Nuclear Theory·nucl-th

Tuesday·January 5, 2021

13 papers—8 primary·5 cross-listed

01
[Submitted on 1 Jan 2021]
Passage of heavy quarks through the fluctuating hot QCD medium
Mohammad Yousuf Jamal🇮🇳 · Bedangadas Mohanty🇮🇳
The change in the energy of the moving heavy (charm and bottom) quarks due to field fluctuations present in the hot QCD medium has been studied. A finite quark chemical potential has been considered while modeling the hot QCD medium counting the fact that the upcoming experimental facilities such as Anti-proton and Ion Research (FAIR) and Nuclotron-based Ion Collider fAcility (NICA) are expected to operate at finite baryon density and moderate temperature. The effective kinetic theory approach has been adopted where the collisions have been incorporated using the well defined collisional kernel, known as Bhatnagar-Gross-Krook (BGK). To incorporate the non-ideal equations of state (EoSs) effects/ medium interaction effects, an extended effective fugacity model has been adopted. The momentum dependence of the energy change due to fluctuation for the charm and bottom quark has been investigated at different values of collision frequency and chemical potential. The results are exciting as the heavy quarks are found to gain energy due to fluctuations while moving through the produced medium at finite chemical potential and collision frequency.
Comments:
6 pages, 4 figures. arXiv admin note: text overlap with arXiv:2002.09230
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2101.00164 [pdf]
EPJC(2021)·11 citations
02
[Submitted on 1 Jan 2021]
A matter of shape: seeing the deformation of atomic nuclei at high-energy colliders
Giuliano Giacalone🇫🇷
This work establishes a deep connection between two seemingly distant branches of nuclear physics: nuclear structure and relativistic heavy-ion collisions. At the heart of this connection is the recent discovery made at particle colliders that the elliptic flow of outgoing hadrons in central nucleus-nucleus collisions is strongly impacted by the quadrupole deformation of the colliding nuclear species. I review the physics of the soft sector of relativistic heavy-ion collisions, and I explain that the interpretation of elliptic flow data in central $^{197}$ Au+ $^{197}$ Au, $^{238}$ U+ $^{238}$ U, and $^{129}$ Xe+ $^{129}$ Xe collisions requires a deep understanding the structure of these ions. Subsequently, I introduce a technique that permits one to isolate collision configurations in which the deformed shapes of the colliding nuclei maximally break rotational (azimuthal) symmetry in the interaction region. This allows me to construct observables that possess an unparalleled sensitivity to the quadrupole deformation of the colliding ions, and thus to conclude that nuclear experiments at high energy can be used to place new quantitative constraints on the deformation of atomic nuclei. I emphasize the great opportunities offered by potential collider experiments aimed at the systematic study of nuclear deformation across the valley of stability.
Comments:
PhD thesis. 150 pages, 53 figures. Describing in a pedagogical fashion the applications of nuclear structure in relativistic heavy-ion collisions
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2101.00168 [pdf]
24 citations
03
[Submitted on 1 Jan 2021]
Chaos in QCD? Gap equations and their fractal properties
T. Klaehn🇺🇸 · L.C. Loveridge🇺🇸 · M. Cierniak🇵🇱
We discuss how iterative solutions of QCD inspired gap-equations at finite chemical potential show domains of chaotic behavior as well as non-chaotic domains which represent one or the other of the only two -- usually distinct -- positive mass gap solutions with broken or restored chiral symmetry, respectively. In the iterative approach gap solutions exist which exhibit restored chiral symmetry beyond a certain dynamical cut-off energy. A chirally broken, non-chaotic domain with no emergent mass poles and hence with no quasi-particle excitations exists below this energy cutoff. The transition domain between these two energy separated domains is chaotic. As a result, the dispersion relation is that of quarks with restored chiral symmetry, cut at a dynamical energy scale, determined by fractal structures. We argue that the chaotic origin of the infrared cut-off could hint at a chaotic nature of confinement and the deconfinement phase transition.
Comments:
10 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Theory (hep-th)
arXiv:
2101.00174 [pdf]
Particles(2023)·1 citation
04
[Submitted on 1 Jan 2021]
Bound-to-continuum potential model for the $(p, γ)$ reactions of the CNO cycle
Le-Anh Nguyen🇻🇳 · Minh-Loc Bui🇻🇳
The study of CNO cycle involves the examination of the proton radiative capture, or the $(p, γ)$ reactions below 2 MeV. The astrophysical $S$ factor characterizing the $(p, γ)$ reaction is usually reduced to the electric dipole transition $E 1$ from the scattering state to the bound state. In this work, the partial scattering and the single-particle bound wave functions in the reduced matrix element of the transition are obtained from the single self-consistent mean-field potential deduced from the Skyrme Hartree-Fock calculation. The astrophysical $S$ factors of the $(p, γ)$ reactions in the CNO cycle were successfully reproduced. The self-consistent Hartree-Fock calculation from the discrete to the continuum is a promising approach for the microscopic analysis of the nucleon-induced reactions in nuclear astrophysics.
Comments:
16 pages, 7 figures, submitted to Physical Review C, revised version with suggestions of referee taken into account
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2101.00199 [pdf]
PRC(2021)·12 citations
05
[Submitted on 1 Jan 2021]
Nuclear charge densities in spherical and deformed nuclei: towards precise calculations of charge radii
Paul-Gerhard Reinhard🇩🇪 · Witold Nazarewicz🇺🇸
Background: Precise measurements of atomic transitions affected by electron-nucleus hyperfine interactions offer sensitivity to explore basic properties of the atomic nucleus and study fundamental symmetries, including the search for new physics beyond the Standard Model of particle physics. Such measurements impose higher precision requirements on a theoretical description. Purpose: The nuclear charge density is composed of the proton point distribution folded with the nucleonic charge distributions. The latter induce subtle relativistic corrections due to the coupling of nucleon magnetic moments with the nuclear spin-orbit density. We assess the precision of nuclear charge density calculations by studying the behavior of relativistic corrections. Methods: The calculations are performed using Skyrme energy density functionals and density-dependent pairing force. We used the general expression for the spin-orbit form factor that is valid for spherical and deformed nuclei. Results: We studied the impact of various correction terms on the charge radii, fourth radial moments, diffraction radii, and surface thickness of spherical and deformed nuclei. The spin-orbit corrections to charge radial moments and surface thickness show strong shell fluctuations which impact high-precision predictions of isotopic shifts. Conclusions: To establish reliable constraints on the existence of new forces from isotope shift measurements,precise calculations of nuclear charge densities of deformed nuclei are needed. The proper inclusion of the spin-orbit charge density and other correction terms is essential when aiming at extraction of subtle effects which become particularly visible in isotopic trends.
Comments:
10 pages, 8 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2101.00320 [pdf]
PRC(2021)·64 citations
06
[Submitted on 4 Jan 2021]
$Ξ$ -nucleus potential for $Ξ^{-}$ quasifree production in the $^{9}$ Be( $K^{-}$ , $K^{+}$ ) reaction
Toru Harada🇯🇵 · Yoshiharu Hirabayashi🇯🇵
We study phenomenologically a $Ξ^{-}$ production spectrum of the $^{9}$ Be( $K^{-}$ , $K^{+}$ ) reaction at 1.8 GeV/ $c$ within the distorted-wave impulse approximation using the optimal Fermi-averaged $K^{-} p \to K^{+} Ξ^{-}$ amplitude. We attempt to clarify properties of a $Ξ$ -nucleus potential for $Ξ^{-}$ - $^{8}$ Li, comparing the calculated spectrum with the data of the BNL-E906 experiment. The results show a weak attraction in the $Ξ$ -nucleus potential for $Ξ^{-}$ - $^{8}$ Li, which can sufficiently explain the data in the $Ξ^{-}$ quasifree region. The strength of $V_{0}^{Ξ} =$ $- 17 \pm 6$ MeV is favored within the Woods-Saxon potential, accompanied by the reasonable absorption of $W_{0}^{Ξ} =$ $- 5$ MeV for $Ξ^{-} p \to Ξ^{0} n$ , $ΛΛ$ transitions in nuclear medium. It is difficult to determine the value of $W_{0}^{Ξ}$ from the data due to the insufficient resolution of 14.7 MeV FWHM. The energy dependence of the Fermi-averaged $K^{-} p \to K^{+} Ξ^{-}$ amplitude is also confirmed by this analysis, and its importance in the nuclear ( $K^{-}$ , $K^{+}$ ) reaction is emphasized.
Comments:
20 pages, 5 figures. arXiv admin note: text overlap with arXiv:1712.02664
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2101.00855 [pdf]
PRC(2021)·15 citations
07
[Submitted on 4 Jan 2021]
Pseudospin and spin symmetry in the relativistic generalized Woods-Saxon potential including Coulomb-like tensor potential
J. Akbar🇮🇩 · A. Suparmi🇮🇩 · C. Cari🇮🇩
The Dirac Equation is solved approximately for relativistic generalized Woods-Saxon potential including Coulomb-like tensor potential in exact pseudospin and spin symmetry limits. The bound states energy eigenvalues are found by using wavefunction boundary conditions, and corresponding radial wavefunctions are obtained in terms of hypergeometric function. Some numerical examples are given for the dependence of bound states energy eigenvalues on quantum numbers and potential parameters.
Comments:
22 pages, 6 gifures, 2 tables, accepted manuscript
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2101.00898 [pdf]
NPA(2021)·3 citations
08
[Submitted on 4 Jan 2021]
Resonances in $^{12}$ C and $^{24}$ Mg: what do we learn from a microscopic cluster theory?
P. Descouvemont🇧🇪
We discuss resonance properties in three-body systems, with examples on $^{12} C$ and $^{24} Mg$ . We use a microscopic cluster model, where the generator coordinate is defined in the hyperspherical formalism. The $^{12} C$ nucleus is described by an $α + α + α$ structure, whereas $^{24} Mg$ is considered as an $^{16} O + α + α$ system. We essentially pay attention to resonances. We review various techniques which may extend variational methods to resonances. We consider $0^{+}$ and $2^{+}$ states in $^{12} C$ and $^{24} Mg$ . We show that the r.m.s. radius of a resonance is strongly sensitive to the variational basis. This has consequences for the Hoyle state ( $0_{2}^{+}$ state in $^{12} C$ ) whose radius has been calculated or measured in several works. In $^{24} Mg$ , we identify two $0^{+}$ resonances slightly below the three-body threshold.
Comments:
8 pages, 6 figures, accepted for publication at EPJA
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2101.00955 [pdf]
EPJA(2021)·4 citations

Affiliations

first authorsco-authorsvia INSPIRE