First observation of the decay Bs2*(5840) 0→B+K and studies of excited Bs0 mesons

Abstract

The properties of the orbitally excited (L=1) Bs0 states are studied by using 1.0 fb-1 of pp collisions at √s=7 TeV collected with the LHCb detector. The first observation of the Bs2*(5840)0meson decaying to B*+K- is reported, and the corresponding branching fraction measured relative to the B+K- decay mode. The Bs1(5830)0→B*+K- decay is observed as well. The width of the Bs2*(5840)0 state is measured for the first time, and the masses of the two states are determined with the highest precision to date. The observation of the Bs2*(5840) 0→B*+K- decay favors the spin-parity assignment JP=2+ for the Bs2*(5840)0 meson. In addition, the most precise measurement of the mass difference m(B*+)-m(B+)=45.01±0.30(stat)±0.23(syst) MeV/c2 is obtained. © 2013 CERN.