Nuclear Theory·nucl-th

Wednesday·October 21, 2020

8 papers—4 primary·4 cross-listed

01
From high $p_{⊥}$ theory and data to inferring anisotropy of Quark-Gluon Plasma
Magdalena Djordjevic🇷🇸 · Stefan Stojku🇷🇸 · Dusan Zigic🇷🇸 · Bojana Ilic🇷🇸 · Jussi Auvinen🇷🇸 · Igor Salom🇷🇸 · Marko Djordjevic🇷🇸 · Pasi Huovinen🇷🇸
High $p_{⊥}$ theory and data are commonly used to study high $p_{⊥}$ parton interactions with QGP, while low $p_{⊥}$ data and corresponding models are employed to infer QGP bulk properties. On the other hand, with a proper description of high $p_{⊥}$ parton-medium interactions, high $p_{⊥}$ probes become also powerful tomography tools, since they are sensitive to global QGP features, such as different temperature profiles or initial conditions. This tomographic role of high $p_{⊥}$ probes can be utilized to assess the spatial anisotropy of the QCD matter. With our dynamical energy loss formalism, we show that a (modified) ratio of $R_{AA}$ and $v_{2}$ presents a reliable and robust observable for straightforward extraction of initial state anisotropy. We analytically estimated the proportionality between the $v_{2} / (1 - R_{AA})$ and anisotropy coefficient $ϵ_{2 L}$ , and found surprisingly good agreement with full-fledged numerical calculations. Within the current error bars, the extraction of the anisotropy from the existing data using this approach is still inaccessible. However, with the expected accuracy improvement in the upcoming LHC runs, the anisotropy of the QGP formed in heavy ion collisions can be straightforwardly derived from the data. Such a data-based anisotropy parameter would present an important test to models describing the initial stages of heavy-ion collision and formation of QGP, and demonstrate the usefulness of high $p_{⊥}$ theory and data in obtaining QGP properties.
nucl-thhep-phNPA(2021)·0 citations
02
Charge-dependent transverse momentum and its impact on the search for the chiral magnetic wave
Wen-Ya Wu🇨🇳 · Chun-Zheng Wang🇨🇳 · Qi-Ye Shou🇨🇳 · Yu-Gang Ma🇨🇳 · Liang Zheng🇨🇳
The chiral magnetic wave (CMW) is sought using the charge asymmetry ( $A_{ch}$ ) dependence of anisotropic flow in heavy-ion collisions. The charge dependent transverse momentum ( $p_{T}$ ), however, could play a role as a background. With the string fragmentation models, including PYTHIA, we demonstrate the origin of the $A_{ch} - p_{T}$ correlation and its connection with the local charge conservation (LCC). The impact of $A_{ch} - p_{T}$ and its behavior in varied kinematic windows are also discussed. This study provides more insights for the search for the CMW and comprehending the collective motion of the quark-gluon plasma.
nucl-thnucl-exPRC(2021)·10 citations
03
Total reaction cross section on a deuteron target and the eclipse effect of the constituent neutron and proton
W. Horiuchi · Y. Suzuki · T. Uesaka · M. Miwa
Background: Eclipse effect of the neutron and proton in a deuteron target is essential to correctly describe high-energy deuteron scattering. The nucleus-deuteron scattering needs information not only on the nucleus-proton but also the nucleus-neutron interaction, for which no direct measurement of the nucleus-neutron cross sections is available for unstable nuclei. Purpose: We systematically evaluated the total reaction cross sections by a deuteron target to explore the feasibility of extracting the nucleus-neutron interaction from measurable cross sections. Methods: High-energy nucleus-deuteron collision is described by the Glauber model, in which the proton and neutron configuration of the deuteron is explicitly taken into account. Results: Our calculation reproduces available experimental total reaction cross section data on the nucleus-deuteron scattering. The possibility of extracting the nucleus-neutron total reaction cross section from nucleus-deuteron and nucleus-proton total reaction cross sections is explored. The total reaction cross sections of a nucleus by proton, neutron, and deuteron targets can be expressed, to good accuracy, in terms of the nuclear matter radius and neutron skin thickness. Incident-energy dependence of the total reaction cross sections is examined. Conclusions: The total reaction cross section on a deuteron target includes information on both the nucleus-neutron and nucleus-proton profile functions. Measuring the cross sections by deuteron and proton targets is a promising tool to extract the nuclear size properties.
nucl-thnucl-exPRC(2020)·5 citations
04
Properties of heaviest nuclei with $98 \leq Z \leq 126$ and $134 \leq N \leq 192$
P. Jachimowicz🇵🇱 · M. Kowal🇵🇱 · J. Skalski🇵🇱
We systematically determine ground-state and saddle-point shapes and masses for 1305 heavy and superheavy nuclei with $Z = 98 - 126$ and $N = 134 - 192$ , including odd- $A$ and odd-odd systems. From these, we derive static fission barrier heights, one- and two-nucleon separation energies, and $Q_{α}$ values for g.s. to g.s transitions. Our study is performed within the microscopic-macroscopic method with the deformed Woods-Saxon single-particle potential and the Yukawa-plus-exponential macroscopic energy taken as the smooth part. We use parameters of the model that were fitted previously to masses of even-even heavy nuclei. For systems with odd numbers of protons, neutrons, or both, we use a standard BCS method with blocking. Ground-state shapes and energies are found by the minimization over seven axially-symmetric deformations. A search for saddle-points was performed by using the "imaginary water flow" method in three consecutive stages, using five- (for nonaxial shapes) and seven-dimensional (for reflection-asymmetric shapes) deformation spaces. The results are collected in two main tables. Calculated ground-state mass excess, nucleon separation- and $Q_{α}$ energies, total, macroscopic(normalized to the macroscopic energy at the spherical shape) and shell corrections energies, and deformations are given for each nucleus in \mbox{Table 1}. \mbox{Table 2} contains calculated properties of the saddle-point configurations and the fission barrier heights. In \mbox{Tables 3-7}, are given calculated ground-state, inner and outer saddle-point and superdeformed secondary minima characteristics for 75 actinide nuclei, from Ac to Cf, for which experimental estimates of fission barrier heights are known. These results are an additional test of our model.
nucl-thAtom.Data Nucl.Data Tabl.(2021)·67 citations
05
Solving relativistic three-body integral equations in the presence of bound states
Andrew W. Jackura🇺🇸 · Raúl A. Briceño🇺🇸 · Sebastian M. Dawid🇺🇸 · Md Habib E Islam🇺🇸 · Connor McCarty🇺🇸
We present a systematically improvable method for numerically solving relativistic three-body integral equations for the partial-wave projected amplitudes. The method consists of a discretization procedure in momentum space, which approximates the continuum problem with a matrix equation. It is solved for different matrix sizes, and in the end, an extrapolation is employed to restore the continuum limit. Our technique is tested by solving a three-body problem of scalar particles with an $S$ wave two-body bound state. We discuss two methods of incorporating the pole contribution in the integral equations, both of them leading to agreement with previous results obtained using finite-volume spectra of the same theory. We provide an analytic and numerical estimate of the systematic errors. Although we focus on kinematics below the three-particle threshold, we provide numerical evidence that the methods presented allow for determination of amplitude above this threshold as well.
↳ hep-lathep-phnucl-thPRD(2021)·61 citations
06
An integral-free representation of the Dyson series using divided differences
Amir Kalev🇺🇸 · Itay Hen🇺🇸
The Dyson series is an infinite sum of multi-dimensional time-ordered integrals, which serves as a formal representation of the quantum time-evolution operator in the interaction-picture. Using the mathematical tool of divided differences, we introduce an alternative representation for the series that is entirely free from both time ordering and integrals. In this new formalism, the Dyson expansion is given as a sum of efficiently-computable divided differences of the exponential function, considerably simplifying the calculation of the Dyson expansion terms, while also allowing for time-dependent perturbation calculations to be performed directly in the Schrödinger-picture. We showcase the utility of this novel representation by studying a number of use cases. We also discuss several immediate applications.
↳ quant-phcond-mat.stat-mechhep-thmath-ph+2New J.Phys.(2021)·12 citations
07
Signatures of $α$ clustering in $^{16}$ O by using a multiphase transport model
Yi-An Li🇨🇳 · Song Zhang🇨🇳 · Yu-Gang Ma🇨🇳
$α$ -clustered structures in light nuclei could be studied through "snapshots" taken by relativistic heavy-ion collisions. A multiphase transport (AMPT) model is employed to simulate the initial structure of collision nuclei and the proceeding collisions at center of mass energy $s_{N N}$ = 6.37 TeV. This initial structure can finally be reflected in the subsequent observations, such as elliptic flow ( $v_{2}$ ), triangular flow ( $v_{3}$ ) and quadrangular flow ( $v_{4}$ ). Three sets of the collision systems are chosen to illustrate system scan is a good way to identify the exotic $α$ -clustered nuclear structure, case I: $^{16} O$ nucleus (with or without $α$ -cluster) + ordinary nuclei (always in Woods-Saxon distribution) in most central collisions, case II: $^{16} O$ nucleus (with or without $α$ -cluster) + $^{197} Au$ nucleus collisions for centrality dependence, and case III: symmetric collision systems (namely, $^{10}$ B + $^{10}$ B, $^{12}$ C + $^{12}$ C, $^{16}$ O + $^{16}$ O (with or without $α$ -cluster), $^{20}$ Ne + $^{20}$ Ne, and $^{40}$ Ca + $^{40}$ Ca) in most central collisions. Our calculations propose that relativistic heavy-ion collision experiments at $s_{N N}$ = 6.37 TeV are promised to distinguish the tetrahedron structure of $^{16} O$ from the Woods-Saxon one and shed lights on the system scan projects in experiments.
↳ hep-phnucl-exnucl-thPRC(2020)·62 citations
08
Medium evolution of a static quark-antiquark pair in the large $N_{c}$ limit
Miguel Ángel Escobedo🇪🇸
We study the transitions between the different color states of a static quark-antiquark pair, singlet and octet, in a thermal medium. This is done non-perturbatively exploiting the infinite mass limit of QCD. This study is interesting because it can be used for future developments within the framework of Effective Field Theories (EFTs) and because it can be combined with other techniques, like lattice QCD or AdS/CFT, to gain non-perturbative information about the evolution of quarkonium in a medium. We also study the obtained expressions in the large $N_{c}$ limit. This allows us to learn lessons that are useful to simplify phenomenological models of quarkonium in a plasma.
↳ hep-phnucl-thPRD(2021)·13 citations

Affiliations

first authorsco-authorsvia INSPIRE