Nuclear Theory·nucl-th

Tuesday·February 20, 2018

7 papers—3 primary·4 cross-listed

04
[Submitted on 16 Feb 2018] (cross-list from hep-ph)
Rho-meson properties in medium
J. P. B. C. de Melo🇧🇷 · K. Tsushima (Laboratório de Física Teórica e Computacional, LFTC, UCS)🇧🇷
Properties of $ρ$ -meson in symmetric nuclear matter are investigated in a light-front constituent quark model (LFCQM), using the in-medium inputs calculated by the quark-meson coupling (QMC) model. The LFCQM used in this study was already applied for the studies of the electromagnetic properties of $ρ$ -meson in vacuum, namely, the charge~ $G_{0}$ , magnetic~ $G_{1}$ , and quadrupole~ $G_{2}$ form factors, electromagnetic charge radius, and electromagnetic decay constant. We predict that the electromagnetic decay constant, charge radius, and quadrupole moment are enhanced as increasing the nuclear matter density, while the magnetic moment is slightly quenched. Furthermore, we predict that the value $Q_{zero}^{2}$ , which crosses zero of the charge form factor, $G_{0} (Q_{zero}^{2}) = 0$ ( $Q^{2} = - q^{2} > 0$ with $q$ being the four-momentum transfer), decreases as increasing the nuclear matter density.
Comments:
21 pages, 17 figures eps. New calculations and improved substantially. To appear in Phys. Lett. B (2018)
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1802.06096 [pdf]
PLB(2019)·10 citations
05
[Submitted on 16 Feb 2018] (cross-list from hep-ph)
The small-x gluon distribution in centrality biased pA and pp collisions
Adrian Dumitru🇺🇸 · Gary Kapilevich🇺🇸 · Vladimir Skokov🇺🇸
The nuclear modification factor $R_{p A} (p_{T})$ provides information on the small- $x$ gluon distribution of a nucleus at hadron colliders. Several experiments have recently measured the nuclear modification factor not only in minimum bias but also for central $p A$ collisions. In this paper we analyze the bias on the configurations of soft gluon fields introduced by a centrality selection via the number of hard particles. Such bias can be viewed as reweighting of configurations of small- $x$ gluons. We find that the biased nuclear modification factor $Q_{p A} (p_{T})$ for central collisions is above $R_{p A} (p_{T})$ for minimum bias events, and that it may redevelop a "Cronin peak" even at small $x$ . The magnitude of the peak is predicted to increase approximately like $1/ A_{⊥}^{ν}$ , $ν \sim 0.6 \pm 0.1$ , if one is able to select more compact configurations of the projectile proton where its gluons occupy a smaller transverse area $A_{⊥}$ . We predict an enhanced $Q_{pp} (p_{T}) - 1 \sim 1/ (p_{T}^{2})^{ν}$ and a Cronin peak even for central $pp$ collisions.
Comments:
14 pages, 5 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1802.06111 [pdf]
NPA(2018)·11 citations
06
[Submitted on 19 Feb 2018] (cross-list from nucl-ex)
Acoustic scaling of linear and mode-coupled anisotropic flow; implications for precision extraction of the specific shear viscosity
Peifeng Liu🇺🇸 · Roy A. Lacey (SUNY Stony Brook Chemistry Dept & SUNY Stony Brook Physics Dept.)🇺🇸
The $n^{th}$ -order linear flow coefficients $v_{n}^{L} (n = 2, 3, 4, 5)$ , and the corresponding nonlinear mode-coupled ( $mc$ ) coefficients $v_{4, (2, 2)}^{mc}$ , $v_{5, (2, 3)}^{mc}$ , $v_{6, (3, 3)}^{mc}$ and $v_{6, (2, 2, 2)}^{mc}$ , are studied for Pb+Pb collisions at $s_{_{NN}} = 2.76$ TeV. Both sets of coefficients indicate a common acoustic scaling pattern of exponential viscous modulation, with a rate proportional to the square of the harmonic numbers and the mean transverse momenta (respectively), and inversely proportional to the cube root of the charged particle multiplicity ( $(N_{ch})^{1/3}$ ), that characterizes the dimensionless size of the systems produced in the collisions. These patterns and their associated scaling parameters, provide new stringent constraints for eccentricity independent estimates of the specific shear viscosity ( $η / s$ ) and the viscous correction to the thermal distribution function for the matter produced in the collisions. They also give crucial constraints for extraction of the initial-state eccentricity spectrum.
Comments:
5 pages, 4 figs., submitted for publication; Improved description of pT-dependent scaling in this version
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1802.06595 [pdf]
PRC(2018)·31 citations
07
[Submitted on 19 Feb 2018] (cross-list from hep-ph)
New class of compact stars: Pion stars
Bastian B. Brandt🇩🇪 · Gergely Endrodi🇩🇪 · Eduardo S. Fraga🇧🇷 · Mauricio Hippert🇧🇷 · Jurgen Schaffner-Bielich🇩🇪 · Sebastian Schmalzbauer🇩🇪
We investigate the viability of a new type of compact star whose main constituent is a Bose-Einstein condensate of charged pions. Several different setups are considered, where a gas of charged leptons and neutrinos is also present. The pionic equation of state is obtained from lattice QCD simulations in the presence of an isospin chemical potential, and requires no modeling of the nuclear force. The gravitationally bound configurations of these systems are found by solving the Tolman-Oppenheimer-Volkov equations. We discuss weak decays within the pion condensed phase and elaborate on the generation mechanism of such objects.
Comments:
8 pages, 5 figures. v2 includes discussion of weak processes in the condensed phase and effects of neutrinos. v3 fixed typos, minor changes, matches journal version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1802.06685 [pdf]
PRD(2018)·104 citations

Affiliations

first authorsco-authorsvia INSPIRE

Rho-meson properties in medium

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

Acoustic scaling of linear and mode-coupled anisotropic flow; implications for precision extraction of the specific shear viscosity

New class of compact stars: Pion stars

Affiliations