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Nuclear Theory·nucl-th

Thursday·January 29, 2026

8 papers—5 primary·3 cross-listed

All8Primary5Cross-lists3
  1. 06

    The 2025 Evaluation of Experimental Thermonuclear Reaction Rates (ETR25)

    Christian Iliadis · Richard Longland · Kiana Setoodehnia · Caleb Marshall · Peter Mohr · Athanasios Psaltis

    This work describes the formalism for estimating thermonuclear reaction rates for astrophysical applications, emphasizing modern statistical approaches such as Monte-Carlo sampling and Bayesian models. We discuss related topics including the calculation of resonance energies from nuclear Q values, indirect estimates of particle partial widths, and matching of reaction rates at elevated temperatures to statistical-model results. We have evaluated available experimental data on cross sections, resonance energies and strengths, partial widths, life-times, spin-parities, and spectroscopic factors. Based on these results, we have estimated numerical values of 78 experimental charged-particle thermonuclear reaction rates for target nuclei in the A = 2 to 40 mass region, for temperatures ranging from 1 MK to 10 GK. For each reaction, three rate values are provided: low, median, and high, corresponding to the 16th, 50th, and 84th percentiles, respectively, of the cumulative reaction rate probability density distribution. Additionally, we present the factor uncertainty of each rate at each temperature grid point. These results enable users to sample the reaction rate probability density in nucleosynthesis calculations, facilitating uncertainty estimates of nuclidic abundances. The rates presented here refer to their laboratory values. For use in stellar model simulations, these values need to be corrected for the effects of thermal excitations of the interacting nuclei. For each reaction, we include graphs that illustrate the fractional contributions to the overall reaction rate along with the associated uncertainty. These visuals are designed to assist both stellar modelers and nuclear experimentalists by identifying the primary sources of rate uncertainty at specific stellar temperatures. A graphical comparison with earlier Monte-Carlo rates is also provided.

    ↳ astro-ph.SRnucl-exnucl-thAstrophys.J.Suppl.(2026)·3 citations
  2. 07

    Toward a Unified Picture of Confinement and Baryon Structure

    Fan Lin🇨🇳 · Xinyang Wang🇨🇳

    In this work, we investigate the infrared structure of quantum chromodynamics from the perspective of the Cho-Faddeev-Niemi decomposition and the Faddeev-Niemi effective theory of Yang-Mills fields. We argue that the topological solitons of the Faddeev-Niemi theory, namely gluon knots characterized by the Hopf invariant, should be regarded as the relevant ground-state degrees of freedom of Yang-Mills theory in the deep infrared region. In this framework, gluon knots provide a unified description of monopole condensation and the center-vortex confinement mechanism. We further propose that baryons are composite objects consisting of quarks immersed in a gluon-knot background. The monopole condensate associated with the gluon knot realizes dual superconductivity, squeezes color-electric flux into flux tubes, and naturally generates the -shaped confinement structure of baryons. Simultaneously, the strong local color-magnetic field generated by the gluon knot induces chiral symmetry breaking through magnetic catalysis and topological vacuum fluctuations. We show that the Hopf invariant of the gluon knot is closely related to the topology of Yang-Mills vacua and discuss its connection with the axial anomaly and instanton-induced chiral symmetry breaking. Furthermore, the topological current associated with gluon knots provides a natural carrier of gluon angular momentum and may account for a substantial fraction of the proton spin. The resulting picture establishes a possible connection between the infrared topology of Yang-Mills theory and the internal structure of baryons, providing a unified framework for confinement, chiral symmetry breaking, and baryon structure in QCD.

    ↳ hep-thhep-phnucl-th0 citations
  3. 08

    Bjorken Initial Energy Density and Viscous Longitudinal Hydrodynamic Evolution in Xe-Xe Collisions

    S. Biswal🇮🇳 · M. A. Bhat🇮🇳 · A. Nayak🇮🇳 · S. I. Sahoo🇮🇳 · D. Dutta🇮🇳 · D. K. Mishra🇮🇳 · P. K. Sahu🇮🇳

    We present a systematic study of the Bjorken initial energy density in Xe-Xe collisions at TeV, estimated using charged-particle multiplicity data and a generalized transverse overlap geometry applicable beyond the most central collisions. The dependence of the extracted energy density is examined by adopting both a constant formation time and a centrality-dependent formation time derived from Pb-Pb collisions at TeV. Corresponding Bjorken energy density estimates for Pb-Pb collisions are also presented for comparison. Taking the Bjorken energy density and formation time as initial conditions, the subsequent longitudinal evolution of the quark-gluon plasma (QGP) formed in these collisions is studied. Both ideal and first-order viscous boost-invariant hydrodynamics are employed to assess the influence of dissipation. We observe that viscous effects slow the longitudinal expansion and lead to entropy production dominated by early-time dynamics. The lifetime of the QGP is observed to increase with centrality and is substantially enhanced by viscous effects. These effects are highly sensitive to the choice of formation time, particularly in peripheral collisions. A comparative analysis of Xe-Xe and Pb-Pb collisions demonstrates that the longitudinal evolution is primarily controlled by the initial energy density scale set by the Bjorken prescription. Consequently, when this scale is comparable, both systems exhibit nearly identical evolution patterns, while appreciable distinctions emerge in peripheral collisions due to system-size and geometric effects.

    ↳ hep-phnucl-th0 citations

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first authorsco-authorsvia INSPIRE