Relaxing the Electroweak Scale: the Role of Broken dS Symmetry

Abstract

Recently, a novel mechanism to address the hierarchy problem has been proposed \cite{Graham:2015cka}, where the hierarchy between weak scale physics and any putative `cutoff' $M$ is translated into a parametrically large field excursion for the so-called relaxion field, driving the Higgs mass to values much less than $M$ through cosmological dynamics. In its simplest incarnation, the relaxion mechanism requires nothing beyond the standard model other than an axion (the relaxion field) and an inflaton. In this note, we critically re-examine the requirements for successfully realizing the relaxion mechanism and point out that parametrically larger field excursions can be obtained for a given number of e-folds by simply requiring that the background break exact de Sitter invariance. We discuss several corollaries of this observation, including the interplay between the upper bound on the scale $M$ and the order parameter $\epsilon$ associated with the breaking of dS symmetry, and entertain the possibility that the relaxion could play the role of a curvaton. We find that a successful realization of the mechanism is possible with as few as $\mathcal{O}(10^3)$ e-foldings, albeit with a reduced cutoff $M\sim 10^6$ GeV for a dark QCD axion and outline a minimal scenario that can be made consistent with CMB observations.

16 pages, 3 figures. Version to appear in JHEP

References in corpus (11)

• Observation of a new particle in the search for the Standard Model Higgs boson with the ATLAS detector at the LHC
• Observation of a new boson at a mass of 125 GeV with the CMS experiment at the LHC
• The Effective Field Theory of Inflation
• Echoes of a Hidden Valley at Hadron Colliders
• Cosmological Relaxation of the Electroweak Scale
• Features and New Physical Scales in Primordial Observables: Theory and Observation
• Emerging Jets
• Discovering Uncolored Naturalness in Exotic Higgs Decays
• Cosmological Higgs-Axion Interplay for a Naturally Small Electroweak Scale
• Baryogenesis from Strong CP Violation and the QCD Axion
• Electroweak relaxation from finite temperature

Cited by in corpus (32)

• Relaxation from particle production
• Relaxion Monodromy and the Weak Gravity Conjecture
• FindBounce: package for multi-field bounce actions
• Is the Relaxion an Axion?
• Axion Monodromy and the Weak Gravity Conjecture
• Constraints on Relaxion Windows
• Dynamics of the cosmological relaxation after reheating
• Higgs relaxation after inflation
• Relaxion and light (pseudo)scalars at the HL-LHC and lepton colliders
• Towards a No-Lose Theorem for Naturalness
• Naturalizing Supersymmetry with a Two-Field Relaxion Mechanism
• Musings on cosmological relaxation and the hierarchy problem
• Relaxation of the Composite Higgs Little Hierarchy
• Relaxion Cosmology and the Price of Fine-Tuning
• Naturalness of the relaxion mechanism
• Stability of domain walls in models with asymmetric potentials
• N-Relaxion: Large Field Excursions from a Few Site Relaxion Model
• Relaxion Dark Matter
• Constraints on the relaxion mechanism with strongly interacting vector-fermions
• Relaxion window
• Towards the fate of the oscillating false vacuum
• Paper-boat relaxion
• Fast-Rolling Relaxion
• A possible interpretation of the Higgs mass by the cosmological attractive relaxion
• A warped relaxion
• Cosmological Relaxation from Dark Fermion Production
• Gravitational tests of electroweak relaxation
• Dynamical relaxation in 2HDM models
• Shift-Symmetries at Higher Order
• Gravitational relaxation of electroweak hierarchy problem
• Non-perturbative reheating and Nnaturalness
• Mixing Particle Production for Relaxion Mechanism