A Double Take on New Physics in Double Higgs Production

TL;DR

This paper tackles the challenge of extracting the Higgs self-coupling from gluon-initiated double Higgs production $gg\to hh$ in the presence of other new-physics effects. It introduces a minimal three-parameter framework with $c_{tri}$, $c_{nl}$ and $c_{box}$ that maps to Higgs-top couplings and analyzes their impact on the kinematic observables $m_{hh}$ and $p_T$ at a future $100\,\text{TeV}$ collider. The results show that differential binning in $m_{hh}$ can help disentangle $c_{box}$ and $c_{nl}$ and partially constrain $c_{tri}$, but degeneracies remain and a precise measurement of the self-coupling requires knowledge of other new-physics magnitudes. The authors advocate using the Matrix Element Method to fully exploit kinematic information for precision Higgs self-interaction studies.

Abstract

Gluon-initiated double Higgs production is the most important channel to extract the Higgs self-coupling at hadron colliders. However, new physics could enter into this channel in several distinctive ways including, but not limited to, the Higgs self-coupling, a modified top Yukawa coupling, and an anomalous Higgs-top quartic coupling. In this work we initiate a study on the interplay of these effects in the kinematic distributions of the Higgs bosons. More specifically, we divide the transverse momentum and the total invariant mass spectra into two bins and use the differential rates in each bin to constrain the magnitude of the aforementioned effects. Significantly improved results could be obtained over those using total cross section alone. However, some degeneracy remains, especially in the determination of the Higgs trilinear coupling. Therefore, an accurate measurement of the Higgs self-coupling in this channel would require precise knowledge of the magnitudes of other new physics effects. We base our analysis on a future 100 TeV proton-proton collider.

Figures (7)

• Figure 1: Feynman diagrams contributing to double Higgs production at hadron colliders.
• Figure 2: Comparison of LO kinematic distributions in the SM at $\sqrt{s}=14$ and 100 TeV.
• Figure 3: Individual contribution from $c_{tri}$, $c_{nl}$ and $c_{box}$, respectively, to the LO kinematic distributions in a $pp$ collider at $\sqrt{s}=100$ TeV.
• Figure 4: Similarities in kinematic distributions for various choices of $c_{box}$, $c_{tri}$, and $c_{nl}$ in a $pp$ collider at $\sqrt{s}=100$ TeV.
• Figure 5: (a) The yellow region shows $\sigma/\sigma^{SM}$ by varying $c_{box}$ and $c_{tri}$ between $-2$ to $2$ and setting $c_{nl}=0$. The horizontal line indicates no deviation from the SM rate. (b) Same as (a), but with $c_{tri}=1$ and $c_{nl}$ varying from $-2$ to $2$.