Effects of in-medium NN inelastic cross sections and the high-momentum tail of nucleon momentum distributions on pion production in heavy-ion collisions
Abstract
Pion production in intermediate-energy heavy-ion collisions (HICs) provides a sensitive probe of the nuclear equation of state and of the isospin dependence of reaction dynamics. In particular, pion production near threshold is strongly affected by the nucleon-nucleon (NN) inelastic cross sections and by the high-momentum components of the nucleon momentum distribution. To explore the influence of these two ingredients on pion production and charged-pion ratios, the in-medium NN inelastic cross sections calculated within the relativistic Boltzmann-Uehling-Uhlenbeck transport theory and the short-range-correlation-induced high-momentum tail (HMT) are introduced into the Ultra-relativistic Quantum Molecular Dynamics (UrQMD) model. By simulating Au+Au collisions at intermediate energies, we find that the in-medium modification of the NN inelastic cross sections suppresses the pion multiplicity by reducing the probability of NΔ production in dense matter. The HMT, on the other hand, enhances the high-momentum components of nucleons and modifies the available energy in individual NN collisions, thereby affecting NN→ NΔ reactions and the subsequent pion production. With the simultaneous inclusion of these two effects, the pion yields measured by HADES and the π-/π+ ratio measured by FOPI can be reasonably reproduced. These results highlight the need to incorporate both in-medium reaction cross sections and short-range-correlation-induced high-momentum components consistently in transport-model studies of pion production in heavy-ion collisions.
Related
- Analytic next-to-leading-order helicity cross sections for vector-boson production at finite transverse momentum
- Spin - resolved momentum distributions and vortex evolution in multiphoton pair production within a modified two-level model
- Probing Orbital Angular Momentum Distributions in Elastic Vector Meson Production in Longitudinally Polarized Electron--Proton Scattering
- Search for supersymmetric particle pair production in final states with two oppositely charged leptons and large missing transverse momentum in proton-proton collisions at √s = 13 TeV
- Vortex structures in momentum distributions from multi-pair production
BibTeX
@misc{li2026effects,
title = {{Effects of in-medium $NN$ inelastic cross sections and the high-momentum tail of nucleon momentum distributions on pion production in heavy-ion collisions}},
author = {Pengcheng Li and A. B. Larionov and Yongjia Wang and Gaochan Yong and Qingfeng Li},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.25818},
eprint = {2609.25818},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.25818},
note = {CC0},
}
RIS
TY - UNPB
TI - Effects of in-medium NN inelastic cross sections and the high-momentum tail of nucleon momentum distributions on pion production in heavy-ion collisions
AU - Pengcheng Li
AU - A. B. Larionov
AU - Yongjia Wang
AU - Gaochan Yong
AU - Qingfeng Li
PY - 2026
DA - 2026/09/22
PB - arXiv
DO - 10.48550/arxiv.2609.25818
UR - https://arxiv.org/abs/2609.25818
AB - Pion production in intermediate-energy heavy-ion collisions (HICs) provides a sensitive probe of the nuclear equation of state and of the isospin dependence of reaction dynamics. In particular, pion production near threshold is strongly affected by the nucleon-nucleon (NN) inelastic cross sections and by the high-momentum components of the nucleon momentum distribution. To explore the influence of these two ingredients on pion production and charged-pion ratios, the in-medium NN inelastic cross sections calculated within the relativistic Boltzmann-Uehling-Uhlenbeck transport theory and the short-range-correlation-induced high-momentum tail (HMT) are introduced into the Ultra-relativistic Quantum Molecular Dynamics (UrQMD) model. By simulating Au+Au collisions at intermediate energies, we find that the in-medium modification of the NN inelastic cross sections suppresses the pion multiplicity by reducing the probability of NΔ production in dense matter. The HMT, on the other hand, enhances the high-momentum components of nucleons and modifies the available energy in individual NN collisions, thereby affecting NN→ NΔ reactions and the subsequent pion production. With the simultaneous inclusion of these two effects, the pion yields measured by HADES and the π^-/π^+ ratio measured by FOPI can be reasonably reproduced. These results highlight the need to incorporate both in-medium reaction cross sections and short-range-correlation-induced high-momentum components consistently in transport-model studies of pion production in heavy-ion collisions.
ER -