000001645 001__ 1645
000001645 005__ 20190827070034.0
000001645 037__ $$aBELLE2-TALK-CONF-2019-114
000001645 041__ $$aeng
000001645 088__ $$aBELLE2-TALK-DRAFT-2019-116
000001645 100__ $$aPablo Goldenzweig
000001645 245__ $$aFirst Look at CKM Parameters from Early Belle II Data
000001645 260__ $$aICNFP 2019$$c2019-08-22
000001645 300__ $$amult. p
000001645 500__ $$a20 min
000001645 520__ $$aThe Belle II experiment at the SuperKEKB energy-asymmetric e+e− collider is a substantial upgrade of the B factory facility at the Japanese KEK laboratory. The design luminosity of the machine is 8×1035 cm−2s−1 and the Belle II experiment aims to record 50 ab−1 of data, a factor of 50 more than its predecessor. From February to July 2018, the machine has completed a commissioning run, achieved a peak luminosity of 5.5×1033 cm−2s−1, and Belle II has recorded a data sample of about 0.5 fb−1. Main operation of SuperKEKB has started in March 2019. We use the early Belle II data to characterize the performance of the detector regarding the tracking of charged particles, the reconstruction of known resonances, and the capability of identifying displaced decay vertices. A first benchmark towards analysing time-dependent CP violation consists in the measurement of the lifetime of B mesons and of the B0−B¯0 mixing frequency. We present the first results, based on samples of B mesons that decay to hadronic and semileptonic final states. We further present estimates of the sensitivity to β in the golden channels B→cc¯s and in the penguin-dominated modes B0→η′K0, ϕK0, KSπ0(γ). A study of the time-dependent analysis of B0→π0π0, relevant for the measurement of α, and feasible only in the clean environment of an e+e− collider, will also be given. Belle II can also measure γ, the third and least well known CKM angle, through the interference between B+→D0K+ and B+→D¯0K+ decays, which occurs if the final state of the charm-meson decay is accessible to both the D0 and D¯0 mesons. We will also discuss the precision that Belle II will be achieved in this measurement.
000001645 8560_ $$fdoris.yangsoo.kim@desy.de
000001645 8564_ $$uhttps://docs.belle2.org/record/1645/files/BELLE2-TALK-CONF-2019-114.pdf