Measurement of CP observables in B0 → DK*0 with D →K+K-

The decay B-0 -> DK*(0) and the charge conjugate mode are studied using 1.0 fb(-1) of pp collision data collected by the LHCb experiment at \/s = 7 TeV in 2011. The CP asymmetry between the B-0 -> DK*(0) and the B-0 -> DK*(0) decay rates, with the neutral D meson in the CP-even final state K+K- , is found to be A(d)(KK) = -0.45 +/- 0.23 +/- 0.02, where the first uncertainty is statistical and the second is systematic. In addition, favoured B-0 -> DK*(0) decays are reconstructed with the D meson in the non-CP eigenstate K+pi(-) . ratio of the B-flavour averaged decay rates in D decays to CP and non-CP eigenstates is measured to be R-d(KK) = 1.36 +/- 0.37 0.32 +/- 0.07, where the ratio of the branching fractions of D-0 -> K- pi(+) to D-0 -> K+K- decays is included as multiplicative factor. The CP asymmetries measured with two control channels, the favoured B-0 -> DK*(0) decay with D -> K-vertical bar pi(-) and the B-s(0) -> DK*(0) decay with D -> K+K-, are also reported.