Measurements of the branching fractions of $\Lambda_c^+ \to p \eta$ and $\Lambda_c^+ \to p \pi^0$ decays at Belle

TL;DR

This paper measures the branching fractions of specific rare decays of the Lambda_c+ baryon using Belle data, providing new precise values and setting an improved upper limit for one decay mode.

Contribution

First measurement of the branching fraction for Lambda_c+ to p eta decay and an improved upper limit for Lambda_c+ to p pi0 decay using the full Belle dataset.

Findings

Measured ${ m BF}(\Lambda_c^+ o p \eta)$ as (1.42 ± 0.05 (stat) ± 0.11 (syst)) × 10^{-3}

Determined the ratio ${ m BF}(\Lambda_c^+ o p \eta)/{ m BF}(\Lambda_c^+ o p K^- \pi^+)$ as (2.258 ± 0.077 (stat) ± 0.136 (syst))×10^{-2}

Set an upper limit on ${ m BF}(\Lambda_c^+ o p \pi^0)$ as <8.0×10^{-5} at 90% CL

Abstract

We report measurements of the branching fractions of singly Cabibbo-suppressed decays $\Lambda_c^+ \to p \eta$ and $\Lambda_c^+ \to p \pi^0$ using the full Belle data sample corresponding to an integrated luminosity of 980.6 $\rm fb^{-1}$. The data were collected by the Belle detector at the KEKB $e^{+}$$e^{-}$ asymmetric-energy collider. A clear $\Lambda_c^+$ signal is seen in the invariant mass distribution of $p \eta$. The signal yield of the $\Lambda_c^+ \to p \eta$ process is $7734 \pm 263$; from this, we measure the ratio of branching fractions ${\cal B}(\Lambda_c^+ \to p \eta)/{\cal B}(\Lambda_c^+ \to p K^- \pi^+) = (2.258 \pm 0. 077(\rm stat. ) \pm 0.136(\rm syst. ))\times 10^{-2}$, from which we infer the branching fraction ${\cal B}(\Lambda_c^+ \to p \eta) = (1.42 \pm 0.05(\rm stat.) \pm 0.11(\rm syst.)) \times 10^{-3}$. In addition, no significant signal for $\Lambda_c^+ \to p \pi^0$ is found so an upper limit on the branching fraction of ${\cal B}(\Lambda_c^+ \to p \pi^0)<8.0 \times 10^{-5}$ at 90\% credibility level is set, more than three times better than the best current upper limit.