniy, Andriy; /Northern Illinois U.

    2006-08-01

    Leptoquarks (LQ) are particles with both color and lepton number predicted in some gauge theories and composite models. Current theory suggests that leptoquarks would come in three different generations. We report on a search for charge 1/3 third generation leptoquarks produced in p{bar p} collisions at {radical}s = 1.96 TeV using data collected by the D0 detector at Fermilab. Such leptoquarks would decay into a tau-neutrino plus a b-quark with branching fraction B. We present preliminary results on an analysis where both leptoquarks decay into neutrinos giving a final state with missing energy and two b-jets. Using 425(recorded) pb{sup -1} of data, we place limits on {sigma}(p{bar p} {yields} LQ{ovr LQ})B{sup 2} as a function of the leptoquark mass. Assuming B = 1, we excluded at the 95% confidence level scalar third generation leptoquarks with M{sub LQ} < 219 GeV.

  11. Entanglement entropy in scalar field theory

    NASA Astrophysics Data System (ADS)

    Hertzberg, Mark P.

    2013-01-01

    Understanding the dependence of entanglement entropy on the renormalized mass in quantum field theories can provide insight into phenomena such as quantum phase transitions, since the mass varies in a singular way near the transition. Here we perturbatively calculate the entanglement entropy in interacting scalar field theory, focusing on the dependence on the field’s mass. We study λϕ4 and gϕ3 theories in their ground state. By tracing over a half space, using the replica trick and position space Green’s functions on the cone, we show that spacetime volume divergences cancel and renormalization can be consistently performed in this conical geometry. We establish finite contributions to the entanglement entropy up to two-loop order, involving a finite area law. The resulting entropy is simple and intuitive: the free theory result in d = 3 (that we included in an earlier publication) ΔS ˜ A m2ln (m2) is altered, to leading order, by replacing the bare mass m by the renormalized mass mr evaluated at the renormalization scale of zero momentum.

  12. RNA structure and scalar coupling constants

    SciTech Connect

    Tinoco, I. Jr.; Cai, Z.; Hines, J.V.; Landry, S.M.; SantaLucia, J. Jr.; Shen, L.X.; Varani, G.

    1994-12-01

    Signs and magnitudes of scalar coupling constants-spin-spin splittings-comprise a very large amount of data that can be used to establish the conformations of RNA molecules. Proton-proton and proton-phosphorus splittings have been used the most, but the availability of {sup 13}C-and {sup 15}N-labeled molecules allow many more coupling constants to be used for determining conformation. We will systematically consider the torsion angles that characterize a nucleotide unit and the coupling constants that depend on the values of these torsion angles. Karplus-type equations have been established relating many three-bond coupling constants to torsion angles. However, one- and two-bond coupling constants can also depend on conformation. Serianni and coworkers measured carbon-proton coupling constants in ribonucleosides and have calculated their values as a function of conformation. The signs of two-bond coupling can be very useful because it is easier to measure a sign than an accurate magnitude.

  13. DBI scalar field theory for QGP hydrodynamics

    NASA Astrophysics Data System (ADS)

    Nastase, Horatiu

    2016-07-01

    A way to describe the hydrodynamics of the quark-gluon plasma using a Dirac-Born-Infeld (DBI) action is proposed, based on the model found by Heisenberg for high energy scattering of nucleons. The expanding plasma is described as a shockwave in a DBI model for a real scalar standing in for the pion, and I show that one obtains a fluid description in terms of a relativistic fluid that near the shock is approximately ideal (η ≃0 ) and conformal. One can introduce an extra term inside the square root of the DBI action that generates a shear viscosity term in the energy-momentum tensor near the shock, as well as a bulk viscosity, and regulates the behavior of the energy density at the shock, making it finite. The resulting fluid satisfies the relativistic Navier-Stokes equation with uμ,ρ ,P ,η defined in terms of ϕ and its derivatives. One finds a relation between the parameters of the theory and the quark-gluon plasma thermodynamics, α /β2=η /(s T ), and by fixing α and β from usual (low multiplicity) particle scattering, one finds T ∝mπ.

  14. Modeling scalar dissipation and scalar variance in large eddy simulation: Algebraic and transport equation closures

    NASA Astrophysics Data System (ADS)

    Knudsen, E.; Richardson, E. S.; Doran, E. M.; Pitsch, H.; Chen, J. H.

    2012-05-01

    Scalar dissipation rates and subfilter scalar variances are important modeling parameters in large eddy simulations (LES) of reacting flows. Currently available models capture the general behavior of these parameters, but these models do not always perform with the degree of accuracy that is needed for predictive LES. Here, two direct numerical simulations (DNS) are used to analyze LES dissipation rate and variance models, and to propose a new model for the dissipation rate that is based on a transport equation. The first DNS that is considered is a non-premixed auto-igniting C2H4 jet flame simulation originally performed by Yoo et al. [Proc. Combust. Inst. 33, 1619-1627 (2011)], 10.1016/j.proci.2010.06.147. A LES of this case is run using algebraic models for the dissipation rate and subfilter variance. It is shown that the algebraic models fail to adequately reproduce the DNS results. This motivates the introduction of a transport equation model for the LES dissipation rate. Closure of the equation is addressed by formulating a new adapted dynamic approach. This approach borrows dynamically computed information from LES quantities that, unlike the dissipation rate, do not reside on the smallest flow length scales. The adapted dynamic approach is analyzed by considering a second DNS of scalar mixing in homogeneous isotropic turbulence. Data from this second DNS are used to confirm that the adapted dynamic approach successfully closes the dissipation rate equation over a wide range of LES filter widths. The first reacting jet case is then returned to and used to test the LES transport equation models. The transport equation model for the dissipation rate is shown to be more accurate than its algebraic counterpoint, and the dissipation rate is eliminated as a source of error in the transported variance model.

  15. Direct numerical simulations of the double scalar mixing layer. Part II: Reactive scalars

    SciTech Connect

    Mortensen, Mikael; de Bruyn Kops, Stephen M.; Cha, Chong M.

    2007-06-15

    The reacting double scalar mixing layer (RDSML) is investigated as a canonical multistream flow and a model problem for simple piloted diffusion flames. In piloted diffusion flames, the reacting fuel and oxidizer streams are initially separated by a central pilot stream at stoichiometric composition. The primary purpose of this pilot is to delay the mixing of the pure streams until a stable flame base can develop. In such multistream systems, the modeling of turbulent scalar mixing is complicated by the multiple feed streams, leading to more complex fine-scale statistics, which remain as yet an unmet modeling challenge compared to the simpler two-feed system. In Part I we described how multimodal mixture fraction probability density functions (PDFs) and conditional scalar dissipation rates can be modeled with a presumed mapping function approach. In this work we present an efficient and robust extension of the modeling to a general multistream reacting flow and compare predictions to three-dimensional direct numerical simulations (DNS) of the RDSML with a single-step reversible chemistry model and varying levels of extinction. With high extinction levels, the interaction with the pilot stream is described. Additionally, state-of-the-art combustion modeling calculations including conditional moment closure (CMC) and stationary laminar flamelet modeling (SLFM) are performed with the newly developed mixing model. Excellent agreement is found between the DNS and modeling predictions, even where the PDF is essentially a triple-delta shape near the flame base, so long as extinction levels are moderate to low. The suggested approach outlined in this paper is strictly valid only for flows that can be described by a single mixture fraction. For these flows the approach should provide engineers with fine-scale models that are of accuracy comparable to those already available for binary mixing, at only marginally higher complexity and cost. (author)

  16. Kasner solutions, climbing scalars and big-bang singularity

    SciTech Connect

    Condeescu, Cezar; Dudas, Emilian E-mail: emilian.dudas@cpht.polytechnique.fr

    2013-08-01

    We elaborate on a recently discovered phenomenon where a scalar field close to big-bang is forced to climb a steep potential by its dynamics. We analyze the phenomenon in more general terms by writing the leading order equations of motion near the singularity. We formulate the conditions for climbing to exist in the case of several scalars and after inclusion of higher-derivative corrections and we apply our results to some models of moduli stabilization. We analyze an example with steep stabilizing potential and notice again a related critical behavior: for a potential steepness above a critical value, going backwards towards big-bang, the scalar undergoes wilder oscillations, with the steep potential pushing it back at every passage and not allowing the scalar to escape to infinity. Whereas it was pointed out earlier that there are possible implications of the climbing phase to CMB, we point out here another potential application, to the issue of initial conditions in inflation.

  17. Nonrelativistic approach for cosmological scalar field dark matter

    NASA Astrophysics Data System (ADS)

    Ureña-López, L. Arturo

    2014-07-01

    We derive nonrelativistic equations of motion for the formation of cosmological structure in a scalar field dark matter (SFDM) model corresponding to a complex scalar field endowed with a quadratic scalar potential. Starting with the equations of motion written in the Newtonian gauge of scalar perturbations, we separate out the involved fields into relativistic and nonrelativistic parts and find the equations of motion for the latter that can be used to build up the full solution. One important assumption will be that the SFDM field is in the regime of fast oscillations, under which its behavior in the homogeneous regime is exactly that of cold dark matter. The resultant equations are quite similar to the Schrödinger-Poisson system of Newtonian boson stars plus relativistic leftovers, and they can be used to study the formation of cosmological structure in SFDM models, and others alike, to ultimately prove their viability as complete dark matter models.

  18. Nonprojectable Horava-Lifshitz gravity without the unwanted scalar graviton

    NASA Astrophysics Data System (ADS)

    Chaichian, Masud; KlusoÅ, Josef; Oksanen, Markku

    2015-11-01

    We consider a way of eliminating the unwanted scalar graviton from Horava-Lifshitz gravity that is achieved via introduction of certain additional constraints. We perform canonical analysis of both projectable and nonprojectable versions of the theory. We obtain the structure of constraints in each case, and analyze its dependence on the values of the coupling constants involved in the additional constraints. In the nonprojectable theory, the scalar graviton is absent when the coupling constants have certain values, while for other values the scalar graviton appears. The projectable theory is free from the scalar graviton regardless of the values of the coupling constants, even though the structure of the constraints does depend on the value of a coupling constant.

  19. Dirac Equation for Scalar, Vector and Tensor Generalized Cornell Interaction

    NASA Astrophysics Data System (ADS)

    Zarrinkamar, S.; Panahi, H.; Rezaei, M.; Baradaran, M.

    2016-03-01

    We consider spin and pseudospin symmetry limits of Dirac equation in the presence of scalar, vector and tensor generalized Cornell interaction and report the solutions via the quasi-exact analytical ansatz approach.

  20. General analytic solutions of scalar field cosmology with arbitrary potential

    NASA Astrophysics Data System (ADS)

    Dimakis, N.; Karagiorgos, A.; Zampeli, Adamantia; Paliathanasis, Andronikos; Christodoulakis, T.; Terzis, Petros A.

    2016-06-01

    We present the solution space for the case of a minimally coupled scalar field with arbitrary potential in a Friedmann-Lemaître-Robertson-Walker metric. This is made possible due to the existence of a nonlocal integral of motion corresponding to the conformal Killing field of the two-dimensional minisuperspace metric. Both the spatially flat and nonflat cases are studied first in the presence of only the scalar field and subsequently with the addition of noninteracting perfect fluids. It is verified that this addition does not change the general form of the solution, but only the particular expressions of the scalar field and the potential. The results are applied in the case of parametric dark energy models where we derive the scalar field equivalence solution for some proposed models in the literature.

  1. Scalar Susceptibility of QCD from Dyson Schwinger Approach

    NASA Astrophysics Data System (ADS)

    Wu, Kong-Ping; Shi, Yuan-Mei; Sun, Wei-Min; Ping, Jia-Lun; Zong, Hong-Shi

    2008-01-01

    In quantum chromodynamics (QCD), the scalar susceptibility represents the modification of the quark condensate, to a small perturbation of the parameter responsible for the explicit breaking of the symmetry, i.e., the current quark mass. By studying the linear response of the dressed quark propagator to the presence of a nonzero quark mass, we derive a model-independent formula for the scalar susceptibility, which contains the dressed quark propagator G(p) and the dressed scalar vertex Γ(p, 0). The numerical values of the scalar susceptibility χs are calculated within the framework of the rainbow-ladder approximation of the Dyson-Schwinger approach by employing two typical forms of model gluon propagator.

  2. Scalar mesons and the search for the 0{sup ++} Glueball

    SciTech Connect

    Ulrike Thoma

    2002-10-01

    The possibility that gluonic excitations of hadronic matter or of the QCD vacuum may exist is perhaps one of the most fascinating topics in hadron spectroscopy. Glueballs are predicted by many models; in particular present-day lattice gauge calculations require their existence. All these models agree that the lightest glueball should have scalar quantum numbers and a mass around 1.6 GeV, which corresponds to the mass region where the scalar qq[bar]-mesons are expected. Therefore mixing effects can complicate the search for the glueball. Experiments indeed show an overpopulation of states, for which many different interpretations exist. This reflects the complexity of the situation. New data from various experiments on scalar states give hints toward an interpretation of the scalar states. But, still many questions remain.

  3. Scalar and vector hysteresis simulations using HysterSoft

    NASA Astrophysics Data System (ADS)

    Dimian, M.; Andrei, P.

    2015-02-01

    Hysteresis modeling has become an important research area with many applications in science and engineering. In this article we present a unified and robust simulation framework designed to perform scalar and vector hysteresis modeling. The framework is based on HysterSoft© which is a simulation platform that can be interfaced with other libraries and simulation programs to model various aspects of hysteresis. We describe the main features of our simulation framework by focusing on scalar and vector hysteresis modeling, direct and inverse modeling, dynamic hysteresis modeling, first-order reversal-curves analysis, identification of the scalar and vector Preisach distribution function using an experimental first- order reversal-curves, noise passage analysis through hysteretic systems, and thermal relaxation in scalar and vector hysteresis. The simulation modules, the user-defined features, and various parameter identification techniques are also presented.

  4. Bianchi type-I models with conformally invariant scalar field

    SciTech Connect

    Accioly, A.J.; Vaidya, A.N.; Som, M.M.

    1983-05-15

    The solutions of the Einstein equations with the trace-free energy-momentum tensor of conformally invariant scalar field as source are obtained in a spatially homogeneous anisotropic space-time. Some interesting features of the solutions are discussed.

  5. Wormholes, the weak energy condition, and scalar-tensor gravity

    NASA Astrophysics Data System (ADS)

    Shaikh, Rajibul; Kar, Sayan

    2016-07-01

    We obtain a large class of Lorentzian wormhole spacetimes in scalar-tensor gravity, for which the matter stress energy does satisfy the weak energy condition. Our constructions have zero Ricci scalar and an everywhere finite, nonzero scalar field profile. Interpreting the scalar-tensor gravity as an effective on-brane theory resulting from a two-brane Randall-Sundrum model of warped extra dimensions, it is possible to link wormhole existence with that of extra dimensions. We study the geometry, matter content, gravitational redshift and circular orbits in such wormholes and argue that our examples are perhaps among those which may have some observational relevance in astrophysics in the future. We also study traversability and find that our wormholes are indeed traversable for values of the metric parameters satisfying the weak energy condition.

  6. The effect of varying the radiative/convective split for internal gains on cooling load calculations: A case study for the Pentagon

    SciTech Connect

    Liesen, R.J.; Strand, R.K.; Pedersen, C.O.

    1998-10-01

    Two new methods for calculating cooling loads have just been introduced. The first algorithm, called the heat balance (HB) method, is a complete formulation of fundamental heat balance principles. The second is called the radiant time series (RTS) method. While based on the HB method, the RTS method is an approximate procedure that separates some of the processes to better show the influence of individual heat gain components. In the HB method, all of the heat transfer mechanisms participate in three simultaneous heat balances: the balance on the outside face of all the building elements that enclose the space, the balance on the inside face of the building elements, and the balance between the surfaces inside the space and the zone air. The focus of this paper is on the second heat balance. It has been customary to define a radiative/convective split for the heat introduced into a zone from such sources as equipment, lights, people, etc. The radiative part is then distributed over the surfaces within the zone in some prescribed manner, and the convective part is assumed to go immediately into the air. Simplified techniques simply cannot accurately portray the complex interaction of building surfaces, so previously used load calculation procedures were not up to the task of analyzing the effect of internal load radiant/convective split variation. This paper will present an investigation of the influence of the radiative/convective split on cooling loads obtained using the heat balance procedure. It will begin with an overview of the model used for a heat balance procedure and then present an exhaustive case study of the effects of changing the mode split on load calculations for Wedge 1 of the Pentagon building.

  7. Search for scalar top and bottom quarks at the Tevatron

    SciTech Connect

    Calfayan, Philippe; /Munich U.

    2009-01-01

    This document reviews recent results on the search for scalar top and scalar bottom quarks in p{bar p} collisions at {radical}s = 1.96 TeV. The analyses presented are based on data samples with integrated luminosities from 1.0 to 1.9 fb{sup -1} recorded at the Tevatron with the D0 and CDF detectors.

  8. Wormhole-induced operators for a massless scalar field

    SciTech Connect

    Goto, T.; Okada, Y. )

    1991-05-15

    Bilocal operators induced by an axionic wormhole solution are obtained in the case of a massless scalar field. For this purpose, we first show that the calculation of a Green's function for the scalar field on the wormhole background is reduced to a one-dimensional potential-barrier problem. We then evaluate numerically the asymptotic behavior of the Green's function and identify the effective interaction induced by the wormhole.

  9. Aharonov-Casher and scalar Aharonov-Bohm topological effects.

    PubMed

    Dulat, Sayipjamal; Ma, Kai

    2012-02-17

    We reexamine the topological and nonlocal natures of the Aharonov-Casher and scalar Aharonov-Bohm phase effects. The underlying U(1) gauge structure is exhibited explicitly. And the conditions for developing topological Aharonov-Casher and scalar Aharonov-Bohm phases are clarified. We analyze the arguments of M. Peshkin and H. J. Lipkin [Phys. Rev. Lett. 74, 2847 (1995)] in detail and show that they are based on the wrong Hamiltonian which yields their conclusion incorrect. PMID:22401183

  10. On the entanglement between interacting scalar field theories

    NASA Astrophysics Data System (ADS)

    Mozaffar, M. Reza Mohammadi; Mollabashi, Ali

    2016-03-01

    We study "field space entanglement" in certain quantum field theories consisting of N number of free scalar fields interacting with each other via kinetic mixing terms. We present exact analytic expressions for entanglement and Renyi entropies between arbitrary numbers of scalar fields by which we could explore certain entanglement inequalities. Other entanglement measures such as mutual information and entanglement negativity have also been studied. We also give some comments about possible holographic realizations of such models.

  11. A unified optical theorem for scalar and vectorial wave fields.

    PubMed

    Wapenaar, Kees; Douma, Huub

    2012-05-01

    The generalized optical theorem is an integral relation for the angle-dependent scattering amplitude of an inhomogeneous scattering object embedded in a homogeneous background. It has been derived separately for several scalar and vectorial wave phenomena. Here a unified optical theorem is derived that encompasses the separate versions for scalar and vectorial waves. Moreover, this unified theorem also holds for scattering by anisotropic elastic and piezoelectric scatterers as well as bianisotropic (non-reciprocal) EM scatterers. PMID:22559339

  12. Dynamic transition to spontaneous scalarization in boson stars

    SciTech Connect

    Alcubierre, Miguel; Degollado, Juan C.; Nunez, Dario; Salgado, Marcelo; Ruiz, Milton

    2010-06-15

    We show that the phenomenon of spontaneous scalarization predicted in neutron stars within the framework of scalar-tensor tensor theories of gravity, also takes place in boson stars without including a self-interaction term for the boson field (other than the mass term), contrary to what was claimed before. The analysis is performed in the physical (Jordan) frame and is based on a 3+1 decomposition of spacetime assuming spherical symmetry.

  13. Renormalizable Electrodynamics of Scalar and Vector Mesons. Part II

    DOE R&D Accomplishments Database

    Salam, Abdus; Delbourgo, Robert

    1964-01-01

    The "gauge" technique" for solving theories introduced in an earlier paper is applied to scalar and vector electrodynamics. It is shown that for scalar electrodynamics, there is no {lambda}φ*2φ2 infinity in the theory, while with conventional subtractions vector electrodynamics is completely finite. The essential ideas of the gauge technique are explained in section 3, and a preliminary set of rules for finite computation in vector electrodynamics is set out in Eqs. (7.28) - (7.34).

  14. Unimodular metagravity vs. general relativity with a scalar field

    SciTech Connect

    Pirogov, Yu. F.

    2010-01-15

    The unimodular metagravity, with the graviscalar as a dark matter, is compared with General Relativity (GR) in the presence of a scalar field. The effect of the graviscalar on the static spherically symmetric metric is studied. An exact limit solution representing a new cosmic object, the (harmonic) graviscalar black hole, is given. The relation with the black hole in the environment of a scalar field in GR is discussed.

  15. Intrinsic and dynamically generated scalar meson states

    NASA Astrophysics Data System (ADS)

    Shakin, C. M.; Wang, Huangsheng

    2001-01-01

    Recent work by Maltman has given us confidence that our assignment of scalar meson states to various nonets based upon our generalized Nambu-Jona-Lasinio (NJL) model is correct. [For example, in our model the a0(980) and the f0(980) are in the same nonet as the K*0(1430).] In this work we make use of our model to provide a precise definition of ``preexisting'' resonances and ``dynamically generated'' resonances when considering various scalar mesons. [This distinction has been noted by Meissner in his characterization of the f0(400-1200) as nonpreexisting.] We define preexisting (or intrinsic) resonances as those that appear as singularities of the qq¯ T matrix and are in correspondence with qq¯ states bound in the confining field. [Additional singularities may be found when studying the T matrices describing π-π or π-K scattering, for example. Such features may be seen to arise, in part, from t-channel and u-channel ρ exchange in the case of π-π scattering, leading to the introduction of the σ(500-600). In addition, threshold effects in the qq¯ T matrix can give rise to significant broad cross section enhancements. The latter is, in part, responsible for the introduction of the κ(900) in a study of π-K scattering, for example.] We suggest that it is only the intrinsic resonances which correspond to qq¯ quark-model states, and it is only the intrinsic states that are to be used to form quark-model qq¯ nonets of states. [While the κ(900) and σ(500-600) could be placed in a nonet of dynamically generated states, it is unclear whether there is evidence that requires the introduction of other members of such a nonet.] In this work we show how the phenomena related to the introduction of the σ(500-600) and the κ(900) are generated in studies of π-π and π-K scattering, making use of our generalized Nambu-Jona-Lasinio model. We also calculate the decay constants for the a0 and K*0 mesons and compare our results with those obtained by Maltman. We find

  16. On a Scalar Theory of Gravitation

    NASA Astrophysics Data System (ADS)

    Arminjon, Mayeul

    2002-12-01

    Our motivation was to extend the Lorentz-Poincaré ether theory so that it could describe gravitation. The latter theory consists in assuming that Maxwell's equations are valid in some fundamental inertial frame or "ether," and that each material object that moves through the ether undergoes a Lorentz contraction. This is physically equivalent to Einstein's special relativity (SR), 1 but it differs from standard SR at the meta-physical (interpretation) level. 1 The construction of the scalar theory is based on a tentative concept of physical vacuum as a space-filling perfect fluid, or "micro-ether." This concept leads to a definite set of equations: it is this set that should be assessed from the predictions it leads to, and from the comparison of these predictions with experimental data. According to that concept, material particles would be organized flows in that fluid, such as vortices, thus each particle would occupy some bounded domain in the fluid. The gravitational force is interpreted as resulting from the forces exerted on any such "particle" (domain), due to the spatial variation of the fluid pressure over macroscopic distances. This leads to define a gravity acceleration vector as follows: 2 g = - {grad pe }/{ρ e }, (1) where pe and ρe = ρe(pe) are the macroscopic fields of pressure and density in the imagined fluid (micro-ether). Note that this equation implies that pe and ρe decrease towards the gravitational attraction. The preferred reference frame of the theory is that one which is obtained by averaging the velocity field of the micro-ether over a very large scale. An equation for the scalar gravitational field pe (or equivalently the field ρe) follows from the requirement that Newtonian gravity should be recovered if the micro-ether were an incompressible fluid, and from the analysis of acoustic-like oscillations of the field pe. 2 However, in this ether theory, an "absolute" version of Einstein's equivalence principle occurs naturally. 3 It

  17. Visual Exploration of High Dimensional Scalar Functions

    PubMed Central

    Gerber, Samuel; Bremer, Peer-Timo; Pascucci, Valerio; Whitaker, Ross

    2011-01-01

    An important goal of scientific data analysis is to understand the behavior of a system or process based on a sample of the system. In many instances it is possible to observe both input parameters and system outputs, and characterize the system as a high-dimensional function. Such data sets arise, for instance, in large numerical simulations, as energy landscapes in optimization problems, or in the analysis of image data relating to biological or medical parameters. This paper proposes an approach to analyze and visualizing such data sets. The proposed method combines topological and geometric techniques to provide interactive visualizations of discretely sampled high-dimensional scalar fields. The method relies on a segmentation of the parameter space using an approximate Morse-Smale complex on the cloud of point samples. For each crystal of the Morse-Smale complex, a regression of the system parameters with respect to the output yields a curve in the parameter space. The result is a simplified geometric representation of the Morse-Smale complex in the high dimensional input domain. Finally, the geometric representation is embedded in 2D, using dimension reduction, to provide a visualization platform. The geometric properties of the regression curves enable the visualization of additional information about each crystal such as local and global shape, width, length, and sampling densities. The method is illustrated on several synthetic examples of two dimensional functions. Two use cases, using data sets from the UCI machine learning repository, demonstrate the utility of the proposed approach on real data. Finally, in collaboration with domain experts the proposed method is applied to two scientific challenges. The analysis of parameters of climate simulations and their relationship to predicted global energy flux and the concentrations of chemical species in a combustion simulation and their integration with temperature. PMID:20975167

  18. Bi-scalar modified gravity and cosmology with conformal invariance

    NASA Astrophysics Data System (ADS)

    Saridakis, Emmanuel N.; Tsoukalas, Minas

    2016-04-01

    We investigate the cosmological applications of a bi-scalar modified gravity that exhibits partial conformal invariance, which could become full conformal invariance in the absence of the usual Einstein-Hilbert term and introducing additionally either the Weyl derivative or properly rescaled fields. Such a theory is constructed by considering the action of a non-minimally conformally-coupled scalar field, and adding a second scalar allowing for a nonminimal derivative coupling with the Einstein tensor and the energy-momentum tensor of the first field. At a cosmological framework we obtain an effective dark-energy sector constituted from both scalars. In the absence of an explicit matter sector we extract analytical solutions, which for some parameter regions correspond to an effective matter era and/or to an effective radiation era, thus the two scalars give rise to "mimetic dark matter" or to "dark radiation" respectively. In the case where an explicit matter sector is included we obtain a cosmological evolution in agreement with observations, that is a transition from matter to dark energy era, with the onset of cosmic acceleration. Furthermore, for particular parameter regions, the effective dark-energy equation of state can transit to the phantom regime at late times. These behaviors reveal the capabilities of the theory, since they arise purely from the novel, bi-scalar construction and the involved couplings between the two fields.

  19. Scalar geometry and masses in Calabi-Yau string models

    NASA Astrophysics Data System (ADS)

    Farquet, Daniel; Scrucca, Claudio A.

    2012-09-01

    We study the geometry of the scalar manifolds emerging in the no-scale sector of Kähler moduli and matter fields in generic Calabi-Yau string compactifications, and describe its implications on scalar masses. We consider both heterotic and orientifold models and compare their characteristics. We start from a general formula for the Kähler potential as a function of the topological compactification data and study the structure of the curvature tensor. We then determine the conditions for the space to be symmetric and show that whenever this is the case the heterotic and the orientifold models give the same scalar manifold. We finally study the structure of scalar masses in this type of geometries, assuming that a generic superpotential triggers spontaneous supersymmetry breaking. We show in particular that their behavior crucially depends on the parameters controlling the departure of the geometry from the coset situation. We first investigate the average sGoldstino mass in the hidden sector and its sign, and study the implications on vacuum metastability and the mass of the lightest scalar. We next examine the soft scalar masses in the visible sector and their flavor structure, and study the possibility of realizing a mild form of sequestering relying on a global symmetry.

  20. Inflation from cosmological constant and nonminimally coupled scalar

    NASA Astrophysics Data System (ADS)

    Glavan, Dražen; Marunović, Anja; Prokopec, Tomislav

    2015-08-01

    We consider inflation in a universe with a positive cosmological constant and a nonminimally coupled scalar field, in which the field couples both quadratically and quartically to the Ricci scalar. When considered in the Einstein frame and when the nonminimal couplings are negative, the field starts in slow roll and inflation ends with an asymptotic value of the principal slow-roll parameter, ɛE=4 /3 . Graceful exit can be achieved by suitably (tightly) coupling the scalar field to matter, such that at late time the total energy density reaches the scaling of matter, ɛE=ɛm . Quite generically the model produces a red spectrum of scalar cosmological perturbations and a small amount of gravitational radiation. With a suitable choice of the nonminimal couplings, the spectral slope can be as large as ns≃0.955 , which is about one standard deviation away from the central value measured by the Planck satellite. The model can be ruled out by future measurements if any of the following is observed: (a) the spectral index of scalar perturbations is ns>0.960 ; (b) the amplitude of tensor perturbations is above about r ˜10-2 ; (c) the running of the spectral index of scalar perturbations is positive.

  1. Charmless hadronic B decays involving scalar mesons: Implications on the nature of light scalar mesons

    SciTech Connect

    Cheng Haiyang; Chua Chunkhiang; Yang Kweichou

    2006-01-01

    The hadronic charmless B decays into a scalar meson and a pseudoscalar meson are studied within the framework of QCD factorization. Based on the QCD sum rule method, we have derived the leading-twist light-cone distribution amplitudes of scalar mesons and their decay constants. Although the light scalar mesons f{sub 0}(980) and a{sub 0}(980) are widely perceived as primarily the four-quark bound states, in practice it is difficult to make quantitative predictions based on the four-quark picture for light scalars. Hence, predictions are made in the 2-quark model for the scalar mesons. The short-distance approach suffices to explain the observed large rates of f{sub 0}(980)K{sup -} and f{sub 0}(980)K{sup 0} that receive major penguin contributions from the b{yields}sss process. When f{sub 0}(980) is assigned as a four-quark bound state, there exist extra diagrams contributing to B{yields}f{sub 0}(980)K. Therefore, a priori the f{sub 0}(980)K rate is not necessarily suppressed for a four-quark state f{sub 0}(980). The predicted B{sup 0}{yields}a{sub 0}{sup {+-}}(980){pi}{sup {+-}} and a{sub 0}{sup +}(980)K{sup -} rates exceed the current experimental limits, favoring a four-quark nature for a{sub 0}(980). The penguin-dominated modes a{sub 0}(980)K and a{sub 0}(1450)K receive predominant weak annihilation contributions. There exists a twofold experimental ambiguity in extracting the branching ratio of B{sup -}{yields}K{sub 0}*{sup 0}(1430){pi}{sup -}, which can be resolved by measuring other K{sub 0}*(1430){pi} modes in conjunction with the isospin symmetry consideration. Large weak annihilation contributions are needed to explain the K{sub 0}*(1430){pi} data. The decay B{sup 0}{yields}{kappa}{sup +}K{sup -} provides a nice ground for testing the 4-quark and 2-quark nature of the {kappa} meson. It can proceed through W-exchange and hence is quite suppressed if {kappa} is made of two quarks, while it receives a tree contribution if {kappa} is predominately a four

  2. Scalar-field coordinates and the spherically symmetric Einstein equations for a zero-mass scalar field

    NASA Astrophysics Data System (ADS)

    Berberian, John Edwin

    1999-01-01

    A new framework is presented for analysing the spherically symmetric Einstein field equations for a zero-mass scalar field. The framework consists of a coordinate system (p, q), where the coordinate p is the scalar field, and q is a coordinate chosen to be orthogonal to p. This idea allows for a reduction of the field equations into a system of two first order partial differential equations for the areal metric function gqq and a mass function m . The metric coefficients in this coordinate system then take on values which are simply related to the scalars of the problem: 1->f˙1 ->f,gq q and-via the field equations-the scalar curvature R as well. The scalar field coordinate system is shown to have many advantages. Many of the known exact solutions (e.g. static, Roberts) are represented simply, and new self- similar solutions are derived. The framework is then applied to the problem of matching spherically symmetric scalar-tensor vacuum solutions to a homogeneous and isotropic dust solution (e.g. scalar- tensor Einstein-Straus swiss cheese solutions, scalar- tensor Oppenheimer-Snyder dust ball collapse). Scalar field coordinates are shown to be ideal for such an application. We derive the necessary matching conditions in scalar field coordinates, and show how they imply a natural extension of the Schücking condition for spherically symmetric vacuum in general relativity. The problem of finding a vacuum solution which matches a given homogeneous and isotropic solution is examined. It is found that the matching conditions are sufficient to guarantee local existence and uniqueness of the vacuum solution if it is assumed that the scalar field has neither maxima nor minima on the matching interface. In order to find explicit matched solutions, criteria are developed to screen known exact vacuum solutions for matchability, and procedures are given for determining the details of the homogeneous and isotropic solution (curvature constant, comoving radial coordinate of the

  3. Scalar coupling limits and diphoton Higgs decay from LHC in an U (1 )' model with scalar dark matter

    NASA Astrophysics Data System (ADS)

    Martinez, R.; Nisperuza, J.; Ochoa, F.; Rubio, J. P.; Sierra, C. F.

    2015-08-01

    We explore constraints on the scalar coupling in a family nonuniversal U (1 )' extension of the standard model free from anomalies with a complex scalar dark matter particle. From unitarity and stability of the Higgs potential, we find the full set of bounds and order relations for the scalar coupling constants. Using recent data from the CERN-LHC collider, we study the signal strength of the diphoton Higgs decay, which imposes very stringent bounds to the scalar couplings and other scalar parameters, including parameters associated to the dark matter. Taking into account these constraints, the observable relic density of the Universe, and the limits from LUX collaboration for direct detection, we obtain allowed masses for the dark matter particle as low as 55 GeV. By assuming that the lightest scalar boson of the model corresponds to the observed Higgs boson, we evaluate deviations from the standard model of the trilineal Higgs self-coupling. The conditions from unitarity, stability and Higgs diphoton decay data allow trilineal deviations in the range 0 ≤δ g ≲-72 %.

  4. Numerical Implementation of the Loop-Tree Duality

    NASA Astrophysics Data System (ADS)

    Buchta, S.

    We present a first numerical implementation of the Loop-Tree Duality (LTD) method for the direct numerical computation of multi-leg one-loop Feynman integrals. We discuss in detail the singular structure of the dual integrands and define a suitable contour deformation in the loop three-momentum space to carry out the numerical integration. Then, we apply the LTD method to the computation of ultraviolet and infrared finite integrals, and present explicit results for scalar integrals with up to five external legs (pentagons) and tensor integrals with up to six legs (hexagons). The LTD method features an excellent performance independently of the number of external legs.

  5. Iterative structure within the five-particle two-loop amplitude

    SciTech Connect

    Cachazo, Freddy; Spradlin, Marcus; Volovich, Anastasia

    2006-08-15

    We find an unexpected iterative structure within the two-loop five-gluon amplitude in N=4 supersymmetric Yang-Mills theory. Specifically, we show that a subset of diagrams contributing to the full amplitude, including a two-loop pentagon-box integral with nontrivial dependence on five kinematical variables, satisfies an iterative relation in terms of one-loop scalar box diagrams. The implications of this result for the possible iterative structure of the full two-loop amplitude are discussed.

  6. Turbulent Transport of Momentum and Scalars Above an Urban Canopy

    NASA Astrophysics Data System (ADS)

    Wang, Linlin; Li, Dan; Gao, Zhiqiu; Sun, Ting; Guo, Xiaofeng; Bou-Zeid, Elie

    2014-03-01

    Turbulent transport of momentum and scalars over an urban canopy is investigated using the quadrant analysis technique. High-frequency measurements are available at three levels above the urban canopy (47, 140 and 280 m). The characteristics of coherent ejection-sweep motions (flux contributions and time fractions) at the three levels are analyzed, particularly focusing on the difference between ejections and sweeps, the dissimilarity between momentum and scalars, and the dissimilarity between the different scalars (i.e., temperature, water vapour and . It is found that ejections dominate momentum and scalar transfer at all three levels under unstable conditions, while sweeps are the dominant eddy motions for transporting momentum and scalars in the urban roughness sublayer under neutral and stable conditions. The flux contributions and time fractions of ejections and sweeps can be adequately captured by assuming a Gaussian joint probability density function for flow variables. However, the inequality of flux contributions from ejections and sweeps is more accurately reproduced by the third-order cumulant expansion method (CEM). The incomplete cumulant expansion method (ICEM) also works well except for at 47 m where the skewness of fluctuations is significantly larger than that for vertical velocity. The dissimilarity between momentum and scalar transfers is linked to the dissimilarity in the characteristics of ejection-sweep motions and is further quantified by measures of transport efficiencies. Atmospheric stability is the controlling factor for the transport efficiencies of momentum and heat, and fitted functions from the literature describe their behaviour fairly accurately. However, transport efficiencies of water vapour and are less affected by the atmospheric stability. The dissimilarity among the three scalars examined in this study is linked to the active role of temperature and to the surface heterogeneity effect.

  7. A Self-Contained Mapping Closure Approximation for Scalar Mixing

    NASA Technical Reports Server (NTRS)

    He, Guo-Wei; Zhang, Zi-Fan

    2003-01-01

    Scalar turbulence exhibits interplays of coherent structures and random fluctuations over a broad range of spatial and temporal scales. This feature necessitates a probabilistic description of the scalar dynamics, which can be achieved comprehensively by using probability density functions (PDFs). Therefore, the challenge is to obtain the scalar PDFs (Lundgren 1967; Dopazo 1979). Generally, the evolution of a scalar is governed by three dynamical processes: advection, diffusion and reaction. In a PDF approach (Pope 1985), the advection and reaction can be treated exactly but the effect of molecular diffusion has to be modeled. It has been shown (Pope 1985) that the effect of molecular diffusion can be expressed as conditional dissipation rates or conditional diffusions. The currently used models for the conditional dissipation rates and conditional diffusions (Pope 1991) have resisted deduction from the fundamental equations and are unable to yield satisfactory results for the basic test cases of decaying scalars in isotropic turbulence, although they have achieved some success in a variety of individual cases. The recently developed mapping closure approach (Pope 1991; Chen, Chen & Kraichnan 1989; Kraichnan 1990; Klimenko & Pope 2003) provides a deductive method for conditional dissipation rates and conditional di usions, and the models obtained can successfully describe the shape relaxation of the scalar PDF from an initial double delta distribution to a Gaussian one. However, the mapping closure approach is not able to provide the rate at which the scalar evolves. The evolution rate has to be modeled. Therefore, the mapping closure approach is not closed. In this letter, we will address this problem.

  8. N-body simulations for coupled scalar-field cosmology

    SciTech Connect

    Li Baojiu; Barrow, John D.

    2011-01-15

    We describe in detail the general methodology and numerical implementation of consistent N-body simulations for coupled-scalar-field models, including background cosmology and the generation of initial conditions (with the different couplings to different matter species taken into account). We perform fully consistent simulations for a class of coupled-scalar-field models with an inverse power-law potential and negative coupling constant, for which the chameleon mechanism does not work. We find that in such cosmological models the scalar-field potential plays a negligible role except in the background expansion, and the fifth force that is produced is proportional to gravity in magnitude, justifying the use of a rescaled gravitational constant G in some earlier N-body simulation works for similar models. We then study the effects of the scalar coupling on the nonlinear matter power spectra and compare with linear perturbation calculations to see the agreement and places where the nonlinear treatment deviates from the linear approximation. We also propose an algorithm to identify gravitationally virialized matter halos, trying to take account of the fact that the virialization itself is also modified by the scalar-field coupling. We use the algorithm to measure the mass function and study the properties of dark-matter halos. We find that the net effect of the scalar coupling helps produce more heavy halos in our simulation boxes and suppresses the inner (but not the outer) density profile of halos compared with the {Lambda}CDM prediction, while the suppression weakens as the coupling between the scalar field and dark-matter particles increases in strength.

  9. The First Experimentally Confirmed Isolated Pentagon Rule (IPR) Isomers of Higher Fullerene C98 Captured as Chlorides, C98(248)Cl22 and C98(116)Cl20.

    PubMed

    Wang, Song; Yang, Shangfeng; Kemnitz, Erhard; Troyanov, Sergey I

    2016-04-01

    High-temperature chlorination of pristine C98 fullerene isomers separated by HPLC from the fullerene soot afforded crystals of C98Cl22 and C98Cl20. An X-ray structure elucidation revealed, respectively, the presence of carbon cages of the most stable C2-C98(248) and rather unstable C1-C98(116), which represent the first isolated pentagon rule (IPR) isomers of fullerene C98 confirmed experimentally. The chlorination patterns of the chlorides are discussed in terms of the formation of isolated C=C bonds and aromatic substructures on the fullerene cages. PMID:26919123

  10. Quasiequilibrium sequences of binary neutron stars undergoing dynamical scalarization

    NASA Astrophysics Data System (ADS)

    Taniguchi, Keisuke; Shibata, Masaru; Buonanno, Alessandra

    2015-01-01

    We calculate quasiequilibrium sequences of equal-mass, irrotational binary neutron stars in a scalar-tensor theory of gravity that admits dynamical scalarization. We model neutron stars with realistic equations of state (notably through piecewise polytropic equations of state). Using these quasiequilibrium sequences we compute the binary's scalar charge and binding energy versus orbital angular frequency. We find that the absolute value of the binding energy is smaller than in general relativity, differing at most by ˜14 % at high frequencies for the cases considered. We use the newly computed binding energy and the balance equation to estimate the number of gravitational-wave (GW) cycles during the adiabatic, quasicircular inspiral stage up to the end of the sequence, which is the last stable orbit or the mass-shedding point, depending on which comes first. We find that, depending on the scalar-tensor parameters, the number of GW cycles can be substantially smaller than in general relativity. In particular, we obtain that when dynamical scalarization sets in around a GW frequency of ˜130 Hz , the sole inclusion of the scalar-tensor binding energy causes a reduction of GW cycles from ˜120 Hz up to the end of the sequence (˜1200 Hz ) of ˜11 % with respect to the general-relativity case. (The number of GW cycles from ˜120 Hz to the end of the sequence in general relativity is ˜270 .) We estimate that when the scalar-tensor energy flux is also included the reduction in GW cycles becomes of ˜24 %. Quite interestingly, dynamical scalarization can produce a difference in the number of GW cycles with respect to the general-relativity point-particle case that is much larger than the effect due to tidal interactions, which is on the order of only a few GW cycles. These results further clarify and confirm recent studies that have evolved binary neutron stars either in full numerical relativity or in post-Newtonian theory, and point out the importance of developing

  11. New scalar constraint operator for loop quantum gravity

    NASA Astrophysics Data System (ADS)

    Assanioussi, Mehdi; Lewandowski, Jerzy; Mäkinen, Ilkka

    2015-08-01

    We present a concrete and explicit construction of a new scalar constraint operator for loop quantum gravity. The operator is defined on the recently introduced space of partially diffeomorphism invariant states, and this space is preserved by the action of the operator. To define the Euclidean part of the scalar constraint operator, we propose a specific regularization based on the idea of so-called "special" loops. The Lorentzian part of the quantum scalar constraint is merely the curvature operator that has been introduced in an earlier work. Due to the properties of the special loops assignment, the adjoint operator of the nonsymmetric constraint operator is densely defined on the partially diffeomorphism invariant Hilbert space. This fact opens up the possibility of defining a symmetric scalar constraint operator as a suitable combination of the original operator and its adjoint. We also show that the algebra of the scalar constraint operators is anomaly free, and describe the structure of the kernel of these operators on a general level.

  12. Dark energy parametrization motivated by scalar field dynamics

    NASA Astrophysics Data System (ADS)

    de la Macorra, Axel

    2016-05-01

    We propose a new dark energy (DE) parametrization motivated by the dynamics of a scalar field ϕ. We use an equation of state w parametrized in terms of two functions L and y, closely related to the dynamics of scalar fields, which is exact and has no approximation. By choosing an appropriate ansatz for L we obtain a wide class of behavior for the evolution of DE without the need to specify the scalar potential V. We parametrize L and y in terms of only four parameters, giving w a rich structure and allowing for a wide class of DE dynamics. Our w can either grow and later decrease, or it can happen the other way around; the steepness of the transition is not fixed and it contains the ansatz w={w}o+{w}a(1-a). Our parametrization follows closely the dynamics of a scalar field, and the function L allows us to connect it with the scalar potential V(φ ). While the Universe is accelerating and the slow roll approximation is valid, we get L≃ {({V}\\prime /V)}2. To determine the dynamics of DE we also calculate the background evolution and its perturbations, since they are important to discriminate between different DE models.

  13. Long-lived, colour-triplet scalars from unnaturalness

    NASA Astrophysics Data System (ADS)

    Barnard, James; Cox, Peter; Gherghetta, Tony; Spray, Andrew

    2016-03-01

    Long-lived, colour-triplet scalars are a generic prediction of unnatural, or split, composite Higgs models where the spontaneous global-symmetry breaking scale f ≳ 10 TeV and an unbroken SU(5) symmetry is preserved. Since the triplet scalars are pseudo NambuGoldstone bosons they are split from the much heavier composite-sector resonances and are the lightest exotic, coloured states. This makes them ideal to search for at colliders. Due to discrete symmetries the triplet scalar decays via a dimension-six term and given the large suppression scale f is often metastable. We show that existing searches for collider-stable R-hadrons from Run-I at the LHC forbid a triplet scalar mass below 845 GeV, whereas with 300 fb-1 at 13 TeV triplet scalar masses up to 1.4 TeV can be discovered. For shorter lifetimes displaced-vertex searches provide a discovery reach of up to 1.8 TeV. In addition we present exclusion and discovery reaches of future hadron colliders as well as indirect limits that arise from modifications of the Higgs couplings.

  14. Growth of spherical overdensities in scalar-tensor cosmologies

    NASA Astrophysics Data System (ADS)

    Nazari-Pooya, N.; Malekjani, M.; Pace, F.; Jassur, D. Mohammad-Zadeh

    2016-06-01

    The accelerated expansion of the universe is a rather established fact in cosmology and many different models have been proposed as a viable explanation. Many of these models are based on the standard general relativistic framework of non-interacting fluids or more recently of coupled (interacting) dark energy models, where dark energy (the scalar field) is coupled to the dark matter component giving rise to a fifth-force. An interesting alternative is to couple the scalar field directly to the gravity sector via the Ricci scalar. These models are dubbed non-minimally coupled models and give rise to a time-dependent gravitational constant. In this work, we study few models falling into this category and describe how observables depend on the strength of the coupling. We extend recent work on the subject by taking into account also the effects of the perturbations of the scalar field and showing their relative importance on the evolution of the mass function. By working in the framework of the spherical collapse model, we show that perturbations of the scalar field have a limited impact on the growth factor (for small coupling constant) and on the mass function with respect to the case where perturbations are neglected.

  15. Effect of dilatation on scalar dissipation in turbulent premixed flames

    SciTech Connect

    Swaminathan, N.; Bray, K.N.C.

    2005-12-01

    The scalar dissipation rate signifies the local mixing rate and thus plays a vital role in the modeling of reaction rate in turbulent flames. The local mixing rate is influenced by the turbulence, the chemical, and the molecular diffusion processes which are strongly coupled in turbulent premixed flames. Thus, a model for the mean scalar dissipation rate, and hence the mean reaction rate, should include the contributions of these processes. Earlier models for the scalar dissipation rate include only a turbulence time scale. In this study, we derive exact transport equations for the instantaneous and the mean scalar dissipation rates. Using these equations, a simple algebraic model for the mean scalar dissipation rate is obtained. This model includes a chemical as well as a turbulence time scale and its prediction compares well with direct numerical simulation results. Reynolds-averaged Navier-Stokes calculations of a test flame using the model obtained here show that the contribution of dilatation to local turbulent mixing rate is important to predict the propagation phenomenon.

  16. Pseudo-scalar form factors at three loops in QCD

    NASA Astrophysics Data System (ADS)

    Ahmed, Taushif; Gehrmann, Thomas; Mathews, Prakash; Rana, Narayan; Ravindran, V.

    2015-11-01

    The coupling of a pseudo-scalar Higgs boson to gluons is mediated through a heavy quark loop. In the limit of large quark mass, it is described by an effective Lagrangian that only admits light degrees of freedom. In this effective theory, we compute the three-loop massless QCD corrections to the form factor that describes the coupling of a pseudo-scalar Higgs boson to gluons. Due to the axial anomaly, the pseudo-scalar operator for the gluonic field strength mixes with the divergence of the axial vector current. Working in dimensional regularization and using the 't Hooft-Veltman prescription for the axial vector current, we compute the three-loop pseudo-scalar form factors for massless quarks and gluons. Using the universal infrared factorization properties, we independently derive the three-loop operator mixing and finite operator renormalisation from the renormalisation group equation for the form factors, thereby confirming recent results in the operator product expansion. The finite part of the three-loop form factor is an important ingredient to the precise prediction of the pseudo-scalar Higgs boson production cross section at hadron colliders. We discuss potential applications and derive the hard matching coefficient in soft-collinear effective theory.

  17. Constraining scalar fields with stellar kinematics and collisional dark matter

    SciTech Connect

    Amaro-Seoane, Pau; Barranco, Juan; Bernal, Argelia; Rezzolla, Luciano E-mail: jbarranc@aei.mpg.de E-mail: rezzolla@aei.mpg.de

    2010-11-01

    The existence and detection of scalar fields could provide solutions to long-standing puzzles about the nature of dark matter, the dark compact objects at the centre of most galaxies, and other phenomena. Yet, self-interacting scalar fields are very poorly constrained by astronomical observations, leading to great uncertainties in estimates of the mass m{sub φ} and the self-interacting coupling constant λ of these fields. To counter this, we have systematically employed available astronomical observations to develop new constraints, considerably restricting this parameter space. In particular, by exploiting precise observations of stellar dynamics at the centre of our Galaxy and assuming that these dynamics can be explained by a single boson star, we determine an upper limit for the boson star compactness and impose significant limits on the values of the properties of possible scalar fields. Requiring the scalar field particle to follow a collisional dark matter model further narrows these constraints. Most importantly, we find that if a scalar dark matter particle does exist, then it cannot account for both the dark-matter halos and the existence of dark compact objects in galactic nuclei.

  18. Quasistationary solutions of scalar fields around accreting black holes

    NASA Astrophysics Data System (ADS)

    Sanchis-Gual, Nicolas; Degollado, Juan Carlos; Izquierdo, Paula; Font, José A.; Montero, Pedro J.

    2016-08-01

    Massive scalar fields can form long-lived configurations around black holes. These configurations, dubbed quasibound states, have been studied both in the linear and nonlinear regimes. In this paper, we show that quasibound states can form in a dynamical scenario in which the mass of the black hole grows significantly due to the capture of infalling matter. We solve the Klein-Gordon equation numerically in spherical symmetry, mimicking the evolution of the spacetime through a sequence of analytic Schwarzschild black hole solutions of increasing mass. It is found that the frequency of oscillation of the quasibound states decreases as the mass of the black hole increases. In addition, accretion leads to an increase of the exponential decay of the scalar field energy. We compare the black hole mass growth rates used in our study with estimates from observational surveys and extrapolate our results to values of the scalar field masses consistent with models that propose scalar fields as dark matter in the universe. We show that, even for unrealistically large mass accretion rates, quasibound states around accreting black holes can survive for cosmological time scales. Our results provide further support to the intriguing possibility of the existence of dark matter halos based on (ultralight) scalar fields surrounding supermassive black holes in galactic centers.

  19. Survival of scalar zero modes in warped extra dimensions

    SciTech Connect

    George, Damien P.

    2011-05-15

    Models with an extra dimension generally contain background scalar fields in a nontrivial configuration, whose stability must be ensured. With gravity present, the extra dimension is warped by the scalars, and the spin-0 degrees of freedom in the metric mix with the scalar perturbations. Where possible, we formally solve the coupled Schroedinger equations for the zero modes of these spin-0 perturbations. When specializing to the case of two scalars with a potential generated by a superpotential, we are able to fully solve the system. We show how these zero modes can be used to construct a solution matrix, whose eigenvalues tell whether a normalizable zero mode exists, and how many negative mass modes exist. These facts are crucial in determining stability of the corresponding background configuration. We provide examples of the general analysis for domain-wall models of an infinite extra dimension and domain-wall soft-wall models. For five-dimensional models with two scalars constructed using a superpotential, we show that a normalizable zero mode survives, even in the presence of warped gravity. Such models, which are widely used in the literature, are therefore phenomenologically unacceptable.

  20. Tensor-to-scalar ratio in punctuated inflation

    SciTech Connect

    Jain, Rajeev Kumar; Sriramkumar, L.; Chingangbam, Pravabati; Souradeep, Tarun

    2010-07-15

    Recently, we have shown that scalar spectra with lower power on large scales and certain other features naturally occur in punctuated inflation, i.e. the scenario wherein a brief period of rapid roll is sandwiched between two stages of slow roll inflation. Such spectra gain importance due to the fact that they can lead to a better fit of the observed CMB anisotropies, when compared to the conventional, featureless, power law spectrum. In this paper, with examples from the canonical scalar field as well as the tachyonic models, we illustrate that, in punctuated inflation, a drop in the scalar power on large scales is always accompanied by a rise in the tensor power and, hence, an even more pronounced increase in the tensor-to-scalar ratio r on these scales. Interestingly, we find that r actually exceeds well beyond unity over a small range of scales. To our knowledge, this work presents for the first time, examples of single scalar field inflationary models wherein r>>1. This feature opens up interesting possibilities. For instance, we show that the rise in r on large scales translates to a rapid increase in the angular power spectrum, C{sub l}{sup BB}, of the B-mode polarization of the CMB at the low multipoles. We discuss the observational implications of these results.

  1. Iron Kα line of Kerr black holes with scalar hair

    NASA Astrophysics Data System (ADS)

    Ni, Yueying; Zhou, Menglei; Cárdenas-Avendaño, Alejandro; Bambi, Cosimo; Herdeiro, Carlos A. R.; Radu, Eugen

    2016-07-01

    Recently, a family of hairy black holes in 4-dimensional Einstein gravity minimally coupled to a complex, massive scalar field was discovered [1]. Besides the mass M and spin angular momentum J, these objects are characterized by a Noether charge Q, measuring the amount of scalar hair, which is not associated to a Gauss law and cannot be measured at spatial infinity. Introducing a dimensionless scalar hair parameter q, ranging from 0 to 1, we recover (a subset of) Kerr black holes for q = 0 and a family of rotating boson stars for q = 1. In the present paper, we explore the possibility of measuring q for astrophysical black holes with current and future X-ray missions. We study the iron Kα line expected in the reflection spectrum of such hairy black holes and we simulate observations with Suzaku and eXTP. As a proof of concept, we point out, by analyzing a sample of hairy black holes, that current observations can already constrain the scalar hair parameter q, because black holes with q close to 1 would have iron lines definitively different from those we observe in the available data. We conclude that a detailed scanning of the full space of solutions, together with data from the future X-ray missions, like eXTP, will be able to put relevant constraints on the astrophysical realization of Kerr black holes with scalar hair.

  2. Modified scalar and tensor spectra in spinor driven inflation

    SciTech Connect

    Gredat, Damien; Shankaranarayanan, S. E-mail: shanki@iisertvm.ac.in

    2010-01-01

    One of the firm predictions of single-scalar field inflationary cosmology is the consistency relation between scalar and tensor perturbations. It has been argued that such a relation, if observationally verified, would offer strong support for the idea of inflation. In this letter, we critically analyze the validity of the consistency relation in the context of spinor driven inflation. The spinflaton – a condensate of the Elko field — has a single scalar degree of freedom and leads to the same acceleration equation as the inflaton. We obtain the perturbation equations for the Einstein-Elko system and show that the scalar perturbations are purely adiabatic and the sound speed of the perturbations is identically one. We obtain the generalized Mukhanov-Sasaki equation for the spinor driven inflation and show that, in the slow-roll limit, the scalar and tensor spectra are nearly scale-invariant. We also show that spinor driven inflation naturally predicts running of spectral indices and the consistency relations for the spectra are modified.

  3. Projected Constraints on Scalarization with Gravitational Waves from Neutron Star Binaries

    NASA Astrophysics Data System (ADS)

    Sampson, Laura; Yunes, Nicolas; Cornish, Neil; Ponce, Marcelo; Barausse, Enrico; Klein, Antoine; Palenzuela, Carlos; Lehner, Luis

    2015-04-01

    Certain scalar-tensor theories endow stars with scalar hair, sourced either by the star's own compactness, or by the companion's scalar charge, or by the orbital binding energy. Scalarized stars in binaries have different conservative dynamics than in General Relativity, and can excite a scalar mode in the metric perturbation that carries away dipolar radiation. As a result, the binary orbit shrinks faster than predicted in General Relativity, modifying the rate of decay of the orbital period. Scalar-tensor theories can pass existing binary pulsar tests, because observed pulsars may not be compact enough or sufficiently orbitally bound to activate scalarization. Gravitational waves emitted during the last stages of compact binary inspirals are thus ideal probes of scalarization effects. In the work presented here, we analyze the types of constraints the gravitational wave measurements from the advanced LIGO detectors will be able to place on these types of scalar-tensor theories.

  4. Scalar multiplet recombination at large N and holography

    NASA Astrophysics Data System (ADS)

    Bashmakov, Vladimir; Bertolini, Matteo; Di Pietro, Lorenzo; Raj, Himanshu

    2016-05-01

    We consider the coupling of a free scalar to a single-trace operator of a large N CFT in d dimensions. This is equivalent to a double-trace deformation coupling two primary operators of the CFT, in the limit when one of the two saturates the unitarity bound. At leading order, the RG-flow has a non-trivial fixed point where multiplets recombine. We show this phenomenon in field theory, and provide the holographic dual description. Free scalars correspond to singleton representations of the AdS algebra. The double-trace interaction is mapped to a boundary condition mixing the singleton with the bulk field dual to the single-trace operator. In the IR, the singleton and the bulk scalar merge, providing just one long representation of the AdS algebra.

  5. Optimized scalar promotion with load and splat SIMD instructions

    DOEpatents

    Eichenberger, Alexandre E.; Gschwind, Michael K.; Gunnels, John A.

    2012-08-28

    Mechanisms for optimizing scalar code executed on a single instruction multiple data (SIMD) engine are provided. Placement of vector operation-splat operations may be determined based on an identification of scalar and SIMD operations in an original code representation. The original code representation may be modified to insert the vector operation-splat operations based on the determined placement of vector operation-splat operations to generate a first modified code representation. Placement of separate splat operations may be determined based on identification of scalar and SIMD operations in the first modified code representation. The first modified code representation may be modified to insert or delete separate splat operations based on the determined placement of the separate splat operations to generate a second modified code representation. SIMD code may be output based on the second modified code representation for execution by the SIMD engine.

  6. Optimized scalar promotion with load and splat SIMD instructions

    DOEpatents

    Eichenberger, Alexander E; Gschwind, Michael K; Gunnels, John A

    2013-10-29

    Mechanisms for optimizing scalar code executed on a single instruction multiple data (SIMD) engine are provided. Placement of vector operation-splat operations may be determined based on an identification of scalar and SIMD operations in an original code representation. The original code representation may be modified to insert the vector operation-splat operations based on the determined placement of vector operation-splat operations to generate a first modified code representation. Placement of separate splat operations may be determined based on identification of scalar and SIMD operations in the first modified code representation. The first modified code representation may be modified to insert or delete separate splat operations based on the determined placement of the separate splat operations to generate a second modified code representation. SIMD code may be output based on the second modified code representation for execution by the SIMD engine.

  7. Knocking on new physics' door with a scalar resonance

    NASA Astrophysics Data System (ADS)

    Buttazzo, Dario; Greljo, Admir; Marzocca, David

    2016-03-01

    We speculate about the origin of the recent excess at ˜ 750 GeV in diphoton resonance searches observed by the ATLAS and CMS experiments using the first 13 TeV data. Its interpretation as a new scalar resonance produced in gluon fusion and decaying to photons is consistent with all relevant exclusion bounds from the 8 TeV LHC run. We provide a simple phenomenological framework to parametrize the properties of the new resonance and show in a model-independent way that, if the scalar is produced in gluon fusion, additional new colored and charged particles are required. Finally, we discuss some interpretations in various concrete setups, such as a singlet (pseudo-) scalar, composite Higgs, and the MSSM.

  8. Pulsar timing signal from ultralight scalar dark matter

    SciTech Connect

    Khmelnitsky, Andrei; Rubakov, Valery E-mail: rubakov@ms2.inr.ac.ru

    2014-02-01

    An ultralight free scalar field with mass around 10{sup −23}−10{sup −22} eV is a viable dark mater candidate, which can help to resolve some of the issues of the cold dark matter on sub-galactic scales. We consider the gravitational field of the galactic halo composed out of such dark matter. The scalar field has oscillating in time pressure, which induces oscillations of gravitational potential with amplitude of the order of 10{sup −15} and frequency in the nanohertz range. This frequency is in the range of pulsar timing array observations. We estimate the magnitude of the pulse arrival time residuals induced by the oscillating gravitational potential. We find that for a range of dark matter masses, the scalar field dark matter signal is comparable to the stochastic gravitational wave signal and can be detected by the planned SKA pulsar timing array experiment.

  9. Primordial scalar power spectrum from the Euclidean big bounce

    NASA Astrophysics Data System (ADS)

    Schander, Susanne; Barrau, Aurélien; Bolliet, Boris; Linsefors, Linda; Mielczarek, Jakub; Grain, Julien

    2016-01-01

    In effective models of loop quantum cosmology, the holonomy corrections are associated with deformations of space-time symmetries. The most evident manifestation of the deformations is the emergence of a Euclidean phase accompanying the nonsingular bouncing dynamics of the scale factor. In this article, we compute the power spectrum of scalar perturbations generated in this model, with a massive scalar field as the matter content. Instantaneous and adiabatic vacuum-type initial conditions for scalar perturbations are imposed in the contracting phase. The evolution through the Euclidean region is calculated based on the extrapolation of the time direction pointed by the vectors normal to the Cauchy hypersurface in the Lorentzian domains. The obtained power spectrum is characterized by a suppression in the IR regime and oscillations in the intermediate energy range. Furthermore, the speculative extension of the analysis in the UV reveals a specific rise of the power leading to results incompatible with the data.

  10. An inflationary model with small scalar and large tensor nongaussianities

    NASA Astrophysics Data System (ADS)

    Cook, Jessica L.; Sorbo, Lorenzo

    2013-11-01

    We study a model of inflation where the scalar perturbations are almost gaussian while there is sizable (equilateral) nongaussianity in the tensor sector. In this model, a rolling pseudoscalar gravitationally coupled to the inflaton amplifies the vacuum fluctuations of a vector field. The vector sources both scalar and tensor metric perturbations. Both kinds of perturbations are nongaussian, but, due to helicity conservation, the tensors have a larger amplitude, so that nongaussianity in the scalar perturbations is negligible. Moreover, the tensors produced this way are chiral. We study, in the flat sky approximation, how constraints on tensor nongaussianities affect the detectability of parity violation in the Cosmic Microwave Background. We expect the model to feature interesting patterns on nongaussianities in the polarization spectra of the CMB.

  11. Adjunctation and Scalar Product in the Dirac Equation - I

    NASA Astrophysics Data System (ADS)

    Dima, M.

    2016-02-01

    The Bargmann-Pauli adjunctator (hermitiser) of {C}{l}_{_{1,3}}(C) is derived in a representation independent way, circumventing the early derivations (Pauli, Ann. inst. Henri Poincaré 6, 109 and 121 1936) using representation-dependent arguments. Relations for the adjunctator's transformation with the scalar product and space generator set are given. The S U(2) adjunctator is shown to determine the {C}{l}_{_{1,3}}(C) adjunctator. Part-II of the paper will approach the problem of the two scalar products used in Dirac theory - an unphysical situation of "piece-wise physics" with erroneous results. The adequate usage of scalar product - via calibration - will be presented, in particular under boosts, yielding the known covariant transformations of physical quantities.

  12. Detecting chameleons: The astronomical polarization produced by chameleonlike scalar fields

    SciTech Connect

    Burrage, Clare; Davis, Anne-Christine; Shaw, Douglas J.

    2009-02-15

    We show that a coupling between chameleonlike scalar fields and photons induces linear and circular polarization in the light from astrophysical sources. In this context chameleonlike scalar fields include those of the Olive-Pospelov (OP) model, which describes a varying fine structure constant. We determine the form of this polarization numerically and give analytic expressions in two useful limits. By comparing the predicted signal with current observations we are able to improve the constraints on the chameleon-photon coupling and the coupling in the OP model by over 2 orders of magnitude. It is argued that, if observed, the distinctive form of the chameleon induced circular polarization would represent a smoking gun for the presence of a chameleon. We also report a tentative statistical detection of a chameleonlike scalar field from observations of starlight polarization in our galaxy.

  13. Scalar field dark matter and the Higgs field

    NASA Astrophysics Data System (ADS)

    Bertolami, O.; Cosme, Catarina; Rosa, João G.

    2016-08-01

    We discuss the possibility that dark matter corresponds to an oscillating scalar field coupled to the Higgs boson. We argue that the initial field amplitude should generically be of the order of the Hubble parameter during inflation, as a result of its quasi-de Sitter fluctuations. This implies that such a field may account for the present dark matter abundance for masses in the range 10-6-10-4eV, if the tensor-to-scalar ratio is within the range of planned CMB experiments. We show that such mass values can naturally be obtained through either Planck-suppressed non-renormalizable interactions with the Higgs boson or, alternatively, through renormalizable interactions within the Randall-Sundrum scenario, where the dark matter scalar resides in the bulk of the warped extra-dimension and the Higgs is confined to the infrared brane.

  14. Primordial power spectra for scalar perturbations in loop quantum cosmology

    NASA Astrophysics Data System (ADS)

    Martín de Blas, Daniel; Olmedo, Javier

    2016-06-01

    We provide the power spectrum of small scalar perturbations propagating in an inflationary scenario within loop quantum cosmology. We consider the hybrid quantization approach applied to a Friedmann-Robertson-Walker spacetime with flat spatial sections coupled to a massive scalar field. We study the quantum dynamics of scalar perturbations on an effective background within this hybrid approach. We consider in our study adiabatic states of different orders. For them, we find that the hybrid quantization is in good agreement with the predictions of the dressed metric approach. We also propose an initial vacuum state for the perturbations, and compute the primordial and the anisotropy power spectrum in order to qualitatively compare with the current observations of Planck mission. We find that our vacuum state is in good agreement with them, showing a suppression of the power spectrum for large scale anisotropies. We compare with other choices already studied in the literature.

  15. A scalar field dark energy model: Noether symmetry approach

    NASA Astrophysics Data System (ADS)

    Dutta, Sourav; Panja, Madan Mohan; Chakraborty, Subenoy

    2016-04-01

    Scalar field dark energy cosmology has been investigated in the present paper in the frame work of Einstein gravity. In the context of Friedmann-Lemaitre-Robertson-Walker space time minimally coupled scalar field with self interacting potential and non-interacting perfect fluid with barotropic equation of state (dark matter) is chosen as the matter context. By imposing Noether symmetry on the Lagrangian of the system the symmetry vector is obtained and the self interacting potential for the scalar field is determined. Then we choose a point transformation (a, φ )→ (u, v) such that one of the transformation variable (say u) is cyclic for the Lagrangian. Subsequently, using conserved charge (corresponding to the cyclic co-ordinate) and the constant of motion, solutions are obtained. Finally, the cosmological implication of the solutions in the perspective of recent observation has been examined.

  16. Inert scalars and vacuum metastability around the electroweak scale

    NASA Astrophysics Data System (ADS)

    Świeżewska, Bogumiła

    2015-07-01

    We analyse effective potential around the electroweak (EW) scale in the Standard Model (SM) extended with a heavy scalar doublet. We show that the additional scalars can have a strong impact on vacuum stability. Although the additional heavy scalars may improve the behaviour of running Higgs self-coupling at large field values, we prove that they can destabilise the vacuum due to EW-scale effects. A new EW symmetry conserving minimum of the effective potential can appear rendering the electroweak symmetry breaking (EWSB) minimum meta- or unstable. However, for the case of the inert doublet model (IDM) with a 125 GeV Higgs boson we demonstrate that the parameter space region where the vacuum is meta- or unstable cannot be reconciled with the constraints from perturbative unitarity, electroweak precision tests (EWPT) and dark matter relic abundance measurements.

  17. Thick branes from self-gravitating scalar fields

    SciTech Connect

    Novikov, Oleg O.; Andrianov, Vladimir A.; Andrianov, Alexander A.

    2014-07-23

    The formation of a domain wall ('thick brane') induced by scalar matter dynamics and triggered by a thin brane defect is considered in noncompact five-dimensional space-time with warped AdS type geometry. The scalar matter is composed of two fields with softly broken O(2) symmetry and minimal coupling to gravity. The nonperturbative effects in the invariant mass spectrum of light localized scalar states are investigated for different values of the tension of the thin brane defect. Especially interesting is the case of the thin brane with negative tension when the singular barriers form a potential well with two infinitely tall walls and the discrete spectrum of localized states arises completely isolated from the bulk.

  18. Bose-Einstein condensates and scalar fields; exploring the similitudes

    NASA Astrophysics Data System (ADS)

    Castellanos, E.; Macías, A.; Núñez, D.

    2014-01-01

    We analyze the the remarkable analogy between the classical Klein-Gordon equation for a test scalar field in a flat and also in a curved background, and the Gross-Pitaevskii equation for a Bose-Einstein condensate trapped by an external potential. We stress here that the solution associated with the Klein-Gordon equation (KG) in a flat space time has the same mathematical structure, under certain circumstances, to those obtained for the Gross-Pitaevskii equation, that is, a static soliton solution. Additionally, Thomas-Fermi approximation is applied to the 3-dimensional version of this equation, in order to calculate some thermodynamical properties of the system in curved a space-time back ground. Finally, we stress the fact that a gravitational background provides, in some cases, a kind of confining potential for the scalar field, allowing us to remarks even more the possible connection between scalar fields and the phenomenon of Bose-Einstein condensation.

  19. Bose–Einstein condensates and scalar fields; exploring the similitudes

    SciTech Connect

    Castellanos, E.; Macías, A.; Núñez, D.

    2014-01-14

    We analyze the the remarkable analogy between the classical Klein–Gordon equation for a test scalar field in a flat and also in a curved background, and the Gross–Pitaevskii equation for a Bose–Einstein condensate trapped by an external potential. We stress here that the solution associated with the Klein–Gordon equation (KG) in a flat space time has the same mathematical structure, under certain circumstances, to those obtained for the Gross–Pitaevskii equation, that is, a static soliton solution. Additionally, Thomas–Fermi approximation is applied to the 3–dimensional version of this equation, in order to calculate some thermodynamical properties of the system in curved a space–time back ground. Finally, we stress the fact that a gravitational background provides, in some cases, a kind of confining potential for the scalar field, allowing us to remarks even more the possible connection between scalar fields and the phenomenon of Bose–Einstein condensation.

  20. Cosmology in new gravitational scalar-tensor theories

    NASA Astrophysics Data System (ADS)

    Saridakis, Emmanuel N.; Tsoukalas, Minas

    2016-06-01

    We investigate the cosmological applications of new gravitational scalar-tensor theories, which are novel modifications of gravity possessing 2 +2 propagating degrees of freedom, arising from a Lagrangian that includes the Ricci scalar and its first and second derivatives. Extracting the field equations we obtain an effective dark energy sector that consists of both extra scalar degrees of freedom, and we determine various observables. We analyze two specific models and we obtain a cosmological behavior in agreement with observations, i.e. transition from matter to dark energy era, with the onset of cosmic acceleration. Additionally, for a particular range of the model parameters, the equation-of-state parameter of the effective dark energy sector can exhibit the phantom-divide crossing. These features reveal the capabilities of these theories, since they arise solely from the novel, higher-derivative terms.