Higgs boson self-coupling constraints from single Higgs, double Higgs and Electroweak measurements

TL;DR

This paper combines electroweak precision data with single and double Higgs measurements from ATLAS to set tighter constraints on the Higgs self-coupling, excluding a broad range of possible values at 95% confidence.

Contribution

It provides a novel combined analysis of electroweak and Higgs data to improve constraints on the Higgs self-coupling, assuming new physics only affects the Higgs potential.

Findings

Excluded $ ext{lambda}_3$ outside $-1.8$ to $9.2$ times SM value at 95% CL.

Stronger constraints than previous analyses without electroweak data.

Demonstrated the importance of electroweak precision observables in Higgs self-coupling constraints.

Abstract

We set constraints on the trilinear Higgs boson self-coupling, $\lambda_3$, by combining the information coming from the $W$ mass and leptonic effective Weinberg angle, electroweak precision observables, with the single Higgs boson analyses targeting the $\gamma \gamma,\, ZZ^*,\, WW^*, \,\tau^+ \tau^-$ and $\bar{b} b$ decay channels and the double Higgs boson analyses in the $b\bar{b}b\bar{b}, \, b\bar{b}b \tau^+ \tau^-$ and $b\bar{b}b \gamma \gamma$ decay channels, performed by the ATLAS collaboration. With the assumption that the new physics affects only the Higgs potential, values outside the interval $ -1.8\, \lambda_3^{\rm SM} < \lambda_3 < 9.2 \, \lambda_3^{\rm SM}$ are excluded at $95\%$ confidence level. With respect to similar analyses that do not include the information coming from the electroweak precision observables our analysis shows a stronger constraint on both positive and negative values of $\lambda_3$.