Low-Energy Theorems in Higgs Physics

TL;DR

The paper develops and extends low-energy theorems for neutral Higgs bosons with vanishing momentum, enabling the integration of heavy loop effects into compact effective Lagrangians for SM and MSSM. It provides explicit one- and two-loop results for Higgs couplings to photons, gluons, Zγ, ZZ, and WW, as well as H→bb and production channels, highlighting top-quark and W-boson contributions and ABJ anomaly implications for pseudoscalars. The LET framework yields precise, compact expressions that simplify predictions for Higgs production and decay at current and future colliders, with quantified QCD and electroweak corrections. Overall, the work delivers a systematic method to obtain high-precision Higgs amplitudes in the low-energy limit by integrating out heavy degrees of freedom, with broad applicability to SM and MSSM phenomenology.

Abstract

We present low-energy theorems for the calculation of loop amplitudes with external scalar or pseudoscalar Higgs bosons which are light compared to the loop particles. Starting from existing lowest-order versions of these theorems, we show how their applicability may be extended to the two--loop level. To illustrate the usefulness of these theorems, we discuss a number of applications to Higgs production and decay at and beyond the one--loop order.