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

Abstract

Based on an $e^{+}{e}^{-}$ collision data sample corresponding to an integrated luminosity of 567${\mathrm{pb}}^{-1}$ 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 $\mathcal{B}({\Lambda }_c^{+}\to \Lambda +X)=(38.2_{-2.2}^{+2.8}\pm 0.8)\%$ 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 ${\mathcal{A}}_{CP}\equiv \frac{\mathcal{B}({\Lambda }_c^{+}\to \Lambda +X)-\mathcal{B}({\bar{\Lambda }}_c^{-}\to \bar{\Lambda }+X)}{\mathcal{B}({\Lambda }_c^{+}\to \Lambda +X)+\mathcal{B}({\bar{\Lambda }}_c^{-}\to \bar{\Lambda }+X)}=(2.1_{-6.6}^{+7.0}\pm 1.4)\%$, a statistically limited result with no evidence of CP violation.

8 pages, 2 figures