Nuclear Theory·nucl-th

Thursday·May 18, 2023

11 papers—5 primary·6 cross-listed

01
[Submitted on 17 May 2023]
Experimental nuclear charge density and theoretical description of the above-barrier light heavy-ion fusion process
I. I. Gontchar · M. V. Chushnyakova
Theoretical modeling of nucleus-nucleus collision often is based on the nucleus-nucleus potential. One of the advanced methods for constructing this potential is the semi-microscopical double-folding model with the M3Y-Paris NN-forces. Proton and neutron densities are significant ingredient of this model. Correct nucleon density (ND) must reproduce experimental nuclear charge density (NCD). We consider several versions of NDs available in the literature and construct our own approximation for the ND of even-even spherical nuclei 12C, 16O, 40Ca which is abbreviated as FE-density (Fermi+exponential). We carefully compare the NCDs resulting from different versions of NDs with the experimental NCSs. After finding the nucleus-nucleus potential using the double-folding model with the density dependent M3Y-Paris NN-forces and FE densities we evaluate the above-barrier fusion cross sections for five reactions, 12C+12C, 12C+16O, 16O+16O, 16O+40Ca, and 40Ca+40Ca, where the experimental data are available. The cross sections are calculated using two approaches: a) the barrier penetration model and b) the Trajectory Model with surface friction (TM). To find the transmission coefficients for TM, the Langevin equations are employed. For all considered reactions, our TM typically reproduces the above-barrier experimental cross sections within 10-15%. The only adjustable parameter of the model, the optimal friction strength K_Rm, was found to be about 90 zs/GeV for light reactions 12C+12C, 12C+16O, 16O+16O and about 15 zs/GeV for heavier reactions 16O+40Ca and 40Ca+40Ca. The latter findings are in reasonable agreement with the systematics found earlier. Thus, the FE-recipe allows reproducing simultaneously with good accuracy both the charge nucleon density and the above-barrier fusion cross sections for five reactions involving 12C, 16O, 40Ca nuclei.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2305.09915 [pdf]
CPC(2023)·2 citations
02
[Submitted on 17 May 2023]
Machine learning study to identify collective flow in small and large colliding systems
Shuang Guo🇨🇳 · Han-Sheng Wang🇨🇳 · Kai Zhou🇩🇪 · Guo-Liang Ma🇨🇳
Collective flow has been found to be similar between small colliding systems ( $p$ $+$ $p$ and $p$ $+$ A collisions) and large colliding systems (peripheral A $+$ A collisions) at the CERN Large Hadron Collider. In order to study the differences of collective flow between small and large colliding systems, we employ a point cloud network to identify $p$ $+$ Pb collisions and peripheral Pb $+$ Pb collisions at $s_{N N} =$ 5.02 TeV generated from a multiphase transport model (AMPT). After removing the discrepancies in the pseudorapidity distribution and the $p_{T}$ spectra, we capture the discrepancy in collective flow. Although the verification accuracy of our PCN is limited due to similar event-by-event distributions of elliptic and triangular flow, we demonstrate that collective flow between $p$ $+$ Pb collisions and peripheral Pb $+$ Pb collisions becomes more distinct with increasing final hadron multiplicity and parton scattering cross section. This study not only highlights the potential of PCN techniques in advancing the understanding of collective flow in varying colliding systems, but more importantly lays the groundwork for the future PCN-related research.
Comments:
10 pages, 11 figures, final published version
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2305.09937 [pdf]
PRC(2024)·10 citations
03
[Submitted on 17 May 2023]
Effect of the Coriolis force on the electrical conductivity of quark matter: A nonrelativistic description
Ashutosh Dwibedi🇮🇳 · Cho Win Aung🇮🇳 · Jayanta Dey🇮🇳 · Sabyasachi Ghosh🇮🇳
Rotating quarks and hadronic systems, produced in peripheral heavy ion collisions, can experience Coriolis force and other forces due to rotational motion. Considering only the effect of Coriolis force, we have calculated the electrical conductivity for non-relativistic rotating matter using the Relaxation Time Approximation based Boltzmann transport equation. A similarity in mathematical calculations of electrical conductivity at finite rotation and finite magnetic fields is exposed, where an equivalence role between Coriolis force on massive particle's motion and Lorentz force on charged particle's motion is noticed. As the beginning level step, we consider only the Coriolis force in the non-relativistic formalism, which will be extended in the future towards the relativistic case, and to adopt other forces for a more realistic description of the rotating quark and hadronic system.
Comments:
10 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th); Statistical Mechanics (cond-mat.stat-mech); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2305.10183 [pdf]
PRC(2024)·11 citations
04
[Submitted on 17 May 2023]
Truncated Partial-Wave Analysis for $η$ -photoproduction observables via Bayesian Statistics
Philipp Kroenert🇩🇪 · Yannick Wunderlich🇩🇪 · Farah Afzal🇩🇪 · Annika Thiel🇩🇪
A truncated partial-wave analysis is performed for $η$ -photoproduction using the polarization observables $σ_{0}, Σ, T, E, F$ and $G$ . Different truncation orders are analyzed for six energy bins within the range of $E_{γ}^{l ab} \in [750, 1250]$ MeV. Bayesian statistics is combined with truncated partial-wave analysis for the first time to investigate the structure of emerging ambiguities and their relevance in comparison to each other. Marginal distributions for the electromagnetic multipole parameters are presented together with predictions for polarization observables which have not yet been measured, in order to determine promising future measurements able to remove remaining mathematical ambiguities.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2305.10367 [pdf]
PRC(2024)·8 citations
05
[Submitted on 17 May 2023]
Baryon diffusion coefficient of the strongly interacting medium
Tribhuban Parida🇮🇳 · Sandeep Chatterjee🇮🇳
We propose that the transverse momentum ( $p_{T}$ ) differential splitting of directed flow ( $Δ v_{1}$ ) between proton and anti-proton can serve as a sensitive observable to extract the baryon diffusion coefficient ( $κ_{B}$ ) of the hot and dense strongly interacting matter produced in relativistic heavy ion collisions. We use relativistic dissipative hydrodynamics framework with Glauber model based initial condition for the energy as well as baryon deposition that is calibrated to capture the rapidity dependence of charged particle multiplicity, net proton yield as well as the elusive $v_{1}$ splitting between proton and anti-proton. We employ the commonly used kinetic theory motivated ansatz: $κ_{B} = C_{B} \frac{n _{B}}{T} (\frac{1}{3} coth (\frac{μ _{B}}{T}) - \frac{n _{B} T}{ϵ + P})$ where $n_{B}$ , $ϵ$ , $P$ , $T$ and $μ_{B}$ are baryon number density, energy density, pressure, temperature and baryon chemical potential respectively while $C_{B}$ is an arbitrary constant which is largely unknown for the Quantum Chromodynamics (QCD) medium. We find that the variation of $Δ v_{1}$ with $p_{T}$ is strongly influenced by the choice of $C_{B}$ . Further, we find that the recent STAR measurement of the centrality dependence of the rapidity slope of $Δ v_{1}$ prefers $0.5 < C_{B} < 1.5$ .
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2305.10371 [pdf]
8 citations
06
[Submitted on 16 May 2023] (cross-list from hep-ph)
The deuteron charge radıus $r_{c}$ in the framework of the hard-wall AdS/QCD model
Shahin Mamedov🇦🇿 · Narmin Akbarova🇦🇿 · Minaya Allahverdiyeva🇦🇿
We study the deuteron charge radius in the framework of a hard-wall AdS/QCD model. We present basic elements of the hard-wall model and write metrics for the AdS space. We introduce a vector field with twist $τ = 6$ describing deuteron in the bulk of AdS space and other vector fields to describe photon respectively, write an effective action for the bulk fields interactions, find a $G_{1} (Q^{2})$ , $G_{2} (Q^{2})$ and $G_{3} (Q^{2})$ form factors, then quadrupole $G_{Q} (Q^{2})$ and charge $G_{C} (Q^{2})$ form-factors of a deuteron. Thus, from the charge $G_{C} (Q^{2})$ form factor we find the deuteron charge radius $R_{C}$ in the framework of a hard-wall AdS/QCD model. Then we compare our result with the results soft-wall model and experimental data.
Comments:
5 pages, 1 table, AYSS-2022 Conference
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2305.09704 [pdf]
Phys.Part.Nucl.Lett.(2023)·1 citation
07
[Submitted on 16 May 2023] (cross-list from hep-ph)
Towards Double Parton Distributions from First Principles using Large Momentum Effective Theory
Max Jaarsma🇳🇱 · Rudi Rahn🇳🇱 · Wouter J. Waalewijn🇳🇱
In double parton scattering (DPS), two partonic collisions take place between one pair of colliding hadrons. The effect of DPS can be significant for precision measurements due to the additional radiation from secondary partonic collisions, and especially for specific processes such as same-sign WW production. Its effect is usually included through Monte Carlo parton showers. In a factorization approach to DPS, the initial state is described by double parton distributions (DPDs). These are currently poorly constrained by experiment, but provide a view on interesting correlations between partons in the hadron. Here we show that the Large Momentum Effective Theory approach can be applied to DPDs. Specifically, we present a general matching relation between DPDs and lattice-calculable quasi-DPDs for general flavor, spin and color structures. We furthermore calculate the one-loop matching coefficients for the quark-quark DPDs, verifying that the infrared logarithms and divergences cancel in the matching. While we restrict to the flavor-non-singlet case, we do take color and spin correlations into account. Interestingly, quasi-DPDs combines nontrivial features from both the collinear and transverse momentum dependent quasi-parton distribution functions. This represents a first step in extending the quasi-PDF approach to DPDs, opening up a new way to constrain these distributions using lattice QCD.
Comments:
33 pages plus appendices, 3 figures, 1 table, v2: journal version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
2305.09716 [pdf]
JHEP(2023)·20 citations
08
[Submitted on 16 May 2023] (cross-list from gr-qc)
The non-relativistic limit of first-order relativistic viscous fluids
Abhishek Hegade K R · Justin L. Ripley · Nicolás Yunes
Out-of-equilibrium effects may play an important role in the dynamics of neutron star mergers and in heavy-ion collisions. Bemfica, Disconzi, Noronha and Kovtun (BDNK) recently derived a causal, locally well-posed, and modally stable relativistic fluid model that incorporates the effects of viscosity and heat diffusion. We study the non-relativistic limit of this fluid model and show that causality for relativistic motion restricts the transport coefficients in the non-relativistic limit. This restriction provides an upper bound on the ratio of the shear viscosity to the entropy density for fluids that can be described as relativistic within the BDNK model and can be exactly modeled using the Navier-Stokes equation in the non-relativistic limit. Furthermore, we show that the Fourier law of heat conduction must be modified by higher gradient corrections for such fluids. We also show that the non-relativistic limit of the BDNK equations of motion are never hyperbolic, in contrast to the non-relativistic limit of extended variable models, whose non-relativistic equations of motion can be hyperbolic or not depending on the scaling of the transport coefficients present in the auxiliary equations for viscous degrees of freedom.
Comments:
v2-matches published version in PRD
Subjects:
General Relativity and Quantum Cosmology (gr-qc); High Energy Physics — Theory (hep-th); Mathematical Physics (math-ph); math.MP (math.MP); Nuclear Theory (nucl-th)
arXiv:
2305.09725 [pdf]
PRD(2023)·11 citations
09
[Submitted on 16 May 2023] (cross-list from hep-ph)
Axial anomaly effect to the chiral-partner structure of diquarks at high temperature
Daiki Suenaga🇯🇵 · Makoto Oka🇯🇵
Masses of positive-parity and negative-parity diquarks are investigated at finite temperature with a quark chemical potential. We employ the three-flavor Nambu-Jona-Lasinio model, in order to delineate chiral properties of the diquarks, in particular, the mass degeneracy of chiral partners under extreme conditions. We focus on the effects of $U (1)_{A}$ axial anomaly on manifestation of the chiral-partner structures. We find that, in the absence of anomaly effects to the diquarks, the mass degeneracies in all $[u d]$ , $[s u]$ and $[s d]$ diquark sectors take place prominently above the pseudocritical temperature of the chiral restoration. On the other hand, the anomaly effects are found to hinder the $[u d]$ diquark from exhibiting the mass degeneracy, accompanied by a slow reduction of the $s ˉ s$ condensate, while the $[s u]$ and $[s d]$ diquarks are not much affected. Our present investigation will provide useful information on the chiral-partner structure with the anomaly effects of diquarks for heavy-ion collision experiments of singly heavy baryons and doubly heavy tetraquarks, and for future lattice simulations of the diquarks.
Comments:
18 pages, 7 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2305.09730 [pdf]
PRD(2023)·11 citations
10
[Submitted on 16 May 2023] (cross-list from hep-ph)
$Δ$ -baryon axialvector and pseudoscalar form factors, and associated PCAC relations
Pei-Lin Yin🇨🇳 · Chen Chen🇨🇳 · Christian S. Fischer🇩🇪 · Craig D. Roberts🇨🇳
A quark+diquark Faddeev equation treatment of the baryon bound state problem in Poincaré-invariant quantum field theory is used to deliver parameter-free predictions for all six $Δ$ -baryon elastic weak form factors. Amongst the results, it is worth highlighting that there are two distinct classes of such $Δ$ -baryon form factors, $(g_{1}, g_{3}, G_{π ΔΔ})$ , $(h_{1}, h_{3}, H_{π ΔΔ})$ , the functions within each of which are separately linked via partial conservation of axial current (PCAC) and Goldberger-Treiman (GT) relations. Respectively within each class, the listed form factors possess qualitatively the same structural features as the nucleon axial, induced pseudoscalar, and pion-nucleon coupling form factors. For instance, the $Δ$ -baryon $g_{1}$ axial form factor can reliably be approximated by a dipole function, characterised by an axial charge $g_{A}^{Δ^{+}} = 0.71 (9)$ and mass-scale $m_{A}^{Δ} = 0.95 (2) m_{Δ}$ . Moreover, the two distinct $Δ$ -baryon PCAC form factor relations are satisfied to a high degree of accuracy on a large range of $Q^{2}$ ; the associated GT relations present good approximations only on $Q^{2} / m_{Δ}^{2} ≃ 0$ ; and pion pole dominance approximations are reliable within both classes. There are two $π ΔΔ$ couplings: $g_{π ΔΔ} = 10.46 (1.88)$ ; $h_{π ΔΔ} = 35.73 (3.75)$ ; and the associated form factors are soft. Such couplings commonly arise in phenomenology, which may therefore benefit from our analyses. A flavour decomposition of the axial charges reveals that quarks carry $71$ \% of the $Δ$ -baryon spin. The analogous result for the proton is $\approx 65$ \%.
Comments:
19 pages, 9 figures, 2 tables
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2305.09831 [pdf]
EPJA(2023)·8 citations
11
[Submitted on 17 May 2023] (cross-list from hep-ph)
Chemical potential of a hadronic fireball in the freeze-out stage
Yaroslav D. Krivenko-Emetov🇦🇹 · Andriy I. Smetana🇦🇹
This article explores the van der Waals gas model proposed to describe the hadronic stages of nuclear fireball evolution during the cooling stage. Two different models were proposed for the early and late stages of hadronization. At the initial stage, a two-component meson model consisting of $π^{0}$ and $π^{+}$ mesons was suggested, and at the later stage, a two-component nucleon model consisting of protons and neutrons was proposed. The interaction potential for both models was represented by a rectangular well, and the statistical sum was calculated using the saddle-point method. The analytic expressions for pressure and chemical potentials obtained from the model were compared with the corresponding numerical results of other authors obtained earlier using quantum chromodynamics (QCD) methods. The possibility of applying and using the effective chemical potential is also analyzed.
Comments:
17 pages, 9 figures, XXI UKRAINIAN SCIENTIFIC AND PRACTICAL CONFERENCE STUDENTS, GRADUATE STUDENTS AND YOUNG SCIENTISTS THEORETICAL AND APPLIED PROBLEMS PHYSICS, MATHEMATICS AND INFORMATICS (May 11 - 12, 2023, Kyiv, Ukraine). arXiv admin note: text overlap with arXiv:2301.00742
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2305.09976 [pdf]
0 citations

Affiliations

first authorsco-authorsvia INSPIRE