Impact parameter-based b-tagging algorithms in the 7 TeV collision data with the ATLAS detector: the TrackCounting and JetProb algorithms

The ability to identify jets containing b-hadrons is important for the high-pT physics program of a general-purpose experiment at the LHC such as ATLAS. Two tagging algorithms taking advantage of the accurate measurement of the transverse impact parameter of charged tracks provided by the ATLAS Inner Detector have been developed and are particulary important for early data. The behaviour of these algorithms is studied in the first 7 TeV collision data recorded in 2010, corresponding to an integrated luminosity of about 1 nb$^{-1}$, and is found to compare well with expectations from Monte Carlo simulation.