The $\hat{H}$-Parameter: An Oblique Higgs View

Abstract

We study, from theoretical and phenomenological angles, the Higgs boson oblique parameter $\hat{H}$, as the hallmark of off-shell Higgs physics. $\hat{H}$ is defined as the Wilson coefficient of the sole dimension-6 operator that modifies the Higgs boson propagator, within a Universal EFT. Theoretically, we describe self-consistency conditions on Wilson coefficients, derived from the Källén-Lehmann representation. Phenomenologically, we demonstrate that the process $gg\to h^{\ast }\to VV$ is insensitive to propagator corrections from $\hat{H}$, and instead advertise four-top production as an effective high-energy probe of off-shell Higgs behaviour, crucial to break flat directions in the EFT.

arXiv commentV2: Discussion of convergence significantly extended. FCC-hh projections added

References in corpus (31)

• The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations
• FeynRules 2.0 - A complete toolbox for tree-level phenomenology
• Dimension-Six Terms in the Standard Model Lagrangian
• Causality, Analyticity and an IR Obstruction to UV Completion
• The Strongly-Interacting Light Higgs
• Renormalization Group Evolution of the Standard Model Dimension Six Operators III: Gauge Coupling Dependence and Phenomenology
• Renormalization Group Evolution of the Standard Model Dimension Six Operators II: Yukawa Dependence
• Renormalization Group Evolution of the Standard Model Dimension Six Operators I: Formalism and lambda Dependence
• Electroweak symmetry breaking after LEP1 and LEP2
• The Minimal Set of Electroweak Precision Parameters
• Beyond S, T and U
• A Clockwork Theory
• Theoretical Constraints on the Higgs Effective Couplings
• Large NLO corrections in $t\bar{t}{W}^{\pm }$ and $t\bar{t}t\bar{t}$ hadroproduction from supposedly subleading EW contributions
• Softness and Amplitudes' Positivity for Spinning Particles
• Energy helps accuracy: electroweak precision tests at hadron colliders
• Mass Effects in the Higgs-Gluon Coupling: Boosted vs Off-Shell Production
• Scaling and tuning of EW and Higgs observables
• What if the Higgs couplings to W and Z bosons are larger than in the Standard Model?
• A Global Fit to Extended Oblique Parameters
• Constraining BSM Physics at the LHC: Four top final states with NLO accuracy in perturbative QCD
• Electroweak Precision Tests in High-Energy Diboson Processes
• Symmetries, Sum Rules and Constraints on Effective Field Theories
• Four Tops for LHC
• Effective theories of universal theories
• Higgs ultraviolet softening
• Standard Model Effective Field Theory: Integrating out Vector-Like Fermions
• Precision Higgs Measurements: Constraints from New Oblique Corrections
• Higgs characterisation in the presence of theoretical uncertainties and invisible decays
• Renormalization group evolution of the universal theories EFT
• Remarks on analyticity and unitarity in the presence of a Strongly Interacting Light Higgs

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• Natural Selection Rules: New Positivity Bounds for Massive Spinning Particles
• Parton distributions in the SMEFT from high-energy Drell-Yan tails
• Massive Higher Spins: Effective Theory and Consistency
• Complete SMEFT predictions for four top quark production at hadron colliders
• Adding Flavor to the SMEFT
• Positivity bounds from multiple vacua and their cosmological consequences
• Charting the Higgs self-coupling boundaries
• ATLAS Violating CP Effectively
• Computing Tools for Effective Field Theories
• Spinning Sum Rules for the Dimension-Six SMEFT
• Probing the Symmetric Higgs Portal with Di-Higgs Boson Production
• Effective field theory and scalar extensions of the top quark sector
• The EFT Bootstrap at Finite $M_{PL}$
• Dispelling the $\sqrt{L}$ myth for the High-Luminosity LHC
• Four-top quark physics at the LHC
• On the BSM reach of four top production at the LHC
• Four-top as probe of light top-philic New Physics
• Stairway to discovery: a report on the CMS programme of cross section measurements from millibarns to femtobarns
• Non-Forward UV/IR Relations
• Multipositivity Bounds for Scattering Amplitudes
• Topic Model for four-top at the LHC
• Form Factors in Higgs Couplings from Physics Beyond the Standard Model
• Positively Identifying HEFT or SMEFT
• Assessing (H)EFT theory errors by pitting EoM against Field Redefinitions
• Quantum Critical Higgs: From AdS${}_5$ to Colliders
• The Rise of Linear Trajectories