Fluctuations of interactions and the peak spacings distribution in Coulombblockade quantum dots

Experimental and theoretical investigations of the distribution of Coulomb blockade peak spacings in chaotic quantum dots have shown a significant dev iation from the Wigner-Dyson distribution predicted by the constant interac tion model. Recently we introduced a random interaction matrix model for ch aotic or diffusive dots that describes the crossover of the peak spacing st atistics from a Wigner-Dyson distribution to a Gaussian-like distribution. Here we use this model to study the dependence of the peak-spacing distribu tions on the underlying space-time symmetries of the one-body Hamiltonian, and in particular we compare the cases of conserved and broken time-reversa l symmetry, We also study the dependence of the peak spacing fluctuations o n disorder strength in diffusive dots using a standard tight-binding Hamilt onian with Coulomb interactions. The fluctuations are found to increase wit h disorder and can be related to the disorder-enhanced fluctuations of the interaction matrix elements. (C) 2001 Elsevier Science S.V. All rights rese rved.