  We construct a number($n$)-resolved master equation (ME) approach under
self-consistent Born approximation (SCBA) for noise spectrum calculation. The
formulation is essentially non-Markovian and incorporates properly the interlay
of the multi-tunneling processes and many-body correlations. We apply this
approach to the challenging nonequilibrium Kondo system and predict a profound
nonequilibrium Kondo signature in the shot noise spectrum. The proposed
$n$-SCBA-ME scheme goes completely beyond the scope of the Born-Markovian
master equation approach, in the sense of being applicable to the shot noise of
transport under small bias voltage, in non-Markovian regime, and with strong
Coulomb correlations as favorably demonstrated in the nonequilibrium Kondo
system.
