Nuclear Theory·nucl-th

Monday·October 23, 2023

6 papers—1 primary·5 cross-listed

02
[Submitted on 19 Oct 2023] (cross-list from nucl-ex)
Estimate of Background Baseline and Upper Limit on the Chiral Magnetic Effect in Isobar Collisions at $s_{NN} = 200$ GeV at the Relativistic Heavy-Ion Collider
STAR Collaboration: M. I. Abdulhamid · B. E. Aboona · J. Adam · J. R. Adams · G. Agakishiev · I. Aggarwal · M. M. Aggarwal · Z. Ahammed · A. Aitbaev · I. Alekseev · E. Alpatov · A. Aparin and 345 other authors
For the search of the chiral magnetic effect (CME), STAR previously presented the results from isobar collisions ( $_{44}^{96} Ru +_{44}^{96} Ru$ , $_{40}^{96} Zr +_{40}^{96} Zr$ ) obtained through a blind analysis. The ratio of results in Ru+Ru to Zr+Zr collisions for the CME-sensitive charge-dependent azimuthal correlator ( $Δ γ$ ), normalized by elliptic anisotropy ( $v_{2}$ ), was observed to be close to but systematically larger than the inverse multiplicity ratio. The background baseline for the isobar ratio, $Y = \frac{( Δ γ / v _{2} ) ^{Ru}}{( Δ γ / v _{2} ) ^{Zr}}$ , is naively expected to be $\frac{( 1/ N ) ^{Ru}}{( 1/ N ) ^{Zr}}$ ; however, genuine two- and three-particle correlations are expected to alter it. We estimate the contributions to $Y$ from those correlations, utilizing both the isobar data and HIJING simulations. After including those contributions, we arrive at a final background baseline for $Y$ , which is consistent with the isobar data. We extract an upper limit for the CME fraction in the $Δ γ$ measurement of approximately $10%$ at a $95%$ confidence level on in isobar collisions at $s_{NN} = 200$ GeV, with an expected $15%$ difference in their squared magnetic fields.
Comments:
19 pages, 14 figures
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2310.13096 [pdf]
PRC(2024)·22 citations
03
[Submitted on 19 Oct 2023] (cross-list from hep-ph)
Describing the speed of sound peak of isospin-asymmetric cold strongly interacting matter using effective models
Alejandro Ayala🇲🇽 · Bruno S. Lopes🇧🇷 · Ricardo L. S. Farias🇧🇷 · Luis C. Parra🇲🇽
The non-monotonic behavior of the speed of sound for isospin imbalanced strongly interacting matter, found by recent lattice QCD simulations, can be reproduced within the Nambu--Jona-Lasinio model and Linear Sigma Model with quarks when the couplings become isospin chemical potential-dependent. The introduction of medium-dependent couplings can potentially affect the equivalence between the thermodynamic relations and their definitions from statistical mechanics. We describe the procedure to compensate for the introduction of medium-dependent couplings to preserve the correct thermodynamic identities. We find the isospin chemical potential dependence for the couplings from the isospin density LQCD data and, after finding the compensating function to correctly describe the pressure, we show that the description of the square of the speed of sound reported by LQCD is well reproduced when using the found medium-dependent couplings in both models.
Comments:
18 pages, 7 figures. Replaced to match the published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2310.13130 [pdf]
EPJA(2024)·16 citations
04
[Submitted on 20 Oct 2023] (cross-list from hep-ph)
Tetraquark bound states in constituent quark models: benchmark test calculations
Lu Meng🇩🇪 · Yan-Ke Chen🇨🇳 · Yao Ma🇨🇳 · Shi-Lin Zhu🇨🇳
We investigate the tetraquark bound states that are manifestly exotic using three distinct few-body methods: Gaussian Expansion Method (GEM), Resonating Group Method (RGM), and Diffusion Monte Carlo (DMC). We refer to manifestly exotic states that do not involve a mixture with the conventional mesons through the creation and annihilation of $n n ˉ$ , where $n = u, d$ . Our calculations are conducted with two types of quark models: the pure constituent quark model featuring one-gluon-exchange interactions and confinement interactions, and the chiral constituent quark model, supplemented by extra one-boson-exchange interactions. This study represents a comprehensive benchmark test of various few-body methods and quark models. Our findings reveal the superiority of GEM over RGM and DMC methods based on present implements for the tetraquark bound states. Additionally, we observe a tendency for the chiral quark model to overestimate the binding energies. We systematically explore the fully, triply, doubly, and singly heavy tetraquark states with $J^{P} = 0^{+}, 1^{+}, 2^{+}$ , encompassing over 150 states in total. We successfully identify several bound states, including $[cc n ˉ n ˉ]_{J^{P} = 1^{+}}^{I = 0}$ , $[bb n ˉ n ˉ]_{J^{P} = 1^{+}}^{I = 0}$ , $[b c n ˉ n ˉ]_{J^{P} = 0^{+}, 1^{+}, 2^{+}}^{I = 0}$ , $[b s n ˉ n ˉ]_{J^{P} = 0^{+}, 1^{+}}^{I = 0}$ , $[cs n ˉ n ˉ]_{J^{P} = 0^{+}}^{I = 0}$ , and $[bb n ˉ s ˉ]_{J^{P} = 1^{+}}$ , all found to be bound states below the dimeson thresholds.
Comments:
15 pages, 7 figures and 5 Tables. Version accepted by PRD
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
2310.13354 [pdf]
PRD(2023)·51 citations
05
[Submitted on 20 Oct 2023] (cross-list from hep-lat)
Pseudo-scalar meson spectral properties in the chiral crossover region of QCD
Dibyendu Bala🇩🇪 · Olaf Kaczmarek🇩🇪 · Peter Lowdon🇩🇪 · Owe Philipsen🇩🇪 · Tristan Ueding🇩🇪
Determining the type of excitations that can exist in a thermal medium is key to understanding how hadronic matter behaves at extreme temperatures. In this work we study this question for pseudo-scalar mesons comprised of light-strange and strange-strange quarks, analysing how their low-energy spectral properties are modified as one passes through the high-temperature chiral crossover region between $T = 145.6 MeV$ and $172.3 MeV$ . We utilise the non-perturbative constraints satisfied by correlation functions at finite temperature in order to extract the low-energy meson spectral function contributions from spatial correlator lattice data in $N_{f} = 2 + 1$ flavour QCD. The robustness of these contributions are tested by comparing their predictions with data for the corresponding temporal correlator at different momentum values. We find that around the pseudo-critical temperature $T_{pc}$ the data in both the light-strange and strange-strange channels is consistent with the presence of a distinct stable particle-like ground state component, a so-called thermoparticle excitation. As the temperature increases this excitation undergoes collisional broadening, and this is qualitatively the same in both channels. These findings suggest that pseudo-scalar mesons in QCD have a bound-state-like structure at low energies within the chiral crossover region which is still strongly influenced by the vacuum states of the theory.
Comments:
26 pages, 15 figures; v2: new appendices added, references updated, matches published version
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2310.13476 [pdf]
JHEP(2024)·26 citations
06
[Submitted on 20 Oct 2023] (cross-list from astro-ph.HE)
The impact of nuclear reactions on the neutron-star g-mode spectrum
A. R. Counsell · F. Gittins · N. Andersson
Mature neutron stars are expected exhibit gravity g-modes due to stratification caused by varying composition. These modes are affected by nuclear reactions, leading to complex (damped) mode frequencies and the suppression of high order g-modes, in contrast with the common non-dissipative analysis which leads to an infinite g-mode spectrum. Focusing on the transition between the fast and slow reaction regimes, we examine the impact of nuclear reactions on the g-mode spectrum. The general framework for the analysis is presented along with sample numerical results for the BSk21 equation of state and the standard Urca reactions.
Comments:
11 pages, 3 figures
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
arXiv:
2310.13586 [pdf]
MNRAS(2024)·15 citations

Affiliations

first authorsco-authorsvia INSPIRE

Estimate of Background Baseline and Upper Limit on the Chiral Magnetic Effect in Isobar Collisions at sNN​​=200 GeV at the Relativistic Heavy-Ion Collider

Describing the speed of sound peak of isospin-asymmetric cold strongly interacting matter using effective models

Tetraquark bound states in constituent quark models: benchmark test calculations

Pseudo-scalar meson spectral properties in the chiral crossover region of QCD

The impact of nuclear reactions on the neutron-star g-mode spectrum

Affiliations

Estimate of Background Baseline and Upper Limit on the Chiral Magnetic Effect in Isobar Collisions at $s_{NN} = 200$ GeV at the Relativistic Heavy-Ion Collider