Nuclear Theory·nucl-th

Friday·August 9, 2019

13 papers—6 primary·7 cross-listed

07
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.
↳ hep-thcond-mat.str-elhep-latnucl-thPRL(2019)·9 citations
08
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.
↳ hep-phnucl-exnucl-thPRC(2019)·39 citations
09
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.
↳ hep-phnucl-exnucl-thPRL(2019)·125 citations
10
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.
↳ astro-ph.HEnucl-thApJ(2019)·35 citations
11
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.
↳ nucl-exnucl-thCPC(2019)·15 citations
12
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.
↳ hep-lathep-phnucl-thJHEP(2019)·39 citations
13
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.
↳ astro-ph.IMastro-ph.SRgr-qcnucl-thPLB(2020)·107 citations

Affiliations

first authorsco-authorsvia INSPIRE

Fractionalized Degrees of Freedom at Infinite Coupling in large Nf QED in 2+1 dimensions

Entropy production in pp and Pb-Pb collisions at energies available at the CERN Large Hadron Collider

Hydrodynamic attractors, initial state energy and particle production in relativistic nuclear collisions

Influence of density dependence of symmetry energy in hot and dense matter for supernova simulations

Recalibration of the binding energy of hypernuclei measured in emulsion experiments and its implications

QCD in the heavy dense regime for general Nc​: On the existence of quarkyonic matter

Real-Time Detection of Gravitational Waves from Binary Neutron Stars using Artificial Neural Networks

Affiliations

QCD in the heavy dense regime for general $N_{c}$ : On the existence of quarkyonic matter