  We have investigated numerically the electron addition spectra in quantum
dots containing a small number (N < 11) of interacting electrons, in presence
of strong disorder. For a short-range Coulomb repulsion, we find regimes in
which two successive electrons enter the dot at very close values of the
chemical potential. In the strongly correlated regime these close additions, or
pairing, are associated with electrons tunneling into distinct electron puddles
within the dot. We discuss the tunneling rates at pairing, and we argue that
our results are related to a phenomenon known as "bunching", recently observed
experimentally.

Mesoscale and Nanoscale Physics;Strongly Correlated Electrons