Search for the decay B0s→ηη.

Abstract

We report results from a search for the decay B 0 s → η η using 121.4

fb − 1 of data collected at the Υ ( 5 S ) 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 × 10 − 5 at 90% confidence level. This result represents a significant improvement over the previous most stringent limit.