Constraints on the trilinear and quartic Higgs couplings from triple Higgs production at the LHC and beyond

Abstract

Experimental information on the trilinear Higgs boson self-coupling ${\kappa }_3$ and the quartic self-coupling ${\kappa }_4$ will be crucial for gaining insight into the shape of the Higgs potential and the nature of the electroweak phase transition. While Higgs pair production processes provide access to ${\kappa }_3$, triple Higgs production processes, despite their small cross sections, will provide valuable complementary information on ${\kappa }_3$ and first experimental constraints on ${\kappa }_4$. We investigate triple Higgs boson production at the HL-LHC, employing efficient Graph Neural Network methodologies to maximise the statistical yield. We show that it will be possible to establish bounds on the variation of both couplings from the HL-LHC analyses that significantly go beyond the constraints from perturbative unitarity. We also discuss the prospects for the analysis of triple Higgs production at future high-energy lepton colliders operating at the TeV scale.

Comments: 15 pages, 11 figures; v2: accepted by EPJC; v3: corrected sign typo in Eq. (4);