Nuclear Theory·nucl-th

Friday·August 9, 2019

13 papers—6 primary·7 cross-listed

01
[Submitted on 7 Aug 2019]
Chiral crossover characterized by Mott transition at finite temperature
Shijun Mao🇨🇳
We discuss the proper definition for the chiral crossover at finite temperature, based on the Goldstone's theorem. Different from the usually used maximum change of chiral condensate, we propose to define the crossover temperature by the Mott transition of pseudo-Goldstone bosons, which, by definition, guarantees the Goldstone's theorem. We analytically and numerically demonstrate this property in frame of a Pauli-Villars regularized NJL model. In external magnetic field, we find that the Mott transition temperature shows an inverse magnetic catalysis effect.
Comments:
6 pages, 2 figs, 2 tables
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Lattice (hep-lat)
arXiv:
1908.02851 [pdf]
CPC(2021)·18 citations
02
[Submitted on 8 Aug 2019]
Neutron skins of heavy nuclei and tidal deformability of neutron star
Bharat Kumar
In this paper, I have discussed the numerical predictions for the neutron-skin thickness (NST) of various finite nuclei starting from $^{40}$ Ca to $^{238}$ U using recently developed effective relativistic mean-field models G3 and IOPB-I \cite{G3, IOPB}. The calculated results are compared with the PREX-II data, and the experiment has been done with antiprotons at CERN. Further, I have also calculated the dimensional tidal deformability of a canonical neutron star 1.4 $M_{⊙}$ and compared it with the recent observation of GW1701817.
Comments:
Accepted; The 15th International Symposium on Origin of Matter and Evolution of Galaxies (OMEG15) at Kyoto University, Japan
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1908.02909 [pdf]
JPS Conf.Proc.(2020)·1 citation
03
[Submitted on 8 Aug 2019]
Viscous coefficients and thermal conductivity of a $π K N$ gas mixture in the medium
Pallavi Kalikotay🇮🇳 · Nilanjan Chaudhuri🇮🇳 · Snigdha Ghosh🇮🇳 · Utsab Gangopadhyaya🇮🇳 · Sourav Sarkar🇮🇳
The temperature and density dependence of the relaxation times, thermal conductivity, shear viscosity and bulk viscosity for a hot and dense gas consisting of pions, kaons and nucleons have been evaluated in the kinetic theory approach. The in-medium cross-sections for $π π$ , $π K$ and $π N$ scatterings were obtained by using complete propagators for the exchanged $ρ$ , $σ$ , $K^{*}$ and $Δ$ excitations derived using thermal field theoretic techniques. Notable deviations can be observed in the temperature dependence of $η$ , $ζ$ and $λ$ when compared with corresponding calculations using vacuum cross-sections usually employed in the literature. The value of the specific shear viscosity $η / s$ is found to be in agreement with available estimates.
Comments:
Version published in European Physical Journal A
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1908.02933 [pdf]
EPJA(2020)·7 citations
04
[Submitted on 8 Aug 2019]
Kinetic freeze-out in central heavy-ion collisions between 7.7 and 2760 GeV per nucleon pair
Ivan Melo🇸🇰 · Boris Tomasik🇸🇰
We fit the single-particle $p_{t}$ spectra of identified pions, kaons, and (anti)protons from central collisions of gold or lead nuclei at energies between 7.7 and 2760~GeV per nucleon pair. Blast wave model with included resonance production and with an assumption of partial chemical equilibrium is used and the fits are performed with the help of a Gaussian emulator process. A kinetic freeze-out temperature is found about 100~MeV for the lowest collision energies and 80~MeV at the LHC. The average transverse expansion velocity grows with increasing $s_{N N}$ from 0.45 to 0.65. Due to partial chemical equilibrium, the influence of resonance decays on the shape of the $p_{t}$ spectra for $s_{N N}$ above 27~GeV is small.
Comments:
21 pages, 12 figures, updated version with improved explanations in the text, results not changed, some figures from the previous version were split, therefore the new version includes more figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1908.03023 [pdf]
J.Phys.G(2020)·23 citations
05
[Submitted on 8 Aug 2019]
A first step in the nuclear inverse Kohn-Sham problem: from densities to potentials
G. Accorto · P. Brandolini · F. Marino · A. Porro · A. Scalesi · G. Colò · X. Roca-Maza · E. Vigezzi
Nuclear Density Functional Theory (DFT) plays a prominent role in the understanding of nuclear structure, being the approach with the widest range of applications. Hohenberg and Kohn theorems warrant the existence of a nuclear Energy Density Functional (EDF), yet its form is unknown. Current efforts to build a nuclear EDF are hindered by the lack of a strategy for systematic improvement. In this context, alternative approaches should be pursued and, so far, an unexplored avenue is that related to the inverse DFT problem. DFT is based on the one-to-one correspondence between Kohn-Sham (KS) potentials and densities. The exact EDF produces the exact density, so that from the knowledge of experimental or {\it ab initio} densities one may deduce useful information through reverse engineering. The idea has already been proven to be useful in the case of electronic systems. The general problem should be dealt with in steps, and the objective of the present work is to focus on testing algorithms to extract the Kohn-Sham potential within the simplest ansatz from the knowledge of the experimental neutron and proton densities. We conclude that while robust algorithms exist, the experimental densities present some critical aspects. Finally, we provide some perspectives for future works.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1908.03068 [pdf]
PRC(2020)·8 citations
06
[Submitted on 8 Aug 2019]
Sum Rule of Femtoscopic Correlation Function
Radoslaw Maj🇵🇱 · Stanislaw Mrowczynski🇵🇱
A correlation function of two particles with small relative velocities obeys a sum rule - the momentum integral of the function is determined due to the completeness of quantum states of the particles. The original sum rule derived in 1995 suffered from a serious problem: the momentum integral was ultraviolet divergent in physically interesting cases. We resolve the problem by considering the sum rule not of a single correlation function but of a sum or difference of two appropriately chosen correlation functions. The improved sum rule is shown to work well for the exact Coulomb correlation functions. We argue that the sum rule can be used to test an accuracy and range of applicability of correlation functions computed in approximate models. The neutron-proton correlation function is discussed as an example.
Comments:
9 pages, 8 figures, to appear in Phys. Rev. C
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1908.03178 [pdf]
PRC(2020)·5 citations
07
[Submitted on 7 Aug 2019] (cross-list from hep-th)
Fractionalized Degrees of Freedom at Infinite Coupling in large Nf QED in 2+1 dimensions
Paul Romatschke🇺🇸
I consider quantum electrodynamics with many electrons in 2+1 space-time dimensions at finite temperature. The relevant dimensionless interaction parameter for this theory is the fine structure constant divided by the temperature. The theory is solvable at any value of the coupling, in particular for very weak (high temperature) and infinitely strong coupling (corresponding to the zero temperature limit). Concentrating on the photon, each of its physical degrees of freedom at infinite coupling only contributes half of the free-theory value to the entropy. These fractional degrees of freedom are reminiscent of what has been observed in other strongly coupled systems (such as N=4 SYM), and bear similarity to the fractional Quantum Hall effect, potentially suggesting connections between these phenomena. The results found for QED3 are fully consistent with the expectations from particle-vortex duality.
Comments:
4 pages, no figures; v2: minor rewordings, typos corrected, matches published version
Subjects:
High Energy Physics — Theory (hep-th); Strongly Correlated Electrons (cond-mat.str-el); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1908.02758 [pdf]
PRL(2019)·9 citations
08
[Submitted on 7 Aug 2019] (cross-list from hep-ph)
Entropy production in pp and Pb-Pb collisions at energies available at the CERN Large Hadron Collider
Patrick Hanus🇩🇪 · Aleksas Mazeliauskas🇩🇪 · Klaus Reygers🇩🇪
We use experimentally measured identified particle spectra and Hanbury Brown-Twiss radii to determine the entropy per unit rapidity $d S / d y$ produced in $s = 7$ TeV pp and $s_{NN} = 2.76$ TeV Pb-Pb collisions. We find that $d S / d y = 11335 \pm 1188$ in 0-10% Pb-Pb, $d S / d y = 135.7 \pm 17.9$ in high-multiplicity pp, and $d S / d y = 37.8 \pm 3.7$ in minimum bias pp collisions and compare the corresponding entropy per charged particle $(d S / d y) / (d N_{ch} / d y)$ to predictions of statistical models. Finally, we use the QCD kinetic theory pre-equilibrium and viscous hydrodynamics to model entropy production in the collision and reconstruct the average temperature profile at $τ_{0} = 1$ fm/ $c$ for high multiplicity pp and Pb-Pb collisions.
Comments:
13 pages, 9 figures; added an appendix on relation between 1D and 3D HBT radii, updated references, small corrections, published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1908.02792 [pdf]
PRC(2019)·39 citations
09
[Submitted on 7 Aug 2019] (cross-list from hep-ph)
Hydrodynamic attractors, initial state energy and particle production in relativistic nuclear collisions
Giuliano Giacalone🇫🇷 · Aleksas Mazeliauskas🇩🇪 · Sören Schlichting🇩🇪
We exploit the concept of hydrodynamic attractors to establish a general relation between the initial state energy and the produced particle multiplicities in high-energy nuclear collisions. When combined with an ab initio model of energy deposition, the entropy production during the pre-equilibrium phase naturally explains the universal centrality dependence of the measured charged particle yields in nucleus-nucleus collisions. We further estimate the energy density of the far-from-equilibrium initial state and discuss how our results can be used to constrain non-equilibrium properties of the quark-gluon plasma.
Comments:
7 pages, 3 figures; v2: minor corrections, published version, plot scripts and data shown in figures are available at https://doi.org/10.4119/unibi/2939684 v3: included supplemental material
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1908.02866 [pdf]
PRL(2019)·125 citations
10
[Submitted on 8 Aug 2019] (cross-list from astro-ph.HE)
Influence of density dependence of symmetry energy in hot and dense matter for supernova simulations
Kohsuke Sumiyoshi · Ken'ichiro Nakazato · Hideyuki Suzuki · Jinniu Hu · Hong Shen
We study the influence of density-dependent symmetry energy at high densities in simulations of core-collapse supernovae, black hole formation and proto-neutron star cooling by extending the relativistic mean field (RMF) theory used for the Shen EOS table. We adopt the extended RMF theory to examine the density dependence of the symmetry energy with a small value of the slope parameter $L$ , while the original properties of the symmetric nuclear matter are unchanged. In order to assess matter effects at high densities, we perform numerical simulations of gravitational collapse of massive stars adopting the EOS table at high densities beyond $1 0^{14}$ g/cm $^{3}$ with the small $L$ value, which is in accord with the experimental and observational constraints, and compare them with the results obtained by using the Shen EOS. Numerical results for 11.2M $_{⊙}$ and 15M $_{⊙}$ stars exhibit minor effects around the core bounce and in the following evolution for 200 ms. Numerical results for 40M $_{⊙}$ and 50M $_{⊙}$ stars reveal a shorter duration toward the black hole formation with a smaller maximum mass for the small $L$ case. Numerical simulations of proto-neutron star cooling over 10 s through neutrino emissions demonstrate increasing effects of the symmetry energy at high densities. Neutrino cooling drastically proceeds in a relatively long timescale with high luminosities and average energies with the small symmetry energy. Evolution toward the cold neutron star is affected because of the different behavior of neutron-rich matter while supernova dynamics around core bounce remains similar in less neutron-rich environments.
Comments:
21 pages, 18 figures, revised version accepted for publication in ApJ
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
1908.02928 [pdf]
ApJ(2019)·35 citations
11
[Submitted on 8 Aug 2019] (cross-list from nucl-ex)
Recalibration of the binding energy of hypernuclei measured in emulsion experiments and its implications
Peng Liu · Jinhui Chen · Declan Keane · Zhangbu Xu · Yu-Gang Ma
The $Λ$ separation energy for $Λ$ -hypernuclei, denoted $B_{Λ}$ , measured in 1967, 1968, and 1973 are recalibrated using the current best mass estimates for particles and nuclei. The recalibrated $B_{Λ}$ are systematically larger (except in the case of $_{Λ}^{6}$ He) than the original published values by about 100 keV. The effect of this level of recalibration is very important for light hypernuclei, especially for the hypertriton. The early $B_{Λ}$ values measured in 1967, 1968, and 1973 are widely used in theoretical research, and the new results provide better constraints on the conclusions from such studies.
Comments:
To be published in Chinese Physics C
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1908.03134 [pdf]
CPC(2019)·15 citations
12
[Submitted on 8 Aug 2019] (cross-list from hep-lat)
QCD in the heavy dense regime for general $N_{c}$ : On the existence of quarkyonic matter
Owe Philipsen🇩🇪 · Jonas Scheunert🇩🇪
Lattice QCD with heavy quarks reduces to a three-dimensional effective theory of Polyakov loops, which is amenable to series expansion methods. We analyse the effective theory in the cold and dense regime for a general number of colours, $N_{c}$ . In particular, we investigate the transition from a hadron gas to baryon condensation. For any finite lattice spacing, we find the transition to become stronger, i.e. ultimately first-order, as $N_{c}$ is made large. Moreover, in the baryon condensed regime, we find the pressure to scale as $p \sim N_{c}$ through three orders in the hopping expansion. Such a phase differs from a hadron gas with $p \sim N_{c}^{0}$ , or a quark gluon plasma, $p \sim N_{c}^{2}$ , and was termed quarkyonic in the literature, since it shows both baryon-like and quark-like aspects. A lattice filling with baryon number shows a rapid and smooth transition from condensing baryons to a crystal of saturated quark matter, due to the Pauli principle, and is consistent with this picture. For continuum physics, the continuum limit needs to be taken before the large $N_{c}$ limit, which is not yet possible in practice. However, in the controlled range of lattice spacings and $N_{c}$ -values, our results are stable when the limits are approached in this order. We discuss possible implications for physical QCD.
Comments:
24 pages, 7 figures; one figure and one reference added, reworded abstract and conclusions, version accepted for publication
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1908.03136 [pdf]
JHEP(2019)·39 citations
13
[Submitted on 8 Aug 2019] (cross-list from astro-ph.IM)
Real-Time Detection of Gravitational Waves from Binary Neutron Stars using Artificial Neural Networks
Plamen G. Krastev (Harvard University)🇺🇸
The groundbreaking discoveries of gravitational waves from binary black-hole mergers and, most recently, coalescing neutron stars started a new era of Multi-Messenger Astrophysics and revolutionized our understanding of the Cosmos. Machine learning techniques such as artificial neural networks are already transforming many technological fields and have also proven successful in gravitational-wave astrophysics for detection and characterization of gravitational-wave signals from binary black holes. Here we use a deep-learning approach to rapidly identify transient gravitational-wave signals from binary neutron star mergers in noisy time series representative of typical gravitational-wave detector data. Specifically, we show that a deep convolution neural network trained on 100,000 data samples can rapidly identify binary neutron star gravitational-wave signals and distinguish them from noise and signals from merging black hole binaries. These results demonstrate the potential of artificial neural networks for real-time detection of gravitational-wave signals from binary neutron star mergers, which is critical for a prompt follow-up and detailed observation of the electromagnetic and astro-particle counterparts accompanying these important transients.
Comments:
6 pages, 4 figures, 1 table. Accepted for publication in Physics Letters B
Subjects:
Instrumentation and Methods for Astrophysics (astro-ph.IM); Solar and Stellar Astrophysics (astro-ph.SR); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
arXiv:
1908.03151 [pdf]
PLB(2020)·107 citations

Affiliations

first authorsco-authorsvia INSPIRE