Thermal Photons Production in ${{\pi }^{ + }}{{\pi }^{ - }} \to \gamma {{\rho }^{0}},$ ${{\pi }^{ \pm }}{{\rho }^{0}} \to \gamma {{\pi }^{ \pm }}$ and ${{\pi }^{ + }}{{\pi }^{ - }} \to \gamma \gamma$ Processes

Abstract

Thermal photons produced in following processes: ${{\pi }^{ + }}{{\pi }^{ - }} \to \gamma {{\rho }^{0}},$ ${{\pi }^{ \pm }}{{\rho }^{0}} \to \gamma {{\pi }^{ \pm }}$ and ${{\pi }^{ + }}{{\pi }^{ - }} \to \gamma \gamma$ was been considered. Differential cross sections of processes was been calculated in Leading Order without and with taking account formfactor of mesons. The dependencies of differential cross sections of processes on energy of colliding mesons ($\sqrt s$), transverse momentum (p_T) and on cosine of scattering angle of photons has been determined and compared. Dominant process has been determined.