A new constraint for matter/antimatter asymmetries

A key characteristic of the SM is that the source of matter-antimatter asymmetries stems from CP violation, quantified by a single phase in the CKM quark-mixing matrix. In the SM, unitarity conditions allow us to represent CP violating parameters as a triangle in the complex plane, with angles α, β and γ, and with an area proportional to the amount of CP violation. The angle γ is one of the least well-known CKM observables, and is also the most theoretically clean. One important measurement that provides access to gamma concerns time-dependent measurements of B0 → D−π+ decays and their charge conjugates[1]. This report presents the selection of the signal, the studies of background decays and the m(D∓π±) multicomponent invariant mass fit aimed to the extract the B0 → D∓π± events, using run 2 LHCb data.