Photon Interferometry of Quark-Gluon Dynamics Revisited

The Bose-Einstein correlations of photons emitted {}from a longitudinally expanding system of excited matter produced in ultrarelativistic heavy ion collision are studied. Two effects found in recent calculations -- that the correlation function in longitudinal direction exhibits oscillations, and that it takes values below unity -- are demonstrated to be numerical artefacts and/or the results of inappropriate approximations. Thus, the general quantum statistical bounds for the two particle correlation function of a chaotic source with Gaussian fluctuations are confirmed. Two different expressions for the two-photon inclusive distribution are considered. Depending on which of the two expressions is used in the calculation, the width of the correlation function may vary by as much as $30\%$. PACS numbers: 05.30.Jp, 13.85.Hd, 25.75.+r, 12.40.Ee