Higgs decays to two leptons and a photon beyond leading order in the SMEFT

Abstract

We present the three-body decay of the Higgs boson into two leptons and a photon to dimension-eight in the Standard Model Effective Field Theory (SMEFT). In order to obtain this result we interfere the full one-loop Standard Model result with the tree-level result in the SMEFT. This is the first calculation of the partial width of the Higgs boson into two leptons and a photon in the SMEFT to incorporate the full one-loop dependence for the Standard Model as well as the full tree level dimension-eight dependence in the SMEFT. We find that this channel can aid in distinguishing strongly interacting and weakly interacting UV completions of the SMEFT under standard assumptions. We also find that this channel presents the opportunity to distinguish different operator Classes within the SMEFT, potentially including contact H\bar\ell\ell\gammaHℓ‾ℓγ operators which are first generated only at dimension-eight in the SMEFT.

Higgs boson decay into a lepton pair and a photon revisited

“…These experimental pursuits align with recent theoretical analyses of the process H → ℓ + ℓ − γ given in several articles [4][5][6][7][8][9][10], building upon earlier studies [11][12][13][14][15]. Furthermore, the analogous decay of the Higgs boson, involving a photon and a neutrino pair in the final state has received relatively less attention [16][17][18].…”

“…The corresponding rates are loop-suppressed in the standard model, providing opportunities to detect signals of physics beyond the standard model, particularly if new particles appear with sufficiently low masses and large enough couplings to produce discernible signatures. In addition to H → Zγ, there is an ongoing effort to search for a decay channel to a photon and a pair of light charged leptons in the region of low lepton-pair invariant mass [3].These experimental pursuits align with recent theoretical analyses of the process H → ℓ + ℓ − γ given in several articles [4][5][6][7][8][9][10], building upon earlier studies [11][12][13][14][15]. Furthermore, the analogous decay of the Higgs boson, involving a photon and a neutrino pair in the final state has received relatively less attention [16][17][18].…”

Higgs associated production with a vector decaying to two fermions in the geoSMEFT

“…3. There are known instances where the dimension-eight terms have significant impacts on the infrared physics that would be missed by only including dimension-six results [14,[21][22][23][24]. This should, for completeness, be contrasted with cases where dimensioneight has little phenomenological impact [12].…”