B → K(∗)νν̄ in covariant confined quark model

Abstract

We study the [Formula: see text] decays within the Standard Model (SM) by using the relevant transition form factors obtained from the covariant confined quark model (CCQM) developed by us. The [Formula: see text] and [Formula: see text] transition form factors are calculated in the full kinematic [Formula: see text] range. The branching fractions are then calculated. It is shown that our results are in an agreement with those obtained in other theoretical approaches. Currently, the BaBar and Belle collaborations provide us by the upper limits at 90% confidence limit. The obtained bounds are roughly an order of magnitude larger than the SM predictions. This should stimulate experimental collaborations to set up experiments that allow one to obtain more accurate branching values, which is quite achievable on the updated LHCb and Belle machines. If the discrepancies between theory and experiment are confirmed, this will open up opportunities for constructing models with new particles and interactions leading to an extension of the SM.