Nuclear Theory·nucl-th

Thursday·June 11, 2015

7 papers—3 primary·4 cross-listed

01
[Submitted on 10 Jun 2015]
Systematic analysis of hadron spectra in p+p collisions using Tsallis distribution
H. Zheng🇮🇹 · Lilin Zhu🇨🇳 · A. Bonasera🇮🇹
Using the experimental data from the STAR, PHENIX, ALICE and CMS programs on the rapidity and energy dependence of the $p_{T}$ spectra in p+p collisions, we show that a universal distribution exists. The energy dependence of temperature $T$ and parameter $n$ of the Tsallis distribution are also discussed in detail. A cascade particle production mechanism in p+p collisions is proposed.
Comments:
13 pages, 8 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1506.03156 [pdf]
PRD(2015)·59 citations
02
[Submitted on 10 Jun 2015]
Statistical features of the thermal neutron capture cross sections
M. S. Hussein🇧🇷 · B. V. Carlson🇧🇷 · A. K. Kerman🇺🇸
We discuss the existence of huge thermal neutron capture cross sections in several nuclei. The values of the cross sections are several orders of magnitude bigger than expected at these very low energies. We lend support to the idea that this phenomenon is random in nature and is similar to what we have learned from the study of parity violation in the actinide region. The idea of statistical doorways is advanced as a unified concept in the delineation of large numbers in the nuclear world. The average number of maxima per unit mass, $< n_{A} >$ in the capture cross section is calculated and related to the underlying cross section correlation function and found to be $< n_{A} >= 3/ (π 2 γ_{A})$ , where $γ_{A}$ is a characteristic mass correlation width which designates the degree of remnant coherence in the system. We trace this coherence to nucleosynthesis which produced the nuclei whose neutron capture cross sections are considered here.
Comments:
7 pages, 6 figures. To appear in Acta Physica Polonica B as a Contribution to the proceedings of:Jagiellonian Symposium of Fundamental and Applied Subatomic Physics, June 7- 12, 2015 Krakow, Poland
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1506.03246 [pdf]
Acta Phys.Polon.B(2016)·4 citations
03
[Submitted on 10 Jun 2015]
Baryon Number Fluctuations from a Crossover Equation of State Compared to Heavy-Ion Collision Measurements in the Beam Energy Range $s_{N N}$ = 7.7 to 200 GeV
M. Albright🇺🇸 · J. Kapusta🇺🇸 · C. Young🇺🇸
Fluctuations of the proton number distribution in central Au-Au collisions have been measured by the STAR collaboration in a beam energy scan at the Relativistic Heavy Ion Collider (RHIC). The motivation is a search for evidence of a critical point in the equation of state. It was found that the skewness and kurtosis display an interesting energy dependence. We compare these measurements to an equation of state which smoothly interpolates between an excluded volume hadron resonance gas at low energy density to a perturbative plasma of quarks and gluons at high energy density. This crossover equation of state agrees very well with the lattice QCD equation of state. The crossover equation of state can reproduce the data if the fluctuations are frozen at a temperature significantly lower than the average chemical freeze-out.
Comments:
17 pages, 10 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1506.03408 [pdf]
PRC(2015)·81 citations
04
[Submitted on 8 Jun 2015] (cross-list from hep-ph)
Correct Definition of the Gluon Distribution Function at High Energy Colliders
Gouranga C. Nayak🇺🇸
Unlike QED, since F_{\mu \nu}^a(x)F^{\mu \nu a}(0) in QCD contains cubic and quartic powers of the gluon field the present definition of the gluon distribution function at high energy colliders is not consistent with the number operator interpretation of the gluon. In this paper we derive the correct definition of the gluon distribution function at high energy colliders from first principles which is consistent with the number operator interpretation of the gluon and is gauge invariant and is consistent with the factorization theorem in QCD.
Comments:
32 pages latex. arXiv admin note: substantial text overlap with arXiv:1506.02593
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
1506.02651 [pdf]
24 citations
05
[Submitted on 10 Jun 2015] (cross-list from nucl-ex)
Elliptic and Triangular Flow of Identified Particles from the AMPT Model at RHIC Energies
Xu Sun🇨🇳 · Jianli Liu🇨🇳 · Alexander Schmah🇺🇸 · Shusu Shi🇨🇳 · Jingbo Zhang🇨🇳 · Lei Huo🇨🇳 · Hanzhi Jiang🇨🇳
The elliptic flow ( $v_{2}$ ) at $s_{NN} =$ 11.5, 39, and 200 GeV and triangular flow ( $v_{3}$ ) at $s_{NN} =$ 200 GeV of identified particles ( $π^{\pm}, K^{\pm}, K_{S}^{0}, p, p ˉ, ϕ, Λ$ and $Λ ˉ$ ) from 0\%--80\% central Au+Au collisions are analyzed using a multiphase transport (AMPT) model. It is shown that the experimental results from the $η$ -sub event plane method can be reproduced with a parton scattering cross section between 1.5 and 3 mb. We also studied the differential and integrated $v_{2} / v_{3}$ ratios and conclude that they are anti-corrected with the parton scattering cross section.
Comments:
7 pages, 7 figures
Subjects:
Nuclear Experiment (nucl-ex); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1506.03158 [pdf]
J.Phys.G(2015)·8 citations
06
[Submitted on 10 Jun 2015] (cross-list from hep-ph)
Quark production in heavy ion collisions I. Formalism and boost invariant fermionic light-cone mode functions
F. Gelis🇫🇷 · N. Tanji🇩🇪
We revisit the problem of quark production in high energy heavy ion collisions, at leading order in $α_{s}$ in the color glass condensate framework. In this first paper, we setup the formalism and express the quark spectrum in terms of a set of mode functions of the Dirac equation. We determine analytically their initial value in the Fock-Schwinger gauge on a proper time surface $Q_{s} τ_{0} ≪ 1$ , in a basis which makes manifest the boost invariance properties of this problem. We also describe a statistical algorithm to perform the sampling of the mode functions.
Comments:
40 pages, 3 figures, alternate derivation in the new appendix B
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1506.03327 [pdf]
JHEP(2016)·21 citations
07
[Submitted on 10 Jun 2015] (cross-list from hep-ph)
Dynamical coupled-channels model for neutrino-induced meson productions in resonance region
S. X. Nakamura (Osaka Univ.)🇯🇵 · H. Kamano (RCNP, Osaka Univ.)🇯🇵 · T. Sato (Osaka Univ.)🇯🇵
A dynamical coupled-channels (DCC) model for neutrino-nucleon reactions in the resonance region is developed. Starting from the DCC model that we have previously developed through an analysis of $π N, γ N \to π N, η N, K Λ, K Σ$ reaction data for $W \leq 2.1$ GeV, we extend the model of the vector current to $Q^{2} \leq$ 3.0 (GeV/ $c$ ) $^{2}$ by analyzing electron-induced reaction data for both proton and neutron targets. We derive axial-current matrix elements that are related to the $π N$ interactions of the DCC model through the Partially Conserved Axial Current (PCAC) relation. Consequently, the interference pattern between resonant and non-resonant amplitudes is uniquely determined. We calculate cross sections for neutrino-induced meson productions, and compare them with available data. Our result for the single-pion production reasonably agrees with the data. We also make a comparison with the double-pion production data. Our model is the first DCC model that can give the double-pion production cross sections in the resonance region. We also make comparison of our result with other existing models to reveal an importance of testing the models in the light of PCAC and electron reaction data. The DCC model developed here will be a useful input for constructing a neutrino-nucleus reaction model and a neutrino event generator for analyses of neutrino experiments.
Comments:
38 pages, 52 figures, published version; minor modifications on v1
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
1506.03403 [pdf]
PRD(2015)·119 citations

Affiliations

first authorsco-authorsvia INSPIRE

Systematic analysis of hadron spectra in p+p collisions using Tsallis distribution

Statistical features of the thermal neutron capture cross sections

Baryon Number Fluctuations from a Crossover Equation of State Compared to Heavy-Ion Collision Measurements in the Beam Energy Range sNN​​ = 7.7 to 200 GeV

Correct Definition of the Gluon Distribution Function at High Energy Colliders

Elliptic and Triangular Flow of Identified Particles from the AMPT Model at RHIC Energies

Quark production in heavy ion collisions I. Formalism and boost invariant fermionic light-cone mode functions

Dynamical coupled-channels model for neutrino-induced meson productions in resonance region

Affiliations

Baryon Number Fluctuations from a Crossover Equation of State Compared to Heavy-Ion Collision Measurements in the Beam Energy Range $s_{N N}$ = 7.7 to 200 GeV