  Results are presented of a search for supersymmetric particles decaying into
final states with significant missing transverse momentum and exactly two
identical flavour leptons (e or mu) of opposite charge in sqrt{s}=7 TeV
collisions at the Large Hadron Collider. This channel is particularly sensitive
to supersymmetric particle cascade decays producing flavour correlated lepton
pairs. Flavour uncorrelated backgrounds are subtracted using a sample of
opposite flavour lepton pair events. Observation of an excess beyond Standard
Model expectations following this subtraction procedure would offer one of the
best routes to measuring the masses of supersymmetric particles. In a data
sample corresponding to an integrated luminosity of 35 pb-1 no such excess is
observed. Model-independent limits are set on the contribution to these final
states from new physics and are used to exclude regions of a phenomenological
supersymmetric parameter space.
