Gluon Bremsstrahlung in Relativistic Heavy Ion Collisions

We study the process $qq\rightarrow qqg$ at lowest order in QCD perturbation theory to understand gluon radiation in the fragmentation region of relativistic heavy-ion collisions. We arrive at a formula for gluon multiplicity that interpolates between $\sim 1/k_{\bot}^2$ behavior at low $k_{\bot}$, to $\sim 1/k_{\bot}^4$ at large $k_{\bot}$.