Probing the equation of state with pions

Abstract

The influence of the isospin-independent, isospin-and momentum-dependent equation of state (EoS), as well as the Coulomb interaction on the pion production in intermediate energy heavy ion collisions (HICs) is studied for both isospin-symmetric and neutron-rich systems. The Coulomb interaction plays an important role in the reaction dynamics, and strongly influences the rapidity and transverse momentum distributions of charged pions. It even leads to the π − /π + ratio deviating slightly from unity for isospin-symmetric systems. The Coulomb interaction between mesons and baryons is also crucial for reproducing the proper pion flow since it changes the behavior of the directed and the elliptic flow components of pions visibly.The EoS can be better investigated in neutron-rich system if multiple probes are measured simultaneously. For example, the rapidity and the transverse momentum distributions of the charged pions, the π − /π + ratio, the various pion flow components, as well as the difference of π + -π − flows. A new sensitive observable is proposed to probe the symmetry potential energy at high densities, namely the transverse momentum distribution of the elliptic flow difference [∆v π + −π − 2 (p c.m.t

Source Regions of the Interplanetary Magnetic Field and Variability in Heavy-Ion Elemental Composition in Gradual Solar Energetic Particle Events

“…Coronal and interplanetary shocks driven by fast coronal mass ejections (CMEs) produce large gradual solar energetic particle (SEP) events, as evidenced by a large and continuously growing body of work that encompasses both observations (e.g., Kahler et al 1978;Cane et al 1988;Reames 1999Reames , 2013Tylka et al 2005;Cliver & Ling 2007;Rouillard et al 2011Rouillard et al , 2012 and successful modeling efforts (e.g., Ng et al 1999Ng et al , 2001Ng et al , 2003Ng et al , 2012Ng & Reames 2008;Zank et al 2000Zank et al , 2006Li et al 2003;Li & Zank 2005;Lee 2005Lee , 2007Tylka & Lee 2006;Sandroos & Vainio 2007). Intrinsic in this picture is the notion that SEPs observed upstream of the shock should reflect not only characteristics of the shock itself, but also characteristics of the environment in which the shock operates.…”

Collective flows of protons andπ−mesons in2H+C,Ta and HeChkhaidze1, Djobava2, Galoyan3 et al. 2011Phys. Rev. C8031View full textAdd to dashboardCite

“…The UrQMD model is now widely applied for simulations of particle production and flow effects in various nucleus-nucleus interactions [8,33,34], although its original design was directed towards high energies. It considers the nuclear mean field, the Coulomb interactions, and stochastic binary collisions.…”

Medium modifications of the nucleon–nucleon elastic cross section in neutron-rich intermediate energy HICs

“…A soft equation of state (EoS) with a symmetry potential energy depending linearly on the nuclear density is adopted in this work [19]. The neutron-rich reactions 96 Zr + 96 Zr and 78 Ni + 96 Zr at a beam energy In this work, we suppose that the in-medium cross sections can be factorized as the product of a medium correction factor (F (u, α, p)) and the free NN elastic scattering cross sections (σ f ree ) based on present results of theoretical calculations in Refs.…”