Speaker
Description
The determination of inclusive $|V_{cb}|$ from $b\to c \ell \nu$ 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 such as dilpeton mass $q^2$ or hadronic part mass $M_{X_c}$ of the decay can be computed in a similar manner and are dependent on the same HQE parameters. As a consequence measurements of $\langle q^2 \rangle$ and $\langle M_{X_c} \rangle$ is a powerful method for constraining the HQE expansion and constraining Cabibbo–Kobayashi–Maskawa matrix elements.
This analysis provides first study of inclusive semileptonic decays of $B_s$-mesons $B_s \to X_c \ell \nu$ with 121.4 $\text{fb}^{−1}$ Belle data collected at $\Upsilon(5S)$ resonance via hadronic tagging. Reconstruction of one of $B_s$-mesons allows to fix parameters of signal particle, which reconstruction is hampered due to undetected neutrino, and suppress background. The study includes modeling of signal and background events, estimation of backgrounds contribution, optimization of selection criteria and methods of kinematical parameters' resolution improvement.
