Exploring Brightarrow pi pi , pi K decays at the high-precision frontier

Abstract

The Brightarrow pi pi ,pi K system offers a powerful laboratory to probe strong and weak interactions. Using the isospin symmetry, we determine hadronic Brightarrow pi pi parameters from data where new measurements of direct CP violation in B^0_drightarrow pi ^0pi ^0 resolve a discrete ambiguity. With the help of the SU(3) flavour symmetry, the Brightarrow pi pi parameters can be converted into their Brightarrow pi K counterparts, thereby allowing us to make predictions of observables. A particularly interesting decay is B^0_drightarrow pi ^0 K_mathrm{S} as it exhibits mixing-induced CP violation. Using an isospin relation, complemented with a robust SU(3) input, we calculate correlations between the direct and mixing-induced CP asymmetries of B^0_drightarrow pi ^0 K_mathrm{S}, which are the theoretically cleanest Brightarrow pi K probes. Interestingly, they show tensions with respect to the Standard Model. Should this Brightarrow pi K puzzle originate from New Physics, electroweak penguins offer an attractive scenario for new particles to enter. We present a strategy to determine the parameters characterising these topologies and obtain the state-of-the-art picture from current data. In the future, this method will allow us to reveal the Brightarrow pi K dynamics and to obtain insights into the electroweak penguin sector with unprecedented precision.