Constraints on the trilinear and quartic Higgs couplings from triple Higgs production at the LHC and beyond
Panagiotis Stylianou, G. Weiglein
Abstract
Abstract Experimental information on the trilinear Higgs boson self-coupling $$\kappa _3$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>κ</mml:mi> <mml:mn>3</mml:mn> </mml:msub> </mml:math> and the quartic self-coupling $$\kappa _4$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>κ</mml:mi> <mml:mn>4</mml:mn> </mml:msub> </mml:math> 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 $$\kappa _3$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>κ</mml:mi> <mml:mn>3</mml:mn> </mml:msub> </mml:math> , triple Higgs production processes, despite their small cross sections, will provide valuable complementary information on $$\kappa _3$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>κ</mml:mi> <mml:mn>3</mml:mn> </mml:msub> </mml:math> and first experimental constraints on $$\kappa _4$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>κ</mml:mi> <mml:mn>4</mml:mn> </mml:msub> </mml:math> . 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.