  We study the ac magnetotransport in a non-Fermi liquid metal, which possesses
explicit x-ray edge singularities in $d=\infty$. Specifically, we compute the
ac conductivity tensor in a formalism that becomes exact in this limit. The ac
Hall constant and Hall angle reveal features that are in striking qualitative
agreement with those observed in optical transmission experiments carried out
on $YBa_{2}Cu_{3}O_{7}$ thin films. Our results provide a concrete realization
of the two-relaxation time picture proposed to explain magnetotransport
anomalies in the normal state of cuprate superconductors.
