Nuclear Theory·nucl-th

Tuesday·May 1, 2018

13 papers—7 primary·6 cross-listed

01
[Submitted on 27 Apr 2018]
Optimized Perturbation Theory Applied to a Model with Flavour Symmetry $S U_{f} (3)$
Juan C. Macías🇧🇷 · Marcus Benghi Pinto🇧🇷
The \textit{optimized perturbation theory} (OPT) is implemented in the $S U_{f} (3)$ flavor symmetric Nambu--Jona-Lasinio (NJL) model to generate non-pertubative corrections to the quark pressure beyond the large- $N$ approximation. The correctness of this implementation is verified by the recovery of the already known non-perturbative results in the Hartree-Fock approximation, and by having the large- $N$ approximation as a limiting case. This formalism is then used to revisit a discussion on the discordance between the lattice data and the two flavor model prediction of the dynamical vector repulsive interactions, beyond the pseudocritical temperature. It is shown that these contradictory predictions can be corrected by considering a three quark flavor system.
Comments:
5 pages, 3 figures, Poster presented at the XIV International Workshop on Hadron Physics, Florianópolis, Brazil, March 2018
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1804.10658 [pdf]
0 citations
02
[Submitted on 27 Apr 2018]
Signatures of thermalized charm quarks in all charged flow observables
Jacquelyn Noronha-Hostler🇺🇸 · Claudia Ratti🇺🇸
A long standing question in the field of heavy-ion collisions is whether charm quarks are thermalized within the Quark Gluon Plasma. In recent years, progress in lattice QCD simulations has led to reliable results for the equation of state of a system of 2+1 flavors (up, down, and strange) and 2+1+1 flavors (up, down, strange, and charm). We find that the equation of state strongly affects differential flow harmonics and a preference is seen for thermalized charm quarks at the LHC. Predictions are also made for the event-plane correlations at RHIC AuAu $s_{N N} = 200$ GeV collisions, and the scaling of differential flow observables and factorization breaking for all charged particles at LHC PbPb $s_{N N} = 5.02$ TeV collisions compared to LHC XeXe $s_{N N} = 5.44$ TeV collisions, which could be useful in answering the question: are charm quarks thermalized?
Comments:
19 pages, 12 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1804.10661 [pdf]
4 citations
03
[Submitted on 28 Apr 2018]
Studies of the structure of massive hybrid stars within a modified NJL model
Cheng-Ming Li🇨🇳 · Jin-Li Zhang🇨🇳 · Yan Yan🇨🇳 · Yong-Feng Huang🇨🇳 · Hong-Shi Zong🇨🇳
In this paper, we use the equation of state based on a modification of 2+1 flavors Nambu-Jona- Lasinio (NJL) model to study the quark matter of hybrid stars. For comparison, we utilize five EOSs of the relativistic mean-field (RMF) model to describe the hadronic phase. With the 3- window crossover interpolation approach, we try to construct relatively soft hybrid EOSs but find the maximum masses of hybrid stars do not differ too much. The results are quite close to two solar mass, which is consistent with the mass constraint of PSR J0348+0432. Furthermore it is noteworthy that the heaviest stable stars have central densities higher than that of the deconfinement transition thus suggesting a pure quark core in the hybrid star.
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
1804.10785 [pdf]
PRD(2018)·41 citations
04
[Submitted on 28 Apr 2018]
Distinct ground state features and the decay chains of Z = 121 Superheavy Nuclei
G. Saxena · U. K. Singh · M. Kumawat · M. Kaushik · S. K. Jain · Mamta Aggarwal
A fully systematic study of even and odd isotopes (281 $\leq$ A $\leq$ 380) of Z = 121 superheavy nuclei is presented in theoretical frameworks of Relativistic mean-field plus state dependent BCS approach and Macroscopic-Microscopic approach with triaxially deformed Nilson Strutinsky prescription. The ground state properties namely shell correction, binding energy, two- and one- proton and neutron separation energy, shape, deformation, density profile and the radius are estimated that show strong evidence for magicity in N = 164, 228. Central depletion in the charge density due to large repulsive Coulomb field indicating bubble-like structure is reported. A comprehensive analysis of the possible decay modes specifically $α$ -decay and spontaneous fission (SF) is presented and the probable $α$ -decay chains are evaluated. Results are compared with FRDM calculations and the available experimental data which show excellent agreement.
Comments:
Submitted to, 11 pages, 7 figures, European Physics Journal A, 2018
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1804.10830 [pdf]
IJMPE(2018)·8 citations
05
[Submitted on 28 Apr 2018]
Description of Nuclei with Magic Number Z(N) = 6
M. Kumawat · G. Saxena · M. Kaushik · R. Sharma · S. K. Jain
Encouraged with the evidence for Z = 6 magic number in neutron-rich carbon isotopes, we have performed relativistic mean-field plus BCS calculations to investigate ground state properties of entire chains of isotopes(isotones) with Z(N) = 6 including even and odd mass nuclei. Our calculations include deformation, binding energy, separation energy, single particle energy, rms radii along with charge and neutron density profile etc., and are found in an excellent match with latest experimental results demonstrating Z = 6 as a strong magic number. N = 6 is also found to own similar kind of strong magic character.
Comments:
Accepted, 7 pages, 7 figures, Canadian Journal of Physics, 2018
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1804.10833 [pdf]
Can.J.Phys.(2018)·4 citations
06
[Submitted on 29 Apr 2018]
Perspectives on Nuclear Structure and Scattering with the Ab Initio No-Core Shell Model
James P. Vary🇺🇸 · Pieter Maris🇺🇸 · Patrick J. Fasano🇺🇸 · Mark A. Caprio🇺🇸
Nuclear structure and reaction theory are undergoing a major renaissance with advances in many-body methods, strong interactions with greatly improved links to Quantum Chromodynamics (QCD), the advent of high performance computing, and improved computational algorithms. Predictive power, with well-quantified uncertainty, is emerging from non-perturbative approaches along with the potential for new discoveries such as predicting nuclear phenomena before they are measured. We present an overview of some recent developments and discuss challenges that lie ahead. Our focus is on explorations of alternative truncation schemes in the harmonic oscillator basis, of which our Japanese--United States collaborative work on the No-Core Monte-Carlo Shell Model is an example. Collaborations with Professor Takaharu Otsuka and his group have been instrumental in these developments.
Comments:
8 pages, 5 figures, accepted for publication in Proceedings of Perspectives of the Physics of Nuclear Structure, JPS Conference Proceedings, Japan (to appear)
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1804.10995 [pdf]
JPS Conf.Proc.(2018)·3 citations
07
[Submitted on 30 Apr 2018]
Z+jet correlation with NLO-matched parton-shower and jet-medium interaction in high-energy nuclear collisions
Shan-Liang Zhang🇨🇳 · Tan Luo🇨🇳 · Xin-Nian Wang🇨🇳 · Ben-Wei Zhang🇨🇳
The impact of jet quenching on $Z^{0}$ -tagged jets in relativistic heavy-ion collisions at the Large Hadron Collider (LHC) is investigated. We employ Sharpa Monte Carlo program that combines next-to-leading order matrix elements with matched resummation of parton shower to compute the initial $Z^{0}$ +jet production. The Linear Boltzmann Transport (LBT) model is then used to simulate the propagation, energy attenuation of and medium response induced by jet partons in the quark-gluon plasma. With both higher-order corrections and matched soft/collinear radiation as well as a sophisticated treatment of parton energy loss and medium response in LBT, our numerical calculations can provide the best description so far of all available observables of $Z^{0}$ +jet simultaneously in both p+p and Pb+Pb collisions, in particular, the shift of the distribution in transverse momentum asymmetry $x_{jZ} = p_{T}^{jet} / p_{T}^{Z}$ , the modification of azimuthal angle correlation in $Δ ϕ_{j Z} = ∣ ϕ_{jet} - ϕ_{Z} ∣$ and the overall suppression of average number of $Z^{0}$ -tagged jets per boson $R_{jZ}$ at $s = 5.02$ TeV as measured by the CMS experiment. We also show that higher-order corrections to $Z^{0}$ +jet production play an indispensable role in understanding $Z^{0}$ +jet azimuthal angle correlation at small and intermediate $Δ ϕ_{jZ}$ , and momentum imbalance at small $x_{jZ}$ . Jet quenching of the sub-leading jets is shown to lead to suppression of $Z^{0}$ +jet correlation at small azimuthal angle difference $Δ ϕ_{jZ}$ and at small $x_{jZ}$ .
Comments:
5 pages, 5 figures. Final version accepted for publication in Rapid Communication of PRC
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1804.11041 [pdf]
PRC(2018)·60 citations
08
[Submitted on 27 Apr 2018] (cross-list from hep-lat)
Color screening in (2+1)-flavor QCD
TUMQCD collaboration: Alexei Bazavov (1)🇺🇸 · Nora Brambilla (2,3)🇩🇪 · Peter Petreczky (4)🇺🇸 · Antonio Vairo (2)🇩🇪 · Johannes Heinrich Weber (1,2,5) ((1) Department of Computational Mathematics, Science and Engineering and Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, USA (2) Physik Department, Technische Universit ät München, D-85748 Garching, Germany (3) Institute of Advanced Studies, Technische Universität München, D-85748 Garching, Germany (4) Physics Department, Brookhaven National Laboratory, Upton, New York 11973, USA (5) Exzellenzcluster Universe, Technische Universität M ünchen, D-85748 Garching, Germany)🇩🇪
We study correlation functions of spatially separated static quark-antiquark pairs in (2+1)-flavor QCD in order to investigate onset and nature of color screening at high temperatures. We perform lattice calculations in a wide temperature range, $140 \leq T \leq 5814 MeV$ , using the highly improved staggered quark action and several lattice spacings to control discretization effects. By comparing at high temperatures our lattice results to weak-coupling calculations as well as to the zero temperature result for the energy of a static quark-antiquark pair, we observe that color screening sets in at $r T \approx 0.3$ . Furthermore, we also observe that in the range $0.3 ≲ r T ≲ 0.6$ weak-coupling calculations in the framework of suitable effective field theories provide an adequate picture of color screening.
Comments:
48 pages; 33 figures
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1804.10600 [pdf]
PRD(2018)·104 citations
09
[Submitted on 28 Apr 2018] (cross-list from hep-ph)
Isotopic Symmetry Breaking in the $η (1405) \to f_{0} (980) π^{0} \to π^{+} π^{-} π^{0}$ . Decay through a $K K ˉ$ Loop Diagram and the Role of Anomalous Landau Thresholds
N.N. Achasov🇷🇺 · G.N. Shestakov🇷🇺
Anomalous isotopic symmetry breaking in the $η (1405) \to f_{0} (980) π^{0} \to π^{+} π^{-} π^{0}$ decay through a mechanism featuring anomalous Landau thresholds in the form of logarithmic triangle singularities, i.e., through the $η (1405) \to (K^{*} K ˉ + K ˉ^{*} K) \to (K^{+} K^{-} + K^{0} K ˉ^{0}) π^{0} \to f_{0} (980) π^{0} \to π^{+} π^{-} π^{0}$ transition, has been analyzed. It has been shown that this effect can be correctly quantified only by taking into account the nonzero $K^{*}$ width. Different scales of isotopic symmetry breaking associated with the $K^{+} - K^{0}$ mass difference are compared.
Comments:
5 pages, 8 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
1804.10749 [pdf]
JETP Lett.(2018)·15 citations
10
[Submitted on 29 Apr 2018] (cross-list from hep-ph)
Predictions for azimuthal anisotropy in Xe+Xe collisions at $s_{N N}$ = 5.44 TeV using a multiphase transport model
Sushanta Tripathy🇮🇳 · Sudipan De🇮🇳 · Mohammed Younus🇮🇳 · Raghunath Sahoo🇮🇳
Xe+Xe collision at relativistic energies may provide us with a partonic system whose size is approximately in between those produced by p+p and Pb+Pb collisions. The experimental results on anisotropic flow in Xe+Xe and Pb+Pb collisions should provide us with an opportunity to study system size dependence of $v_{2}$ . In the present work, we have used AMPT transport model to calculate charged particles' $v_{2}$ for Xe+Xe collisions at $s_{N N}$ =5.44 TeV. We have also tried to demonstrate the no. of constituent quark, $N_{q}$ , and $m_{T}$ scaling of the elliptic flow. We find that $n_{q}$ scaling of $v_{2}$ is not observed for the identified hadrons. The $v_{2}$ results from Xe+Xe collisions have also been compared to Pb+Pb collisions at $s_{N N}$ = 5.02 TeV. We find that flow of charged particles in (50-60)\% central collisions for Xenon nuclei is almost 30\% less than particle flow developed in lead ion collisions, implying the important role the system size play in development of particle collective motion in relativistic heavy ion collisions.
Comments:
Same as the published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1804.10906 [pdf]
PRC(2018)·23 citations
11
[Submitted on 29 Apr 2018] (cross-list from math-ph)
Connection formulas between Coulomb wave functions
David Gaspard
The mathematical relations between the regular Coulomb function $F_{η ℓ} (ρ)$ and the irregular Coulomb functions $H_{η ℓ}^{\pm} (ρ)$ and $G_{η ℓ} (ρ)$ are obtained in the complex plane of the variables $η$ and $ρ$ for integer or half-integer values of $ℓ$ . These relations, referred to as "connection formulas", form the basis of the theory of Coulomb wave functions, and play an important role in many fields of physics, especially in the quantum theory of charged particle scattering. As a first step, the symmetry properties of the regular function $F_{η ℓ} (ρ)$ are studied, in particular under the transformation $ℓ \mapsto - ℓ - 1$ , by means of the modified Coulomb function $Φ_{η ℓ} (ρ)$ , which is entire in the dimensionless energy $η^{- 2}$ and the angular momentum $ℓ$ . Then, it is shown that, for integer or half-integer $ℓ$ , the irregular functions $H_{η ℓ}^{\pm} (ρ)$ and $G_{η ℓ} (ρ)$ can be expressed in terms of the derivatives of $Φ_{η, ℓ} (ρ)$ and $Φ_{η, - ℓ - 1} (ρ)$ with respect to $ℓ$ . As a consequence, the connection formulas directly lead to the description of the singular structures of $H_{η ℓ}^{\pm} (ρ)$ and $G_{η ℓ} (ρ)$ at complex energies in their whole Riemann surface. The analysis of the functions is supplemented by novel graphical representations in the complex plane of $η^{- 1}$ .
Comments:
24 pages, 4 figures, 39 references
Subjects:
Mathematical Physics (math-ph); math.MP (math.MP); Nuclear Theory (nucl-th)
arXiv:
1804.10976 [pdf]
J.Math.Phys.(2018)·18 citations
12
[Submitted on 30 Apr 2018] (cross-list from hep-ph)
Vector mesons as dynamical resonances in the Bethe-Salpeter framework
Richard Williams🇩🇪
We present the first dynamical calculation of the $ρ$ -meson as a resonance in the Dyson-Schwinger/Bethe-Salpeter framework by including explicit two-pion exchange in addition to the t-channel one-gluon exchange of rainbow-ladder in the interaction kernel. The width is determined from the imaginary part of the resonance pole and is generated by the singularity structure of the integrand, treated by means of suitable path deformations. We find the resonant mass and width to be $640$ MeV and $100$ MeV respectively, corresponding to a coupling constant $g_{ρ π π} = 5.7$ ; repulsive corrections beyond rainbow-ladder are known to bring these in alignment with experiment. Furthermore we present the dependence of these parameters on the pion mass and compare with results from lattice QCD.
Comments:
6 pages, 4 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1804.11161 [pdf]
PLB(2019)·51 citations
13
[Submitted on 30 Apr 2018] (cross-list from hep-ph)
General structure of gauge boson propagator and its spectra in a hot magnetized medium
Bithika Karmakar🇮🇳 · Aritra Bandyopadhyay🇧🇷 · Najmul Haque🇮🇳 · Munshi G Mustafa🇮🇳
Based on transversality condition of gauge boson self-energy we have systematically constructed the general structure of the gauge boson two-point functions using four linearly independent basis tensors in presence of a nontrivial background, i.e., hot magnetized material medium. The hard thermal loop approximation has been used for the heat bath to compute various form factors associated with the gauge boson's two point functions both in strong and weak field approximation. We have also analyzed the dispersion of a gauge boson (e.g., gluon) using the effective propagator both in strong and weak magnetic field approximation. The formalism is also applicable to QED. The presence of only thermal background leads to a longitudinal (plasmon) mode and a two-fold degenerate transverse mode. In presence of a hot magnetized background medium the degeneracy of the two transverse modes is lifted and one gets three quasiparticle modes. In weak field approximation one gets two transverse modes and one plasmon mode. On the other hand, in strong field approximation also one gets the three modes in Lowest Landau Level. The general structure of two-point function may be useful for computing the thermo-magnetic correction of various quantities associated with a gauge boson.
Comments:
39 pages, 7 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1804.11336 [pdf]
EPJC(2019)·49 citations

Affiliations

first authorsco-authorsvia INSPIRE