CP violation in D 0 - D̄ 0 oscillations: General considerations and applications to the Littlest Higgs model with T-parity

Abstract

The observed D 0 - D̄ 0 oscillations provide a new stage in our search for New Physics in heavy flavour dynamics. The theoretical verdict on the observed values of x D and y D remains ambiguous: while they could be totally generated by Standard Model dynamics, they could also contain a sizable or even leading contribution from New Physics. Those oscillations are likely to enhance the observability of CP violation as clear manifestations of New Physics. We present general formulae for D 0 - D̄ 0 oscillations, concentrating on the case of negligible direct CP violation. In particular we derive a general formula for the time-dependent mixing-induced CP asymmetry in decays to a CP eigenstate and its correlation with the semileptonic CP asymmetry a SL(D 0) in D 0(t) → ℓνK. We apply our formalism to the Littlest Higgs model with T-parity, using the time-dependent CP asymmetry in D 0 K Sφ as an example. We find observable effects at a level well beyond anything possible with CKM dynamics. Comparisons with CP violation in the K and B systems offer an excellent test of this scenario and reveal the specific pattern of flavour and CP violation in the D 0 - D̄ 0 system predicted by this model. We discuss a number of charm decays that could potentially offer an insight in the dynamics of CP violation in D decays. We also apply our formalism to B s-B̄ s mixing. © SISSA 2009.