7-9 April 2014
Royal Holloway, University of London
Europe/London timezone
Institute of Physics 2014 Joint High Energy Particle Physics and Astro Particle Physics Groups Annual Meeting

ATLAS results on the Higgs boson properties in the decay channel $H\rightarrow ZZ\rightarrow 4\ell$

8 Apr 2014, 16:15
15m
Room C (Windsor Building)

Room C

Windsor Building

contributed talk The Energy Frontier Programme Parallel 2C

Speaker

Ludovica Aperio Bella (University of Birmingham (GB))

Description

This contribution will review the latest ATLAS results on the properties of the Higgs boson in the decay channel $H\rightarrow ZZ\rightarrow 4\ell$ using approximately 25 fb-1 of pp collision data collected during the LHC Run1 at 7 TeV and 8 TeV. The measurements of the mass and the couplings of the newly discovered boson are presented together with the spin-parity analysis results.

Summary

Since the discovery of a Higgs-like boson by the ATLAS and
CMS experiments at the LHC, the emphasis has shifted towards
measurements of its properties. A review of the latest ATLAS results on the properties of the Higgs boson in the decay channel H—>ZZ—>4l channel using approximately 25 fb-1 of pp collision data collected during the LHC Run1 at 7 TeV and 8 TeV, is presented.
In the four lepton final state a clear excess of events over the background is observed at mH = 124.3 GeV with a significance of 6.6 standard deviations.
Thanks to the very good lepton's energy resolution was possible to perform a mass measurement which is found to be mH = 124.3+0.6-0.5 (stat)+0.5-0.3 (syst) GeV, and the signal strength (the ratio of the observed cross section to the expected SM cross section) at this mass is found to be μ = 1.7+0.5-0.4.
Moreover, a study of Higgs boson production mechanisms allows a first measurement of couplings with this channel. A spin-parity analysis is also performed on the events with reconstructed four-lepton invariant mass m4l satisfying 115 GeV < m4l < 130 GeV. The Higgs-like boson is found to be compatible with the SM expectation of 0+ when compared pair-wise with 0− , 1+ , 1− , 2+ , and 2− . The 0− and 1+ states are excluded at the 97.8% confidence level or higher using CLS in favour of 0+.

Primary author

Ludovica Aperio Bella (University of Birmingham (GB))

Presentation Materials