Dresden 2013 – wissenschaftliches Programm
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T: Fachverband Teilchenphysik
T 42: CP-Verletzung und Mischungswinkel 1
T 42.8: Vortrag
Dienstag, 5. März 2013, 18:35–18:50, GER-054
Measurement of ACP in fully inclusive B→ Xs+dγ decay, using a leptonic tag — •Luis Pesantez, Jochen Dingfelder, and Phillip Urquijo — Universität Bonn
The Belle experiment recorded a data set corresponding to 770×106 BB pairs produced in e+e− collisions. This large sample allows for studies of rare B decays, such as the radiative decay B→ Xs+dγ, where Xs+d denotes a hadronic final state with an s or a d quark. The CP asymmetry for this decay, ACPB→ Xs+d γ, is negligible in the Standard Model (SM), any significant deviation would give hints for physics beyond the SM.
We measure ACPB→ Xs+d γ fully inclusively using a semileptonic tag of the second B meson in the BB event. The suppression of the main background from continuum processes (e+e−→ qq, q = u,d,s,c ), requires the selection of highly discriminating variables and the use of multivariate techniques. We carefully evaluate the effects of detector induced asymmetries and asymmetries arising from lepton identification and tracking. The optimized selection procedure and the use of the full Belle data set allow to achieve an improved statistical uncertainty compared to previous measurements at the B-factories.