Observation of B+ to p Lambdabar pi+ pi- at Belle

Abstract

We study charmless $B^{+}$ meson decays to the $p\bar{\Lambda }{\pi }^{+}{\pi }^{-}$ final state using a $605{\mathrm{fb}}^{-1}$ data sample collected at the ${\rm Y}(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. There are significant signals found with the $p\bar{\Lambda }$ mass peaking near threshold. The observed branching fraction for non-resonant $ B^+ \to p \barΛ} π^+ π^-$ is $(5.92_{-0.84}^{+0.88}(stat.)\pm 0.69(syst.))\times 10^{-6}$ with a significance of 9.1 standard deviations. We also observe the intermediate three-body decay $B^{+}\to p\bar{\Lambda }{\rho }^0$ with a branching fraction of $(4.78_{-0.64}^{+0.67}(stat.)\pm 0.60(syst.))\times 10^{-6}$ and a significance of 9.5 standard deviations, and find a hint of a $B^{+}\to p\bar{\Lambda }{f}_2(1270)$ signal. No other intermediate three-body decay is found in this study.

14 pages, 2 figures and 2 tables; submitted to PRD

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• Angular asymmetries in $B\to \Lambda \bar{p}M$ decays
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