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T: Fachverband Teilchenphysik

T 88: Flavor Physik III

T 88.3: Vortrag

Donnerstag, 22. März 2018, 17:00–17:15, Z6 - SR 2.006

Measurement of inclusive |V_ub| and the shape function of the B meson — Florian Bernlochner, Lu Cao, William Sutcliffe, and •Raynette van Tonder — Karlsruhe Institute of Technology, Germany

|V_ub| is the least known element of the CKM matrix and plays an important role in testing the unitary of the CKM matrix. One method to determine this parameter is to measure the rate of inclusive B → X_u l ν decays in a region of phase space where the abundant background from the CKM flavoured B → X_c l ν decays is suppressed. However, predictions in this region are sensitive to the Fermi motion of the b-quark inside the B meson which is described by a non-perturbative distribution function called the shape function. In order to make use of the experimentally precise regions of phase space an alternative approach has been proposed in which key kinematic differential distributions of B → X_u l ν decays are measured and combined into a single global fit to simultaneously determine |V_ub|, as well as the shape function. This analysis on the full dataset of the Belle experiment consisting of 772 million BB pairs, recorded at the KEK-B factory, aims to perform the first measurement of the differential distributions of B → X_u l ν decays. By making use of the fully reconstructed hadronic B tag various kinematic variables of the signal side can be accessed, for example the hadronic mass spectrum. This talk presents the current analysis status, with a focus on optimising the event selections necessary for background suppression.