Gluon radiation from a classical point particle. II. Dense gluon fields

The goal of this paper is to extend the results of [K. Kajantie, L. D. McLerran, and R. Paatelainen, Gluon radiation from a classical point particle, Phys. Rev. D 100, 054011 (2019)., where formulas were derived for gluonic radiation for a high energy nucleus colliding with a classical colored particle. In [K. Kajantie, L. D. McLerran, and R. Paatelainen, Gluon radiation from a classical point particle, Phys. Rev. D 100, 054011 (2019).], we computed the amplitudes for radiation in the fragmentation region of the particle for a dilute gluonic field. In this paper, we compute the radiation by solving the fluctuation equations of the dense background field in a specific gauge, which makes it simple to solve the asymptotic radiation from an initial condition immediately after the passage of the nucleus. We identify and compute two components of gluon radiation, a bulk component which extends to the central region and bremsstrahlung, which may give rise to an experimentally observable intensity peak in the target fragmentation region.