Search for the decay $B_s^0\rightarrow\eta\eta$

TL;DR

This paper reports a search for the rare decay $B_s^0\rightarrow\eta\eta$ using Belle data, setting a new upper limit on its branching fraction due to no observed signal.

Contribution

The study provides the most stringent upper limit to date on the branching fraction of $B_s^0\rightarrow\eta\eta$ decay, improving previous constraints.

Findings

No signal observed for $B_s^0\rightarrow\eta\eta$ decay.

Upper limit on branching fraction set at $14.3\times 10^{-5}$.

Significant improvement over previous limits.

Abstract

We report results from a search for the decay $B_s^0\rightarrow\eta\eta$ using 121.4 fb$^{-1}$ of data collected at the $\Upsilon(5S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. We do not observe any signal and set an upper limit on the branching fraction of $14.3\times 10^{-5}$ at $90\%$ confidence level. This result represents a significant improvement over the previous most stringent limit.