Benchmarks for Higgs effective theory: extended Higgs sectors

Abstract

Precise measurements of SM particles properties at the LHC allows to look for heavy New Physics in the context of an Effective Field Theory (EFT). These searches, however, often rely on kinematic regions where the validity of the EFT may be compromised. In this paper we propose to address this issue by comparing with benchmark models. The connection between models and their manifestations as EFTs at low energies allows us to quantify the breakdown of the EFT, and describe ways to combine different sources of constraints beyond Higgs physics. To illustrate these techniques, in this paper we propose a set of benchmark models based on extensions of the Higgs sector, namely the inclusion of a singlet, a dilaton and generic 2HDMs. We obtain the matching between these models and the EFT involving the Higgs, electroweak bosons and fermions. We then describe current and future indirect and direct constraints, consider the effect of correlations among the coefficients within models, and discuss the validity of the EFT.

The effective Standard Model after LHC Run I

“…Moreover, in the 2DHM one also finds generically thatc 3W is suppressed [130] c 3W ∼ O(0.1)g 2c HW , (4.4) so that it can be an order of magnitude smaller. In our application to the 2HDM we set it to zero, as well as using the constraints (4.3).…”

“…The case of a singlet scalar and stops contributing to dimension-6 operators was recently considered in [129]. Here we briefly look at applying our constraints to the 2HDM scenario, which is worth further investigation [130]. Figure 7.…”

“…Below we give the results of the fit using LHC diboson and Higgs data only, as with the combination of diboson ATLAS and CMS data, the inclusion of LEP data does not substantially affect our results. Examples of models in this class include a general two-Higgs doublet model (2HDM) [130], supersymmetry with electroweakino/sfermion loops [134], and the exchange of a radion/dilaton particle [133]. In the former two models these operators are generated at loop level, whereas in the third case the operators appear at tree-level through the exchange of the radion/dilaton particle.…”

“…The translation between the coefficients and the 2HDM will be presented in ref. [130], but let us comment here how these values relate to the validity of the effective theory. Roughly speaking, we find thatc…”

The gauge-Higgs legacy of the LHC Run I

“…One caveat applies to these results the same way it applies to the Higgs analyses alone [6,7,[79][80][81][82][83][84][85]. 1 If we consider the dimension-six Lagrangian of eq.…”