D0 dimuon asymmetry in Bs - (B)over-bars mixing and constraints on new physics

We study the consequences of the large dimuon asymmetry observed at D0. Physics beyond the standard model (SM) in B-s - (B) over bar (s) mixing is required to explain the data. We first present a detailed analysis for model independent constraints on physics beyond the SM, and then study the implications for theoretical models which modify the SM results in different ways, such as Z' with flavor changing neutral current and R-parity violating supersymmetry contributions.