Putting a Stop to di-Higgs Modifications

TL;DR

This paper investigates how new physics, especially top squarks in supersymmetry, can enhance di-Higgs production at colliders, finding that while generally constrained, certain tuned scenarios allow significant increases detectable in future experiments.

Contribution

It demonstrates that in supersymmetric models, di-Higgs production enhancements are usually limited but can reach large values in specific tuned parameter regions, challenging EFT-based expectations.

Findings

Most di-Higgs enhancements are constrained by single Higgs data.

Tuned parameter regions can produce up to 100% increase in di-Higgs rates.

Potential observability of these effects at future colliders.

Abstract

Pair production of Higgs bosons at hadron colliders is an enticing channel to search for new physics. New colored particles that couple strongly to the Higgs, such as those most often called upon to address the hierarchy problem, provide well motivated examples in which large enhancements of the di-Higgs rate are possible, at least in principle. However, in such scenarios the di-Higgs production rate is tightly correlated with the single Higgs production rate and, since the latter is observed to be SM-like, one generally expects that only modest enhancements in di-Higgs production are allowed by the LHC Run 1 data. We examine the contribution of top squarks (stops) in a simplified supersymmetry model to di-Higgs production and find that this general expectation is indeed borne out. In particular, the allowed deviations are typically small, but there are tuned regions of parameter space where expectations based on EFT arguments break down in which order 100% enhancements to the di-Higgs production rate are possible and are simultaneously consistent with the observed single Higgs production rates. These effects are potentially observable with the high luminosity run of the LHC or at a future hadron collider.