Probing the Higgs self coupling via single Higgs production at the LHC

TL;DR

This paper introduces an indirect method to measure the Higgs self-coupling at the LHC by analyzing electroweak loop effects on single Higgs production, offering a promising alternative to direct pair production measurements.

Contribution

It develops a novel approach to constrain the Higgs self-coupling through electroweak loop effects on single Higgs processes, providing a complementary measurement method.

Findings

Bounds on the Higgs self-coupling are competitive with direct measurements.

Current LHC data already constrain the self-coupling effectively.

Future LHC runs will improve the bounds further.

Abstract

We propose a method to determine the trilinear Higgs self coupling that is alternative to the direct measurement of Higgs pair production total cross sections and differential distributions. The method relies on the effects that electroweak loops featuring an anomalous trilinear coupling would imprint on single Higgs production at the LHC. We first calculate these contributions to all the phenomenologically relevant Higgs production ($gg{\rm F}$, VBF, $WH$, $ZH$, $t\bar tH$) and decay ($\gamma \gamma$, $WW^{*}/ZZ^{*}\to 4f$, $b\bar b$, $\tau \tau$) modes at the LHC and then estimate the sensitivity to the trilinear coupling via a one-parameter fit to the single Higgs measurements at the LHC 8 TeV. We find that the bounds on the self coupling are already competitive with those from Higgs pair production and will be further improved in the current and next LHC runs.