Higgs Boson Physics at ATLAS

Abstract

The discovery of a new boson with the ATLAS detector at the LHC proton-proton collider is confirmed using the full data set collected at centre-of-mass energies of 7 and 8 TeV. The spin and parity properties of the boson are consistent with that of a scalar particle with positive parity. Comparison of the $J^{P}=0^+$ hypothesis to alternatives $J^{P} = 0^-,1^{+},1^-,2^+$ result in exclusion of these other choices at 97.8\%, 99.97\%, 99.7\%, and 99.3\% CL. The Higgs-boson Mass is $m_H = 125.5 \pm 0.2 {\rm (stat.)} ^{+0.5}_{-0.5} {\rm (syst.)}$ \GeV. Evidence for production of the Higgs boson by vector boson fusion is obtained in a model-independent approach by comparing the signal strengths $\mu$ of vector boson fusion and production associated with a vector boson to to that for gluon fusion including associated production of top quark pairs: $\mu_{\rm VBF+VH}/\mu_{\rm ggF+ttH}= 1.4 ^{+0.4}_{-0.3} \rm{(stat.)} ^{+0.6}_{-0.4} \rm{(syst.)}$ which is 3.3 Gaussian standard deviations from zero