Electroweak and BSM Searches in B Physics with ATLAS

A wide program of studies is performed by ATLAS in the B0 and B0s systems. The talk will discuss the measurement of the width difference in the B0 system (currently, the most precise single measurement) and the recent study of the angular correlations in the B0 to K* mu+mu- decays. The ongoing programs on the rare decays of B0(s) to muon pairs and on the B0s width difference and CP violating phase phi_s in the decay B0s to J/psi phi will also be discussed.