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

The first observation of the decay (B) over bar (0)(S) -> D(0)K*(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) -> D(0)K*(0) branching fraction is measured relative to that of (B) over bar (0) -> D(0)rho(0): B((B) over bar (0)(S)-> D(0)K*(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.