Search for $X(3872)\to\pi^+\pi^-\pi^0$ at Belle

TL;DR

This study searches for the decay of the exotic particle X(3872) into three pions using Belle data but finds no signal, setting upper limits on its branching fraction under different decay models.

Contribution

First search for the decay mode $X(3872) o \pi^+\pi^-\pi^0$ at Belle, providing upper limits on its branching fraction in different decay scenarios.

Findings

No signal observed for $X(3872) o \pi^+\pi^-\pi^0$ decay.

Upper limit on branching fraction: <1.3% for uniform phase space.

Upper limit on branching fraction: <1.2×10^{-3} for $D^0ar{D}^0$-dominated decay.

Abstract

We present a search for the decay $X(3872) \to \pi^+\pi^-\pi^0$ in the $(772\pm11)\times10^6$ $\Upsilon(4S)\to B \bar B$ data sample collected at the Belle detector, where the $X(3872)$ is produced in $B^{\pm}\to K^{\pm}X(3872)$ and $B^{0}\to K_{S}^0 X(3872)$ decays. We do not observe a signal, and set 90\% credible upper limits for two different models of the decay processes: if the decay products are distributed uniformly in phase space, $\mathcal{B}(X(3872) \to \pi^+\pi^-\pi^0) < 1.3\%$; if $M(\pi^+\pi^-)$ is concentrated near the mass of the $D^0 \bar D^0$ pair in the process $X(3872)\to D^0\bar{D}^{*0}+c.c.\to D^0 \bar D^{0}\pi^0\to\pi^+ \pi^- \pi^0$, $\mathcal{B}(X(3872) \to \pi^+\pi^-\pi^0) < 1.2\times10^{-3}$.