Constraints on coloured scalars from global fits

Abstract

We consider a simple extension of the electroweak theory, incorporating one $SU(2{)}_L$ doublet of colour-octet scalars with Yukawa couplings satisfying the principle of minimal flavour violation. Using the HEPfit package, we perform a global fit to the available data, including all relevant theoretical constraints, and extract the current bounds on the model parameters. Coloured scalars with masses below 1.05 TeV are already excluded, provided they are not fermiophobic. The mass splittings among the different (charged and CP-even and CP-odd neutral) scalars are restricted to be smaller than 20 GeV. Moreover, for scalar masses smaller than 1.5 TeV, the Yukawa coupling of the coloured scalar multiplet to the top quark cannot exceed the one of the SM Higgs doublet by more than 80%. These conclusions are quite generic and apply in more general frameworks (without fine tunings). The theoretical requirements of perturbative unitarity and vacuum stability enforce relevant constraints on the quartic scalar potential parameters that are not yet experimentally tested.

References in corpus (8)

• The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations
• Flavor Changing Neutral Currents, an Extended Scalar Sector, and the Higgs Production Rate at the LHC
• Color-octet scalars at the LHC
• Color Octet Scalar Production at the LHC
• Next-to-leading order unitarity fits in Two-Higgs-Doublet models with soft ${\mathbb{Z}}_2$ breaking
• Simple Left-Right Theory: Lepton Number Violation at the LHC
• LHC bounds on coloured scalars
• Top and bottom tensor couplings from a color octet scalar