First Observation of the Decay B∗s2(5840)0→B*+K− and Studies of Excited B0s Mesons

Abstract

The properties of the orbitally excited ( L = 1 ) B 0 s states are studied by using 1.0 fb − 1 of p p collisions at √ s = 7 TeV collected with the LHCb detector. The first observation of the B ∗ s 2 ( 5840 ) 0 meson decaying to B * + K − is reported, and the corresponding branching fraction measured relative to the B + K − decay mode. The B s 1 ( 5830 ) 0 → B * + K − decay is observed as well. The width of the B ∗ s 2 ( 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 ∗ s 2 ( 5840 ) 0 → B * + K − decay favors the spin-parity assignment J P = 2 + for the B ∗ s 2 ( 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.