  The low-frequency dynamical response of an Anderson insulator is dominated by
so-called Mott resonances: hybridization of pairs of states close in energy,
but separated spatially. We study the effect of interaction on Mott resonances
in the model of spinful fermions (electrons) with local attraction. This model
is known to exhibit a so-called pseudogap: a suppression of the low-energy
single-particle excitations. Correspondingly, the low-energy dynamical response
is also reduced. However this reduction has mostly quantitative character. In
particular, the Mott formula for frequency-dependent conductivity preserves its
functional asymptotic behavior at low frequencies, but with a small numerical
prefactor. This result can be explained in terms of Mott resonances for
electron pairs instead of single electrons.
