Nuclear Theory·nucl-th

Friday·March 20, 2026

7 papers—4 primary·3 cross-listed

01
[Submitted on 18 Mar 2026]
Calculation of the transport coefficients in neutron star
Utsab Gangopadhyaya🇮🇳 · Suman Pal🇮🇳 · Gargi Chaudhuri🇮🇳
In this work, we have calculated the transport coefficients: shear viscosity and thermal conductivity inside the neutron star core. Our calculation is based on the relativistic kinetic theory approach using a modified BUU equation for quasi-particles whose mass and the chemical-potential and thus in turn the Fermi surface varies with the baryonic density $ρ_{B}$ and the temperature of the medium, and we have used the relaxation time approximation. For the description of the hadronic matter inside the neutron star, we consider the relativistic mean field model with three different kinds of parameterizations. We have found that the shear viscosity is predominantly influenced by neutrons, while thermal conductivity is primarily dominated by electrons.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2603.18229 [pdf]
NPA(2026)·1 citation
02
[Submitted on 19 Mar 2026]
Primordial deuterium abundance from calculations of $p (n, γ)$ and $d (p, γ)$ reactions within potential-model approach
Nguyen Le Anh · Dao Nhut Anh · Hoang Thai An · Nguyen Gia Huy · Bui Minh Loc
The $p (n, γ)$ and $d (p, γ)$ reactions are key nuclear inputs for Big Bang nucleosynthesis. In this work, both reactions are analyzed within a consistent two-body potential framework based on the Malfliet-Tjon interaction, including contributions from both $E 1$ and $M 1$ transitions. A single scaling factor $λ$ controlling the low-energy scattering dynamics is constrained by the $p (n, γ)$ and propagated consistently to the $d (p, γ)$ . The obtained abundance, $D/H = 2.47 9_{- 0.177}^{+ 0.350} \times 1 0^{- 5}$ , is in good agreement with values inferred from metal-poor damped Lyman- $α$ systems. The modest variations of $λ$ lead to a significant change in the predicted $D/H$ ratio and light-element abundances.
Comments:
13 pages, 3 figures, 5 tables, accepted for publication in Physica Scripta
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2603.18717 [pdf]
Phys.Scripta(2026)·0 citations
03
[Submitted on 19 Mar 2026]
Matter radii from interaction cross sections using microscopic nuclear densities
A. J. Smith🇺🇸 · K. Godbey🇺🇸 · C. Hebborn🇺🇸 · W. Nazarewicz🇺🇸 · F. M. Nunes🇺🇸 · P.-G. Reinhard🇩🇪
Understanding how nuclear size evolves with the number of protons and neutrons tests our models of strongly interacting matter. The nuclear charge (and proton) radii accessible through electromagnetic probes carry fundamental information on the saturation density and nuclear correlations. The radii of the neutron distribution are more difficult to measure, but they are important for our understanding of the isovector properties of nuclei that depend on the proton-to-neutron asymmetry, and on extended nucleonic matter in neutron stars. Interaction cross sections offer one of the few direct experimental windows into the neutron radii of nuclei far from stability, but translating these measurements into reliable structural information requires an integrated theoretical framework that links structure and reactions with a rigorous treatment of uncertainty. In this work, we compute interaction cross sections by using uncertainty-quantified proton and neutron distributions obtained in the self-consistent nuclear Density Functional Theory (DFT) with the Fayans energy density functional. The resulting densities are used in a modernized Glauber reaction framework, which features the refit of nucleon-nucleon profile functions. Applying this pipeline to the existing data on the calcium isotopic chain, we find no evidence for the dramatic neutron swelling reported earlier. While focusing here on the Ca chain, the methodology proposed in this work is applicable to interaction cross section measurements across the nuclear chart and is well-suited for new experiments currently planned at leading rare isotope facilities.
Comments:
7 pages, 2 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2603.18862 [pdf]
1 citation
04
[Submitted on 19 Mar 2026]
Isentropic hybrid stars in the Nambu-Jona-Lasinio model: effects of neutrino trapping
Andrea Sabatucci🇵🇱 · Armen Sedrakian🇵🇱
Binary neutron star mergers and proto-neutron stars provide unique environments where dense matter is hot, lepton rich, and potentially undergoes a transition from hadronic to deconfined quark matter. We investigate the thermodynamics and stellar properties of hybrid matter under such conditions. The hadronic phase is described within a covariant density functional framework, while the quark phase is modeled using a Nambu-Jona-Lasinio (NJL) model that includes repulsive vector interactions, the axial $U_{A} (1)$ -breaking 't Hooft determinant interaction, and two-flavor color-superconducting (2SC) pairing. The phase transition between hadronic and quark matter is constructed using a mixed-phase prescription that enforces baryon and lepton number conservation, allowing us to follow thermodynamic trajectories at fixed entropy per baryon and fixed lepton fraction. We analyze the phase structure of dense matter at finite temperature and study the composition of the hadronic, mixed, and quark phases in both neutrino-trapped and neutrino-free regimes. Our results show that neutrino trapping significantly modifies the particle composition and shifts the onset of deconfinement to higher densities. Using the resulting equations of state, we compute static stellar configurations and examine the influence of temperature and lepton content on the mass-radius relation of hybrid stars. Hot, neutrino-rich configurations are found to have larger radii and slightly higher maximum masses than their cold counterparts.
Comments:
V3: Minor correction to Figure 5, conclusion and discussion unchanged. Published: 26 May 2026
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
2603.19085 [pdf]
Particles(2026)·3 citations

Affiliations

first authorsco-authorsvia INSPIRE

Calculation of the transport coefficients in neutron star

Primordial deuterium abundance from calculations of p(n,γ) and d(p,γ) reactions within potential-model approach

Matter radii from interaction cross sections using microscopic nuclear densities

Isentropic hybrid stars in the Nambu-Jona-Lasinio model: effects of neutrino trapping

Affiliations

Primordial deuterium abundance from calculations of $p (n, γ)$ and $d (p, γ)$ reactions within potential-model approach