Dortmund 2021 – scientific programme
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T: Fachverband Teilchenphysik
T 56: Flavour physics III
T 56.8: Talk
Wednesday, March 17, 2021, 17:45–18:00, Tf
Measurement of the q2 moments in semi-leptonic B meson decays at Belle II — Jochen Dingfelder, Florian Bernlochner, and •Maximilian Welsch — Physikalisches Institut der Rheinischen Friedrich-Wilhelms-Universität Bonn
The determination of inclusive |Vcb| from b → c ℓ ν decays relies on the Heavy Quark Expansion (HQE) involving coefficients and associated non-perturbative matrix elements, which can be expressed in terms of a number of expansion parameters. The moments of the kinematic distribution of the decay can be computed in a similar manner and are dependent on the same HQE parameters. Consequently, measurements of such moments can be used to better constrain the expansion parameters and, thereby, more precisely determine |Vcb|. In this talk, we present the first measurement of the q2 moments of B → Xc ℓ ν decays with 74 fb−1 of Belle II data. The q2 moments of the b → c ℓ ν transition are particularly powerful for constraining the HQE expansion as they can be expressed in terms of a reduced set of non-perturbative parameters due to reparametrization invariance.