Measurement of lepton mass squared moments in B → Xcl(ν)over-barl decays with the Belle II experiment
Abstrakt
We present measurements of the first to fourth moments of the lepton mass squared q(2) of B -> X(c)l (nu) over bar (l) decays for l = e, mu and with X-c a hadronic system containing a charm quark. These results use a sample of electron-positron collisions at the Upsilon(4S) resonance corresponding to 62.8 fb(-1) of integrated luminosity and collected by the Belle II 2 experiment in 2019 and 2020.
To identify the X-c system and reconstruct q(2), one of the B mesons from an Upsilon(4S) -> B (B) over bar decay is fully reconstructed in a hadronic decay mode using a multivariate B tagging algorithm. We report raw and central moments for q(2) > 1.5 GeV2/c(4) up to q(2) > 8.5 GeV2/c(4), probing up to 77% of the accessible B -> X(c)l (nu) over bar (l) phase space.
This is the first measurement of moments in the experimentally challenging range of [1.5, 2.5] GeV2/c(4). The results can be used for a new determination of vertical bar V-cb vertical bar using inclusive B -> X(c)l (nu) over bar (l) decays.