First Observation of the Decay B_(s2)~*(5840)~0 → B~(*+)K~- and Studies of Excited B_s~0 Mesons

摘要

The properties of the orbitally excited (L = 1) B_s~0 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 B_(s2)~*(5840)~0 meson decaying to B~(*+)K~- is reported, and the corresponding branching fraction measured relative to the B~+ K~- decay mode. The B_(s1)(5830)~0→B~(*+)K~- 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 → B~(*+)K~- 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.