Rare Semileptonic $B_{s}$ Decays to $\eta$ and $\eta'$ mesons in QCD

TL;DR

This paper investigates rare semileptonic $B_s$ decays to $ a$ and $ a'$ mesons using QCD sum rules, calculating form factors, branching ratios, and polarization asymmetries, consistent with other approaches.

Contribution

It provides new calculations of form factors and decay observables for $B_s$ to $ a$ and $ a'$ transitions using three-point QCD sum rules, enhancing understanding of these rare decays.

Findings

Calculated form factors for $B_s o a, a'$ transitions.

Estimated branching fractions for these rare decays.

Predicted lepton polarization asymmetries consistent with other models.

Abstract

We analyze the rare semileptonic $B_s \to (\eta, \eta') l^+ l^-$, $(l=e, \mu, \tau)$ and $B_s \to (\eta, \eta') \nu \bar{\nu}$ transitions probing the $\bar s s$ content of the $\eta$ and $\eta'$ mesons via three--point QCD sum rules. We calculate responsible form factors for these transitions in full theory. Using the obtained form factors, we also estimate the related branching fractions and longitudinal lepton polarization asymmetries. Our results are in a good consistency with the predictions of the other existing nonperturbative approaches.