Measurement of absolute branching fraction of the inclusive decay $\Lambda_{c}^{+} \to \Lambda + X$

TL;DR

This paper measures the absolute branching fraction of the inclusive decay $\, ext{Lambda}_c^+ o ext{Lambda} + X$ using BESIII data and searches for direct CP violation, finding no significant asymmetry.

Contribution

First measurement of the absolute branching fraction of $\, ext{Lambda}_c^+ o ext{Lambda} + X$ and the first search for CP violation in this decay channel.

Findings

Branching fraction: (38.2^{+2.8}_{-2.2} ext{(stat)} \pm 0.8 ext{(sys)})",

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Abstract

Based on an $e^+e^-$ collision data sample corresponding to an integrated luminosity of 567$\,\rm{pb}^{-1}$ taken at the center-of-mass energy of $\sqrt{s} = 4.6$ GeV with the BESIII detector, we measure the absolute branching fraction of the inclusive decay $\Lambda_{c}^{+} \to \Lambda + X$ to be $\mathcal{B}(\Lambda_{c}^{+} \to \Lambda + X)=(38.2^{+2.8}_{-2.2}\pm0.8)\%$ using the double-tag method, where $X$ refers to any possible final state particles. In addition, we search for direct CP violation in the charge asymmetry of this inclusive decay for the first time, and obtain $\mathcal{A}_{CP} \equiv \frac{\mathcal{B}(\Lambda_{c}^{+} \to \Lambda + X)-\mathcal{B}(\bar{\Lambda}_{c}^{-} \to \bar{\Lambda} + X)}{\mathcal{B}(\Lambda_{c}^{+} \to \Lambda + X)+\mathcal{B}(\bar{\Lambda}_{c}^{-} \to \bar{\Lambda} + X)} = (2.1^{+7.0}_{-6.6}\pm1.4)\%$, a statistically limited result with no evidence of CP violation.