arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1902.07564nucl-thhep-phnucl-ex
收藏

相对论重离子碰撞中光子发射的非平衡方法的基准

Benchmarking a Non-Equilibrium Approach to Photon Emission in Relativistic Heavy-Ion Collisions

Anna Schäfer, Juan M. Torres-Rincon, Jonas Rothermel, Niklas Ehlert, Charles Gale, Hannah Elfner

摘要:

在这项工作中,通过二元散射过程的光子的生产被调查的平衡强子系统。更准确地说,一个非平衡强子输运的方法来描述相对论性重离子碰撞的基准相对于光子发射。从有效手征场论导出了$π+ ρ\to π+ γ$和$π+ π\to ρ+ γ$散射过程中光子产生的截面,并应用到强子输运方法SMASH(Simulating Many Accelerated Strongly-Interacting Hadrons)中.通过系统地比较热光子速率与理论预期来验证该实现。此外,形状因子的影响进行了讨论,散射过程介导的$ω$介子被发现显着贡献的总光子产生。产生的光子率进行了几个比较:参数化的非常相同的速率,用于流体动力学模拟,以前的作品依赖于不同的截面的生产直接光子从强子阶段,和部分率。最后,考虑有限宽度的$ρ$介子的影响进行了研究,在低能区的光子产生的显着增强被观察到。这个基准是迈向一致的治疗光子发射的混合流体动力学+运输方法和一个真正的动力学描述的第一步。

英文摘要:

In this work, the production of photons through binary scattering processes is investigated for equilibrated hadronic systems. More precisely, a non-equilibrium hadronic transport approach to describe relativistic heavy-ion collisions is benchmarked with respect to photon emission. Cross sections for photon production in $π+ ρ\to π+ γ$ and $π+ π\to ρ+ γ$ scattering processes are derived from an effective chiral field theory and implemented into the hadronic transport approach, SMASH (Simulating Many Accelerated Strongly-interacting Hadrons). The implementation is verified by systematically comparing the thermal photon rate to theoretical expectations. Further, the impact of form factors is discussed, scattering processes mediated by $ω$ mesons are found to contribute significantly to the total photon production. Several comparisons of the yielded photon rates are performed: to parametrizations of the very same rates, as used in hydrodynamic simulations, to previous works relying on different cross sections for the production of direct photons from the hadronic stage, and to partonic rates. Finally, the impact of considering the finite width of the $ρ$ meson is investigated, where a significant enhancement of photon production in the low-energy region is observed. This benchmark is the first step towards a consistent treatment of photon emission in hybrid hydrodynamics+transport approaches and a genuine dynamical description.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑