Observation of the Decay $B^{0} \to \pi^{0}\pi^{0}$

TL;DR

This paper reports the first significant observation of the rare decay $B^{0} o c0c0$, measuring its branching fraction and establishing its existence with over 4 sigma significance.

Contribution

The study provides the first observation of the decay $B^{0} o c0c0$ with a measured branching fraction, based on a large data sample from the BABAR detector.

Findings

Observed 46 d7 13 d7 3 events with 4.2 sigma significance.

Measured branching fraction d7 2.1 d7 0.6 d7 0.3 imes 10^{-6}.

Confirmed the decay mode $B^{0} o c0c0$ exists.

Abstract

We present an observation of the decay $B^{0} \to \pi^{0} \pi^{0}$ based on a sample of 124 million $B\bar{B}$ pairs recorded by the BABAR detector at the PEP-II asymmetric-energy $B$ Factory at SLAC. We observe $46 \pm 13 \pm 3$ events, where the first error is statistical and the second is systematic, corresponding to a significance of 4.2 standard deviations including systematic uncertainties. We measure the branching fraction $\BR(B^{0} \to \pi^{0} \pi^{0}) = (2.1 \pm 0.6 \pm 0.3) \times 10^{-6}$, averaged over $B^{0}$ and $\bar{B}^{0}$ decays.