The first measurement of ${ C\!P}$ asymmetries in the decay ${ B_s^0\to J/\psi \overline{ K}^{ *}(892)^{ 0}}$ and an updated measurement of its branching fraction and polarisation fractions are presented. The results are obtained using data corresponding to an integrated luminosity of $3.0\,fb^{ -1}$ of proton-proton collisions recorded with the LHCb detector at centre-of-mass energies of $7$ and $8\,\mathrm{ TeV}$. Together with constraints from ${ B^0\to J/\psi \rho^0}$, the results are used to constrain additional contributions due to penguin diagrams in the ${ C\!P}$-violating phase ${ { \phi}_{ s}}$, measured through ${ B_s^0}$ decays to charmonium.
Categories: hep-ex