Evidence for the singly Cabibbo suppressed decay ${\mathrm{\ensuremath{\Lambda}}}_{c}^{+}\ensuremath{\rightarrow}p\ensuremath{\eta}$ and search for ${\mathrm{\ensuremath{\Lambda}}}_{c}^{+}\ensuremath{\rightarrow}p{\ensuremath{\pi}}^{0}$

Rapid Communication

Evidence for the singly Cabibbo suppressed decay $Λ_{c}^{+} \to p η$ and search for $Λ_{c}^{+} \to p π^{0}$

M. Ablikim et al. (BESIII Collaboration)

Phys. Rev. D 95, 111102(R) – Published 30 June 2017

Abstract

We study the singly Cabibbo suppressed decays $Λ_{c}^{+} \to p η$ and $Λ_{c}^{+} \to p π^{0}$ using $Λ_{c}^{+} {\bar{Λ}}_{c}^{-}$ pairs produced by $e^{+} e^{-}$ collisions at a center-of-mass energy of $\sqrt{s} = 4.6 GeV$ . The data sample was collected by the BESIII detector at the BEPCII collider and corresponds to an integrated luminosity of $567 {pb}^{- 1}$ . We find the first evidence for the decay $Λ_{c}^{+} \to p η$ with a statistical significance of $4.2 σ$ and measure its branching fraction to be $B (Λ_{c}^{+} \to p η) = (1.24 \pm 0.28 (stat) \pm 0.10 (syst)) \times 10^{- 3}$ . No significant $Λ_{c}^{+} \to p π^{0}$ signal is observed. We set an upper limit on its branching fraction $B (Λ_{c}^{+} \to p π^{0}) < 2.7 \times 10^{- 4}$ at the 90% confidence level.