Nuclear Theory·nucl-th

Wednesday·February 24, 2021

15 papers—8 primary·7 cross-listed

01
Determining the jet transport coefficient $q^$ from inclusive hadron suppression measurements using Bayesian parameter estimation
S. Cao🇺🇸 · Y. Chen🇺🇸 · J. Coleman🇺🇸 · J. Mulligan🇺🇸 · P. M. Jacobs🇺🇸 · R. A. Soltz🇺🇸 · A. Angerami🇺🇸 · R. Arora🇺🇸 · S. A. Bass🇺🇸 · L. Cunqueiro🇺🇸 · T. Dai🇺🇸 · L. Du🇺🇸 and 35 other authors
We report a new determination of $q^$ , the jet transport coefficient of the Quark-Gluon Plasma. We use the JETSCAPE framework, which incorporates a novel multi-stage theoretical approach to in-medium jet evolution and Bayesian inference for parameter extraction. The calculations, based on the MATTER and LBT jet quenching models, are compared to experimental measurements of inclusive hadron suppression in Au+Au collisions at RHIC and Pb+Pb collisions at the LHC. The correlation of experimental systematic uncertainties is accounted for in the parameter extraction. The functional dependence of $q^$ on jet energy or virtuality and medium temperature is based on a perturbative picture of in-medium scattering, with components reflecting the different regimes of applicability of MATTER and LBT. In the multi-stage approach, the switch between MATTER and LBT is governed by a virtuality scale $Q_{0}$ . Comparison of the posterior model predictions to the RHIC and LHC hadron suppression data shows reasonable agreement, with moderate tension in limited regions of phase space. The distribution of $q^/ T^{3}$ extracted from the posterior distributions exhibits weak dependence on jet momentum and medium temperature $T$ , with 90\% Credible Region (CR) depending on the specific choice of model configuration. The choice of MATTER+LBT, with switching at virtuality $Q_{0}$ , has 90\% CR of $2 < q^/ T^{3} < 4$ for $p_{T}^{jet} > 40$ GeV/c. The value of $Q_{0}$ , determined here for the first time, is in the range 2.0-2.7 GeV.
nucl-thhep-phnucl-exPRC(2021)·196 citations
02
$β$ -Delayed Neutron and Fission Calculations with Relativistic QRPA and Statistical Model
Futoshi Minato · Tomislav Marketin · Nils Paar
A role of \beta-delayed neutron emission and fission in r-process nucleosynthesis attracts a high interest. Although the number of study on them covering r-process nuclei is increasing recently, uncertainties of \beta-delayed neutron and fission are still large for r-process simulations. Our purpose is to make a new database on \beta-delayed neutron emission and fission rates. To this end, the data that are not investigated experimentally have to be predicted. Microscopic theoretical approaches based on a nuclear energy density functional and statistical models are one of the competent tools for the prediction. To obtain \beta strength function, p-n relativistic QRPA is adopted. Particle evaporations and fission from nuclear highly excited states are estimated by the Hauser-Feshbach statistical model. \beta-delayed neutron branching ratios (P_n) are calculated and compared with experimental data. \beta-delayed fission branching ratio (P_f) are also assessed by using four different fission barrier data. Calculated P_n values are in a good agreement with experimental data. It is found that energy withdrawal by \beta-delayed neutron emission sensitively varies P_n values for nuclei near the neutron drip line. P_f are sensitively dependent on fission barrier data. Newly calculated data on \beta-delayed neutron emission and fission are summarized as a table in supplement material. They are provided for studies of r-process as well as other fields such as nuclear engineering.
nucl-thnucl-ex0 citations
03
Effects of ground-state correlations on damping of giant dipole resonaces in $L S$ closed shell nuclei
Mitsuru Tohyama
The effects of ground-state correlations on the damping of isovector giant dipole resonances in $L S$ closed shell nuclei $^{16}$ O and $^{40}$ Ca are studied using extended random-phase-approximation (RPA) approaches derived from the time-dependent density-matrix theory. It is pointed out that unconventional two-body amplitudes of one particle--three hole and three particle--one hole types which are neglected in most extended RPA theories play an important role in the fragmentation of isovector dipole strength.
nucl-thPTEP(2022)·2 citations
04
$K_{1} / K^{*}$ enhancement as a signature of chiral symmetry restoration in heavy ion collisions
Haesom Sung🇰🇷 · Sungtae Cho🇰🇷 · Juhee Hong🇰🇷 · Su Houng Lee🇰🇷 · Sanghoon Lim🇰🇷 · Taesoo Song🇩🇪
Based on the fact that the mass difference between the chiral partners is an order parameter of chiral phase transition and that the chiral order parameter reduces substantially at the chemical freeze-out point in ultra-relativistic heavy ion collisions, we argue that the production ratio of $K_{1}$ over $K^{*}$ in such collisions should be substantially larger than that predicted in the statistical hadronization model. We further show that while the enhancement effect might be contaminated by the relatively larger decrease of $K_{1}$ meson than $K^{*}$ meson during the hadronic phase, the signal will be visible through a systematic study on centrality as the kinetic freeze-out temperature is higher and the hadronic life time shorter in peripheral collisions than in central collisions.
nucl-thhep-phnucl-exPLB(2021)·13 citations
05
alpha clustering and neutron-skin thickness of carbon isotopes
Q. Zhao🇯🇵 · Y. Suzuki🇯🇵 · J. He🇯🇵 · B. Zhou🇯🇵 · M. Kimura🇯🇵
The interplay between the formation of neutron skin and alpha cluster at the dilute surface of neutron-rich nuclei is one of the interesting subjects in the study of neutron-rich nuclei and nuclear clustering. A theoretical model has predicted that the growth of neutron skin will prevent the alpha clustering at the nuclear surface. Quite recently, this theoretical perspective; the suppression of alpha clustering by the neutron-skin formation was first confirmed experimentally in Sn isotopes as the reduction of the (p, p alpha) reaction cross-section. Motivated by the novel discovery, in this work, we have investigated the relationship between the neutron-skin thickness and alpha clustering in C isotopes. Based on the analysis by the antisymmetrized molecular dynamics, we show that the alpha spectroscopic factor at nuclear exterior decreases in neutron-rich C isotopes, and the clustering suppression looks correlated with the growth of the neutron-skin thickness.
nucl-thnucl-exEPJA(2021)·17 citations
06
Bjorken flow attractors with transverse dynamics
Victor E. Ambrus🇩🇪 · Sergiu Busuioc🇬🇧 · Jan A. Fotakis🇩🇪 · Kai Gallmeister🇩🇪 · Carsten Greiner🇩🇪
In the context of the longitudinally boost-invariant Bjorken flow with transverse expansion, we use three different numerical methods to analyze the emergence of attractor solutions in an ideal gas of massless particles exhibiting constant shear viscosity to entropy density ratio $η / s$ . The fluid energy density is initialized using a Gaussian profile in the transverse plane, while the ratio $χ = P_{L} / P_{T}$ between the longitudinal and transverse pressures is set at initial time $τ_{0}$ to a constant value $χ_{0}$ throughout the system employing the Romatschke-Strickland distribution. We introduce the hydrodynamization time $δ τ_{H} = (τ_{H} - τ_{0}) / τ_{0}$ based on the time $τ_{H}$ when the standard deviation $σ (χ)$ of a family of solutions with different $χ_{0}$ reaches a minimum value at the point of maximum convergence of the solutions. In the $0 + 1 D$ setup, $δ τ_{H}$ exhibits scale invariance, being a function only of $(η / s) / (τ_{0} T_{0})$ . With transverse expansion, we find a similar $δ τ_{H}$ computed with respect to the local initial temperature, $T_{0} (r)$ . We highlight the transition between the regimes where the longitudinal and transverse expansions dominate. We find that the hydrodynamization time required for the attractor solution to be reached increases with the distance from the origin, as expected based on the properties of the $0 + 1 D$ system defined by the local initial conditions. We argue that hydrodynamization is predominantly the effect of the longitudinal expansion, being significantly influenced by the transverse dynamics only for small systems or for large values of $η / s$ .
nucl-thhep-phphysics.flu-dynPRD(2021)·34 citations
07
Newly Evaluated Neutron Reaction Data on Chromium Isotopes
G.P.A. Nobre🇺🇸 · M.T. Pigni🇺🇸 · D.A. Brown🇺🇸 · R. Capote🇦🇹 · A. Trkov🇸🇮 · K.H. Guber🇺🇸 · R. Arcilla🇺🇸 · J. Gutierrez🇺🇸 · A. Cuadra🇺🇸 · G. Arbanas🇺🇸 · B. Kos🇸🇮 · D. Bernard🇫🇷 · P. Leconte🇫🇷
Neutron reaction data for the set of major chromium isotopes were reevaluated from the thermal energy range up to 20 MeV. In the low energy region, updates to the thermal values together with an improved $R$ -matrix analysis of the resonance parameters characterizing the cluster of large $s$ -wave resonances for $^{50, 53}$ Cr isotopes were performed. In the intermediate and high energy range up to 20 MeV, the evaluation methodology used statistical nuclear reaction models implemented in the EMPIRE code within the Hauser-Feshbach framework to evaluate the reaction cross sections and angular distributions. Exceptionally, experimental data were used to evaluate relevant cross sections above the resonance region up to 5 MeV in the major $^{52}$ Cr isotope. Evaluations were benchmarked with Monte Carlo simulations of a small suite of critical assemblies highly sensitive to Chromium data, and with the Oktavian shielding benchmark to judge deep penetration performance with a 14-MeV D-T neutron source. A significant improvement in performance is demonstrated compared to existing evaluations.
nucl-thnucl-exNucl.Data Sheets(2021)·10 citations
08
Beam-normal single-spin asymmetry in elastic scattering of electrons from a spin-0 nucleus
Oleksandr Koshchii🇩🇪 · Mikhail Gorchtein🇩🇪 · Xavier Roca-Maza🇮🇹 · Hubert Spiesberger🇩🇪
We study the beam-normal single-spin asymmetry (BNSSA) in high-energy elastic electron scattering from several spin-0 nuclei. Existing theoretical approaches work in the plane-wave formalism and predict the BNSSA to scale as $\sim A / Z$ with the atomic number $Z$ and nuclear mass number $A$ . While this prediction holds for light and intermediate nuclei, a striking disagreement in both the sign and the magnitude of BNSSA was observed by the PREX collaboration for $^{208}$ Pb, coined the "PREX puzzle". To shed light on this disagreement, we go beyond the plane-wave approach which neglects Coulomb distortions known to be significant for heavy nuclei. We explicitly investigate the dependence of BNSSA on $A$ and $Z$ by i) including inelastic intermediate states' contributions into the Coulomb problem in the form of an optical potential, ii) by accounting for the experimental information on the $A$ -dependence of the Compton slope parameter, and iii) giving a thorough account of the uncertainties of the calculation. Despite of these improvements, the PREX puzzle remains unexplained. We discuss further strategies to resolve this riddle.
nucl-thhep-phnucl-exPRC(2021)·15 citations
09
Supernova neutrino signals based on long-term axisymmetric simulations
Hiroki Nagakura🇺🇸 · Adam Burrows🇺🇸 · David Vartanyan🇺🇸
We study theoretical neutrino signals from core-collapse supernova (CCSN) computed using axisymmetric CCSN simulations that cover the post-bounce phase up to $\sim 4$ ~s. We provide basic quantities of the neutrino signals such as event rates, energy spectra, and cumulative number of events at some terrestrial neutrino detectors, and then discuss some new features in the late phase that emerge in our models. Contrary to popular belief, neutrino emissions in the late phase are not always steady, but rather have temporal fluctuations, the vigor of which hinges on the CCSN model and neutrino flavor. We find that such temporal variations are not primarily driven by proto-neutron star (PNS) convection, but by fallback accretion in exploding models. We assess the detectability of these temporal variations, and find that IceCube is the most promising detector with which to resolve them. We also update fitting formulae first proposed in our previous paper for which the total neutrino energy (TONE) emitted at the CCSN source is estimated from the cumulative number of events in each detector. This will be a powerful technique with which to analyze real observations, particularly for low-statistics data.
↳ astro-ph.HEhep-exhep-thnucl-ex+1MNRAS(2021)·53 citations
10
On systems of maximal quantum chaos
Mike Blake🇬🇧 · Hong Liu🇺🇸
A remarkable feature of chaos in many-body quantum systems is the existence of a bound on the quantum Lyapunov exponent. An important question is to understand what is special about maximally chaotic systems which saturate this bound. Here we provide further evidence for the `hydrodynamic' origin of chaos in such systems, and discuss hallmarks of maximally chaotic systems. We first provide evidence that a hydrodynamic effective field theory of chaos we previously proposed should be understood as a theory of maximally chaotic systems. We then emphasize and make explicit a signature of maximal chaos which was only implicit in prior literature, namely the suppression of exponential growth in commutator squares of generic few-body operators. We provide a general argument for this suppression within our chaos effective field theory, and illustrate it using SYK models and holographic systems. We speculate that this suppression indicates that the nature of operator scrambling in maximally chaotic systems is fundamentally different to scrambling in non-maximally chaotic systems. We also discuss a simplest scenario for the existence of a maximally chaotic regime at sufficiently large distances even for non-maximally chaotic systems.
↳ hep-thcond-mat.str-elnlin.CDnucl-th+1JHEP(2021)·51 citations
11
Deconfinement Phase Transition in the $S U (3)$ Instanton-dyon Ensemble
Dallas DeMartini🇺🇸 · Edward Shuryak🇺🇸
Confinement remains one the most interesting and challenging nonperturbative phenomenon in non-Abelian gauge theories. Recent semiclassical (for SU(2)) and lattice (for QCD) studies have suggested that confinement arises from interactions of statistical ensembles of instanton-dyons with the Polyakov loop. In this work, we extend studies of semiclassical ensemble of dyons to the $S U (3)$ Yang-Mills theory. We find that such interactions do generate the expected first-order deconfinement phase transition. The properties of the ensemble, including correlations and topological susceptibility, are studied over a range of temperatures above and below $T_{c}$ . Additionally, the dyon ensemble is studied in the Yang-Mills theory containing an extra trace-deformation term. It is shown that such a term can cause the theory to remain confined and even retain the same topological observables at high temperatures.
↳ hep-phnucl-thPRD(2021)·9 citations
12
High-precision determination of the electric and magnetic radius of the proton
Yong-Hui Lin🇩🇪 · Hans-Werner Hammer🇩🇪 · Ulf-G. Meißner🇩🇪
Using dispersion theory with an improved description of the two-pion continuum based on the precise Roy-Steiner analysis of pion-nucleon scattering, we analyze recent data from electron-proton scattering. This allows for a high-precision determination of the electric and magnetic radius of the proton, $r_{E} = (0.83 8_{- 0.004}^{+ 0.005}_{- 0.003}^{+ 0.004})$ fm and $r_{M} = (0.847 \pm 0.004 \pm 0.004)$ fm, where the first error refers to the fitting procedure using bootstrap and the data while the second one refers to the systematic uncertainty related to the underlying spectral functions.
↳ hep-phhep-exhep-latnucl-ex+1PLB(2021)·49 citations
13
Anomalous Hall instability in the Chern-Simons magnetohydrodynamics
M. Kiamari🇮🇷 · M. Rahbardar🇮🇷 · M. Shokri🇮🇷 · N. Sadooghi🇮🇷
The Chern-Simons magnetohydrodynamics (CSMHD) is introduced using a Maxwell-Chern-Simons (MCS) Lagrangian including an axion-like field $Θ$ . The MCS equation of motion derived from this Lagrangian consists of a modified current, including a chiral magnetic (CM) and an anomalous Hall (AH) current, in addition to the ordinary Ohm current of resistive magnetohydrodynamics (MHD). The former consists of an axial chemical potential, which is given in terms of the temporal comoving derivative of $Θ$ , and the latter arises from the spatial gradient of $Θ$ . As it turns out, the existence of the axial chemical potential is a nonequilibrium effect that plays no role in the linear stability analysis, whereas the AH current arises as in the first-order linear perturbation of the thermal equilibrium. We analyze the linear stability and causality of the CSMHD in a resistive and chiral medium. We show that the Alfven modes propagating sufficiently close to the direction of the magnetic field are unstable but causal. They are also accompanied by a genuine nonhydro mode. A stable mode in a particular direction can correspond to an unstable mode propagating in the exact opposite direction. The AH instability is a manifestation of a breakdown of the parity. A numerical analysis of the phase velocity confirms these results.
↳ hep-thcond-mat.str-elhep-phnucl-thPRD(2021)·6 citations
14
Revealing the structure of light pseudoscalar mesons at the Electron-Ion Collider
John Arrington🇺🇸 · Carlos Ayerbe Gayoso🇺🇸 · Patrick C Barry🇺🇸 · Vladimir Berdnikov🇺🇸 · Daniele Binosi🇮🇹 · Lei Chang🇨🇳 · Markus Diefenthaler🇺🇸 · Minghui Ding🇮🇹 · Rolf Ent🇺🇸 · Tobias Frederico🇧🇷 · Yulia Furletova🇺🇸 · Tim J Hobbs🇺🇸 and 20 other authors
How the bulk of the Universe's visible mass emerges and how it is manifest in the existence and properties of hadrons are profound questions that probe into the heart of strongly interacting matter. Paradoxically, the lightest pseudoscalar mesons appear to be the key to the further understanding of the emergent mass and structure mechanisms. These mesons, namely the pion and kaon, are the Nambu-Goldstone boson modes of QCD. Unravelling their partonic structure and the interplay between emergent and Higgs-boson mass mechanisms is a common goal of three interdependent approaches -- continuum QCD phenomenology, lattice-regularised QCD, and the global analysis of parton distributions -- linked to experimental measurements of hadron structure. Experimentally, the foreseen electron-ion collider will enable a revolution in our ability to study pion and kaon structure, accessed by scattering from the "meson cloud" of the proton through the Sullivan process. With the goal of enabling a suite of measurements that can address these questions, we examine key reactions to identify the critical detector system requirements needed to map tagged pion and kaon cross sections over a wide range of kinematics. The excellent prospects for extracting pion structure function and form factor data are shown, and similar prospects for kaon structure are discussed in the context of a worldwide programme. Successful completion of the programme outlined herein will deliver deep, far-reaching insights into the emergence of pions and kaons, their properties, and their role as QCD's Goldstone boson modes.
↳ nucl-exhep-phnucl-thJ.Phys.G(2021)·134 citations
15
Phenomenological study of the anisotropic quark matter in the 2-flavor Nambu-Jona-Lasinio model
He-Xia Zhang🇨🇳 · Yu-Xin Xiao🇨🇳 · Jin-Wen Kang🇨🇳 · Ben-Wei Zhang🇨🇳
With the two flavor Nambu-Jona-Lasinio (NJL) model we carry out a phenomenological study on the chiral phase structure, mesonic properties and transport properties in a momentum-space anisotropic quark matter. To calculate transport coefficients we have utilized the kinetic theory in the relaxation time approximation, where the momentum anisotropy is embedded in the estimation of both distribution function and the relaxation time. It is shown that an increase of the anisotropy parameter $ξ$ may results in a catalysis of chiral symmetry breaking. The critical endpoint (CEP) is shifted to smaller temperatures and larger quark chemical potentials as $ξ$ increases, the impact of momentum anisotropy on temperature of CEP is almost the same as that on the quark chemical potential of CEP. The meson masses and the associated decay widths also exhibit a significant $ξ$ dependence. It is observed that the temperature behavior of scaled shear viscosity $η / T^{3}$ and scaled electrical conductivity $σ_{e l} / T$ exhibit a similar dip structure, with the minima of both $η / T^{3}$ and $σ_{e l} / T$ shifting toward higher temperatures with increasing $ξ$ . Furthermore, we demonstrate that the Seebeck coefficient $S$ decreases when temperature goes up and its sign is positive, indicating the dominant carriers for converting the temperature gradient to the electric field are up-quarks. The Seebeck coefficient $S$ is significantly enhanced with a large $ξ$ for the temperature below the critical temperature.
↳ hep-phnucl-thNucl.Sci.Tech.(2022)·19 citations

Affiliations

first authorsco-authorsvia INSPIRE