Evidence for the decay ${B}^{0}\ensuremath{\rightarrow}\ensuremath{\eta}{\ensuremath{\pi}}^{0}$

Rapid Communication

Evidence for the decay $B^{0} \to η π^{0}$

B. Pal et al. (Belle Collaboration)

Phys. Rev. D 92, 011101(R) – Published 9 July 2015

Abstract

We report a search for the charmless hadronic decay $B^{0} \to η π^{0}$ with a data sample corresponding to an integrated luminosity of $694 {fb}^{- 1}$ containing $753 \times 1 0^{6}$ $B \bar{B}$ pairs. The data were collected by the Belle experiment running on the $Υ (4 S)$ resonance at the KEKB $e^{+} e^{-}$ collider. We measure a branching fraction $B (B^{0} \to η π^{0}) = (4. 1_{- 1.5 - 0.7}^{+ 1.7 + 0.5}) \times 1 0^{- 7}$ , where the first uncertainty is statistical and the second is systematic. Our measurement gives an upper limit of $B (B^{0} \to η π^{0}) < 6.5 \times 1 0^{- 7}$ at 90% confidence level. The signal has a significance of 3.0 standard deviations and constitutes the first evidence for this decay mode.