CP-conserving and CP-violating properties in semileptonic Bs decays with the D0 experiment

Abstract

A search for CP violation has been performed in a sample of semileptonic Bs decays corresponding to approximately 5fb^-1 of data collected by the D0 detector in Run II at the Fermilab Tevatron collider. A time-dependent fit to the distributions of Bs candidates yields the flavour-specific asymmetry a^s_fs = [-1.7 +/- 9.1 (stat) +1.2 -2.3 (syst)] x 10^-3, corresponding to the most precise measurement to date for this CP violation parameter. Furthermore a search for the semi-inclusive process Bs to Ds^(*)Ds^(*) has been performed on a data sample of 2.8fb^-1. 26.6 +/- 8.4 signal events are observed with a significance of 3.2 standard deviations above background, leading to a branching ratio of 0.035 +/- 0.010 (stat) +/- 0.011 (syst). Under certain theoretical assumptions, these double-charm final states saturate CP-even eigenstates in the $B_s$ decays, resulting in a width difference of Delta Gamma_s^CP / Gamma_s = 0.072 +/- 0.021 (stat) +/- 0.022 (syst).