Precision Higgs Measurements: Constraints from New Oblique Corrections

TL;DR

This paper explores how new particles at the TeV scale can affect Higgs boson couplings through oblique corrections, providing theoretical calculations and emphasizing the importance of precise Higgs measurements for constraining new physics.

Contribution

It offers next-to-leading order QCD corrections for Higgs couplings to digluon and diphoton channels, improving theoretical precision and aiding constraints on new particles.

Findings

Deviations in Higgs couplings can reach about 5% for 1 TeV new particles.

Provides two-loop order QCD corrections for Higgs couplings in arbitrary color representations.

New calculations for top squark contributions to Higgs digluon decay differ from previous results.

Abstract

New particles entering into self-energies of the Higgs boson would necessarily modify loop-induced couplings of the Higgs, if the new particle carries standard model gauge quantum numbers. For a 1 TeV new particle, deviations in these "Higgs oblique corrections" are generically of the order of v^2/(1 TeV)^2 ~ 5%. We study constraints on masses and couplings of new scalars and fermions that can be derived from 5-10% deviations in the Higgs digluon and diphoton partial widths. To reduce theoretical uncertainties, we present next-to-leading order QCD corrections to the Higgs-to-digluon coupling for scalars and fermions in arbitrary representations of SU(3) color group, by applying the low-energy Higgs theorems at two-loop order. As a by-product we provide a new value for NLO QCD corrections to the top squark contributions to digluon decays that differs from existing literature. We also emphasize that precise measurements of Higgs couplings to W boson and top quark are prerequisite to precise determinations of Higgs oblique corrections from new particles.