ICHEP 2016 Chicago

Boosted Higgs —> bb tagging in ATLAS

6 Aug 2016, 18:00

2h

Riverwalk A/B

Poster Higgs Physics Poster Session

Speaker

Nikola Lazar Whallon (University of Washington (US))

Description

High $p_T$ (``boosted'') Higgs bosons decaying into a pair of $b$-quarks are an important signature for many physics searches in Run 2. The reconstruction and identification of such signatures relies mainly on the long-lived nature of the $b$-hadrons arising from the fragmentation of the $b$-quarks. Several advanced Higgs boson tagging techniques are presented here, including the reconstruction of the $b$-hadrons as subjets, the reconstruction of the vertices from the $b$-hadron decays, and the combination of this information into a boosted decision tree (BDT). In addition, new subjet tagging techniques are investigated: the use of variable radius track jets and of exclusive $k_T$ calorimeter subjets, as well as a multiple secondary vertex (MSV) algorithm to reconstruct simultaneously the decay chain of both $b$-hadrons. The best performing Higgs boson tagger is found to be a BDT combination of the MSV algorithm and the subjet-based $b$-tagging algorithms.