Novel Methods and Expected Run 2 Performance for ATLAS Track Reconstruction in Dense Environments

Novel algorithmic developments to the ATLAS track reconstruction software targeting the core of high pT objects is discussed explaining improvements made for Run 2 resulting in: 5%increaseofefficiencytoreconstructallthreechargeddaughtersofahadronicllydecay- ing τ with pT above 600 GeV 10% more pixel clusters found on tracks in the jet core, 17% efficiency gain is seen for charged particles created at a radius of 30 mm, 10% (14%) efficiency improvement in the core of high pT light (b) jets, 7-13% increase in b-tagging efficiency for a given light-jet rejection.