Nuclear Theory·nucl-th

Tuesday·August 25, 2026

22 papers—9 primary·13 cross-listed

01
[Submitted on 22 Aug 2026]
QCD phase transition at finite isospin density and magnetic field within the three-flavor NJL model
Gaoqing Cao
Previously, the QCD phase transition at finite isospin density and magnetic field was explored within the two-flavor Nambu--Jona-Lasinio model. This work extends the study to the more realistic three-flavor case, where not only strange quark contributions but also quark mass splitting in a strong magnetic field are fully taken into account. Adopting the Ginzburg-Landau approximation and the Landau representation for fermion propagators, we re-explore the transitions from the normal chiral symmetry breaking phase to pion superfluidity or rho superconductivity. Unlike the previous study, we project the mesonic fields onto the eigenstates of a charged point particle in a magnetic field and prove that the corresponding self-energies from quark loops are gauge invariant and degenerate with respect to the extra transverse degrees of freedom. However, the numerical results are qualitatively consistent with previous findings: as the isospin chemical potential increases, pion superfluidity is favored at small magnetic fields, while rho superconductivity is favored at large magnetic fields. In the three-flavor model, since the lowest energy of the rho meson increases with stronger magnetic field, the corresponding critical isospin chemical potential also increases with the magnetic field.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2608.21996 [pdf]
0 citations
02
[Submitted on 23 Aug 2026]
Constraining hyperonic relativistic mean-field models with rapidly rotating neutron stars
Gihwan Nam · Prashant Thakur · Yeunhwan Lim · Jeremy W. Holt
Motivated by the recent mass measurement of the black-widow pulsar PSR~J0952 $-$ 0607 with $M = 2.35 \pm 0.11 M_{⊙}$ , we investigate how the masses of heavy, rapidly rotating millisecond pulsars can be used to constrain relativistic mean-field (RMF) models containing hyperonic degrees of freedom. In our approach, hyperons are incorporated following the spin-flavor SU(6) symmetry scheme for the vector-meson couplings. We find that increasing the nonlinear $ω$ -meson vector self-coupling parameter $ζ$ suppresses the hyperon fraction and can alter the onset ordering of the $Σ^{-}$ and $Ξ^{-}$ hyperons. By computing rotating neutron-star configurations at the observed spin frequency $707 Hz$ of PSR~J0952 $-$ 0607, we identify RMF models compatible with this pulsar's observed lower-mass bound. Using an empirical relation for the maximum neutron star mass, the PSR~J0952 $-$ 0607 observational contraint is mapped onto the allowed RMF parameter space in $n_{0}$ , $m^{*}$ , and $ζ$ .
Comments:
19 pages, 12 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2608.22392 [pdf]
0 citations
03
[Submitted on 24 Aug 2026]
Ab initio anatomy of quadrupole correlations in $^{16}$ O and $^{20}$ Ne
Chenrong Ding · Benjamin Bally · Stavros Bofos · Thomas Duguet · Yi Li · Jiangming Yao
Azimuthal hadronic flow measured in ultra-relativistic ion--ion collisions provides a new means of imaging multipole correlations in the ground state of atomic nuclei. Early interpretations largely relied on a classical-rotor picture, in which the measured mean-square elliptic flow is directly related to an intrinsic quadrupole deformation. Atomic nuclei, however, contain additional many-body correlations generated by the Pauli exclusion principle, collective shape fluctuations and non-collective dynamical processes, whose impact on this correspondence has not yet been elucidated. Here, we resolve this issue through an ab initio analysis of $^{16}$ O and $^{20}$ Ne based on chiral nuclear interactions, combining the in-medium similarity renormalization group with the quantum-number-projected generator coordinate method. By successively isolating antisymmetrization, collective rotational and vibrational, and non-collective dynamical correlations, we determine, for the first time, how each component contributes to the mean-square quadrupole eccentricity. We uncover an unexpected compensation among these distinct correlation mechanisms: despite sizable individual contributions, the squared effective quadrupole deformation inferred from the elliptic flow remains close to the square intrinsic deformation of the nucleus. This result provides a microscopic explanation for the surprising success of the classical-rotor approximation and establishes a quantitative foundation for interpreting $^{16}$ O+ $^{16}$ O and $^{20}$ Ne+ $^{20}$ Ne collision data recently collected at the Large Hadron Collider.
Comments:
5+1 pages with 3+3 figures, suggestions and comments are welcome
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2608.22699 [pdf]
0 citations
04
[Submitted on 24 Aug 2026]
Effects of femtoscopic correlations on spin-spin correlation measurements
Bijun Fan · Like Liu · Shusu Shi
Hyperon spin correlations serve as sensitive probes of spin dynamics in high-energy collisions, yet their extraction from weak-decay angular distributions can be contaminated by femtoscopic effects due to quantum statistics and final-state interactions. In this work, we quantitatively assess this contamination for $ΛΛ$ and $Λ Λ ˉ$ pairs using the AMPT model combined with spin-dependent weights from the Lednický--Lyuboshits formalism. Because the singlet and triplet spin configurations contribute differently to the decay-angle distribution, femtoscopic weighting induces an apparent angular modulation, creating a fake correlation signal even when no intrinsic spin correlation is present. We find that the induced bias can become substantial in the low- $q_{inv}$ region, where the combined femtoscopic effect reaches a magnitude comparable to that of the preliminary CMS measurements. Our results establish a framework for evaluating such systematics, highlighting that femtoscopic corrections must be carefully considered in future differential analyses that emphasize the low-relative-momentum region.
Comments:
10 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2608.22707 [pdf]
0 citations
05
[Submitted on 24 Aug 2026]
Nuclear excitation by radiative electron-ion recombination
Jingyan Zhao · Yuanbin Wu
A nuclear excitation mechanism, nuclear excitation by radiative electron-ion recombination (NERER), is put forward theoretically here. NERER is a third-order process that proceeds via a virtual electronic state: an electron recombines into an atomic vacancy of an ion with the simultaneous emission of a real photon and excitation of the nucleus. The photon emission compensates the energy mismatch between the free-bound electronic transition and the nuclear transition energies, thus there is no resonant condition imposed to the incident electron. We develop here the theoretical framework for NERER, and investigate the case of the $8.4$ eV isomeric excitation of $^{229}$ Th for the production of the nuclear clock isomer $^{229 m}$ Th. Our results show that, with the coupling to the inner atomic shells for highly-charged ions, the NERER cross section can exceed the one of the known lower-order process of nuclear excitation by inelastic electron scattering by more than one order of magnitude. Our findings offer a new pathway for nuclear excitation and efficient isomer production, and support further investigations for high-order effects in the interplay between the atomic and nuclear systems.
Comments:
9 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2608.22803 [pdf]
0 citations
06
[Submitted on 24 Aug 2026]
Microscopic study of quasifission dynamics in hot fusion reactions for synthesizing superheavy nuclei with Z = 112-120
Xiangquan Deng · Lu Guo
In the synthesis of superheavy element (SHE) via heavy-ion fusion reactions, quasifission is one of the major factors hindering superheavy nuclei (SHN) formation and the mechanism behind this process is intricate. We investigate dynamics of quasifission in hot fusion reactions synthesizing SHN with Z = 112-120 using microscopic time-dependent Hartree-Fock theory in a total of 18 reactions. Remarkably, the nucleon numbers of heavy fragments distribute closely around certain quantum shells in these reactions, highlighting the crucial role of shell effects in fragment formation. In the reactions with 48Ca, 45Sc, 50Ti and 51V projectiles, the formation of heavy fragment is dominantly driven by the double spherical shells of 208Pb. In contrast, the influence of the double octupole deformed shells at Z = 88 and N = 136 is more pronounced in 54Cr-induced reactions, resulting in a tendency of producing pear-shaped 224Ra heavy fragment. Moreover, in the reaction with a heavier projectile, the colliding system tends to undergo a more rapid quasifission. This may be responsible for significantly reduced fusion probability and synthesis cross section observed in the reactions with projectiles heavier than 48Ca. These results elucidate quasifission mechanisms behind the reactions for synthesizing new SHEs Z = 119 and Z = 120.
Comments:
accepted by Physics Letters B, in press
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2608.22947 [pdf]
0 citations
07
[Submitted on 24 Aug 2026]
Signed Sound-Speed Deformations of BSk24-Anchored Barotropes: Neutron-Star Response
Ioannis Papathanasiou
Background: Localized structure in the equilibrium squared sound speed can affect neutron-star observables, but modifying $d P / d ϵ$ requires thermodynamically consistent reconstruction and assessment over the complete declared domain. Purpose: We quantify the response to positive and negative localized sound-speed changes around a unified BSk24 baseline while keeping the deformation geometry, admission criteria, reconstruction, and fixed-mass comparison protocol fixed. Method: A Gaussian profile with quintic smootherstep activation is added to $c_{s}^{2}$ . Proposals violating $P > 0$ or $0 < c_{s}^{2} \leq 1$ anywhere in the retained domain are rejected before reconstruction. Passing cases are reconstructed as effective cold one-fluid barotropes and evolved with the Tolman-Oppenheimer-Volkoff and tidal equations. Results: The $A = 0$ case reproduces the undeformed control exactly. A localized change produces a persistent pressure offset, relocates the fixed-mass central state, and yields a mass-dependent, nonlinear, sign-asymmetric response. For $A = - 0.8$ and $+ 0.8$ , respectively, $ΔΛ/ Λ_{0} = (- 46.02%, + 35.33%)$ at $1.4 M_{⊙}$ and $(- 63.52%, + 87.17%)$ at $2.0 M_{⊙}$ . The reached stiffened feature remains core connected at the reporting endpoints, whereas the softened feature becomes an off-center shell at high mass. Conclusions: These phenomenological BSk24-anchored effective barotropes illustrate how a local sound-speed intervention propagates through thermodynamic reconstruction and stellar structure. They are not BSk24 predictions or evidence for a microscopic composition or phase transition.
Comments:
19 pages, 10 figures, 6 tables; includes appendices and reproducibility metadata
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
2608.23033 [pdf]
0 citations
08
[Submitted on 24 Aug 2026]
Modeling quasielastic lepton-nucleus interactions with ab initio spectral functions from infinite nuclear matter
Alma L. Cavallin · Francesco Marino · Joanna E. Sobczyk
We present a study of quasielastic lepton-nucleus scattering within the local density approximation, using ab initio spectral functions from infinite nuclear matter derived with self-consistent Green's functions theory and interpolated by neural networks. We include final-state interactions in terms of the particle spectral function and investigate the importance and range of validity of this treatment for varying momentum transfer. The performance of the model is tested for inclusive electron scattering on different isospin-symmetric target nuclei, and we present results for $^{12}$ C, $^{16}$ O, and $^{40}$ Ca. Theoretical uncertainties originating from the neural network interpolation and the Hamiltonian dependence are assessed. We also present a calculation of charged-current responses of $^{16}$ O and the flux-averaged total $ν_{μ} -^{12}$ C cross section. Our model shows good agreement with experimental data within the range of validity of our approximations. The framework can be readily extended to include additional dynamical mechanisms, such as pion production, as well as other nuclear Hamiltonians.
Comments:
14 pages, 10 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Theory (hep-th)
arXiv:
2608.23057 [pdf]
0 citations
09
[Submitted on 24 Aug 2026]
Open Quantum Systems Approaches for Heavy-Ion Collisions
Alexander Rothkopf
In this contribution to Strangeness in Quark Matter 2026, I review the open quantum systems approach, a modern theoretical framework for addressing the interaction of a quantum system with its environment, and highlight recent progress in its application to the understanding of in-medium heavy quarkonium in relativistic heavy-ion collisions.
Comments:
9 pages, 5 figures; invited plenary talk at the Strangeness in Quark Matter 2026 conference, March 27th 2026, UCLA, Los Angeles, USA
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2608.23147 [pdf]
0 citations

Affiliations

first authorsco-authorsvia INSPIRE