Studies of time dependent CP violation in charm decays of B 0 s mesons

Abstract

The thesis describes the world-first, time-dependent measurement of charge-parity (CP ) violation in B 0 s → D∓ s K± decays. The study is performed at the LHCb experiment using data sample corresponding to an integrated luminosity of 1.0 fb− 1 of proton-proton collisions at a center-of-mass energy of √ s = 7 TeV, recorded in 2011. The CP violating observables are found to be: C = 0.52 ± 0.25 ± 0.04, D f = 0.29 ± 0.42 ± 0.17, D ¯ f = 0.14 ± 0.41 ± 0.18, S f = − 0.90 ± 0.31 ± 0.06, S ¯ f = − 0.36 ± 0.34 ± 0.06, where the first (second) uncertainty is statistical (systematic). These observables are used to perform the first measurement of the Cabibbo-Kobayashi-Maskawa angle γ in B 0 s → D∓ s K± decays, finding γ = (113 +30 − 44 )◦ modulo 180◦ at 68% CL, where the error contains both statistical and systematic uncertainties.