Bonn 2020 – scientific programme

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T: Fachverband Teilchenphysik

T 96: Higgs: Decay into fermions III

T 96.7: Talk

Friday, April 3, 2020, 12:30–12:45, H-HS X

Development of a jet substructure based multivariate Higgs tagger and its calibration using g→ bb events with the ATLAS experiment. — •Shubham Bansal, Tatjana Lenz, and Norbert Wermes — Physikalisches Institut, Universität Bonn

Within the ATLAS collaboration, the most recent algorithm to separate boosted H→ bb from dominant backgrounds like multijets and jets originating from hadronically decaying top-quarks, employs a cut based approach using jet kinematics, b-tagging and jet substructure. Jet substructure variables in particular, gave an additional multijet background rejection over mass and b-tagging requirement, which are the most powerful variables, in some regions of phase space. This sensitivity from individual jet substructure variables can be seen as a motivation to combine many jet substructure variables in a multivariate discriminant to tag a boosted object like Higgs, in order to gain a larger improvement in the performance.

This talk presents a jet substructure based multivariate algorithm which is designed to separate 2-prong jets (two track-jets of R = 0.2 associated to a large-R = 1.0 jet, e.g. H→ bb) from 1-prong jets (a single track-jet associated to a large-R jet, e.g. QCD jets). This multivariate Higgs tagger is optimised in multijet simulated events and the modelling of the tagger and its input variables is examined in 15.4 fb⁻¹ of data collected in 2016 at √s = 13 TeV using g→ bb event selection in data. The calibration of the tagger is carried out in both g→ bb and H→ bb simulated events and a comparison between these two topologies is made.