Reentrance of proton-neutron pairing in hot nuclear systems
Abstract
We develop a generalized finite-temperature proton-neutron BCS framework using the superoperator formalism, incorporating both isovector and isoscalar monopole pairing channels. Numerical calculations for a schematic equidistant multilevel model and realistic even-even Ge isotopes demonstrate the emergence of proton-neutron (pn) pairing reentrance in even-even asymmetric (N>Z) nuclei with preexisting like-nucleon pairing correlations. This nonmonotonic behavior arises from thermal excitations that partially lift Pauli blocking of single-particle orbitals near the chemical potentials, thereby enlarging the phase space for pn pair formation. We uncover a delicate interplay between thermal unblocking and like-nucleon pairing, which can either suppress or enhance pn correlations depending on temperature and shell filling. A qualitative analysis of Fermi charge-exchange strength functions in hot 72Ge, which neglects the residual interaction between thermal quasiparticles, suggests that pn pairing reentrance may alter the transition strength distribution around T≈1~MeV. This indicates that finite-temperature pn correlations could potentially impact stellar weak-interaction rates in rp-process and supernova environments.
Versions
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BibTeX
@misc{dong2026reentrance,
title = {{Reentrance of proton-neutron pairing in hot nuclear systems}},
author = {T. Vu Dong and Alan A. Dzhioev and A. I. Vdovin and N. Quang Hung},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.06638},
eprint = {2609.06638},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.06638},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Reentrance of proton-neutron pairing in hot nuclear systems
AU - T. Vu Dong
AU - Alan A. Dzhioev
AU - A. I. Vdovin
AU - N. Quang Hung
PY - 2026
DA - 2026/09/06
PB - arXiv
DO - 10.48550/arxiv.2609.06638
UR - https://arxiv.org/abs/2609.06638
AB - We develop a generalized finite-temperature proton-neutron BCS framework using the superoperator formalism, incorporating both isovector and isoscalar monopole pairing channels. Numerical calculations for a schematic equidistant multilevel model and realistic even-even Ge isotopes demonstrate the emergence of proton-neutron (pn) pairing reentrance in even-even asymmetric (N>Z) nuclei with preexisting like-nucleon pairing correlations. This nonmonotonic behavior arises from thermal excitations that partially lift Pauli blocking of single-particle orbitals near the chemical potentials, thereby enlarging the phase space for pn pair formation. We uncover a delicate interplay between thermal unblocking and like-nucleon pairing, which can either suppress or enhance pn correlations depending on temperature and shell filling. A qualitative analysis of Fermi charge-exchange strength functions in hot ^72Ge, which neglects the residual interaction between thermal quasiparticles, suggests that pn pairing reentrance may alter the transition strength distribution around T≈1~MeV. This indicates that finite-temperature pn correlations could potentially impact stellar weak-interaction rates in rp-process and supernova environments.
ER -