Measurements of Higgs boson production and couplings in the four-lepton channel in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>p</mml:mi><mml:mi>p</mml:mi></mml:mrow></mml:math>collisions at center-of-mass energies of 7 and 8 TeV with the ATLAS detector

Abstract

The final ATLAS Run 1 measurements of Higgs boson production and couplings in the decay channel H ZZ l l -l 0 l 0-, where l, l 0 e or , are presented. These measurements were performed using pp collision data corresponding to integrated luminosities of 4.5 and 20.3 fb -1 at center-of-mass energies of 7 and 8 TeV, respectively, recorded with the ATLAS detector at the LHC. The H ZZ 4l signal is observed with a significance of 8.1 standard deviations, with an expectation of 6.2 standard deviations, at m H 125.36 GeV, the combined ATLAS measurement of the Higgs boson mass from the H and H ZZ 4l channels. The production rate relative to the Standard Model expectation, the signal strength, is measured in four different production categories in the H ZZ 4l channel. The measured signal strength, at this mass, and with all categories combined, is 1.44 0.40 -0.33 . The signal strength for Higgs boson production in gluon fusion or in association with t t or b b pairs is found to be 1.7 0.5 -0.4 , while the signal strength for vector-boson fusion combined with WH=ZH associated production is found to be 0.3 1.6 -0.9 .