Searcharxiv⌕ Search
Home/Archive/arXiv

arXiv · 2609.34338

Medium effects on neutron star modified and direct Urca cooling rates

B. X. Zhou·Jin-Biao Wei·Z. H. Li·G. F. Burgio·H. -J. Schulze
View original source ↗Read source document ↗Export metadata ↓

Abstract

We study the effects of in-medium modification of the elementary cooling processes on observable properties of isolated neutron stars. We then deduce the neutron star mass distributions compatible with the cooling analysis and compare with current theoretical models. We conclude that current cooling data require fast direct Urca (DU) cooling, moderated by proton superfluidity, to be active in most neutron stars, and that the DU onset threshold must lie below canonical masses. In that case medium modifications of modified Urca (MU) rates are practically insignificant, but the $nn$ Bremsstrahlung rate plays a dominant role.

Explore related subjects

nucl-thastro-ph.HE

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

B. X. Zhou, Jin-Biao Wei, Z. H. Li, G. F. Burgio, H. -J. Schulze. 2026-09-28. Medium effects on neutron star modified and direct Urca cooling rates. https://arxiv.org/abs/2609.34338

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Electromagnetic form factors of ${}^7$Li and ${}^7$Be in cluster effective field theory

Effective field theory (EFT) provides a powerful model-independent theoretical framework for illuminating complicated interactions across a wide range of physics areas and subfields. In this work, we study the electromagnetic form factors of Lithium-7 and Beryllium-7 at low momentum transfers in cluster EFT, treating the nuclei as triton-Helium-4 and helion-Helium-4 bound states. We demonstrate how to directly extract the asymptotic normalization coefficients from the experimental measurements of charge radii, and use them to calculate several electromagnetic observables of these nuclei.

nucl-th↗
arXiv2026

Trace Anomaly and Effective Topological Sources in Neutron Stars

This work investigates whether the trace anomaly can diagnose the stellar response to a topological scalar field in tensor multi-scalar gravity. Eleven cold tabulated equations of state (EoSs) were examined, with six selected after conservative GR stability and speed of sound checks over the tabulated density range. Their fiducial topological configurations were compared with the corresponding GR models under complementary matching prescriptions. After controlling for stellar mass and EoS dependence, the GR trace source strength $S_T$ remained strongly correlated with the topological mass response, with a partial Spearman coefficient $ρ= 0.975$ within the sampled fiducial sequences. Near $1.4\,M_\odot$, the topological configurations were systematically more compact, with reductions in the Jordan frame radius of $6.7$--$8.7\%$ at fixed baryonic mass and $0.87$--$1.29\,\mathrm{km}$ at fixed gravitational mass. These shifts are comparable to current uncertainties from the Neutron Star Interior Composition Explorer (NICER) and their observational impact depends on the source. Despite the global deformation, the interior effective source remained dominated by matter, with a median topological contribution of about $0.8\%$. The GR matter trace therefore emerges as a useful diagnostic of the fiducial topological stellar response.

nucl-th↗
arXiv2026

BRST quantization for the restoration of broken symmetries: a pedagogical example

We present a pedagogical showcase of BRST quantization for restoring symmetries in nuclear many-body systems as a reformulation and potential alternative to conventional projection methods. The formalism is illustrated using translational invariance for a simple system of two interacting masses in one dimension, but with an eye toward generalizing to more particles, higher dimensions, and other symmetries. We explain the considerations underlying particular choices within the BRST construction, and develop both Hamiltonian and path integral formulations to provide guidance for the variety of many-body and effective field theory contexts where gauge fixing for symmetry restoration might be useful. For the demonstration system we show how to diagonalize within the extended BRST phase space, how variation after projection is recovered for product reference states, how the corresponding gauge-fixed functional integral is constructed, and how collective zero modes are isolated and controlled. Throughout, we keep in mind extensions of BRST symmetry to various approximation schemes as a guide for consistent symmetry restoration.

nucl-th↗