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Nuclear Theory·nucl-th

Friday·December 5, 2025

10 papers—7 primary·3 cross-listed

All10Primary7Cross-lists3
  1. 08

    Nucleon to Roper transition amplitudes and electromagnetic form factors

    G. Ramalho🇰🇷

    The second excitation of the nucleon, the Roper, has properties differentiated from other low-lying nucleon resonances. Their properties challenge our understanding of the structure of the baryons in terms of the degrees of freedom from QCD. In the present work we discuss the properties of the Roper resonance and the nucleon to Roper electromagnetic transition, based on the quark degrees of freedom, that are expected to dominate for large square momentum transfer . We also discuss the analytic structure of the transition amplitudes in the low- region, and how the contributions of baryon-meson states can help to describe the low and intermediate data, and the nature of the Roper.

    ↳ hep-phhep-exhep-latnucl-ex+1Acta Phys.Polon.B(2026)·1 citation
  2. 09

    Internal superfluid response and torque evolution in the giant glitch of PSR J1718-3718

    Peng Liu · Zhonghao Tu · Jianping Yuan · Ang Li

    We investigate the post-glitch rotational evolution of pulsars by analyzing the 2007 giant glitch of PSR J17183718 using a vortex creep model that incorporates both inward and outward nonlinear vortex motion, along with a time-varying external torque. A comprehensive fitting framework is developed, constrained by prior knowledge of moment of inertia participation from previous glitch studies. We apply a Markov Chain Monte Carlo approach to quantify uncertainties and parameter correlations. The model reproduces the observed timing data and yields physically consistent values for moment of inertia fractions and creep timescales. Our results indicate that inward creep and a long-term change in external torque dominate the observed increase in spin-down rate, pointing to structural changes within the star-likely triggered by a crustquake that initiated both vortex motion and a change in the moment of inertia. We estimate that the glitch involved approximately inward-moving vortices and crustal plates with a typical size of km. This study demonstrates that detailed post-glitch modeling of sparse timing data can simultaneously constrain internal superfluid dynamics and external torque evolution, providing a quantitative framework to probe the structural properties of neutron star interiors.

    ↳ astro-ph.HEastro-ph.SRnucl-th1 citation
  3. 10

    Geometry of particle emission in UrQMD Ar+Sc collisions at SPS energies

    Barnabas Porfy🇭🇺 · Mate Csanad🇭🇺

    Over the past few decades, progress in femtoscopy has been driven by the interplay between experimental measurements and theoretical calculations. Measurements provide data to support the theory, while theoretical predictions guide new measurements. In the recent decade, several experiments have confirmed that the two-particle pion-emitting source is well described by Lévy alpha-stable distributions. To enable theoretical interpretation, phenomenological simulations have been done at RHIC and LHC energies, in large systems such as Au+Au or Pb+Pb, using various available heavy-ion collision models. However, such simulations have not been done in intermediate systems. In this paper, we investigate three-dimensional two-pion pair source distributions from Ar+Sc central collisions at SPS energies, generated with the Ultra-Relativistic Quantum Molecular Dynamics Monte-Carlo event generator. Supplemented by a validation of the simulated hadronic spectra, we find that the pair source can be described with Lévy-stable distributions. We subsequently interpret the physical meaning of the extracted Lévy parameters corresponding to the spatial scale, shape, and strength of the source. Our results form a baseline for future experimental measurements in intermediate systems.

    ↳ hep-phnucl-thPLB(2026)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE