Opposite-side flavour tagging of mesons at the LHCb experiment.

The calibration and performance of the opposite-side flavour tagging algorithms used for the measurements of time-dependent asymmetries at the LHCb experiment are described. The algorithms have been developed using simulated events and optimized and calibrated with →/, →/ and → decay modes with 0.37 fb of data collected in collisions at [Formula: see text] during the 2011 physics run. The opposite-side tagging power is determined in the →/ channel to be (2.10±0.08±0.24) %, where the first uncertainty is statistical and the second is systematic.