Identifying the Higgs spin and parity in decays to Z pairs

Abstract

Higgs decays to Z boson pairs may be exploited to determine spin and parity of the Higgs boson, a method complementary to spin-parity measurements in Higgsstrahlung. For a Higgs mass above the on-shell ZZ decay threshold, a modelindependent analysis can be performed, but only by making use of additional angular correlation effects in gluon-gluon fusion at the LHC and γγ fusion at linear colliders. In the intermediate mass range, in which the Higgs boson decays into pairs of real and virtual Z bosons, threshold effects and angular correlations, parallel to Higgs-strahlung, may be adopted to determine spin and parity, though high event rates will be required for the analysis in practice.

Scrutinizing the Higgs signal and background in the 2e2μ golden channel

“…It has been shown in recent studies [3][4][5][6][7][8] and also emphasized for quite some time [9][10][11][12][13], that the decay to four charged leptons is a powerful channel in accomplishing this goal. Because of the experimental precision with which this channel is measured, it offers one of the few opportunities to use analytic methods to analyze the data.…”

Higgs physics: Theory

“…One example is to study the threshold behaviour of the M Z * spectrum in the H → ZZ ( * ) →→ 4ℓ decay for M H < ∼ 2M Z [88,89]. Since the relative fraction of the longitudinally to transversely polarised Z bosons varies with M Z * , this distribution is sensitive to both the spin and the CP nature of the Higgs.…”

“…14 [88]. Center: Higgs spin determination via the threshold behaviour of the distribution in MZ * for the H → ZZ * → ℓ decay [89]. Right: Azimuthal angle distribution for the two jets produced in association with the Higgs for CP-even and CP-odd cases [90].…”

“…Another very useful diagnostic of the CP nature of the Higgs boson is the azimuthal distribution between the decay planes of the two lepton pairs arising from the Z, Z ( * ) bosons coming from the Higgs decay [14,88,89,92]. Alternatively, one can study the distribution in the azimuthal angle between the two jets produced in association with the Higgs produced in the vector boson fusion process or in gluon fusion in Higgs plus jet events [90,91].…”

Precision calculations for the Higgs decays H → ZZ/WW → 4 leptons

“…Thereby, it is important to include radiative corrections, in particular real photon radiation. In addition, the verification of the spin and the CP properties of the Higgs boson relies on the study of angular and invariantmass distributions [3,4]. As a consequence a Monte Carlo generator for H → ZZ/WW → 4f including electroweak corrections is needed.…”