Nuclear Theory·nucl-th

Friday·June 26, 2026

9 papers—6 primary·3 cross-listed

01
[Submitted on 24 Jun 2026]
Studying the QCD Matter produced in Heavy-Ion Collisions using the MUSES Calculation Engine
Johannes Jahan · Kevin P. Pala · Yumu Yang · Isabella Danhoni · Prachi Garella · Jonathan Gonzales · Joaquin Grefa · Mauricio Hippert · Surkhab Kaur Virk · Micheal Kahangirwe · Musa R. Khan · Feyisola Nana and 33 other authors
The equation of state of hot and dense matter is essential for describing heavy-ion collisions at all collision energies. Here, we explore the capabilities of the latest version of the MUSES Calculation Engine, $Calliope$ , focusing on software modules and workflows that compute the equation of state and observable properties of the matter produced in heavy-ion collisions. These include several equations of state, ranging from first-principles lattice QCD to phenomenological approaches, with or without a critical point, and with phase-space dimensionality ranging from two dimensions defined by temperature $T$ and baryon chemical potential $μ_{B}$ , to four dimensions after the addition of strangeness and electric-charge chemical potentials $μ_{S}$ and $μ_{Q}$ . We also discuss modules that provide additional thermodynamic quantities and observables relevant for heavy-ion modeling, including elements of the pressure Hessian matrix and transport coefficients. Workflow examples are constructed that merge two equations of state thermodynamically consistently to extend phase-diagram coverage, and feed the results into an equation of state inverter to produce inputs suitable for hydrodynamic simulations. Finally, we apply this framework to perform a relativistic viscous hydrodynamic simulation with equations of state with an extended $T$ and $μ_{B}$ coverage and a movable critical point, including effects from transport coefficients that phenomenologically encode critical scaling, at collision energies $s_{N N} = 7.7, 19.6$ , and $39$ GeV.
Comments:
58 pages, 31 figures; links to code repositories and associated MUSES calculation engine release will be made publicly available upon journal publication
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2606.26326 [pdf]
6 citations
02
[Submitted on 25 Jun 2026]
Thermal Effects on the Moment of Inertia and Gravitational Redshift of PSR J1012+5307: Implications for Hyperonic Matter under SU(3) and SU(6) Symmetries
Y.Xu🇨🇳 · X.L.Huang🇨🇳 · Y.B.Wang🇨🇳 · Q.Yuan🇨🇳 · W.B.Ding🇨🇳 · N.An🇨🇳 · Y.F.Shen🇨🇳 · Z.Yu🇨🇳
The temperature dependence of neutron star structure significantly alters the equation of state, thereby affecting observable properties such as the moment of inertia and gravitational redshift. Utilizing the relativistic mean-field theory with hyperonic degrees of freedom under SU(3) flavor and SU(6) spin-flavor symmetries, we investigate the thermal effects on the structural properties of protoneutron stars and cold neutron stars. Focusing on PSR J1012+5307, we analyze the drastic structural transformations occurring during the transition from a PNS to a CNS. For a 1.94 Msun hyperonic star under SU(3) flavor symmetry, decreasing the temperature from T =30 MeV to 0 MeV induces a radius contraction of approximately 50 percent, accompanied by a drop in the moment of inertia by nearly 26% and a significant increase in gravitational redshift by approximately 154 percent. Furthermore, we examine the variations in the moment of inertia and gravitational redshift arising from mass uncertainties of PSR J1012+5307.Taking SU(3) flavor symmetry at T =20 MeV as an example, increasing the mass across the range 1.72 Msun to 1.94Msun results in a radius contraction of 2.749 km, an 8 percent increase in the moment of inertia, and a significant 40 percent increase in the gravitational redshift.We find that in the cold regime and at a fixed mass, the radius, moment of inertia,and gravitational redshift of hyperonic matter under SU(3) flavor symmetry differ only marginally from those of purely nucleonic matter, rendering it difficult to observationally confirm the presence of hyperons in the core of PSR J1012+5307. Moreover, future observations capable of precisely constraining pulsar masses,ideally through long-termonitoring from birth,hold the potential to determine more conclusively whether hyperons or other exotic matter reside in individual pulsars.
Comments:
15 pages,3 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2606.26539 [pdf]
0 citations
03
[Submitted on 25 Jun 2026]
The $^{229}$ Th Isomer: Nuclear Structure, Clocks, and Tests of Fundamental Physics
Xiao Lu🇨🇳 · Rui Zhao🇨🇳 · Shan-Gui Zhou🇨🇳
The $^{229}$ Th nucleus possesses an isomeric state at an excitation energy of $\sim 8$ eV, the lowest known nuclear transition energy, placing its frequency in the vacuum-ultraviolet range and making it directly accessible to laser spectroscopy. In this review, we discuss the $^{229}$ Th isomer from three connected perspectives: experimental spectroscopy and clock development, nuclear structure theory, and applications to precision tests of fundamental physics. We first trace the experimental progress from indirect $γ$ -ray energy inference to resonant laser excitation, absolute frequency comparison with an atomic clock, and feedback-loop operation of a solid-state nuclear clock, and discuss trapped-ion, highly charged ion, and solid-state platforms together with mechanisms for nuclear-state manipulation and readout. We then review, from the nuclear-structure perspective, how the near-degeneracy of the $5/ 2^{+} [633]$ and $3/ 2^{+} [631]$ neutron Nilsson configurations, together with Coriolis mixing and octupole correlations, underlies the anomalously low transition energy and its electromagnetic properties. Comparisons among different phenomenological and microscopic models show that octupole correlations are a common structural ingredient, while magnetic moments and transition strengths remain sensitive tests of the calculated wave functions. Finally, we discuss how the near-cancellation of MeV-scale nuclear contributions into an eV-scale transition can enhance sensitivity to variations of fundamental constants, signatures of ultralight dark matter, CP-violating interactions, Lorentz-invariance violation, and possible nuclear quantum technologies.
Comments:
23 pages, 6 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2606.26600 [pdf]
Chin.Phys.B(2026)·1 citation
04
[Submitted on 25 Jun 2026]
Applicability of kinetic theory in strongly coupled thermal quantum systems
Shile Chen · Shuzhe Shi · Pengfei Zhuang
In this work, we construct one-dimensional interacting lattice spinor theories with discretization in momentum space. We focus on strongly interacting Schwinger and Nambu--Jona-Lasinio models and perform ab-initio calculation of their single-particle and two-particle momentum distribution functions at finite temperature. We observe, at low temperature, high-momentum tail in single-particle and two particle distribution which reveals relative momentum in fermion-antifermion boundstates, as well as quasi-free spinor gases behavior at high temperature. The non-vanishing connected four-momentum function reveals the quantum coherence in momentum space under thermal equilibrium of the system and indicate the single particle correlation would remember more microscopic details within a thermal system. Overall, for a high-enough temperature at which the thermal kinetic energy comparable with the interaction, we observe that the two-particle correlation is subdominant compared to the single particle distributions, which indicates the applicability of kinetic theory.
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2606.26696 [pdf]
0 citations
05
[Submitted on 25 Jun 2026]
Challenging chiral EFT with tritium beta decay
D.F. Ramirez Jimenez🇵🇱 · S. Heihoff🇩🇪 · J. Golak🇵🇱 · E. Epelbaum🇩🇪 · H. Krebs🇩🇪 · P. Reinert🇩🇪 · R. Skibinski🇵🇱 · K. Topolnicki🇵🇱 · H. Witala
We present a detailed investigation of tritium beta decay up to third order (N2LO) in chiral effective field theory (EFT) using the LENPIC interactions. Unlike existing studies, we use nucleon-deuteron scattering observables to fix the low-energy constant D that governs the strength of the short-range contributions to the exchange axial current operator and three-nucleon forces. Surprisingly, the resulting parameter-free predictions for the tritium Gamow-Teller reduced matrix element are found to considerably overestimate its empirical value. This result remains robust against reasonable variations of the pion-nucleon coupling constants and regularization scheme. A closer look at the size of the parameter-free long-range two-body contributions to the Gamow-Teller matrix element reveals the fine-tuned nature this observable in chiral EFT, which may partially explain the observed deviation. Our results indicate a considerable N2LO truncation uncertainty for tritium beta decay and point towards large higher-order two-body corrections. More definite conclusions await a complete fourth-order analysis of nucleon-deuteron scattering observables and tritium half-life.
Comments:
26 pages, 1 figure
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2606.26926 [pdf]
2 citations
06
[Submitted on 25 Jun 2026]
Rapidity-even directed flow splitting of protons and antiprotons as a probe of baryon stopping in relativistic heavy-ion collisions
Tribhuban Parida🇮🇳 · Sandeep Chatterjee🇮🇳
We compare the rapidity-even directed flow $v_{1}^{even}$ in Au+Au collisions at Beam Energy Scan (BES) energies for baryons and anti-baryons within a (3+1)-dimensional viscous relativistic hydrodynamics coupled to hadronic transport framework. The double-junction baryon stopping picture motivates a rapidity-even component in the baryon deposition in the initial state. We demonstrate that the split in the $v_{1}^{even}$ of protons and anti-protons is sensitive to the rapidity extension of the baryon deposition that we associate with the double junction baryon stopping. Particularly, we find that the mid-rapidity curvature $\frac{d ^{2} Δ v _{1}^{even} ( p - p ˉ )}{d y ^{2}} ∣_{y = 0}$ is a robust discriminator of the initial state baryon rapidity profiles. A simultaneous measurement of $Δ v_{1}^{even}$ and its curvature at mid-rapidity could constrain both the baryon diffusion strength and the baryon stopping profile, providing access to the physics of baryon stopping in relativistic heavy ion collisions.
Comments:
6 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2606.27156 [pdf]
1 citation

Affiliations

first authorsco-authorsvia INSPIRE

Studying the QCD Matter produced in Heavy-Ion Collisions using the MUSES Calculation Engine

Thermal Effects on the Moment of Inertia and Gravitational Redshift of PSR J1012+5307: Implications for Hyperonic Matter under SU(3) and SU(6) Symmetries

The 229Th Isomer: Nuclear Structure, Clocks, and Tests of Fundamental Physics

Applicability of kinetic theory in strongly coupled thermal quantum systems

Challenging chiral EFT with tritium beta decay

Rapidity-even directed flow splitting of protons and antiprotons as a probe of baryon stopping in relativistic heavy-ion collisions

Affiliations

The $^{229}$ Th Isomer: Nuclear Structure, Clocks, and Tests of Fundamental Physics