A search for B0
(s) → K0
SK∗
(892)0 decays is performed using pp collision data,
corresponding to an integrated luminosity of 1.0 fb−1
, collected with the LHCb detector at
a centre-of-mass energy of 7 TeV. The B0
s → K0
SK∗
(892)0 decay is observed for the first
time, with a significance of 7.1 standard deviations. The branching fraction is measured
to be
B(B
0
s → K¯ 0K∗
(892)0
) + B(B
0
s → K0K¯ ∗
(892)0
) = (16.4 ± 3.4 ± 2.3) × 10−6
,
where the first uncertainty is statistical and the second is systematic. No evidence is found
for the decay B0 → K0
SK∗
(892)0 and an upper limit is set on the branching fraction,
B(B0 → K¯ 0K∗
(892)0
) + B(B0 → K0K¯ ∗
(892)0
) < 0.96 × 10−6
, at 90 % confidence level.
All results are consistent with Standard Model predictions.