New physics searches with b-hadrons in the ATLAS experiment

Flavour changing neutral currents and precision measurements of CP violation are investigated in ATLAS as probes to new physics beyond the standard model. This talk presents the most recent results on the search for the rare decay Bs (B0) -> mu+mu-, as well as providing the latest update on the study of the different angular amplitudes contributing to flavour tagged Bs -> J/psi phi (mu+mu-K+K-) decays. The latter analysis measures the CP-violating phase phi_s, as well as the average B_s meson lifetime Gamma_s and the decay width difference DeltaGamma_s.