Form Factors in Higgs Couplings from Physics Beyond the Standard Model

Abstract

We consider the momentum dependent effects in Higgs couplings generated by physics beyond the standard model. We take a model dependent approach, in which we can compute fully the non-local effects from physics not directly reachable by the LHC energy. We consider several scenarios, including composite Higgs models, additional scalars, and the continuum contributions of a quasi-conformal sector, as examples. For each specific model, we obtain the full form factor, with which one can eventually fully simulate the effects in kinematics distributions. The momentum dependent effects appear as a consequence of off-shellness in the process. We show how the sensitivity of different channels to the various models depends on the flow of off-shellness in the Higgs couplings.

A new evaluation of the $HZZ$ coupling: direct bounds on anomalous contributions and $CP$ violating effects via a new assymetry

“…Z µ (p 1 ) We are interested in the coupling with an off-shell Higgs boson H * ZZ. Nevertheless, for completeness we will also study the HZZ * coupling, which has been largely studied as it has several implications at particle colliders [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]. Therefore, from Lagrangian (1) neglecting the scalar component of the Z bosons (we use ∂ µ Z µ = 0) and considering the kinematics H * → ZZ(Z * → HZ) along with the notation of Fig.…”

“…For illustration purposes, the values of the real and imaginary parts of the h H 2 form factors at a few q values are presented in Table III, along with the values for bZ , a ZZ 2 and c zz , which can be obtained from Eqs. ( 9), ( 15) and (32), respectively. In effective field theories the couplings are taken as constant and do not depend on q , but our results can be useful to constraint the energy scale Λ of the model.…”

“…The phenomenological and experimental implications of the H * ZZ coupling at the LCH and future colliders have been explored in the past and also very recently [7][8][9][10][11][12][13][14][15]. Furthermore, the off-shell HZZ * coupling has also several phenomenological implications, which have been studied through HZ production [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34]. Thus, the HZZ coupling is worth studying, thereby requiring a highly precise determination of all its lowest order contributions.…”