Nuclear Theory·nucl-th

Monday·December 15, 2025

10 papers—6 primary·4 cross-listed

07
Structure and Formation of the Deeply Bound $p ˉ$ atoms
Nobuhide Miyazaki🇯🇵 · Junko Yamagata-Sekihara🇯🇵 · Satoru Hirenzaki🇯🇵
We study theoretically the structure and formation of the deeply bound $p ˉ$ atoms. We find that the widths of the atomic states are narrower than the level spacing even for deeply bound states so that the well-isolated deeply bound $p ˉ$ atoms are expected to exist. We also find the $p ˉ$ -nuclear states with huge widths. For the observation of the deep $p ˉ$ -atomic states, we investigate theoretically the $(p ˉ, p)$ reactions for $^{12}$ C, $^{16}$ O, and $^{31}$ P target nuclei. We find that the momentum transfer of the $(p ˉ, p)$ reaction is small and the formation of the $p ˉ$ -atomic states can be observed as the discrete peak structures in the $(p ˉ, p)$ spectrum. We conclude that the $(p ˉ, p)$ reactions are very much suited for the $p ˉ$ atom formation and the spectra of the reaction are expected to provide new valuable information on the $p ˉ$ atoms and $p ˉ$ -nucleus interaction.
↳ hep-phnucl-thPTEP(2026)·0 citations
08
An anlaysis on $J / ψ \to π^{0} γ^{*}$ within resonance chiral theory
Yi-Hao Zhang🇨🇳 · Shao-Zhou Jiang🇨🇳 · Ling-Yun Dai🇨🇳
In this study, we analyze the first measurement of the electron-positron invariant mass spectrum in $J / ψ \to π^{0} e^{+} e^{-}$ by BESIII, using the framework of resonance chiral theory. Our results indicate that both strong interaction and electromagnetic transition are essential to accurately describe the data. We obtain the $π^{0}$ transition form factor for $J / ψ \to π^{0} γ^{*}$ and the corresponding decay branching ratios for $J / ψ \to π^{0} l^{+} l^{-}$ . The decay process $J / ψ \to π^{0} V$ is also examined. It is found that $J / ψ \to π^{0} ρ^{0}$ is dominated by the strong interaction, while the other two channels, $J / ψ \to π^{0} ω$ and $π^{0} ϕ$ , arise primarily from electromagnetic transitions.
↳ hep-phnucl-thEPJC(2026)·3 citations
09
Lindblad-driven recombination of the X(3872) tetraquark
Néstor Armesto🇪🇸 · Miguel Ángel Escobedo🇪🇸 · Elena G. Ferreiro🇪🇸 · Víctor López-Pardo🇪🇸
The internal structure of the exotic meson X(3872) remains an open question. We investigate its production in heavy-ion collisions under the hypothesis that it is a compact tetraquark. To this end, we derive a coalescence model from the Lindblad equation, assuming that unbound heavy quarks are thermalized within the quark-gluon plasma and that the adiabatic approximation holds. Using this model, we predict the nuclear modification factor of the X(3872) at LHC energies, with proton-proton baseline cross sections estimated from available experimental data. We also consider the effect of simplifying assumptions on the model, and a complementary approach based on chemical equilibration. Our results indicate that recombination is the dominant production mechanism for a tetraquark X(3872). It leads to a significant yield enhancement in heavy-ion collisions, suggesting that the nuclear modification factor is a powerful observable for probing the exotic nature of this state
↳ hep-phnucl-th0 citations
10
HPRMAT: A high-performance R-matrix solver with GPU acceleration for coupled-channel problems in nuclear physics
Jin Lei
I present HPRMAT, a high-performance solver library for the linear systems arising in R-matrix coupled-channel scattering calculations in nuclear physics. Designed as a drop-in replacement for the linear algebra routines in existing R-matrix codes, HPRMAT employs direct linear equation solving with optimized libraries instead of traditional matrix inversion, achieving significant performance improvements. The package provides four solver backends: (1) double-precision LU factorization, (2) mixed-precision arithmetic with iterative refinement, (3) a Woodbury formula approach exploiting the kinetic-coupling matrix structure, and (4) GPU acceleration. Benchmark calculations demonstrate that the GPU solver achieves up to 9 $\times$ speedup over optimized CPU direct solvers, and 18 $\times$ over legacy inversion-based codes, for large matrices ( $N = 25600$ ). The mixed-precision strategy is particularly effective on consumer GPUs (e.g., NVIDIA RTX 3090/4090), where single-precision throughput exceeds double-precision by a factor of 64:1; by performing factorization in single precision with iterative refinement, HPRMAT overcomes the poor FP64 performance of consumer hardware while maintaining double-precision accuracy. This makes large-scale CDCC and coupled-channel calculations accessible to researchers using standard desktop workstations, without requiring expensive data-center GPUs. CPU-only solvers provide 5--7 $\times$ speedup through optimized libraries and algorithmic improvements. All solvers maintain physics accuracy with relative errors below $1 0^{- 5}$ in cross-section calculations, validated against Descouvemont's reference code (Comput.\ Phys.\ Commun.\ 200, 199--219 (2016)). HPRMAT provides interfaces for Fortran, C, Python, and Julia.
↳ physics.comp-phnucl-th0 citations

Affiliations

first authorsco-authorsvia INSPIRE

Structure and Formation of the Deeply Bound pˉ​ atoms

An anlaysis on J/ψ→π0γ∗ within resonance chiral theory

Lindblad-driven recombination of the X(3872) tetraquark

HPRMAT: A high-performance R-matrix solver with GPU acceleration for coupled-channel problems in nuclear physics

Affiliations

Structure and Formation of the Deeply Bound $p ˉ$ atoms

An anlaysis on $J / ψ \to π^{0} γ^{*}$ within resonance chiral theory