On $B\to K^{(*)}\bar \nu\nu$ decays in and beyond the Standard Model

TL;DR

This paper provides precise Standard Model predictions for rare B decays involving neutrinos, explores new physics effects using effective operators, and examines leptoquark models for potential large deviations.

Contribution

It combines lattice QCD, sum rules, and electroweak corrections to refine SM predictions and constrains new physics using experimental data, including leptoquark scenarios.

Findings

Precise SM predictions for B→K(*)νν decays.

Constraints on new physics from B→K(*)ℓ+ℓ− data.

Potential for large effects in leptoquark models.

Abstract

In this talk an analysis of the rare exclusive $B$ decays $B\to K\nu\bar\nu$ and $B\to K^{*}\nu\bar\nu$ within and beyond the Standard Model is presented. Combining new form factor determinations from lattice QCD with light-cone sum rule results and including complete two-loop electroweak corrections to the SM Wilson coefficient, precise Standard Model predictions will be given. Beyond the SM, we make use of an effective theory with dimension-six operators invariant under the SM gauge symmetries to relate NP effects in $b\to s\bar\nu\nu$ transitions to $b\to s\ell^+\ell^-$ transitions and use the wealth of experimental data on $B\to K^{(*)}\ell^+\ell^-$ and related modes to constrain NP effects in $B\to K^{(*)}\nu\bar\nu$. We then consider leptoquark models as a showcase for models where in principle large effects are possible.