A new method to distinguish hadronically decaying boosted Z bosons from W bosons using the ATLAS detector

Journal article

The distribution of particles inside hadronic jets produced in the decay of boosted W and Z bosons can be used to discriminate such jets from the continuum background. Given that a jet has been identified as likely resulting from the hadronic decay of a boosted W or Z boson, this paper presents a technique for further differentiating Z bosons from W bosons. The variables used are jet mass, jet charge, and a b-tagging discriminant. A likelihood tagger is constructed from these variables and tested in the simulation of W′→ WZ for bosons in the transverse momentum range 200 GeV < pT< 400 GeV in s= 8 TeV pp collisions with the ATLAS detector at the LHC. For Z-boson tagging efficiencies of ϵZ= 90 , 50, and 10 % , one can achieve W+-boson tagging rejection factors (1 / ϵW+ ) of 1.7, 8.3 and 1000, respectively. It is not possible to measure these efficiencies in the data due to the lack of a pure sample of high pT, hadronically decaying Z bosons. However, the modelling of the tagger inputs for boosted W bosons is studied in data using a tt¯ -enriched sample of events in 20.3 fb- 1 of data at s= 8 TeV. The inputs are well modelled within uncertainties, which builds confidence in the expected tagger performance.

Authors: ATLAS Collaboration; Barr, A; Becker, K; Behr, J; Beresford, L

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Springer Verlag
• Journal: European Physical Journal C
• Volume: 76
• Issue: 5
• Publication date: 2016-04-28
• Acceptance date: 2016-04-08
• DOI: 10.1140/epjc/s10052-016-4065-1
• EISSN: 1434-6052
• ISSN: 1434-6044