Effective Higgs Lagrangian and Constraints on Higgs Couplings

TL;DR

This paper uses an effective field theory approach to analyze deviations in Higgs boson couplings from Standard Model predictions, constraining possible new physics effects with recent collider and precision data.

Contribution

It develops a reduced effective Lagrangian framework including CP-even and CP-odd operators, and provides updated constraints on Higgs couplings using latest experimental data.

Findings

Current data significantly constrains CP-even operators.

Constraints on some CP-odd operators are also established.

The framework reduces the number of independent effective couplings.

Abstract

Probing the properties of the discovered Higgs boson may tell us whether or not it is the same particle as the one predicted by the Standard Model. To this aim we parametrize deviations of the Higgs couplings to matter from the Standard Model by using the Higgs Effective Field Theory framework. Starting with a general dimension-6 effective Lagrangian including both CP-even and CP-odd operators, and requiring that the operators do not introduce power divergences in the oblique parameters, we reduce the number of independent effective couplings of the theory. This framework is then used to put updated constraints on the effective couplings, using the latest Higgs rates data from the Run-I of the ATLAS and CMS experiments, and electroweak precision data from LEP, SLC and Tevatron. We show that the current data is able to significantly constrain the CP-even and some CP-odd operators of the effective Lagrangian.