Measurements of the Branching Fractions of the Semileptonic Decays Ξ_{c}^{0}→Ξ^{-}ℓ^{+}ν_{ℓ} and the Asymmetry Parameter of Ξ_{c}^{0}→Ξ^{-}π^{+}.

TLDR: In this paper, the authors reported measurements of branching fractions of semileptonic decays with the Belle detector at the KEKB e$+}$e$^{-}$ ) collider at energies of 10.52 and 10.58 GeV, respectively.

Abstract: Using data samples of 89.5 and 711fb$^{-1}$ recorded at energies of $\sqrt{s}$=10.52 and 10.58 GeV, respectively, with the Belle detector at the KEKB e$^{+}$e$^{-}$ collider, we report measurements of branching fractions of semileptonic decays Ξ$_{c}$$^{0}$ → Ξ$^{-}$l$^{+}$ν$_{l}$(l=e or μ) and the CP-asymmetry parameter of Ξ$_{c}$$^{0}$ → Ξ$^{-}$π$^{+}$ decay. The branching fractions are measured to be B(Ξ$_{c}$$^{0}$ → Ξ$^{-}$e$^{+}$ν$_{e}$)= 1.31±0.04±0.07±0.38)% and B(Ξ$_{c}$$^{0}$ → Ξ$^{-}$μ$^{+}$ν$_{μ}$ = (1.27±0.06±0.10±0.37)% , and the decay parameter α$_{Ξπ}$ is measured to be 0.63±0.03±0.01 with much improved precision compared with the current world average. The corresponding ratio B(Ξ$_{c}$$^{0}$ → Ξ$^{-}$e$^{+}$ν$_{e}$) /B(Ξ$_{c}$$^{0}$ → Ξ$^{-}$μ$^{+}$ν$_{μ}$) is 1.03±0.05±0.07, which is consistent with the expectation of lepton flavor universality. The first measured asymmetry parameter A$_{CP}$=(α$_{Ξ^{-}π^{+}}$+α$_{Ξ^{+}π^{-}}$)/(α$_{Ξ^{-}π^{+}}$+α$_{Ξ^{+}π^{-}}$) = 0.024±0.052±0.014 is found to be consistent with zero. The first and the second uncertainties above are statistical and systematic, respectively, while the third ones arise due to the uncertainty of the Ξ$_{c}$$^{0}$ → Ξ$^{-}$π$^{+}$ branching fraction.