Constraints on the spin-parity and anomalousHVVcouplings of the Higgs boson in proton collisions at 7 and 8 TeV

Abstract

The study of the spin-parity and tensor structure of the interactions of the recently discovered Higgs boson is performed using the H → ZZ; Zγ Ã ; γ Ã γ Ã → 4l, H → WW → lνlν, and H → γγ decay modes. The full data set recorded by the CMS experiment during the LHC run 1 is used, corresponding to an integrated luminosity of up to 5.1 fb −1 at a center-of-mass energy of 7 TeV and up to 19.7 fb −1 at 8 TeV. A wide range of spin-two models is excluded at a 99% confidence level or higher, or at a 99.87% confidence level for the minimal gravitylike couplings, regardless of whether assumptions are made on the production mechanism. Any mixed-parity spin-one state is excluded in the ZZ and WW modes at a greater than 99.999% confidence level. Under the hypothesis that the resonance is a spin-zero boson, the tensor structure of the interactions of the Higgs boson with two vector bosons ZZ, Zγ, γγ, and WW is investigated and limits on eleven anomalous contributions are set. Tighter constraints on anomalous HVV interactions are obtained by combining the HZZ and HWW measurements. All observations are consistent with the expectations for the standard model Higgs boson with the quantum numbers J PC ¼ 0 þþ .

Limits on the Higgs boson lifetime and width from its decay to four charged leptons

“…The effective cross-section fraction due to the Λ Q term, denoted as f ΛQ , allows a parametrization similar to the conventions of Λ 1 in Ref. [17]. It is defined for the on-shell gg→H →VV process assuming no contribution from other anomalous couplings as…”

“…An enhancement of the off-shell signal production is suggested with anomalous HVV couplings [10, [25][26][27], but neither experimental studies of off-shell production nor realistic treatment of signal-background interference has been done with these anomalous couplings. We extend the methodology of the recent analysis of anomalous HVV couplings of the H boson [17] to study these couplings and introduce in the scattering amplitude an additional term that depends on the H boson invariant mass, ðq V1 þ q V2 Þ 2 :…”

“…In the SM, only the a 1 term appears at tree level in couplings to ZZ and WW, and it remains dominant after loop corrections. Constraints on the anomalous contributions from the a 2 , a 3 and Λ 1 terms to the H → VV decay have been set by the CMS and ATLAS experiments [16][17][18] through on-shell H boson production.…”

“…From the latter measurement, a joint constraint is set on the H boson width and a parameter that quantifies an anomalous coupling contribution as an onshell cross-section fraction. The event reconstruction and analysis techniques rely on the previously published results [10,16,17,20], and their implementations are discussed in detail. Only the final state with four charged leptons is considered in this paper, but the constraints on the width could be improved by including final states with neutrinos in the off-shell production [10,11].…”

“…The precision on Γ H from direct on-shell measurements alone is approximately 1 GeV [12,13], which is significantly larger. The two experiments have also set constraints on the spin-parity properties and anomalous couplings of the H boson [14][15][16][17][18], finding its quantum numbers to be consistent with J PC ¼ 0 þþ but allowing small anomalous coupling contributions. No direct experimental limit on the H boson lifetime was set, and the possible presence of anomalous couplings was not considered in the constraints on the H boson width.…”