Nuclear Theory·nucl-th

Tuesday·December 12, 2023

13 papers—5 primary·8 cross-listed

01
Exact Polarization of Particles of Any Spin at Global Equilibrium
Andrea Palermo🇺🇸
The polarization of the $Λ$ particle offers the unique opportunity to study the hydrodynamic gradients in the Quark-Gluon Plasma formed in heavy-ion collisions. However, the theoretical formula commonly used to calculate polarization is only a linear order expansion in thermal vorticity and neglects higher-order corrections. Here, I present an exact calculation to all orders in (constant) thermal vorticity at global equilibrium, obtaining the analytic form of the spin density matrix and the polarization vector for massive particles of any spin. Finally, I extend these results to local equilibrium and assess their phenomenological impact by numerically calculating the polarization vector in a 3+1 hydrodynamic simulation.
nucl-thhep-thEPJ Web Conf.(2024)·4 citations
02
Correlating isothermal compressibility to nucleon fluctuations in the inner crust of neutron stars
R. Shafieepour · H. R. Moshfegh · J. Piekarewicz
The question of how and which physical observables or thermodynamic parameters can best predict the onset of a possible phase transition in the inner crust of neutron stars remains largely unresolved. Using semiclassical Monte Carlo simulations, we investigate the isothermal compressibility and density fluctuations in a region of relevance to the dynamics of the inner crust. We show that the isothermal compressibility serves as a robust observable to characterize the transition from the non-uniform crust to the uniform core for proton fractions over 0.2. Moreover, we show explicitly how the two-component isothermal compressibility, computed using the Kirkwood-Buff theory, is directly connected to the fluctuations in the number density, recorded in the grand canonical ensemble by monitoring the number of particles in a small volume located at the center of the simulation box. That is, we compute mean-square particle fluctuations and compare them against the isothermal compressibility for different proton fractions. Although our results show that the mean-square particle fluctuations are proportional to the isothermal compressibility, the lack of a perfect correlation is attributed to the relatively small number of particles included in the simulations. The non-unity slope observed in the dimensionless isothermal compressibility-total nucleon fluctuation variance relationship suggests that the inner crust of neutron stars is composed of anisotropic and inhomogeneous matter.
nucl-thPRC(2024)·0 citations
03
Effect of hadronic interaction on the flow of $K^{* 0}$
Tribhuban Parida🇮🇳 · Sandeep Chatterjee🇮🇳 · Md. Nasim🇮🇳
We explore the implications of the late stage hadronic rescattering phase on the flow of $K^{* 0}$ . The model calculations are done using a (3+1)-dimensional hybrid framework, incorporating both hydrodynamic evolution and hadronic transport that is calibrated to agree with bulk observables including the elusive rapidity differential $v_{1}$ of light-flavor hadrons. We find that the late stage hadronic rescattering phase causes significant qualitative modification of the $K^{* 0}$ $v_{1}$ resulting in $\frac{d v _{1}}{d y} (K^{* 0}) - \frac{d v _{1}}{d y} (K^{+})$ and $\frac{d v _{1}}{d y} (ϕ) - \frac{d v _{1}}{d y} (K^{+})$ to have opposite signs with the effect being more pronounced in central collisions as compared to peripheral ones due to the larger multiplicity as well as longer duration of the hadronic phase. Further, this effect is enhanced in low-energy collisions owing to a stronger breaking of boost invariance. On the contrary, the influence of the hadronic phase on the $K^{* 0}$ elliptic flow $v_{2}$ is found to be less significant and quantitative.
nucl-thhep-phnucl-exPRC(2024)·7 citations
04
Constraints on initial baryon stopping and equation of state from directed flow
Lipei Du🇨🇦 · Chun Shen🇺🇸 · Sangyong Jeon🇨🇦 · Charles Gale🇨🇦
Our investigation focuses on the rapidity-dependent directed flow, $v_{1} (y)$ , of identified hadrons in Au+Au collisions across a broad range of $s_{NN}$ from 7.7 to 200 GeV. Employing a (3+1)-dimensional hybrid framework, our study successfully reproduces the characteristic features of the measured $v_{1} (y)$ for both mesons and baryons across the considered beam energies. Notably, our analysis reveals the constraining power of baryonic $v_{1} (y)$ on the initial baryon stopping mechanism. Together with mesonic $v_{1} (y)$ , the directed flow serves as a crucial tool for probing the equation of state governing dense nuclear matter at finite chemical potentials.
nucl-thhep-exhep-phnucl-exEPJ Web Conf.(2024)·2 citations
05
Interplay of baryonic chiral partners in fluctuations of net-baryon number density
Michał Marczenko🇵🇱 · Volker Koch🇺🇸 · Krzysztof Redlich🇵🇱 · Chihiro Sasaki🇵🇱
In this contribution, we use the parity doublet model to investigate the fluctuations of the net-baryon number density. We discuss the systematics of the susceptibilities and their ratios for nucleons of positive and negative parity, as well as their correlator. We demonstrate that the fluctuations of positive-parity nucleon do not reflect the fluctuations of the total net-baryon number at the chiral phase transition.
nucl-thhep-phEPJ Web Conf.(2024)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE

Exact Polarization of Particles of Any Spin at Global Equilibrium

Correlating isothermal compressibility to nucleon fluctuations in the inner crust of neutron stars

Effect of hadronic interaction on the flow of K∗0

Constraints on initial baryon stopping and equation of state from directed flow

Interplay of baryonic chiral partners in fluctuations of net-baryon number density

Affiliations

Effect of hadronic interaction on the flow of $K^{* 0}$