Evidence for the semileptonic decay ${\Lambda }_c^{+}\to p{\pi }^{-}{e}^{+}{\nu }_e$

Abstract

Based on $4.5{\mathrm{fb}}^{-1}$ of $e^{+}{e}^{-}$ collision data collected with the BESIII detector at the BEPCII collider at center-of-mass energies between $4.600\mathrm{GeV}$ and $4.699\mathrm{GeV}$, the first search for the Cabbibo-suppressed semileptonic decay ${\Lambda }_c^{+}\to p{\pi }^{-}{e}^{+}{\nu }_e$ is performed. The branching fraction of ${\Lambda }_c^{+}\to p{\pi }^{-}{e}^{+}{\nu }_e$ is measured to be $(2.96\pm 0.95_{\mathrm{stat}}\pm 0.23_{\mathrm{syst}})\times 10^{-4}$ with a signal significance of $4.2\sigma$.

arXiv comment9 pages, 2 figures