Nuclear Theory·nucl-th

Monday·June 1, 2020

17 papers—7 primary·10 cross-listed

01
Light-nuclei production and search for the QCD critical point
Edward Shuryak🇺🇸 · Juan M. Torres-Rincon🇩🇪
We discuss the potential of light-nuclei measurement in heavy-ion collisions at intermediate energies for the search of the hypothetical QCD critical end-point. A previous proposal based on neutron density fluctuations has brought appealing experimental evidences of a maximum in a ratio involving tritons, protons and deuterons, $O_{tp d}$ . However these results are difficult to reconcile with the state-of-the-art statistical thermal model predictions. Based on the idea that the QCD critical point can lead to a substantial attraction among nucleons, we propose new ratios involving $^{4}$ He in which the maximum would be more evident. We argue that the experimental extraction is feasible by presenting actual measurements at low and high collision energies. We also illustrate the possible behavior of these ratios at intermediate energies applying the semiclassical method based on flucton paths using preliminary STAR data for $O_{tp d}$ .
nucl-thhep-phnucl-exEPJA(2020)·31 citations
02
Core swelling in spherical nuclei: An indication of the saturation of nuclear density
W. Horiuchi · T. Inakura
Background: Nuclear radius is one of the most important and basic properties of atomic nuclei and its evolution is closely related to the saturation of the nuclear density in the internal region but the systematics of the nuclear radii for the neutron-rich unstable nuclei is not well known. Purpose: Motivated by the recent interaction cross section measurement which indicates the 48Ca core swelling in the neutron-rich Ca isotopes, we explore the mechanism of the enhancement of the neutron and proton radii for spherical nuclei. Methods: Microscopic Hartree-Fock calculations with three sets of Skyrme-type effective interactions are performed for the neutron-rich Ca, Ni and Sn isotopes. The total reaction cross sections for the Ca isotopes are evaluated with the Glauber model to compare them with the recent cross section data. Results: We obtain good agreement with the measured cross sections and charge radii. The neutron and proton radii of the various "core" configurations are extracted from the full Hartree-Fock calculation and discuss the core swelling mechanism. Conclusions: The core swelling phenomena occur depending on the properties of the occupying valence single-neutron states to minimize the energy loss that comes from the saturation of the densities in the internal region, which appears to be prominent in light nuclei such as Ca isotopes.
nucl-thPRC(2020)·17 citations
03
Few-body systems consisting of mesons
A. Martinez Torres🇧🇷 · K. P. Khemchandani🇧🇷 · L. Roca🇪🇸 · E. Oset🇪🇸
We present a work which is meant to inspire the few-body practitioners to venture into the study of new, more exotic, systems and to hadron physicists, working mostly on two-body problems, to move in the direction of studying related few-body systems. For this purpose we devote the discussions in the introduction to show how the input two-body amplitudes can be easily obtained using techniques of the chiral unitary theory, or its extensions to the heavy quark sector. We then briefly explain how these amplitudes can be used to solve the Faddeev equations or a simpler version obtained by treating the three-body scattering as that of a particle on a fixed center. Further, we give some examples of the results obtained by studying systems involving mesons. We have also addressed the field of many meson systems, which is currently almost unexplored, but for which we envisage a bright future. Finally, we give a complete list of works dealing with unconventional few-body systems involving one or several mesons, summarizing in this way the findings on the topic, and providing a motivation for those willing to investigate such systems.
nucl-thhep-phFew Body Syst.(2020)·49 citations
04
Neutron star equation of state and tidal deformability with nuclear energy density functionals
Young-Min Kim🇰🇷 · Kyujin Kwak🇰🇷 · Chang Ho Hyun🇰🇷 · Hana Gil🇰🇷 · Chang-Hwan Lee🇰🇷
Neutron star is the ultimate testing place for the physics of dense nuclear matter. Before the detection of gravitational waves from the merger of binary neutron stars, various nuclear equations of state have been used to estimate the macroscopic properties of neutron stars, such as masses and radii, based on the electromagnetic observations. However, recent observations on the tidal deformability of neutron star from the gravitational waves GW170817 opened a new era of multi-messenger astronomy and astrophysics, and many theoretical works have been extended to estimate the tidal deformability of neutron stars. In this article, we review our recent works on the application of nuclear energy density functionals to the properties of neutron stars including tidal deformability. We found that many nuclear energy density functionals, including new KIDS (Korea: IBS-Daegu-Sungkyunkwan) model, satisfy both constraints from current electromagnetic and gravitational wave observations. We discuss future possibilities of constraining nuclear matter equation of state from ground-based experiments and multi-messenger observations.
nucl-thEPJA(2020)·4 citations
05
Speed of sound and quark confinement inside neutron stars
Michał Marczenko🇵🇱
Several observations of high-mass neutron stars (NSs), as well as the first historic detection of the binary neutron star merger GW170817, have delivered stringent constraints on the equation of state (EoS) of cold and dense matter. Recent studies suggest that, in order to simultaneously accommodate a $2 M_{⊙}$ NS and the upper limit on the compactness, the pressure has to swiftly increase with density and the corresponding speed of sound likely exceeds the conformal limit. In this work, we employ a unified description of hadron-quark matter, the hybrid quark-meson-nucleon (QMN) model, to investigate the EoS under NS conditions. We show that the dynamical confining mechanism of the model plays an important role in explaining the observed properties of NSs.
nucl-thEur.Phys.J.ST(2020)·22 citations
06
Accurate nuclear symmetry energy at finite temperature within a BHF approach
Jia-Jing Lu · Fan Li · Zeng-Hua Li · Chong-Yang Chen · G. F. Burgio · H.-J. Schulze
We compute the free energy of asymmetric nuclear matter in a Brueckner-Hartree-Fock approach at finite temperature, paying particular attention to the dependence on isospin asymmetry. The first- and second-order symmetry energies are determined as functions of density and temperature and useful parametrizations are provided. We find small deviations from the quadratic isospin dependence and very small corresponding effects on (proto)neutron star structure.
nucl-thPRC(2021)·11 citations
07
Running the gamut of high energy nuclear collisions
Bjoern Schenke🇺🇸 · Chun Shen🇺🇸 · Prithwish Tribedy🇺🇸
We present calculations of bulk properties and multiparticle correlations in a large variety of collision systems within a hybrid formalism consisting of IP-Glasma initial conditions, MUSIC viscous relativistic hydrodynamics, and UrQMD microscopic hadronic transport. In particular, we study heavy ion collisions at the Large Hadron Collider (LHC), including Pb+Pb, Xe+Xe, and O+O collisions, and Au+Au, U+U, Ru+Ru, Zr+Zr, and O+O collisions at the Relativistic Heavy Ion Collider (RHIC). We further study asymmetric systems, including p+Au, d+Au, $^{3}$ He+Au, and p+Pb collisions at various energies as well as p+p collisions at 0.5 and 13 TeV. We describe experimental observables in all heavy ion systems well with one fixed set of parameters, validating the energy and system dependence of the framework. Many observables in the smaller systems are also well described, although they test the limits of the model. Calculations of O+O collisions provide predictions for potential future runs at RHIC and LHC.
nucl-thhep-phnucl-exPRC(2020)·225 citations
08
Transport in strongly coupled quark matter
Carlos Hoyos🇪🇸 · Niko Jokela🇫🇮 · Matti Jarvinen🇮🇱 · Javier G. Subils🇪🇸 · Javier Tarrio🇫🇮 · Aleksi Vuorinen🇫🇮
Motivated by the possible presence of deconfined quark matter in neutron stars and their mergers and the important role of transport phenomena in these systems, we perform the first-ever systematic study of different viscosities and conductivities of dense quark matter using the gauge/gravity duality. Utilizing the V-QCD model, we arrive at results that are in qualitative disagreement with the predictions of perturbation theory, which highlights the differing transport properties of the system at weak and strong coupling and calls for caution in the use of the perturbative results in neutron-star applications.
↳ hep-thastro-ph.HEhep-phnucl-thPRL(2020)·42 citations
09
The landscape of disk outflows from black hole - neutron star mergers
Rodrigo Fernández · Francois Foucart · Jonas Lippuner
We investigate mass ejection from accretion disks formed in mergers of black holes (BHs) and neutron stars (NSs). The third observing run of the LIGO/Virgo interferometers provided BH-NS candidate events that yielded no electromagnetic (EM) counterparts. The broad range of disk configurations expected from BH-NS mergers motivates a thorough exploration of parameter space to improve EM signal predictions. Here we conduct 27 high-resolution, axisymmetric, long-term hydrodynamic simulations of the viscous evolution of BH accretion disks that include neutrino emission/absorption effects and post-processing with a nuclear reaction network. In the absence of magnetic fields, these simulations provide a lower-limit to the fraction of the initial disk mass ejected. We find a nearly linear inverse dependence of this fraction on disk compactness (BH mass over initial disk radius). The dependence is related to the fraction of the disk mass accreted before the outflow is launched, which depends on the disk position relative to the innermost stable circular orbit. We also characterize a trend of decreasing ejected fraction and decreasing lanthanide/actinide content with increasing disk mass at fixed BH mass. This trend results from a longer time to reach weak freezout and an increasingly dominant role of neutrino absorption at higher disk masses. We estimate the radioactive luminosity from the disk outflow alone available to power kilonovae over the range of configurations studied, finding a spread of two orders of magnitude. For most of the BH-NS parameter space, the disk outflow contribution is well below the kilonova mass upper limits for GW190814.
↳ astro-ph.HEastro-ph.SRgr-qcnucl-thMNRAS(2020)·74 citations
10
The Drell-Yan process with pions and polarized nucleons
S. Bastami🇺🇸 · L. Gamberg🇺🇸 · B. Parsamyan🇮🇹 · B. Pasquini🇮🇹 · A. Prokudin🇺🇸 · P. Schweitzer🇺🇸
The Drell-Yan process provides important information on the internal structure of hadrons including transverse momentum dependent parton distribution functions (TMDs). In this work we present calculations for all leading twist structure functions describing the pion induced Drell-Yan process. The non-perturbative input for the TMDs is taken from the light-front constituent quark model, the spectator model, and available parametrizations of TMDs extracted from the experimental data. TMD evolution is implemented at Next-to-Leading Logarithmic precision for the first time for all asymmetries. Our results are compatible with the first experimental information, help to interpret the data from ongoing experiments, and will allow one to quantitatively assess the models in future when more precise data will become available.
↳ hep-phhep-exnucl-thJHEP(2021)·25 citations
11
Unitarization Technics in Hadron Physics with Historical Remarks
J. A. Oller🇪🇸
We review a series of unitarization techniques that have been used during the last decades, many of them in connection with the advent and development of current algebra and later of Chiral Perturbation Theory. Several methods are discussed like the generalized effective-range expansion, K-matrix approach, Inverse Amplitude Method, Padé approximants and the N/D method. More details are given for the latter though. We also consider how to implement them in order to correct by final-state interactions. In connection with this some other methods are also introduced like the expansion of the inverse of the form factor, the Omnés solution, generalization to coupled channels and the Khuri-Treiman formalism, among others.
↳ hep-phnucl-thSymmetry(2020)·51 citations
12
Impact of off-shell dynamics on the transport properties and the dynamical evolution of Charm Quarks at RHIC and LHC temperatures
Maria Lucia Sambataro (1 and 2)🇮🇹 · Salvatore Plumari (1 and 2)🇮🇹 · Vincenzo Greco (1 and 2) ((1) Department of Physics and Astronomy 'E. Majorana', University of Catania, (2) Laboratori Nazionali del Sud, INFN-LNS)🇮🇹
We evaluate drag and diffusion transport coefficients comparing a quasi-particle approximation with on-shell constituents of the QGP medium and a dynamical quasi-particles model with off-shell bulk medium at finite temperature T. We study the effects of the width $γ$ of the particles of the bulk medium on the charm quark transport properties exploring the range where $γ < M_{q, g}$ . We find that off-shell effects are in general quite moderate and can induce a reduction of the drag coefficient at low momenta that disappear already at moderate momenta, $p ≳ 2 - 3 GeV$ . We also observe a moderate reduction of the breaking of the Fluctuation-Dissipation theorem (FDT) at finite momenta. Moreover, we have performed a first study of the dynamical evolution of HQ elastic energy loss in a bulk medium at fixed temperature extending the Boltzmann (BM) collision integral to include off-shell dynamics. A comparison among the Langevin dynamics, the BM collisional integral with on-shell and the BM extension to off-shell dynamics shows that the evolution of charm energy when off-shell effects are included remain quite similar to the case of the on-shell BM collision integral.
↳ hep-phnucl-thEPJC(2020)·22 citations
13
Re-evaluation of the $^{22}$ Ne( $α, γ$ ) $^{26}$ Mg and $^{22}$ Ne( $α, n$ ) $^{25}$ Mg reaction rates
Philip Adsley🇫🇷 · Umberto Battino🇬🇧 · Andreas Best🇮🇹 · Antonio Caciolli🇮🇹 · Alessandra Guglielmetti🇮🇹 · Gianluca Imbriani🇮🇹 · Heshani Jayatissa🇺🇸 · Marco La Cognata🇮🇹 · Livio Lamia🇮🇹 · Eliana Masha🇮🇹 · Cristian Massimi🇮🇹 · Sara Palmerini🇮🇹 · Ashley Tattersall🇬🇧 · Raphael Hirschi🇬🇧
The competing $^{22}$ Ne( $α, γ$ ) $^{26}$ Mg and $^{22}$ Ne( $α, n$ ) $^{25}$ Mg reactions control the production of neutrons for the weak $s$ -process in massive and AGB stars. In both systems, the ratio between the corresponding reaction rates strongly impacts the total neutron budget and strongly influences the final nucleosynthesis. The $^{22}$ Ne( $α, γ$ ) $^{26}$ Mg and $^{22}$ Ne( $α, n$ ) $^{25}$ Mg reaction rates was re-evaluated by using newly available information on $^{26}$ Mg given by various recent experimental studies. Evaluations of The evaluated $^{22}$ Ne( $α, γ$ ) $^{26}$ Mg reaction rate remains substantially similar to that of Longland {\it et al.} but, including recent results from Texas A\&M, the $^{22}$ Ne( $α, n$ ) $^{25}$ Mg reaction rate is lower at a range of astrophysically important temperatures. Stellar models computed with NEWTON and MESA predict decreased production of the weak branch $s$ -process due to the decreased efficiency of $^{22}$ Ne as a neutron source. Using the new reaction rates in the MESA model results in $^{96}$ Zr/ $^{94}$ Zr and $^{135}$ Ba/ $^{136}$ Ba ratios in much better agreement with the measured ratios from presolar SiC grains.
↳ nucl-exastro-ph.SRnucl-thPRC(2021)·48 citations
14
Energy dependence of the optical potential of the weakly bound 9Be projectile on the 197Au target
F. Gollana🇦🇷 · D. Abriola🇦🇷 · A. Arazia🇦🇷 · M. A. Cardonaa🇦🇷 · E. de Barbara🇦🇷 · D. Hojmana🇦🇷 · R.M. Id Betan🇦🇷 · G.V. Marti🇦🇷 · A.J. Pacheco🇦🇷 · D. Rodriguesa🇦🇷 · M. Togneri🇦🇷
In this work we measured elastic and inelastic angular distributions of the weakly bound 9Be projectile on the 197Au target at several bombarding energies from 84% up to 140% of the Coulomb barrier. The elastic angular distributions were analyzed using a phenomenological Woods-Saxon potential and a double folding Sao Paulo potential and the energy dependence was extracted. Angular distributions from two inelastic peaks were compared with coupled channel calculations using reduced transition probabilities available in the literature. The energy dependence of the two interaction potential models show a similar trend in the region of the Coulomb barrier. Dispersion relation calculation demonstrates the presence of the breakup threshold anomaly proposed for weakly bound systems.
↳ nucl-exnucl-thNPA(2020)·17 citations
15
Helicity-dependent extension of the McLerran-Venugopalan model
Florian Cougoulic🇺🇸 · Yuri V. Kovchegov🇺🇸
We construct a generalization of the McLerran-Venugopalan (MV) model including helicity effects for a longitudinally polarized target (a proton or a large nucleus). The extended MV model can serve as the initial condition for the helicity generalization of the JIMWLK evolution equation constructed in our previous paper, as well as for calculation of helicity-dependent observables in the quasi-classical approximation to QCD.
↳ hep-phhep-exnucl-exnucl-thNPA(2020)·55 citations
16
Sensitivity of $^{44}$ Ti and $^{56}$ Ni production in CCSN shock-driven nucleosynthesis to reaction rates
Shiv K. Subedi · Zach Meisel · Grant Merz
Recent observational advances have enabled high resolution mapping of $^{44}$ Ti in core-collapse supernova (CCSN) remnants. Comparisons between observations and models provide stringent constraints on the CCSN mechanism. However, past work has identified several uncertain nuclear reaction rates that influence $^{44}$ Ti and $^{56}$ Ni production in post-processing model calculations. We evolved one dimensional models of $15 M_{⊙}$ , $18 M_{⊙}$ , $22 M_{⊙}$ and $25 M_{⊙}$ stars from zero-age main sequence through CCSN using {\tt MESA} (Modules for Experiments in Stellar Astrophysics) and investigated the previously identified reaction rate sensitivities of $^{44}$ Ti and $^{56}$ Ni production. We tested the robustness of our results by making various assumptions about the CCSN explosion energy and mass-cut. We found a number of reactions that have a significant impact on the nucleosynthesis of $^{44}$ Ti and $^{56}$ Ni, particularly for lower progenitor masses. Notably, the reaction rates $^{13} N (α, p)^{16} O$ , $^{17} F (α, p)^{20} Ne$ , $^{52} Fe (α, p)^{55} Co$ , $^{56} Ni (α, p)^{59} Cu$ , $^{57} Ni (n, p)^{57} Co$ , $^{56} Co (p, n)^{56} Ni$ , $^{39} K (p, γ)^{40} Ca$ , $^{47} V (p, γ)^{48} Cr$ , $^{52} Mn (p, γ)^{53} Fe$ , $^{57} Co (p, γ)^{58} Ni$ , and $^{39} K (p, α)^{36} Ar$ are influential for a large number of model conditions. Furthermore, we found the list of influential reactions identified by previous post-processing studies of CCSN shock-driven nucleosynthesis is likely incomplete, motivating future larger-scale sensitivity studies.
↳ astro-ph.HEastro-ph.SRnucl-exnucl-thApJ(2020)·14 citations
17
Probing short-range correlations in the deuteron via incoherent diffractive $J / ψ$ production with spectator tagging at the EIC
Zhoudunming Tu🇺🇸 · Alexander Jentsch🇺🇸 · Mark Baker · Liang Zheng🇨🇳 · Jeong-Hun Lee🇺🇸 · Raju Venugopalan🇺🇸 · Or Hen🇺🇸 · Douglas Higinbotham🇺🇸 · Elke-Caroline Aschenauer🇺🇸 · Thomas Ullrich🇺🇸
Understanding the role of Quantum Chromodynamics in generating nuclear forces is important for uncovering the mechanism of short-ranged nuclear interactions and their manifestation in short range correlations (SRC). The future Electron-Ion-Collider (EIC) at Brookhaven National Laboratory in the US will provide an unprecedented opportunity to systematically investigate the underlying physics of SRC for energies and kinematic regions that are otherwise impossible to reach. We study SRCs in electron-deuteron scattering events using the Monte Carlo event generator BeAGLE. Specifically, we investigate the sensitivity of observables to high internal nucleon momentum in incoherent diffractive $J / ψ$ vector meson production. In a plane wave impulse approximation, the initial state deuteron wavefunction can be accessed directly from the four-momentum of the spectator nucleon. We use realistic physics simulations and far-forward detector simulations of the EIC to fully reveal the physics potential of this exclusive process. In particular, we provide the luminosity and detector requirements necessary to study SRCs in the deuteron at an EIC.
↳ nucl-exhep-exhep-phnucl-thPLB(2020)·40 citations

Affiliations

first authorsco-authorsvia INSPIRE