Mario Merola

26 July 2021
EPS-HEP 2021

Abstract: Precision determinations of 𝑉𝑢𝑏 and 𝑉𝑐𝑏 play a central role in precision tests of the CKM sector of the Standard Model and complement direct measurements of CP violation of B meson decays. In this talk, we present first studies towards measurements of |𝑉𝑢𝑏| and 𝑉𝑐𝑏, with semileptonic decays using collision events recorded at the Υ(4𝑆) resonance by the Belle II experiment. We report the status of measuring branching fractions and kinematic properties of inclusive and exclusive 𝑏→𝑢ℓ𝜈¯ℓ and 𝑏→𝑐ℓ𝜈¯ℓ decays using untagged and tagged approaches in the full available Belle II data set. In addition, we present a Belle II measurement of the 𝑞2 moments of 𝐵→𝑋𝑐ℓ𝜈 decay. The 𝑞2 moments of the 𝑏→𝑐ℓ𝜈 transition are particularly powerful for constraining the Heavy Quark Expansion as they can be expressed in terms of a reduced set of matrix elements due to reparametrization invariance.