Evidence for the Charmless Annihilation Decay Mode Bs0→π+π-

Abstract

We search for annihilation decay modes of neutral b mesons into pairs of charmless charged hadrons with the upgraded Collider Detector at the Fermilab Tevatron. Using a data sample corresponding to 6 fb-1 of integrated luminosity, we obtain the first evidence for the Bs0→π+π- decay, with a significance of 3.7σ, and a measured branching ratio B(Bs0→π+π-)=(0.57±0.15(stat)±0.10(syst))×10-6. A search for the B0→K+K- mode in the same sample yields a significance of 2.0σ, and a central value estimate B(B0→K+K-)=(0.23±0.10(stat)±0.10(syst))×10-6.