First test of lepton flavor universality in the charmed baryon decays Ωc0 → Ω-l+νl using data of the Belle experiment

We present the first observation of the Omega(0)(c) -> Omega(-)mu(+)nu(mu) decay and present measurements of the branching fraction ratios of the Omega(0)(c) -> Omega(-)l(+)nu(l) decays compared to the reference mode Omega(0)(c) -> Omega(-)pi(+), (l = e or mu). This analysis is based on 89.5 fb(-1), 711 fb(-1), and 121.1 fb(-1) data samples collected with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider at the center-of-mass energies of 10.52 GeV, 10.58 GeV, and 10.86 GeV, respectively. The Omega(0)(c) signal yields are extracted by fitting M-Omega l' and M-Omega pi spectra. The branching fraction ratios B(Omega(0)(c) -> Omega(-)e(+)nu(e))/B(Omega(0)(c) -> Omega(-)pi(+)) and B(Omega(0)(c) -> Omega(-)mu(+)nu(mu))/B(Omega(0)(c) -> Omega(-)pi(+)) are measured to be 1.98 +/- 0.13(stat) +/- 0.08(syst) and 1.94 +/- 0.18(stat) +/- 0.10(syst), respectively. The ratio of B(Omega(0)(c) -> Omega(-)e(+)nu(e))/B(Omega c0 -> Omega(-)mu(+)nu(mu)) is measured to be 1.02 +/- 0.10(stat) +/- 0.02(syst), which is consistent with the expectation of lepton flavor universality.

Automated summary

We report the first observation of the Omega(0)(c) -> Omega(-)mu(+)nu(mu) decay and measure the branching fraction ratios of the Omega(0)(c) -> Omega(-)l(+)nu(l) decays in comparison with the reference mode Omega(0)(c) -> Omega(-)pi(+), (l = e or mu). Using data samples collected at the KEKB e(+)e(-) collider, we extract the Omega(0)(c) signal yields and measure the branching fraction ratios to be 1.98 +/- 0.13(stat) +/- 0.08(syst) and 1.94 +/- 0.18(stat) +/- 0.10(syst) for Omega(0)(c) -> Omega(-)e(+)nu(e) and Omega(0)(c) -> Omega(-)mu(+)nu(mu), respectively. The ratio of B(Omega(0)(c) -> Omega(-)e(+)nu(e))/B(Omega c0 -> Omega(-)mu(+)nu(mu)) is measured to be 1.02 +/- 0.10(stat) +/- 0.02(syst), which is consistent with lepton flavor universality.