$B \to K^{(\ast)} \nu \bar{\nu}$ in covariant confined quark model

TL;DR

This paper calculates the $B o K^{(*)} u ar{ u}$ decay form factors and branching ratios within the Standard Model using the covariant confined quark model, providing results consistent with other theories and encouraging future experimental measurements.

Contribution

The paper introduces a full kinematic range calculation of transition form factors for $B o K^{(*)} u ar{ u}$ decays using the covariant confined quark model, aligning with existing theoretical results.

Findings

Branching ratios agree with other theoretical approaches.

Current experimental upper limits are about an order of magnitude above SM predictions.

Results suggest potential for future experiments to refine measurements and explore new physics.

Abstract

We study the $B \to K^{(\ast)} \nu \bar{\nu}$ 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 $B \to K$ and $B\to K^\ast$ transition form factors are calculated in the full kinematic $q^2$ 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.