Two Problems in Many Body Physics: I. Photon Production: A Probe of Heavy Ion Collisions. II. Structure of Matter in Strong Magnetic Fields

In Part 1 we examine the theoretical framework for the use of photon spectra to probe heavy ion collisions. We first calculate single photon emission spectra from nuclear matter in the incoherent limit and combine them with the simplified participant-spectator model and with the semiclassical VUU model, to predict photon production cross sections in heavy ion collisions. The spectra differ from previous estimates based on a classical soft-photon approximation and lead to good agreement with experiment, except for an overall normalization factor of order (2-5), which we interpret as direct evidence for medium effects. We then proceed to examine the Hanbury-Brown-Twiss correlation of high-energy photons emitted from heavy ion collisions. We find that both the polarization average and a possible coherent component complicate the extraction of the size and lifetime of the emitting source from the correlation function. In Part 2 we calculate the binding energies of atoms and molecular chains in 1012 G magnetic fields using the Hartree-Fock method. Our calculations are the first self-consistent ones treating exchange properly for atoms heavier than helium in high fields. For Z > 2 at 1012G and Z > 4 at 5 x 1012G the isolated atom is energetically favored over the molecular chains.