First measurement of the $B^{+}\to\pi^{+}\pi^{0}\pi^{0}$ branching fraction and \textit{CP} asymmetry

TL;DR

This paper reports the first measurement of the branching fraction and CP asymmetry of the decay $B^{+} o ext{pi}^{+} ext{pi}^{0} ext{pi}^{0}$, including a new structure observation in the $ ext{pi}^{0} ext{pi}^{0}$ spectrum, using Belle data.

Contribution

It provides the first measurement of the $B^{+} o ext{pi}^{+} ext{pi}^{0} ext{pi}^{0}$ branching fraction and CP asymmetry, and observes a new resonance structure in the $ ext{pi}^{0} ext{pi}^{0}$ mass spectrum.

Findings

Branching fraction of $B^{+} o ext{pi}^{+} ext{pi}^{0} ext{pi}^{0}$ measured as $(19.0 extpm 1.5 extpm 1.4) imes 10^{-6}$.

First observation of a structure around 1 GeV/$c^{2}$ in $ ext{pi}^{0} ext{pi}^{0}$ spectrum with 6.4$\sigma$ significance.

Measured CP asymmetry of $(9.2 extpm 6.8 extpm 0.7)\%$ in the decay.

Abstract

We study $B^{+}\to \pi^{+}\pi^{0}\pi^{0}$ using 711 $\rm{fb}^{-1}$ of data collected at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+}e^{-}$ collider. We measure an inclusive branching fraction of $(19.0\pm 1.5\pm 1.4)\times 10^{-6}$ and an inclusive \textit{CP} asymmetry of $(9.2 \pm 6.8 \pm 0.7)\%$, where the first uncertainties are statistical and the second are systematic; and a $B^{+}\to \rho(770)^{+}\pi^{0}$ branching fraction of $(11.2\pm 1.1\pm 0.9 ^{+0.8}_{-1.6})\times 10^{-6}$, where the third uncertainty is due to possible interference with $B^{+}\to \rho(1450)^{+}\pi^{0}$. We present the first observation of a structure around 1 GeV/$c^{2}$ in the $\pi^{0}\pi^{0}$ mass spectrum, with a significance of 6.4$\sigma$, and measure a branching fraction to be $(6.9\pm 0.9\pm 0.6)\times 10^{-6}$. We also report a measurement of local \textit{CP} asymmetry in this structure.