22-29 July 2015
Europe/Vienna timezone

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

Jul 24, 2015, 12:50 PM


talk Flavour Physics and Fundamental Symmetries Flavour Physics and Fundamental Symmetries


Christoph Niehoff (Excellence Cluster Universe, Munich)


We present an analysis of the rare exclusive $B$ decays $B\to K\nu\bar\nu$ and $B\to K^{\star}\nu\bar\nu$ within the Standard Model (SM), in a model-independent manner, and in a number of new physics (NP) models. 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, we obtain the SM predictions $\mbox{BR}(B^+\to K^+\nu\bar\nu) = (4.0 \pm 0.5) \times 10^{-6}$ and $\mbox{BR}(B^0\to K^{\star 0}\nu\bar\nu) = (9.2\pm1.0) \times 10^{-6}$, more precise and more robust than previous estimates. 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 $b\to s\nu\bar\nu$ transitions to $b\to s\ell^+\ell^-$ transitions and use the wealth of experimental data on $B\to K^{(\star)}\ell^+\ell^-$ and related modes to constrain NP effects in $B\to K^{(\star)}\nu\bar\nu$. We then consider several specific NP models, including $Z$' models, the MSSM, models with partial compositeness, and leptoquark models, demonstrating that the correlations between $b\to s\nu\bar\nu$ observables among themselves and with $B_s\to\mu^+\mu^-$ and $b\to s\ell^+\ell^-$ transitions offer powerful tests of NP with new right-handed couplings and non-MFV interactions.

Primary authors

Andrzej Buras (Munich) Christoph Niehoff (Excellence Cluster Universe, Munich) David Straub (Excellence Cluster Universe, Munich) Jennifer Girrbach (Technical University Munich)

Presentation materials