# The Higgs width in the SMEFT

## TL;DR

This paper calculates the Higgs decay widths within the SMEFT framework, incorporating corrections beyond the narrow width approximation, providing a practical method for evaluating Higgs decay properties with various parameters.

## Contribution

It introduces a direct evaluation method for Higgs decay widths in SMEFT without relying on the narrow width approximation, accommodating different input schemes.

## Key findings

- SMEFT corrections significantly affect Higgs decay widths.
- The narrow width approximation is less valid in SMEFT than in the SM.
- The method enables quick computation of decay widths for various Wilson coefficients.

## Abstract

We calculate the total and partial inclusive Higgs widths at leading order in the Standard Model Effective Field Theory (SMEFT). We report results incorporating SMEFT corrections for two and four body Higgs decays through vector currents in this limit. The narrow width approximation is avoided and all phase space integrals are directly evaluated. We explain why the narrow width approximation fails more significantly in the SMEFT compared to the SM, despite the narrowness of the observed $\rm SU(2) \times U(1)$ bosons in both theories. Our results are presented in a manner that allows various input parameter schemes to be used, and they allow the inclusive branching ratios and decay widths of the Higgs to be numerically determined without a Monte Carlo generation of phase space for each Wilson coefficient value chosen.