Nuclear Theory·nucl-th

Monday·August 15, 2022

6 papers—4 primary·2 cross-listed

01
The shear viscosity of parton matter under anisotropic scatterings
Noah M. MacKay🇺🇸 · Zi-Wei Lin🇺🇸
The shear viscosity $η$ of a quark-gluon plasma in equilibrium can be calculated analytically using multiple methods or numerically using the Green-Kubo relation. It has been realized, which we confirm here, that the Chapman-Enskog method agrees well with the Green-Kubo result for both isotropic and anisotropic two-body scatterings. We then apply the Chapman-Enskog method to study the shear viscosity of the parton matter from a multi-phase transport model. In particular, we study the parton matter in the center cell of central and midcentral Au+Au collisions at $200 A$ GeV and Pb+Pb collisions at $2760 A$ GeV, which is assumed to be a plasma in thermal equilibrium but partial chemical equilibrium. As a result of using a constant Debye mass or cross section $σ$ for parton scatterings, the $η / s$ ratio increases with time (as the effective temperature decreases), contrary to the trend preferred by Bayesian analysis of the experimental data or pQCD results that use temperature-dependent Debye masses. At $σ = 3$ mb that enables the transport model to approximately reproduce the elliptic flow data of the bulk matter, the average $η / s$ of the parton matter in partial equilibrium is found to be very small, between one to two times $1/ (4 π)$ .
nucl-thEPJC(2022)·20 citations
02
Dark matter effects on tidal deformabilities and moment of inertia in a hadronic model with short-range correlations
O. Lourenço🇧🇷 · C. H. Lenzi🇧🇷 · T. Frederico🇧🇷 · M. Dutra🇧🇷
In this work we study the outcomes related to dimensionless tidal deformability $(Λ)$ obtained through a relativistic mean-field (RMF) hadronic model including short-range correlations (SRC) and dark matter (DM) content [Phys. Rev. D 105, 023008 (2022)]. As a dark particle candidate, we use the lightest neutralino interacting with nucleons through the Higgs boson exchange. In particular, we test the model against the constraints regarding the observation of gravitational waves from the binary neutron star merger GW170817 event provided by LIGO and Virgo collaboration (LVC). We show that $Λ$ decreases as the dark particle Fermi momentum ( $k_{F}^{D M}$ ) increases. This feature favors the RMF-SRC-DM model used here to satisfy the limits of $Λ_{1.4} = 19 0_{- 120}^{+ 390}$ ( $Λ$ of a $1.4 M_{⊙}$ neutron star), and $Λ ~ = 30 0_{- 230}^{+ 420}$ given by the LVC. We also show that as $k_{F}^{D M}$ increases, $Λ_{1}$ and $Λ_{2}$ , namely, tidal deformabilities of the binary system, are also moved to the direction of the GW170817 observational data. Finally, we verify that the inclusion of DM in the system does not destroy the \mbox{ $I$ -Love} relation (correlation between $Λ$ and dimensionless moment of inertia, $I ˉ$ ). The observation data for $I ˉ_{⋆} \equiv I ˉ (M_{⋆}) = 11.1 0_{- 2.28}^{+ 3.68}$ , with $M_{⋆} = 1.338 M_{⊙}$ , is attained by the RMF-SRC-DM model.
nucl-thastro-ph.HEPRD(2022)·47 citations
03
Photon Production in High-Energy Heavy-Ion Collisions: Thermal Photons and Radiative Recombination
Hirotsugu Fujii🇯🇵 · Kazunori Itakura🇯🇵 · Katsunori Miyachi🇯🇵 · Chiho Nonaka🇯🇵
We present a comprehensive analysis of photon production at RHIC and the LHC, proposing radiative hadronization as an additional photon source in high-energy heavy-ion collisions. For thermal photon, we perform relativistic viscous hydrodynamic calculation with event-by-event fluctuations.
nucl-thhep-phnucl-exActa Phys.Polon.Supp.(2023)·2 citations
04
Two-proton radioactivity within Coulomb and proximity potential model
De-Xing Zhu · Hong-Ming Liu · Yang-Yang Xu · You-Tian Zou · Xi-Jun Wu · Peng-Cheng Chu · Xiao-Hua Li
Considering the preformation probability of the two emitted protons in the parent nucleus, we extend the Coulomb and proximity potential model (CPPM) to systematically study two-proton (2p) radioactivity half-lives of the nuclei close to proton drip line. The proximity potential chosen is Prox. 81 proposed by Blocki et al. in 1981. Furthermore, we apply this model to predict the half-lives of possible 2p radioactive candidates whose 2p radioactivity is energetically allowed or observed but not yet quantified in the evaluated nuclear properties table NUBASE2016. The predicted results are in good agreement with those from other theoretical models and empirical formulas, namely the effective liquid drop model (ELDM), generalized liquid drop model (GLDM), Gamow-like model, Sreeja formula and Liu formula.
nucl-thCPC(2022)·15 citations
05
Constraints on neutron skin thickness and nuclear deformations using relativistic heavy-ion collisions from STAR
Haojie Xu (for the STAR Collaboration)🇨🇳
In these proceedings, we present the measurements of neutron skin thickness and nuclear deformation using isobar $_{44}^{96}$ Ru+ $_{44}^{96}$ Ru and $_{40}^{96}$ Zr+ $_{40}^{96}$ Zr collisions at $s_{_{NN}} = 200$ GeV by the STAR detector. The significant deviations from unity of the isobar ratios of elliptic flow $v_{2}$ , triangular flow $v_{3}$ , mean $p_{T}$ fluctuations $⟨ δ p_{T}^{2} ⟩ / ⟨ p_{T} ⟩^{2}$ , and asymmetric cumulant $ac_{2} {3}$ indicate large differences in their quadrupole and octuple deformations. The significant deviations of the isobar ratios of produced hadron multiplicity $N_{ch}$ , mean transverse momentum $⟨ p_{T} ⟩$ , and net charge number $Δ Q$ indicate a halo-type neutron skin for the Zr nucleus, much thicker than for the Ru nucleus, consistent with nuclear structure calculations. We discuss how we extract the neutron skin thickness, the symmetry energy slope parameter, and deformation parameters from data.
↳ nucl-exnucl-thActa Phys.Polon.Supp.(2023)·15 citations
06
The Influence of Beta Decay Rates on r-Process Observables
Kelsey A. Lund · J. Engel · G.C. McLaughlin · M.R. Mumpower · E.M. Ney · R. Surman
The rapid neutron capture process (r-process) is one of the main mechanisms whereby elements heavier than iron are synthesized, and is entirely responsible for the natural production of the actinides. Kilonova emissions are modeled as being largely powered by the radioactive decay of species synthesized via the r -process. Given that the r -process occurs far from nuclear stability, unmeasured beta decay rates play an essential role in setting the time scale for the r -process. In an effort to better understand the sensitivity of kilonova modeling to different theoretical global beta-decay descriptions, we incorporate these into nucleosynthesis calculations. We compare the results of these calculations and highlight differences in kilonova nuclear energy generation and light curve predictions, as well as final abundances and their implications for nuclear cosmochronometry. We investigate scenarios where differences in beta decay rates are responsible for increased nuclear heating on time scales of days that propagates into a significantly increased average bolometric luminosity between 1-10 days post-merger. We identify key nuclei, both measured and unmeasured, whose decay rates are directly impact nuclear heating generation on timescales responsible for light curve evolution. We also find that uncertainties in beta decay rates significantly impact ages estimates from cosmochronometry.
↳ astro-ph.HEastro-ph.SRnucl-exnucl-thApJ(2023)·31 citations

Affiliations

first authorsco-authorsvia INSPIRE

The shear viscosity of parton matter under anisotropic scatterings

Dark matter effects on tidal deformabilities and moment of inertia in a hadronic model with short-range correlations

Photon Production in High-Energy Heavy-Ion Collisions: Thermal Photons and Radiative Recombination

Two-proton radioactivity within Coulomb and proximity potential model

Constraints on neutron skin thickness and nuclear deformations using relativistic heavy-ion collisions from STAR

The Influence of Beta Decay Rates on r-Process Observables

Affiliations