  We investigate the transient evolution of finite-frequency current noise
after abrupt switching on of the tunneling coupling in two paradigmatic,
exactly solvable models of mesoscopic physics: the resonant level model and the
Majorana resonant level model, which emerges as an effective model for a Kondo
quantum dot at the Toulouse point. We find a parameter window in which the
transient noise can become negative, a property it shares with the transient
current. However, in contrast to the transient current, which approaches the
steady state exponentially fast, we observe an algebraic decay in time of the
transient noise for a system at zero temperature. This behaviour is dominant
for characteristic parameter regimes in both models. At finite temperature the
decay is altered from an algebraic to an exponential one with a damping
constant proportional to temperature.
