  We have observed the propagation of an approximately 35 ns long light pulse
with a negative group velocity through a laser-cooled 85Rb atomic medium. The
anomalous dispersion results from linear atom-light interaction, and is
unrelated to long-lived ground state coherences often associated with fast
light in atomic media. The observed negative group velocity (-c/360) in the Rb
magneto-optical trap for a pulse attenuated by less than 50% is in good
agreement with the value of dispersion measured independently by an RF
heterodyne method. The spectral region of anomalous dispersion is between 15
and 40 MHz, which is an order of magnitude wider than that typically associated
with ground-state coherences.
