Nuclear Theory·nucl-th

Thursday·September 9, 2021

9 papers—4 primary·5 cross-listed

01
Systematic trends of neutron skin thickness versus relative neutron excess
J. T. Zhang · X. L. Tu · P. Sarriguren · K. Yue · Q. Zeng · Z. Y. Sun · M. Wang · Y. H. Zhang · X. H. Zhou · Yu. A. Litvinov
Available experimental neutron skin thicknesses of even-even stable Ca, Ni, Sn, Pb, and Cd isotopes are evaluated, and separate trends of neutron skin thickness versus relative neutron excess $δ = (N - Z) / A$ are firstly observed for different isotopic chains. This phenomenon is quantitatively reproduced by the deformed Skyrme Hartree-Fock $+$ BCS model with SLy4 force.
nucl-thPRC(2021)·27 citations
02
Study on deformed halo nucleus $^{31}$ Ne with Glauber model based on microscopic self-consistent structures
Shi-Yi Zhong · Shi-Sheng Zhang · Xiang-Xiang Sun · Michael S. Smith
We study the exotic deformed nucleus $^{31}$ Ne using an approach that combines self-consistent structure and reaction theory. We utilize the fully-relativistic, microscopic deformed Hartree-Bogoliubov theory in continuum (DRHBc) to demonstrate that deformation and pairing correlations give rise to a halo structure with large-amplitude $p$ -wave configuration in $^{31}$ Ne. We then use the valence nucleon wave functions and angle-averaged density distributions of $^{30}$ Ne from this model as input for a Glauber reaction model to study the observables of neutron-rich Neon isotopes and search for halo signatures. Our predictions of the reaction cross sections of these exotic Neon isotopes on a Carbon target can better reproduce the experimental data than those from relativistic mean field model for a spherical shape with resonances and pairing correlations contributions, as well as those from a Skyrme-Hartree-Fock model. The one-neutron removal cross section at 240 MeV/nucleon, the inclusive longitudinal momentum distribution of the $^{30}$ Ne, and the valence neutron residues from the $^{31}$ Ne breakup reaction are largely improved over previous theoretical predictions and agree well with data. These reaction data indicate a dilute density distribution in coordinate space and are a canonical signature of a halo structure.
nucl-thSCPMA(2022)·47 citations
03
Effects of chiral symmetry restoration on meson and dilepton production in relativistic heavy-ion collisions
A.B. Larionov🇷🇺 · L. von Smekal🇩🇪
We include effects of chiral symmetry and its restoration in the kinetic equations for baryon propagation and explore the consequences for $η$ , $π^{0}$ , $ρ$ and dilepton production in heavy-ion collisions at 1-2A GeV. Numerical calculations are performed using the GiBUU microscopic transport model supplemented by the parity-doublet model for the mean fields of the nucleon and the $N^{*} (1535)$ resonance. In this chiral model, a strong dropping of the Dirac mass of the $N^{*} (1535)$ in the high-density stage of a collision leads to a considerable enhancement in the production of this resonance as compared to the standard (non-linear) Walecka model. As the system expands, the Dirac masses of these abundant soft $N^{*} (1535)$ resonances gradually increase and ultimately cross the $N η$ decay threshold. As a result, an enhanced low-energy $η$ production is observed in the calculations with chiral mean fields. Comparing with TAPS data on $η$ and $π^{0}$ production we find that the chiral model improves the agreement for the $m_{t}$ -spectra of $η$ 's at small $m_{t}$ in heavy colliding systems. A similar enhancement is also observed in the soft $ρ$ production due to chiral symmetry and its partial restoration. The resulting dilepton yields at low and intermediate invariant masses are slightly enhanced due to these chiral effects which further improve the agreement between GiBUU transport simulations and HADES data for C+C at 1A GeV.
nucl-thhep-exhep-phnucl-exPRC(2022)·12 citations
04
Potential model with bound-to-continuum approach for low-energy nucleon radiative capture by $^{12}$ C and $^{16}$ O
Le-Anh Nguyen · Nhut-Huan Phan · Minh-Loc Bui
The nucleon radiative capture reactions are important in pure and applied nuclear physics, especially in nuclear astrophysics. The keV-nucleon radiative capture reactions are studied with $^{12}$ C and $^{16}$ O targets using the bound-to-continuum potential model in which both scattering and bound states are treated simultaneously and based on the Skyrme Hartree-Fock approximation. The obtained results are shown to be in good agreement with the available experimental data. Alongside astrophysical aspects, the nuclear structure features were revisited for enlarging the prospect of adopting the nucleon radiative capture processes as a spectroscopic tool.
nucl-thPRC(2021)·8 citations
05
Effective Debye Screening Mass in an Anisotropic Quark Gluon Plasma
Lihua Dong🇨🇳 · Yun Guo🇨🇳 · Ajaharul Islam🇺🇸 · Michael Strickland🇺🇸
Due to the rapid longitudinal expansion of the quark-gluon plasma created in heavy-ion collisions, large local-rest-frame momentum-space anisotropies are generated during the system's evolution. These momentum-space anisotropies complicate the modeling of heavy-quarkonium dynamics in the quark-gluon plasma due to the fact that the resulting inter-quark potentials are spatially anisotropic, requiring real-time solution of the 3D Schrödinger equation. Herein, we introduce a method for reducing anisotropic heavy-quark potentials to isotropic ones by introducing an effective screening mass that depends on the quantum numbers $l$ and $m$ of a given state. We demonstrate that, using the resulting effective Debye screening masses, one can solve a 1D Schrödinger equation and reproduce the full 3D results for the energies and binding energies of low-lying heavy-quarkonium bound states to relatively high accuracy. The resulting effective isotropic potential models could provide an efficient method for including momentum-anisotropy effects in open quantum system simulations of heavy-quarkonium dynamics in the quark-gluon plasma.
↳ hep-phnucl-thPRD(2021)·12 citations
06
Novel description of $P_{c} (4312)^{+}$ , $P_{c} (4380)^{+}$ , and $P_{c} (4457)^{+}$ with double triangle cusps
Satoshi X. Nakamura🇺🇸
We propose a novel scenario for the peak structures, usually interpreted as hidden charm pentaquark ( $P_{c}$ ) contributions, in the LHCb's $Λ_{b}^{0} \to J / ψ p K^{-}$ data. The key idea is to utilize leading or lower-order singularities from double triangle mechanisms. The singularities cause anomalous threshold cusps, which are significantly more singular than the ordinary ones, at the $Σ_{c}^{(*)} D ˉ^{(*)}$ threshold. We demonstrate that the double triangle amplitudes interfere with other common mechanisms to create peak structure that fit well the $P_{c} (4312)^{+}$ , $P_{c} (4380)^{+}$ , and $P_{c} (4457)^{+}$ peaks in the data. This picture is completely different from commonly used ones such as hadron molecules and compact pentaquarks. Meanwhile, $P_{c} (4440)^{+}$ is included in the proposed model as a resonance with width and strength significantly smaller than previously estimated. The proposed model can (partly) explain the current data for other processes where $P_{c}^{+}$ signals are expected such as: no $P_{c}^{+}$ signals in the GlueX $J / ψ$ photoproduction data; a possible signal only from $P_{c} (4440)^{+}$ in the LHCb's $Λ_{b}^{0} \to J / ψ p π^{-}$ data.
↳ hep-phhep-exnucl-thPoS(2021)·3 citations
07
Asymmetric longitudinal flow decorrelations in proton-nucleus collisions
Xiang-Yu Wu🇨🇳 · Guang-You Qin🇨🇳
We perform the first study on asymmetric longitudinal decorrelations of elliptic, triangular and quadrangular flows in proton-nucleus collisions at the LHC and RHIC energies. To measure the longitudinal flow decorrelations for asymmetric collision systems, we propose a new set of rapidity-asymmetric flow decorrelation functions. Our event-by-event hydrodynamic calculations show that the flow decorrelations in proton-going direction are larger than those in nucleus-going direction. We also find that proton-nucleus collisions at RHIC have larger longitudinal flow decorrelation effects than those at the LHC. Our study opens a new window to probe the longitudinal properties and the origin of flows in relativistic nuclear collisions.
↳ hep-phnucl-exnucl-th13 citations
08
Gluon EMC effects in nuclear matter
Xuan-Gong Wang🇦🇺 · Wolfgang Bentz🇯🇵 · Ian C. Cloët🇺🇸 · Anthony W. Thomas🇦🇺
We investigate the gluonic structure of nuclei within a mean-field model of nuclear structure based upon the modification of the structure of a bound nucleon, with the nucleon described by the Nambu--Jona-Lasinio model. This approach has been shown to reproduce the European Muon Collaboration (EMC) effect, involving the ratio of the spin-independent structure functions of a heavier nucleus to that of the deuteron. It also predicts a significant nuclear modification for the spin structure functions, known as the polarized EMC effect. Here we report sizeable nuclear modifications of the gluon distributions (a "gluon EMC effect") for the ratios of both the unpolarized and polarized gluon distributions in nuclear matter to those of a free nucleon.
↳ hep-phhep-exhep-latnucl-thJ.Phys.G(2022)·11 citations
09
Bosonic Dark Matter in Neutron Stars and its Effect on Gravitational Wave Signal
Davood Rafiei Karkevandi🇮🇷 · Soroush Shakeri🇮🇷 · Violetta Sagun🇵🇹 · Oleksii Ivanytskyi🇵🇱
We study an impact of self-interacting bosonic dark matter (DM) on various observable properties of neutron stars (NSs). The analysis is performed for asymmetric DM with masses from few MeV to GeV, the self-coupling constant of order $O (1)$ and various DM fractions. Allowing a mixture between DM and baryonic matter, the formation of a dense DM core or an extended dark halo have been explored. We find that both distribution regimes crucially depend on the mass and fraction of DM for sub-GeV boson masses in the strong coupling regime. From the combined analysis of the mass-radius relation and the tidal deformability of compact stars including bosonic DM, we set a stringent constraint on DM fraction. We conclude that observations of 2 $M_{⊙}$ NSs together with $Λ_{1.4} \leq 580$ constraint, set by LIGO/Virgo Collaboration, favour sub-GeV DM particles with low fractions below $\sim 5%$ .
↳ astro-ph.HEhep-phnucl-thPRD(2022)·198 citations

Affiliations

first authorsco-authorsvia INSPIRE