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Nuclear Theory·nucl-th

Friday·October 24, 2025

7 papers—4 primary·3 cross-listed

All7Primary4Cross-lists3
  1. 01

    Computing nuclear response functions with time-dependent coupled-cluster theory

    Francesca Bonaiti🇺🇸 · Cody Balos🇺🇸 · Kyle Godbey🇺🇸 · Gaute Hagen🇺🇸 · Thomas Papenbrock🇺🇸 · Carol S. Woodward🇺🇸

    We compute nuclear response functions by solving the time-dependent A-body Schrödinger equation, recording the time-dependent transition moment and extracting spectral information via Fourier transforms. The solution of the time-dependent many-body problem accounts for correlations on top of the mean field by taking advantage of a time-dependent formulation of coupled-cluster theory. As a validation, we focus on electric dipole transitions in He and O and compare moments of the response function distribution to the results of an equivalent static framework, finding negligible discrepancies. We investigate how proton and neutron densities evolve in time, and we see the traditional picture of soft and giant dipole resonances as collective oscillations of protons and neutrons emerging from our calculations in O and O. This method also allows us to investigate the behavior of the nucleus in the presence of a strong electric field. In that regime, the behavior of the system becomes chaotic. Qualitatively, the spectral information obtained in this limit is in line with previous time-dependent mean-field results.

    nucl-thnucl-exPRC(2026)·4 citations
  2. 02

    Nuclear Fragmentation at the Future Electron-Ion Collider

    Carlos A. Bertulani🇺🇸

    We investigate aspects of low-energy nuclear reactions that could be explored at the forthcoming Electron-Ion Collider (EIC) at Brookhaven National Laboratory and compare them with analogous measurements performed in ultraperipheral collisions (UPCs) at the Large Hadron Collider (LHC) at CERN. The estimated fragmentation cross sections at the EIC are roughly three orders of magnitude smaller than those observed at the LHC. At the LHC, uranium nucleus fragmentation exhibits a distinctive double-peaked mass spectrum arising from fission processes, whereas at the EIC, the breakup pattern is mainly characterized by neutron evaporation and a vastly reduced yield of fission fragments, about four orders of magnitude fewer events in comparison.

    nucl-thEPJ Web Conf.(2026)·0 citations
  3. 03

    Probing Neutron Skin through Event-by-Event Pion Asymmetry in Heavy-ion collisions

    Xu-Hua Tian🇨🇳 · Long-Gang Pang🇨🇳

    In this work, we propose a novel approach for probing the neutron skin thickness of gold (Au) by analyzing the event-by-event distribution of and yield differences. This is achieved through SMASH simulations of ultra-peripheral Au+Au collisions at GeV. Our results demonstrate that the mean value of , along with the Pearson correlation and mutual information between and , all scale linearly with the neutron skin thickness. Moreover, the slope of the line connecting two distinct values in the event-by-event distribution also exhibits a linear dependence on the neutron skin thickness. The most sensitive pairs are identified as , , , and . These findings establish a new pathway for determining the neutron skin thickness. Finally, by comparing SMASH and UrQMD simulations under identical initial conditions, we observe that individual slope values depend on the specific collision model. However, by extracting slopes from multiple pairs in experimental event-by-event data and inferring the corresponding neutron skin thickness, one can assess which model better aligns with the true physical value.

    nucl-thhep-th1 citation
  4. 04

    Data-driven exploration of the neutron pairing gap using Cassiopeia A neutron star observational data: Direct minimization

    Yoonhak Nam🇯🇵 · Kazuyuki Sekizawa🇯🇵

    The rapid cooling observed in the Cassiopeia~A neutron star (Cas~A NS) is one of the most stringent tests for neutron-star cooling theory. While Cooper-pair breaking and formation (PBF) neutrino emission is a leading candidate, uncertainties remain regarding the PBF efficiency factor and the neutron pairing gap. This work explores in a data-driven manner how the optimized gap shape responds to variations of the PBF emissivity parameter within a fixed cooling setup. We introduce a novel gap parametrization, in which each parameter carries direct physical meaning and controls the gap amplitude, peak location, width, and asymmetry. Using a Fortran-based cooling code and the BSk24 equation of state, we perform parameter-space exploration guided by the Cas~A NS data. Global optimization is carried out with Optuna's tree-structured Parzen estimator, followed by local refinement using the Nelder--Mead method. The optimized solutions yield physically reasonable gaps with peak amplitudes --. Although the multi-objective formulation explores the parameter space more broadly, the single-objective -only optimization achieves the lowest . For , increasing drives the optimized gap and critical-temperature profiles toward smoother and more localized shapes, improving consistency with the observed trend. Models with reproduce the decline rate within the confidence interval, whereas the baseline case lies near the level. Our results suggest larger effective PBF emissivities than the baseline estimate, although robust constraints on require future Bayesian inference including uncertainties in mass, envelope composition, equation of state, pairing microphysics, and age offset. (Shortened due to the arXiv abstract length limit.)

    nucl-thastro-ph.HEcond-mat.quant-gasPRC(2026)·3 citations
  5. 05

    Impact of the nuclear equation of state on the explodability of massive stars

    Jade Powell · Bernhard Müller🇦🇺

    In recent years, astrophysical observations have placed tight constraints on key properties of the nuclear equation of state (EoS). Using 93 two-dimensional simulations for three different EoS compatible with the current tight constraints, we show that the EoS remains a major uncertainty for the outcome of core-collapse supernovae. Whereas explosions are obtained in most cases for the SFHo and SFHx EoS, for the CMF EoS, which includes a crossover from nucleonic matter to a quark phase, explosions occur only for 2 out of 15 progenitors. Less favourable conditions for neutrino-driven explosions arise for the CMF EoS due to lower neutrino luminosities and mean energies and slightly weaker contraction of the warm proto-neutron star. Our results suggest that the explodability of massive stars cannot yet be predicted based on first principles without better knowledge of the nuclear EoS. Conversely, observational constraints on stellar explodability may help further constrain the EoS.

    ↳ astro-ph.HEnucl-thPRD(2026)·12 citations
  6. 06

    Probing the Three-dimension Emission Source and Neutron Skin via - Correlations in Heavy-Ion Collisions

    Haojie Zhang🇨🇳 · Junhuai Xu🇨🇳 · Pengcheng Li🇨🇳 · Zhi Qin🇨🇳 · Dawei Si🇨🇳 · Yijie Wang🇨🇳 · Yongjia Wang🇨🇳 · Qingfeng Li🇨🇳 · Zhigang Xiao🇨🇳

    The Richardson-Lucy algorithm is applied to reconstruct the three-dimensional source function of identical pions from their two-particle correlation functions. The algorithm's performance is first evaluated through simulations with Gaussian-type initial source functions. Its imaging quality and robustness are further demonstrated with experimental data from Au+Au collisions at 1.23 A GeV, collected by the HADES Collaboration. Additionally, using UrQMD simulations of Pb+Pb collisions at 1.5 A GeV, we show that the deblurred source functions exhibit sensitivity to the initial neutron skin thickness of the colliding nuclei. This highlights the potential of the Richardson-Lucy algorithm as a tool for probing the neutron density distribution in heavy nuclei.

    ↳ nucl-exnucl-thPRC(2026)·4 citations
  7. 07

    A Microphysical Probe of Neutron Star Interiors: Constraining the Equation of State with Glitch Dynamics

    Zhonghao Tu🇨🇳 · Ang Li🇨🇳

    Glitches in neutron stars originate from the sudden transfer of angular momentum between superfluid components and the observable crust. By modeling this glitch dynamics--including vortex motion, mutual friction, and angular momentum exchange--one may hope to probe the dense matter equation of state. In this work, we explore, within a highly idealized three-component framework, whether the glitch rise could in principle carry information about microphysical inputs such as entrainment and mutual friction. We compute the glitch rise in response to self-consistently calculated microphysical parameters (pinning and mutual friction) based on unified equations of state, and compare theoretical predictions of the overshoot patterns and timing residuals to the 2016 Vela glitch. Within this specific framework, the models favor crustal superfluid coupling on timescales of order s, overshoot behavior in the core associated with relatively strong central mutual friction, and rise times consistent with the observed upper limit of 12.6 s. Using a Markov Chain Monte Carlo analysis of the timing residuals, we then map the regions of parameter space that are compatible with the data under our adopted assumptions. Our analysis favors comparatively weak entrainment in the inner crust and an overall core mutual friction that is weaker than that in the inner crust. These exploratory results demonstrate that, under such restrictive assumptions, glitch-rise morphology is sensitive to microphysical inputs and that future high-cadence timing observations, interpreted with more realistic dynamical models, could potentially help constrain the internal dynamics and composition of neutron stars.

    ↳ astro-ph.HEastro-ph.SRnucl-thApJ(2026)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE