Search for the Decay $B_s^0 \rightarrow \eta^\prime \eta$

TL;DR

This paper reports on the search for the rare decay $B_s^0 ightarrow ext{eta'} ext{eta}$, which is sensitive to new physics beyond the Standard Model, aiming to measure its branching fraction to understand CP violation.

Contribution

It presents the first search for the decay $B_s^0 ightarrow ext{eta'} ext{eta}$, expanding the experimental data on charmless hadronic B_s decays relevant for CP violation studies.

Findings

No significant signal observed for $B_s^0 ightarrow ext{eta'} ext{eta}$.

Sets an upper limit on the branching fraction of the decay.

Provides data to help reduce theoretical uncertainties in CP violation parameters.

Abstract

In the Standard Model (SM) charmless hadronic decays $B_s^0 \rightarrow \eta^\prime \eta$ proceed via tree-level $b\to u$ and penguin $b\to s$ transitions. Penguin transitions are sensitive to Beyond-the-Standard-Model (BSM) physics scenarios and could affect the branching fractions and {\it CP} asymmetries in such decays. Once branching fractions for two-body decays $B_s \to \eta\eta, \eta\eta^{\prime}, \eta^{\prime}\eta^{\prime} $ are measured, and the theoretical uncertainties are reduced, it would be possible to extract {\it CP} violating parameters from the data using the formalism based on SU(3)/U(3) symmetry. To achieve this goal, at least four of these six branching fractions need to be measured. Only the branching fraction for $B_s^0 \to \eta^{\prime}\eta^{\prime}$ has been measured so far.