First Observation of the Decay B*(s2)(5840)(0) -> B*K-+(-) and Studies of Excited B-s(0) Mesons

The properties of the orbitally excited (L =1) B-s(0) states are studied by using 1.0 fb(-1) of pp collisions at root s = 7 TeV collected with the LHCb detector. The first observation of the B-s2*(5840)(0) meson decaying to BK-+(-) is reported, and the corresponding branching fraction measured relative to the B+K- decay mode. The B-s1(5830)(0) -> BK-+(-) decay is observed as well. The width of the B*(s2)(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 B-s2*(5840)(0) -> BK-+(-) decay favors the spin-parity assignment J(P) = 2(+) for the B-s2(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 = c(2) is obtained. DOI: 10.1103/PhysRevLett.110.151803