Observation of orbitally excited B(s) mesons

We report the observation of two narrow resonances consistent with states of orbitally excited (L=1) B(s) mesons using 1 fb(-1) of p (p) over bar collisions at root s =1.96 TeV collected with the Collider Detector at Fermilab II detector at the Fermilab Tevatron. We use two-body decays into K(-) and B(+) mesons reconstructed as B(+)-> J/psi K(+), J/psi ->mu(+)mu(-) or B(+)->(D) over bar (0)pi(+), (D) over bar (0)-> K(+)pi(-). We deduce the masses of the two states to be m(B(s1))=5829.4 +/- 0.7 MeV/c(2) and m(B(s2)(*))=5839.6 +/- 0.7 MeV/c(2).