Nuclear Theory·nucl-th

Monday·September 14, 2015

10 papers—6 primary·4 cross-listed

01
[Submitted on 10 Sept 2015]
Contact-interaction Faddeev equation and, inter alia, proton tensor charges
Shu-Sheng Xu🇨🇳 · Chen Chen🇨🇳 · Ian C.Cloet🇺🇸 · Craig D. Roberts🇺🇸 · Jorge Segovia🇪🇸 · Hong-Shi Zong🇨🇳
A confining, symmetry-preserving, Dyson-Schwinger equation treatment of a vector-vector contact interaction is used to formulate Faddeev equations for the nucleon and Delta-baryon in which the kernel involves dynamical dressed-quark exchange and whose solutions therefore provide momentum-dependent Faddeev amplitudes. These solutions are compared with those obtained in the static approximation and with a QCD-kindred formulation of the Faddeev kernel. They are also used to compute a range of nucleon properties, amongst them: the proton's sigma-term; the large Bjorken-x values of separate ratios of unpolarised and longitudinally-polarised valence u- and d-quark parton distribution functions; and the proton's tensor charges, which enable one to directly determine the effect of dressed-quark electric dipole moments (EDMs) on neutron and proton EDMs.
Comments:
19 pages, 5 figures, 5 tables. Includes estimate of s-quark contribution to proton tensor charge. Phys. Rev. D (in press)
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1509.03311 [pdf]
PRD(2015)·60 citations
02
[Submitted on 11 Sept 2015]
Dynamical and statistical description of multifragmentation in heavy-ion collisions
Lihua Mao · Ning Wang · Li Ou
To explore the roles of dynamical model and statistical model in the description of multifragmentation in heavy-ion collisions at intermediate energies, the fragments charge distributions of $^{197}$ Au+ $^{197}$ Au at 35 MeV/u are analyzed by using the hybrid model of improved quantum molecular dynamics (ImQMD) model plus the statistical model GEMINI. We find that, the ImQMD model can well describe the charge distributions of fragments produced in central and semi-central collisions. But for the peripheral collisions of Au+Au at 35 MeV/u, the statistical model is required at the end of the ImQMD simulations for the better description of the charge distribution of fragments. By using the hybrid model of ImQMD+GEMINI, the fragment charge distribution of Au+Au at 35 MeV/u can be reproduced reasonably well. The time evolution of the excitation energies of primary fragments is simultaneously investigated.
Comments:
6 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1509.03404 [pdf]
PRC(2015)·7 citations
03
[Submitted on 11 Sept 2015]
Further study on mechanism of production of light complex particles in nucleon-induced reactions
Dexian Wei · Lihua Mao · Ning Wang · Min Liu · Li Ou
The Improved Quantum Molecular Dynamics (ImQMD) model incorporated with the statistical decay model is used to investigate the intermediate energy nucleon-induced reactions. In our last work, the description on light complex particle emission has been great improved with a phenomenological mechanism called surface coalescence and emission introduced into ImQMD model. In this work, taking account of different specific binding energies and separation energies for various light complex particles, the phase space parameters in surface coalescence model are readjusted. By using the new phase space parameters set with better physical fundament, the double differential cross sections of emitted light complex particles are found to be in better agreement with experimental data.
Comments:
11 pages, 4 figures. arXiv admin note: substantial text overlap with arXiv:1309.7534
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1509.03412 [pdf]
NPA(2015)·3 citations
04
[Submitted on 11 Sept 2015]
Chemical and thermal freeze-out of identified hadrons at the LHC
Xiangrong Zhu🇨🇳 · Huichao Song (Peking U.)🇨🇳
This proceeding briefly summarizes our recent VISHNU hybrid model investigations on the chemical and thermal freeze-out of various hadrons species in 2.76 A TeV Pb+Pb collisions. Detailed analysis on the evolution of particle yields and the last elastic collisions distributions during the hadronic evolution reveals that the two multi-strange hadrons, $Ξ$ and $Ω$ , experience early chemical and thermal freeze-out when compared with other hadron species.
Comments:
4 pages, 3 figures, SQM2015 proceeding
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1509.03450 [pdf]
J.Phys.Conf.Ser.(2016)·0 citations
05
[Submitted on 11 Sept 2015]
Chiral Three-Nucleon Interactions in Light Nuclei, Neutron- $α$ Scattering, and Neutron Matter
J. E. Lynn · I. Tews · J. Carlson · S. Gandolfi · A. Gezerlis · K. E. Schmidt · A. Schwenk
We present quantum Monte Carlo calculations of light nuclei, neutron- $α$ scattering, and neutron matter using local two- and three-nucleon ( $3 N$ ) interactions derived from chiral effective field theory up to next-to-next-to-leading order (N $^{2}$ LO). The two undetermined $3 N$ low-energy couplings are fit to the $^{4}$ He binding energy and, for the first time, to the spin-orbit splitting in the neutron- $α$ $P$ -wave phase shifts. Furthermore, we investigate different choices of local $3 N$ -operator structures and find that chiral interactions at N $^{2}$ LO are able to simultaneously reproduce the properties of $A = 3, 4, 5$ systems and of neutron matter, in contrast to commonly used phenomenological $3 N$ interactions.
Comments:
5 pages, 3 figures, 1 table - updated version: small wording changes, one reference change
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1509.03470 [pdf]
PRL(2016)·323 citations
06
[Submitted on 11 Sept 2015]
Hyperons in Neutron Stars
Isaac Vidana🇵🇹
In this work I briefly review some of the effects of hyperons on the properties of neutron and proto-neutron stars. In particular, I revise the problem of the strong softening of the EoS, and the consequent reduction of the maximum mass, induced by the presence of hyperons, a puzzle which has become more intringuing and difficult to solve due the recent measurements of the unusually high masses of the millisecond pulsars PSR J1903+0327 ( $1.667 \pm 0.021 M_{⊙}$ ), PSR J1614-2230 ( $1.97 \pm 0.04 M_{⊙}$ ), and PSR J0348+0432 ( $2.01 \pm 0.04 M_{⊙}$ ). Some of the solutions proposed to tackle this problem are discussed. Finally, I re-examine also the role of hyperons on the cooling properties of newly born neutron stars and on the so-called r-mode instability.
Comments:
8 pages, 3 figures. Plenary talk at the 15th International Conference on Strangeness in Quark Matter (SQM2015), 6-11 July 2015, JINR, Dubna, Russia. To be published in Journal of Physics: Conference Series (JPCS)
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
1509.03587 [pdf]
J.Phys.Conf.Ser.(2016)·36 citations
07
[Submitted on 10 Sept 2015] (cross-list from hep-ph)
The magnetized effective QCD phase diagram
Alejandro Ayala🇿🇦 · C. A. Dominguez🇿🇦 · L. A. Hernandez🇿🇦 · M. Loewe🇿🇦 · R. Zamora🇨🇱
The QCD phase diagram in the temperature versus quark chemical potential plane is studied in the presence of a magnetic field, using the linear sigma model coupled to quarks. It is shown that the decrease of the couplings with increasing field strength obtained in this model leads to the critical temperature for the phase transition to decrease with increasing field intensity (inverse magnetic catalysis). This happens provided that plasma screening is properly accounted for. It is also found that with increasing field strength the location of the critical end point (CEP) in the phase diagram moves toward lower values of the critical quark chemical potential and larger values of the critical temperature. In addition, the CEP approaches the temperature axis for large values of the magnetic field. We argue that a similar behavior is to be expected in QCD, since the physical impact of the magnetic field, regardless of strength, is to produce a spatial dimension reduction, whereby virtual quark-antiquark pairs are closer on average and thus, the strength of their interaction decreases due to asymptotic freedom.
Comments:
Minor typos and one affiliation corrected
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1509.03345 [pdf]
PRD(2015)·87 citations
08
[Submitted on 11 Sept 2015] (cross-list from hep-ph)
Studies of two-solar-mass hybrid stars within the framework of Dyson-Schwinger equations
Tong Zhao🇨🇳 · Shu-Sheng Xu🇨🇳 · Yan Yan🇨🇳 · Xin-Lian Luo🇨🇳 · Xiao-Jun Liu🇨🇳 · Hong-Shi Zong🇨🇳
In this paper we introduce an equation of state (EOS) of quark matter within the framework of Dyson-Schwinger equations (DSEs) to study the structure of compact stars. The smooth crossover from hadronic matter to quark matter in the hybrid star is studied. We compare different strategies to obtain crossover EOSs and find a new way to construct two-solar-mass hybrid stars with even a relatively soft quark EOS, while earlier works show that the quark EOS should be stiff enough to support a massive hybrid star.
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1509.03377 [pdf]
PRD(2015)·33 citations
09
[Submitted on 11 Sept 2015] (cross-list from hep-ph)
Tracing the origin of azimuthal gluon correlations in the color glass condensate
T. Lappi🇫🇮 · B. Schenke🇺🇸 · S. Schlichting🇺🇸 · R. Venugopalan🇩🇪
We examine the origins of azimuthal correlations observed in high energy proton-nucleus collisions by considering the simple example of the scattering of uncorrelated partons off color fields in a large nucleus. We demonstrate how the physics of fluctuating color fields in the color glass condensate (CGC) effective theory generates these azimuthal multiparticle correlations and compute the corresponding Fourier coefficients v_n within different CGC approximation schemes. We discuss in detail the qualitative and quantitative differences between the different schemes. We will show how a recently introduced color field domain model that captures key features of the observed azimuthal correlations can be understood in the CGC effective theory as a model of non-Gaussian correlations in the target nucleus.
Comments:
15 pages, 6 figures, RevTeX. V2: small clarifications and added references. To be published in JHEP
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1509.03499 [pdf]
JHEP(2016)·119 citations
10
[Submitted on 11 Sept 2015] (cross-list from hep-ph)
Production of strange and charmed baryons in pion induced reactions
Sang-Ho Kim🇯🇵 · Atsushi Hosaka🇯🇵 · Hyun-Chul Kim🇯🇵 · Hiroyuki Noumi🇯🇵
We study the strangeness and charm productions induced by the pion beam, i.e. the $π^{-}$ p $\to$ $K^{* 0} Λ$ and $π^{-}$ p $\to$ $D^{*-} Λ_{c}^{+}$ reactions, based on two different theoretical frameworks: an effective Lagrangian method and a Regge approach. In order to estimate the magnitude of the charm production relative to that of the strangeness production, we assume that the coupling constants for the charmed meson and baryon vertices are the same as those for the strangeness channel. We found that the total cross section for the charm production was about $1 0^{3} - 1 0^{6}$ times smaller than that for the strangeness production, depending on theoretical approaches and kinematical regions. We also discuss each contribution to observables for both reactions. In general, the Regge approach explains the experimental data very well over the whole energy region.
Comments:
20 pages, 15 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1509.03567 [pdf]
PRD(2015)·33 citations

Affiliations

first authorsco-authorsvia INSPIRE