First observation of the decay B-s(0) -> K*(0)(K)over-bar*(0)

The first observation of the decay B-s(0) -> K*(0)(K) over bar*(0) is reported using 35 pb(-1) of data collected by LHCb in proton-proton collisions at a centre-of-mass energy of 7 TeV. A total of 49.8 +/- 7.5 B-s(0) -> (K+pi(-))(K-pi(+)) events are observed within +/- 50 MeV/c(2) of the B-s(0) mass and 746 MeV/c(2) < m(K pi) < 1046 MeV/c(2), mostly coming from a resonant B-s(0) -> K*(0)(K) over bar*(0) signal. The branching fraction and the CP-averaged K*(0) longitudinal polarization fraction are measured to B(B-s(0) -> K*(0)(K) over bar*(0)) = (2.81 +/- 0.46(stat.) +/- 0.45(syst.) +/- 0.34(f(s)/f(d))) x 10(-5) and f(L) = 0.31 +/- 0.12(stat.) +/- 0.04(syst.). (C) 2012 CERN. Published by Elsevier B.V. All rights reserved. RI Galli, Domenico/A-1606-2012; Leflat, Alexander/D-7284-2012; Coca, Cornelia/B-6015-2012; Petrolini, Alessandro/H-3782-2011; Sarti, Alessio/I-2833-2012; manca, giulia/I-9264-2012; de Paula, Leandro/I-9278-2012; Patrignani, Claudia/C-5223-2009; Marconi, Umberto/J-2263-2012; de Simone, Patrizia/J-3549-2012; Cardini, Alessandro/J-5736-2012; Teodorescu, Eliza/K-3044-2012