Probing the Higgs Couplings to Photons inh→4ℓat the LHC

Abstract

We explore the sensitivity of the Higgs decay to four leptons, the so-called golden channel, to higher dimensional loop-induced couplings of the Higgs boson to ZZ, Zγ, and γγ pairs, allowing for general CP mixtures. The larger standard model tree level coupling hZ µ Zµ is the dominant "background" for the loop induced couplings. However this large background interferes with the smaller loop induced couplings, enhancing the sensitivity. We perform a maximum likelihood analysis based on analytic expressions of the fully differential decay width for h → 4 (4 ≡ 2e2µ, 4e, 4µ) including all interference effects. We find that the spectral shapes induced by Higgs couplings to photons are particularly different than the hZ µ Zµ background leading to enhanced sensitivity to these couplings. We show that even if the h → γγ and h → 4 rates agree with that predicted by the Standard Model, the golden channel has the potential to probe both the CP nature as well as the overall sign of the Higgs coupling to photons well before the end of a high-luminosity LHC.

Off-shell Higgs coupling measurements in BSM scenarios

“…The importance of high invariant mass measurements in this particular channel in a wider context has been discussed in refs. [37,[43][44][45][46][47][48][49][50] In the particular case of pp → ZZ → 4ℓ, we can classify models according to their effect in the on-shell and off-shell phase space regions. We can identify four regions depending on the measured value of µ off ZZ , which can provide a strong hint for new physics in the above scenarios (ii)-(iv): We can write a generalized version of eq.…”

Supersymmetric custodial Higgs triplets and the breaking of universality

“…Generically, the particle spectrum has several TeV-scale charged particles which can contribute to the Hγγ decay width. These particles will also modify the H → 4 and H → 2 γ decays, which could be used to probe the underlying CP properties of the model [56][57][58][59][60][61][62]. Furthermore, the model will be tested by the direct searches for the additional scalars and fermions arising in the spectrum.…”

Electroweak bounds on Higgs pseudo-observables and $$h\rightarrow 4\ell $$ h → 4 ℓ decays

“…[23][24][25][26][27] for a recent discussion). In this work we focus only on the invariant-mass distributions, both because the effect of the contact terms in h → 4 is the one less studied in the previous literature and because, as shown above, these PO are the less constrained at the moment (at least in the general TGC case).…”