000001499 001__ 1499
000001499 005__ 20190624161548.0
000001499 037__ $$aBELLE2-CONF-PROC-2019-007
000001499 041__ $$aeng
000001499 100__ $$aStefano  Lacaprara
000001499 245__ $$aFirst look at time-dependent CP violation using early Belle II data
000001499 260__ $$a$$c2019-06-24
000001499 300__ $$a3
000001499 520__ $$a Time dependent CP-violation phenomena are a powerful tool to precisely measure fundamental parameters of the Standard Model and search for New Physics. The Belle II experiment at the SuperKEKB energy-asymmetric $\Pep\Pem$ collider is a substantial upgrade of the B factory facility at the Japanese KEK laboratory. The design luminosity of the machine is $8\times{10}^{35}~cm^{-2}s^{-1}$ 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 $5.5\times10^{33}~cm^{-2}s^{-1}$ , and Belle II has recorded a data sample of about $0.5~fb{-1}$ . Main operation of SuperKEKB has started in March 2019. This early data set is used to establish the performance of the detector in terms of reconstruction efficiency of final states of interest for the measurement of time dependent CP violation, such as $\PJpsi\PKst$ , $\Petaprime \PKs$, and $\phi K_s$. A first assessment of the B flavor tagging capabilities of the experiment will be given, along with estimates of the Belle II sensitivity to the CKM angles $\phi_1/\beta$ and $\phi_2/\alpha$ and to potential New Physics contributions in penguin amplitudes dominated decays and in $b\to s\gamma$ transitions. In this talk we will present estimates of the sensitivity to $\phi_1$ in the golden channels $\Pqb\to\Pqc\APqc\Pqs$ and in the penguin-dominated modes $\PBz\to\Petaprime\PKz,\quad\Pphi\PKz,\quad \PKz\Pgpz(\gamma)$. A study for the time-dependent analysis of $\PBz\to\Pgpz\Pgpz$, relevant for the measurement of $\phi_2$, and feasible only in the clean environment of an $\Pep\Pem$ collider, will also be given.
000001499 6531_ $$aTDCPV
000001499 6531_ $$aBelle II
000001499 6531_ $$aPhase 3
000001499 8560_ $$fstefano.lacaprara@desy.de
000001499 8564_ $$uhttps://docs.belle2.org/record/1499/files/BELLE2-CONF-PROC-2019-007.pdf