Single Higgs production in association with a photon at electron-positron colliders in extended Higgs models

Abstract

We study associated Higgs production with a photon at electron-positron colliders, e + e − → hγ, in various extended Higgs models, such as the inert doublet model (IDM), the inert triplet model (ITM) and the two Higgs doublet model (THDM). The cross section in the standard model (SM) is maximal around √ s = 250 GeV, and we present how and how much the new physics can enhance or reduce the production rate. We also discuss the correlation with the h → γγ and h → Zγ decay rates. We find that, with a sizable coupling to a SMlike Higgs boson, charged scalars can give considerable contributions to both the production and the decay if their masses are around 100 GeV. Under the theoretical constraints from vacuum stability and perturbative unitarity as well as the current constraints from the Higgs measurements at the LHC, the production rate can be enhanced from the SM prediction at most by a factor of two in the IDM. In the ITM, in addition, we find a particular parameter region where the hγ production significantly increases by a factor of about six to eight, but the h → γγ decay still remains as in the SM. In the THDM, possible deviations from the SM prediction are minor in the viable parameter space.

Higgs boson to γZ decay as a probe of flavor-changing neutral Yukawa couplings

“…[94][95][96]. There are also some works on this process in many new physics models, for example, the MSSM [96][97][98][99], extended scalar sector models [100,101], VLQ models [102], effective field theory framework [103][104][105][106], and simplified scenarios [107]. Besides, we can also probe the FCNY couplings through direct production processes pp → Tth; Tt; ThW; Thj.…”

Associated production of SM Higgs with a photon in type-II seesaw models at the ILC

“…We first comment about e + e − → γH in the SM. Like H → γγ and H → γZ, the vertex contribution in e + e − → γH is dominated by the W loops while the top contribution is sub-leading and interfere destructively with the W loops [34]. For center of mass energy ≤ 350 GeV, the SM box contribution is almost of the same order as the vertex and interfere destructively while for higher cm energy ≥ 350 GeV the total cross section is dominated by the boxes and are constructive with the vertex.…”

“…At the LC, the one loop mediated process e + e − → γh 0 if measured could also shed some light on h 0 γγ and h 0 γZ couplings. Such process has been investigated in the SM [30,31], and also in many Beyond SM (BSM) scenarios, like SUSY [32,36], extended Higgs sector [33,34], and in the Inert Higgs Model [35].…”

“…In this work, we examine the effect of a singly and a doubly charged Higgs bosons in the associated production of the SM Higgs with a photon e + e − → h 0 γ at the LC and also e − γ → h 0 e − which would take place if the e − γ collisions are available at the LC. In Ref [34], the authors study e + e − → γh 0 in the framework of Inert Triplet Model with an exact Z 2 symmetry under which the triplet scalar is odd while all the other SM particles are even which guaranty that the model have a dark matter candidate. Because of Z 2 symmetry, the SM Higgs comes only from the doublet, the couplings h 0 H ± H ∓ and h 0 H ±± H ∓∓ originate only from triplet interaction with SM doublet while in our case there is extra terms that come from the mixing between the doublet and triplet components.…”

“…Because of Z 2 symmetry, the SM Higgs comes only from the doublet, the couplings h 0 H ± H ∓ and h 0 H ±± H ∓∓ originate only from triplet interaction with SM doublet while in our case there is extra terms that come from the mixing between the doublet and triplet components. In addition, in our study, we will also address the process e − γ → h 0 e − which is not covered in Ref [34].…”