Eur. Phys. J. A (2017) 53: 30
https://doi.org/10.1140/epja/i2017-12217-6

Regular Article - Theoretical Physics

Preequilibrium particle emissions and in-medium effects on the pion production in heavy-ion collisions

Institute of Modern Physics, Chinese Academy of Sciences, 730000, Lanzhou, China

^* e-mail: fengzhq@impcas.ac.cn

Received: 10 November 2016
Accepted: 29 January 2017
Published online: 20 February 2017

Abstract

Within the framework of the Lanzhou quantum molecular dynamics (LQMD) transport model, pion dynamics in heavy-ion collisions near threshold energies and the emission of preequilibrium particles (nucleons and light complex fragments) have been investigated. A density, momentum and isospin-dependent pion-nucleon potential based on the -hole model is implemented in the transport approach, which slightly leads to the increase of the ratio, but reduces the total pion yields. It is found that a bump structure of the ratio in the kinetic energy spectra appears at the pion energy close to the resonance region. The yield ratios of neutrons to protons from the squeeze-out particles perpendicular to the reaction plane are sensitive to the stiffness of nuclear symmetry energy, in particular at the high-momentum (kinetic energy) tails.