Tagging of Bd0–B̄d0 using B∗∗±→B0(∗)dπ± decay with the CMS experiment Original Research Article

A new tagging method to measure the angle β in the unitarity triangle by the decay B0d→J/ψ K0s has been studied. The nature of the b-quark is known by the charge of the emitted pion in the B∗∗± decay: B∗∗±→B0d(B̄ 0d)π±. The study, in this article presents a accurate description of the CMS (Compact Muon Solenoid) detector performance, it also takes into account pile-up effect at low luminosity. The expected precision of the CMS detector measurement for angle β with this method has been evaluated to be δ(sin2β)=0.022.