A global view on the Higgs self-coupling at lepton colliders

TL;DR

This paper assesses the potential precision of measuring the Higgs self-coupling at future lepton colliders using a global effective-field-theory approach, considering different energy scenarios and collider configurations.

Contribution

It provides a comprehensive analysis of Higgs self-coupling determination at lepton colliders, highlighting the importance of collider energy and global fits for accurate measurements.

Findings

Low-energy colliders can achieve ~40% precision with combined measurements.

High-energy colliders can reach ~20% precision through Higgs pair production.

Global fits are crucial for robust Higgs self-coupling extraction.

Abstract

We perform a global effective-field-theory analysis to assess the precision on the determination of the Higgs trilinear self-coupling at future lepton colliders. Two main scenarios are considered, depending on whether the center-of-mass energy of the colliders is sufficient or not to access Higgs pair production processes. Low-energy machines allow for ~40% precision on the extraction of the Higgs trilinear coupling through the exploitation of next-to-leading-order effects in single Higgs measurements, provided that runs at both 240/250 GeV and 350 GeV are available with luminosities in the few attobarns range. A global fit, including possible deviations in other SM couplings, is essential in this case to obtain a robust determination of the Higgs self-coupling. High-energy machines can easily achieve a ~20% precision through Higgs pair production processes. In this case, the impact of additional coupling modifications is milder, although not completely negligible.