First observation of the decay (B)over-bar(S)(0) -> (DK)-K-0*(0) and a measurement of the ratio of branching fractions B((B)over-bar(S)(0)->(DK)-K-0*(0))/B((B)over-bar(0)-> D-0 rho(0))

The first observation of the decay (B) over bar (0)(S) -> (DK)-K-0*(0) using pp data collected by the LHCb detector at a centre-of-mass energy of 7 TeV, corresponding to an integrated luminosity of 36 pb(-1), is reported. A signal of 34.4 +/- 6.8 events is obtained and the absence of signal is rejected with a statistical significance of more than nine standard deviations. The (B) over bar (0)(S) -> (DK)-K-0*(0) branching fraction is measured relative to that of (B) over bar (0) -> D-0 rho(0): B((B) over bar (0)(S)->(DK)-K-0*(0))/B((B) over bar (0)-> D-0 rho(0)) = 1.48+/-0.34+/-0.15+/-0.12, where the first uncertainty is statistical, the second systematic and the third is due to the uncertainty on the ratio of the B-0 and B-s(0) hadronisation fractions. (C) 2011 CERN. Published by Elsevier B.V. All rights reserved.