Due to the strong collective deceleration during the initial stage of relativistic heavy-ion collisions, the nuclear matter irradiates real and virtual bremsstrahlung. We describe the process of bremsstrahlung emission in the framework of a semiclassical model in order to study coherence and incoherence effects in the production process. Guided by the intuitive notation of shock fronts being formed between the incident nuclei, we use a simple parametrization of the nuclear current density. The photon spectrum is studied up to photon energies of 300 MeV. In particular, a gradual transition from the coherent production process of low-energy photons to the incoherent one for hard photons is demonstrated. For heavy collision systems coherence effects in the photon spectra dominate, showing characteristic structures arising from shock fronts. The dilepton spectrum is described in first-order perturbation theory. Generally, dileptons are found to be produced incoherently. Only in the case of dielectron production with small invariant pair masses do moderate coherence effects survive.
Abstract. Electron-positron pair creation in relativistic heavy ion collisions is non-perturbatively described by coupled channel equations in a coordinate system with equal constant, but opposite velocities of the ions. The basis states are obtained by discretizing the states of the free Dirac equation in the positive and negative continuum. With the standard (fermionic) coupled channel method the free pair production in Pb 82+ on Pb 82+ at Elab = 10 GeV/nucleon is calculated. In order to treat multiple pair production with a reduced number of states we introduce a bosonic formalism for the electron-positron pairs in the framework of coupled channels including the rescattering of the electrons and positrons by the electromagnetic field of the ions. We apply this formalism to collisions of Pb s2+ on pbS2+at Elab = 200 GeV/nucleon.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.