Identification and Tagging of Double b-hadron jets with the ATLAS Detector

A method is presented allowing the identification of jets containing two b-hadrons. The technique exploits the kinematic differences between these and single b-jets using track-based jet shape and jet substructure variables combined in a multivariate likelihood discriminant. The ability to reject double b-hadron jets is important in order to reduce and to improve the estimation of the b-tag background in Standard Model analyses and in new physics searches that rely on the presence of b-jets containing a single b-quark or antiquark. In the simulation, the algorithm rejects 95% of the double b-hadron jets while retaining 50% of the single b-jets, although the exact values depend on the jet pT.