Semi-inclusive $b\to s\bar{\ell}\ell$ transitions at high $q^2$

TL;DR

This paper provides an updated Standard Model estimate for high-$q^2$ $b o sar{ ext{lepton}} ext{lepton}$ transitions, compares it with semi-inclusive data, and discusses potential implications of observed deficits in muon modes.

Contribution

It offers a refined SM prediction for inclusive $b o sar{ ext{lepton}} ext{lepton}$ rates at high $q^2$ and analyzes discrepancies with experimental data, highlighting a possible muon mode deficit.

Findings

SM estimate agrees with sum of leading modes and non-resonant channels

Data shows a muon mode deficit with less than 2$\sigma$ significance

Deficit is consistent with low-$q^2$ exclusive mode anomalies

Abstract

We present an updated Standard Model (SM) estimate of the inclusive $b\to s\bar{\ell}\ell$ rate at high dilepton invariant mass ($q^2\geq 15~{\rm GeV}^2$). We show that this estimate is in good agreement with the result obtained summing the SM predictions for the leading one-body modes ($K$ and $K^*$) and the subleading non-resonant $K\pi$ channel (for which we also present an updated estimate). On the contrary, the semi-inclusive sum based on data exhibits a deficit compared to the inclusive SM prediction in the muon modes. The statistical significance of this deficit does not exceed $2\sigma$, but is free from uncertainties on hadronic form factors, and fully compatible with the deficit observed at low-$q^2$ on the exclusive modes. The implications of these results in conjunction with other SM tests on $b\to s\bar{\mu}\mu$ modes are briefly discussed.