Nuclear Theory·nucl-th

Thursday·July 10, 2025

8 papers—4 primary·4 cross-listed

01
New approach for the quantification of uncertainties in reaction modeling via data-driven multi-objective optimization
N. Dimitrakopoulos · G. Perdikakis · F. Montes · P. Gastis · S. A. Kuvin · H. Y. Lee · P. Tsintari · A. V. Voinov
We introduce a new multi-objective optimization approach to determine uncertainty-quantified nuclear reaction parameters in the Hauser-Feshbach framework. By simultaneously accounting for all available data across multiple reaction channels we capture parameter correlations and estimate data-driven uncertainties. We implement in the Ni-Ge region yielding uncertainty-quantified model parameters for both stable and unstable isotopes. We estimate resonance spacings for nuclei beyond experimental reach and validate our method by calculating a known cross-section outside our optimization region.
nucl-th1 citation
02
Ferromagnetic instabilities in quarkyonic matter
Bikai Gao🇯🇵 · Kenichi Yoshida🇯🇵
We investigate the magnetic properties of quarkyonic matter, which naturally bridges nuclear and quark matter at intermediate densities relevant to neutron star cores. We extend the quarkyonic model to include spin polarization, where nucleons near the Fermi surface can be polarized while quarks in the deep Fermi sea remain unpolarized due to strong Pauli blocking. After including neutron interactions with spin-dependent terms, we find that quarkyonic matter can develop ferromagnetic instabilities at low densities, characterized by negative magnetic susceptibility. This ferromagnetic behavior occurs in pure neutron matter, independent of proton contributions, and results from the competition between attractive spin-dependent interactions and kinetic energy costs. The system returns to paramagnetic behavior at higher densities when Pauli pressure dominates. Our results demonstrate that the splitting of Fermi momenta of quarkyonic matter produces fundamentally different magnetic responses compared to conventional nuclear matter, with important implications for neutron star magnetism and magnetar physics.
nucl-thPRC(2025)·5 citations
03
Asymptotic behavior of the Speed of Sound in Dense Matter
Udita Shukla🇵🇱 · Pok Man Lo🇵🇱
We show that a class of NJL-like models fails to reproduce the expected conformal limit of the speed of sound, making them unsuitable for analyzing the equation of state of dense matter. We then demonstrate how this issue can be resolved within a simple dynamical quark model.
nucl-thastro-ph.HEhep-phActa Phys.Polon.Supp.(2025)·3 citations
04
Does HESS J1731-347 have a thick crust ?
Sebastian Kubis · Włodzimierz Wójcik
A relativistic mean-field model with a crossing term of isovector-scalar and isoscalar mesons, the Cracow crossing terms (CCT) model, has previously been shown to be capable of explaining the light and compact object HESS J1731-347. Here, the model is supplemented with a correct treatment of the phase transition. Applying the thermodynamically consistent Gibbs conditions shows that a mixed-phase system occurs in the core of the neutron star over a wide range of densities, extending up to the neutron star crust, leading to an intriguing stellar structure with a thick and massive crust.
nucl-thastro-ph.HEastro-ph.SR2 citations
05
High-Dimensional Unfolding in Large Backgrounds
Alexandre Falcão🇳🇴 · Adam Takacs🇩🇪
We propose new methodologies in multi-dimensional unfolding in dense environments, and show that incorporating auxiliary observables can significantly improve performance. Our approach builds on the ML-based OmniFold algorithm, which we extend to account for background, detector acceptance, efficiency, and uncertainties, enabling its application in high-luminosity and heavy-ion collision settings. We derive this algorithm and demonstrate its mathematical and numerical equivalence to expectation-maximization and Iterative Bayesian Unfolding (IBU). We illustrate our method with a realistic jet substructure analysis incorporating both large background and detector simulation. Our analysis includes up to 18 observables, leading to significantly improved performance in the unfolding. We propose a method that integrates calibration and unfolding into a single, consistent framework, and demonstrate enhanced performance relative to traditional methods. These developments lay the groundwork for robust, high-dimensional, ML-based unfolding and calibration in complex collider environments across a wide range of analyses.
↳ hep-phhep-exnucl-exnucl-thJHEP(2026)·7 citations
06
Chiral symmetry breaking and pion condensation in the early universe
Osvaldo Ferreira🇧🇷 · Eduardo S. Fraga🇧🇷 · Maurício Hippert🇧🇷 · Jürgen Schaffner-Bielich🇩🇪
We determine the possible trajectories the universe may have followed in the QCD phase diagram during the QCD epoch. We focus on the roles of chiral symmetry breaking and pion condensation under high imbalances in lepton asymmetry. Adopting the quark-meson model as an effective description of QCD at finite temperature, charge and baryon chemical potentials we show that, for sufficiently large but physically motivated asymmetries, the universe may have entered the pion condensation phase through a first-order phase transition, followed by a second-order phase transition when exiting it. Such a first-order phase transition represents a new possible source of primordial gravitational waves during the QCD epoch.
↳ hep-phnucl-thPRD(2025)·11 citations
07
Two-flavor color superconductivity in a general Nambu-Jona-Lasinio model with color and charge neutrality
Li-Kang Yang🇨🇳 · Di-Sheng Fan🇨🇳 · Cheng-Ming Li🇨🇳 · Yong-Liang Ma🇨🇳
By using a general NJL model including as many interaction channels as possible, and taking into account the constraints imposed by color and charge neutrality, we analyze how the different interaction channels contribute to the charge-neutral two-flavor color-superconducting matter. After taking the Fierz transformation, the number of parameters in the NJL model is reduced and thereby quark-antiquark condensates and diquark condensates are related. Through a self-consistent solution of the gap equations, we find that in addition to the diquark and vector channels, the scalar-isovector, vector-isovector, and vector-isovector-color-octet channels are also important, while other channels can be neglected. Moreover, between the normal quark matter phase and two-flavor color-superconducting phase, there is a gapless two-flavor color-superconducting phase. The fractions of quarks with different flavors and colors are calculated in both gaped and gapless two-flavor color-superconducting phases. In addition, We illustrate the phase diagrams in the diquark coupling and chemical potential plane, and discuss in detail how the dominant channels influence these phase diagrams.
↳ hep-phnucl-thPRD(2025)·8 citations
08
Transition from weak to strong coupling in thermal gauge theories: Lessons from $N = 4$ SYM Theory
Berndt Müller🇺🇸
We investigate the transition between weak and strong coupling in thermal $N = 4$ supersymmetric Yang-Mills (SYM) theory as a function of 't Hooft coupling $λ$ for several quantities of phenomenological interest for which next-to-leading order calculations are available in both regimes. We use Padé approximants to interpolate between the weak and strong coupling expansions and determine the location and width of the transition between the asymptotic regimes.
↳ hep-thhep-phnucl-thPRD(2025)·4 citations

Affiliations

first authorsco-authorsvia INSPIRE