Abstract
The first observation of the decay
$ B_s^0\to \phi \overline{K}{*^0} $
is reported. The analysis is based on a data sample corresponding to an integrated luminosity of 1.0 fb−1 of pp collisions at
$ \sqrt{s}=7 $
TeV, collected with the LHCb detector. A yield of 30 ± 6
$ B_s^0\to \left( {{K^{+}}{K^{-}}} \right)\left( {{K^{-}}{\pi^{+}}} \right) $
decays is found in the mass windows 1012.5 < M (K
+
K
−) < 1026.5 MeV/c
2 and 746 < M(K
−
π
+) < 1046 MeV/c
2. The signal yield is found to be dominated by
$ B_s^0\to \phi \overline{K}{*^0} $
decays, and the corresponding branching fraction is measured to be
$ \mathcal{B}\left( {B_s^0\to \phi \overline{K}{*^0}} \right) $
= (1.10 ± 0.24 (stat) ± 0.14 (syst) ± 0.08 (f
d
/f
s
)) × 10−6, where the uncertainties are statistical, systematic and from the ratio of fragmentation fractions f
d
/f
s
which accounts for the different production rate of B
0 and
$ B_s^0 $
mesons. The significance of
$ B_s^0\to \phi \overline{K}{*^0} $
signal is 6.1 standard deviations. The fraction of longitudinal polarization in
$ B_s^0\to \phi \overline{K}{*^0} $
decays is found to be f
0 = 0.51 ± 0.15 (stat) ± 0.07 (syst).
