Nuclear Theory·nucl-th

Thursday·May 4, 2023

7 papers—4 primary·3 cross-listed

01
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.
nucl-thPRD(2023)·16 citations
02
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.
nucl-thPRC(2024)·13 citations
03
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.
nucl-thPLB(2023)·17 citations
04
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.
nucl-thastro-ph.HEgr-qchep-ph1 citation
05
Baryons, multi-hadron systems, and composite dark matter in non-relativistic QCD
Benoît Assi🇺🇸 · Michael L. Wagman🇺🇸
We provide a formulation of potential non-relativistic quantum chromodynamics (pNRQCD) suitable for calculating binding energies and matrix elements of generic hadron and multi-hadron states made of heavy quarks in $S U (N_{c})$ gauge theory using quantum Monte Carlo techniques. We compute masses of quarkonium and triply-heavy baryons in order to study the perturbative convergence of pNRQCD and validate our numerical methods. Further, we study $S U (N_{c})$ models of composite dark matter and provide simple power series fits to our pNRQCD results that can be used to relate dark meson and baryon masses to the fundamental parameters of these models. For many systems comprised entirely of heavy quarks, the quantum Monte Carlo methods employed here are less computationally demanding than lattice field theory methods, although they introduce additional perturbative approximations. The formalism presented here may therefore be particularly useful for predicting composite dark matter properties for a wide range of $N_{c}$ and heavy fermion masses.
↳ hep-phhep-latnucl-thPRD(2023)·14 citations
06
$Σ$ Resonances from a Neural Network-based Partial Wave Analysis on $K^{-} p$ Scattering
Jun Shi🇨🇳 · Long-Cheng Gui🇨🇳 · Jian Liang🇨🇳 · Guoming Liu🇨🇳
We implement a convolutional neural network to study the $Σ$ hyperons using experimental data of the $K^{-} p \to π^{0} Λ$ reaction. The averaged accuracy of the NN models in resolving resonances on the test data sets is $98.5%$ , $94.8%$ and $82.5%$ for one-, two- and three-additional-resonance case. We find that the three most significant resonances are $1/ 2^{+}$ , $3/ 2^{+}$ and $3/ 2^{-}$ states with mass being $1.62 (11) GeV$ , $1.72 (6) GeV$ and $1.61 (9) GeV$ , and probability being $100 (3) %$ , $72 (24) %$ and $98 (52) %$ , respectively, where the errors mostly come from the uncertainties of the experimental data. Our results support the three-star $Σ (1660) 1/ 2^{+}$ , the one-star $Σ (1780) 3/ 2^{+}$ and the one-star $Σ (1580) 3/ 2^{-}$ in PDG. The ability of giving quantitative probabilities in resonance resolving and numerical stability make NN potentially a life-changing tool in baryon partial wave analysis, and this approach can be easily extended to accommodate other theoretical models and/or to include more experimental data.
↳ hep-phnucl-th1 citation
07
Sea contribution to the charge radii and quadrupole moment of $J^{P} = \frac{1}{2}^{+}, \frac{3}{2}^{+}$ baryons
Preeti Bhall🇮🇳 · Meenakshi Batra🇮🇳 · Alka Upadhyay🇮🇳
An operator formalism is used on the wavefunction of baryons to compute their charge radii and quadrupole moments. Total anti-symmetric wavefunction in spin, color and flavor space is framed for $J^{P} = \frac{1}{2}^{+}$ nucleons and $J^{P} = \frac{3}{2}^{+}$ hyperons. To understand the importance of sea, statistical model is used in conjugation with the detailed balance principle. Within the statistical approach, the importance of sea with quarks and gluons are studied using the relevant probabilities that are associated with spin, flavor, and color space. The present work also focuses on individual contributions of valence and sea which contains terms of scalar, vector and tensor sea. The obtained results are in agreement with available theories and few experimental outcomes. Our computed results may provide important information for upcoming experimental findings.
↳ hep-phnucl-thPTEP(2023)·4 citations

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

Baryons, multi-hadron systems, and composite dark matter in non-relativistic QCD

Σ Resonances from a Neural Network-based Partial Wave Analysis on K−p Scattering

Sea contribution to the charge radii and quadrupole moment of JP=21​+,23​+ baryons

Affiliations

$Σ$ Resonances from a Neural Network-based Partial Wave Analysis on $K^{-} p$ Scattering

Sea contribution to the charge radii and quadrupole moment of $J^{P} = \frac{1}{2}^{+}, \frac{3}{2}^{+}$ baryons