Nuclear Theory·nucl-th

Thursday·May 4, 2023

7 papers—4 primary·3 cross-listed

01
[Submitted on 2 May 2023]
Properties of quark-matter cores in massive hybrid stars
He Liu🇨🇳 · Xiao-Min Zhang🇨🇳 · Peng-Cheng Chu🇨🇳
Using the constraints from astrophysical observations and heavy-ion experiments, we investigate the equation of state (EOS) of hybrid star matter and the properties of quark-matter cores in hybrid stars. The quark matter interactions in hybrid stars are described based on 3-flavor Nambu-Jona-Lasinio model with various vector and vector-isovector coupling constants. In this work, we find that the hybrid star matter EOS is more sensitive to the strength of the vector interaction, and the EOS becomes stiffer with increasing vector strength $R_{V}$ . The vector-isovector interaction characterized by the coupling constant $R_{I V}$ make main contribution to the hadron-quark mixed phase. Meanwhile, we note that a step change of both the sound velocity and the polytropic index $γ$ occurs in the hadron-quark phase transition, and it is restored with the decrease of nucleon and lepton degrees of freedom in the high density quark phase. Although the coupling constants increase the hybrid star maximum mass up to $2.08 M_{⊙}$ , they also decrease the mass and radius of the quark core and the mixed core. With different quark coupling constants, we also find that the maximum mass and radius of the quark matter core in a stable hybrid star can reach $0.80 M_{⊙}$ and 6.95 km, which are close to half of the maximum mass and radius of the complete star. However, properties of quark matter have no effect on the $M = 1.4 M_{⊙}$ hybrid star as a result of no quark matter inner core, which can also be confirmed by the criterion of the polytropic index, and thus our results also indicate that the quark interactions have no effect on the tidal deformability $Λ_{1.4}$ of hybrid stars.
Comments:
10 pages, 5 figures. arXiv admin note: substantial text overlap with arXiv:2305.01246
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2305.01662 [pdf]
PRD(2023)·16 citations
02
[Submitted on 2 May 2023]
Uncertainty Quantification of Mass Models using Ensemble Bayesian Model Averaging
Yukiya Saito · Iris Dillmann · Reiner Kruecken · Matthew R. Mumpower · Rebecca Surman
Developments in the description of the masses of atomic nuclei have led to various nuclear mass models that provide predictions for masses across the whole chart of nuclides. These mass models play an important role in understanding the synthesis of heavy elements in the rapid neutron capture ( $r$ -) process. However, it is still a challenging task to estimate the size of uncertainty associated with the predictions of each mass model. In this work, a method to quantify the mass uncertainty using \textit{ensemble Bayesian model averaging} (EBMA) is introduced. This Bayesian method provides a natural way to perform model averaging, selection, calibration, and uncertainty quantification, by combining the mass models as a mixture of normal distributions, whose parameters are optimized against the experimental data, employing the Markov chain Monte Carlo (MCMC) method using the No-U-Turn sampler (NUTS). The average size of our best uncertainty estimates of neutron separation energies based on the AME2003 data is 0.48 MeV and covers 95% of new data in the AME2020. The uncertainty estimates can also be used to detect outliers with respect to the trend of experimental data and theoretical predictions.
Comments:
15 pages, 7 figures. Footnote removed from the previous version. Submitted to PRC
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2305.01782 [pdf]
PRC(2024)·13 citations
03
[Submitted on 3 May 2023]
Hydrodynamic fluctuations and ultra-central flow puzzle in heavy-ion collisions
Kenshi Kuroki🇯🇵 · Azumi Sakai🇯🇵 · Koichi Murase🇯🇵 · Tetsufumi Hirano🇯🇵
One of the long-standing problems in the field of high-energy heavy-ion collisions is that the dynamical models based on viscous hydrodynamics fail to describe the experimental elliptic flow $v_{2}$ and the triangular flow $v_{3}$ simultaneously in ultra-central collisions. The problem, known as the "ultra-central flow puzzle", is specifically that hydrodynamics-based models predict the flow ratio of the two-particle cumulant method $v_{2} {2} / v_{3} {2} > 1$ while $v_{2} {2} / v_{3} {2} \sim 1$ in the experimental data. In this Letter, we focus on the effects of hydrodynamic fluctuations during the space-time evolution of the QGP fluid on the flow observables in the ultra-central collisions. Using the (3+1)-dimensional integrated dynamical model which includes relativistic fluctuating hydrodynamics, we analyze the anisotropic flow coefficients $v_{n} {2}$ in 0-0.2% central Pb+Pb collisions at $s_{NN} = 2.76 TeV$ . We find that the hydrodynamic fluctuations decrease the model overestimate of $v_{2} {2} / v_{3} {2}$ from the experimental data by about 19% within the present setup of $η / s = 1/2 π$ . This means that the hydrodynamic fluctuations qualitatively have an effect to improve the situation for the puzzle, but the effect of the hydrodynamic fluctuations alone is quantitatively insufficient to resolve the puzzle. The decrease of the ratio largely depends on the shear viscosity $η / s$ , which calls for future comprehensive analyses with, for example, a realistic temperature-dependent viscosity.
Comments:
7 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2305.01977 [pdf]
PLB(2023)·17 citations
04
[Submitted on 3 May 2023]
Impacts of dark matter interaction on nuclear and neutron star matter within the relativistic mean-field model
H. C. Das🇮🇳
This thesis explores the effects of dark matter (DM) on neutron stars (NSs) using the relativistic mean-field (RMF) model. The effects of DM on NS properties, including the mass-radius relation, the moment of inertia, and tidal deformability, are calculated by varying its fraction. The study found that the EOS becomes softer with increasing DM momentum, and the DM has marginal effects on nuclear matter properties, except for the EOSs and binding energy per particle. The study also calculated the properties of isolated, static, and rotating DM admixed NS and found that the DM has significant effects on both static and rotating NS. We have also observed that a tiny amount of DM can accumulate inside the NS, and more amount of it makes the NS unstable. The study also suggests that the secondary component might be a NS with DM content if the underlying nuclear EOS is sufficiently stiff. The $f$ -mode oscillations of the DM admixed hyperon stars are calculated and found that there exist a correlation between canonical $f$ -mode frequency and the dimensionless tidal deformability parameter ( $Λ_{1.4}$ ) and we have put a constraint on $f$ -mode frequency using GW170817 data. Finally, we have calculated the DM admixed binary NS properties and found that the binary system becomes less deformed and sustains more time in its inspiral phases with the addition of DM. Therefore, we suggest that one can take DM inside the compact objects while modeling the inspiral waveforms for the BNS systems.
Comments:
PhD Thesis
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2305.02065 [pdf]
1 citation

Affiliations

first authorsco-authorsvia INSPIRE

Properties of quark-matter cores in massive hybrid stars

Uncertainty Quantification of Mass Models using Ensemble Bayesian Model Averaging

Hydrodynamic fluctuations and ultra-central flow puzzle in heavy-ion collisions

Impacts of dark matter interaction on nuclear and neutron star matter within the relativistic mean-field model

Affiliations