Tagging of jets initiated by individual b/c-quarks or b-quark pairs, and soft b-tagging techniques in SUSY searches in ATLAS

The production of jets initiated by heavy flavour quarks (b-quarks and c-quarks) is important in many contexts, especially including studies of particles which couple more strongly to massive particles, such as the Higgs boson. The distinct properties of these b-jets and c-jets can be identified by the ATLAS detector and differentiated with respect to jets initiated by light quarks and gluons, where the algorithms used for tagging such heavy flavour jets will be discussed. Additionally, the identification of boosted decays of massive particles to pairs of b-quarks reconstructed within a single large-R jet will be presented, together with methods to evaluate the the differences between simulation and data. Supersymmetric models with compressed stop/sbottom scenarios, where the mass of the squark is close to that of the lightest supersymmetric particle, are well motivated by electroweak baryogengesis and dark matter density regulation considerations. In such scenarios, the b-quarks emitted in the squark decay may carry low momentum, making them difficult to detect for ATLAS through standard b-tagging techniques. This talk will discuss soft b-tagging: different approaches, based either on modification of the jet b-tagging algorithm or on the explicit reconstruction of secondary vertices independently of the presence of jets, will be introduced and compared. The impact on 3rd generation squark searches in the relevant region of the parameter space will also be addressed.