Discovering the Origin of Yukawa Couplings at the LHC with a Singlet Higgs and Vector-like Quarks

Abstract

Although the 125 GeV Higgs boson discovered at the LHC is often heralded as the origin of mass, it may not in fact be the origin of Yukawa couplings. In alternative models, Yukawa couplings may instead arise from a seesaw type mechanism involving the mixing of Standard Model (SM) chiral fermions with new vector-like fermions, controlled by the vacuum expectation value (VEV) of a new complex Higgs singlet field $⟨\Phi ⟩$. For example, the largest third family $(t,b)$ quark Yukawa couplings may be forbidden by a $U(1{)}^{\prime }$ gauge or global symmetry, broken by $⟨\Phi ⟩$, and generated effectively via mixing with a vector-like fourth family quark doublet $(T,B)$. Such theories predict a new physical Higgs singlet $\varphi$, which we refer to as the Yukon, resulting from $⟨\Phi ⟩$, in the same way that the Higgs boson $h^0$ results from $⟨H⟩$. In a simplified model we discuss the prospects for discovering the Yukon $\varphi$ in gluon-gluon fusion production, with $(t,b)$ and $(T,B)$ quarks in the loops, and decaying in the channels $\varphi \to \gamma \gamma ,Z\gamma$ and $\varphi \to tT\to tt{h}^0,ttZ$. The potential for discovery of the Yukon $\varphi$ is studied at present or future hadron colliders such as the LHC (Run 3), HL-LHC, HE-LHC and/or FCC. For example, we find that a 300-350 GeV Yukon $\varphi$ could be accessed at LHC Run 3 in the di-photon channel in the global model, providing a smoking gun signature of the origin of Yukawa couplings. The $tt{h}^0,ttZ$ channels are more involved and warrant a more sophisticated analysis.

arXiv comment30 pages, 11 figures. Version published in JHEP

References in corpus (26)

• Automatic Generation of Tree Level Helicity Amplitudes
• Little Higgs Review
• Light custodians in natural composite Higgs models
• Physics potential and experimental challenges of the LHC luminosity upgrade
• The Soft Supersymmetry-Breaking Lagrangian: Theory and Applications
• A handbook of vector-like quarks: mixing and single production
• QCD Effects in Higgs Physics
• Warped/Composite Phenomenology Simplified
• Top Quarks and Electroweak Symmetry Breaking in Little Higgs Models
• Light Top Partners for a Light Composite Higgs
• Extra vector-like matter and the lightest Higgs scalar boson mass in low-energy supersymmetry
• A Higgs Conundrum with Vector Fermions
• Finding New Physics without learning about it: Anomaly Detection as a tool for Searches at Colliders
• Stabilizing Electroweak Vacuum in a Vector-like Fermion Model
• Novel signatures for vector-like quarks
• Raising the Higgs mass with Yukawa couplings for isotriplets in vector-like extensions of minimal supersymmetry
• Constraints on Abelian Extensions of the Standard Model from Two-Loop Vacuum Stability and $U(1{)}_{B-L}$
• Diphoton production at the LHC: a QCD study up to NNLO
• $Z^{\prime }$, Higgses and heavy neutrinos in $U(1{)}^{\prime }$ models: from the LHC to the GUT scale
• $R_{K^{(\ast )}}$ and the origin of Yukawa couplings
• Flavour from accidental symmetries
• Phenomenology of flavon fields at the LHC
• Higgs-flavon mixing and LHC phenomenology in a simplified model of broken flavor symmetry
• Vector-like Quarks at the Origin of Light Quark Masses and Mixing
• Higgs boson to $\gamma Z$ decay as a probe of flavour changing neutral Yukawa couplings
• Quark and Lepton Mass and Mixing with non-universal $Z^{\prime }$ from a 5d Standard Model with gauged $SO(3)$

Cited by in corpus (4)

• Single production of vectorlike $B$ quarks at the CLIC
• Search for single vector-like $B$ quark production in hadronic final states at the LHC
• Spontaneous symmetry breakings in the singlet scalar Yukawa model within the auxiliary field method
• The Resurgence of the G(2) Group for the Strong Sector and the Emergence of Dark Matter