Naturalness of the relaxion mechanism

  title={Naturalness of the relaxion mechanism},
  author={Andrew Fowlie and Csaba Bal{\'a}zs and Graham White and Luca Marzola and Martti Raidal},
  journal={Journal of High Energy Physics},
A bstractThe relaxion mechanism is a novel solution to the hierarchy problem. In this first statistical analysis of the relaxion mechanism, we quantify the relative plausibility of a QCD and a non-QCD relaxion model versus the Standard Model with Bayesian statistics, which includes an automatic penalty for fine-tuning. We find that in light of the hierarchy between the weak and Planck scales, relaxion models are favoured by colossal Bayes-factors. Constraints upon e.g., the vacuum energy during… Expand

Figures and Tables from this paper

Relaxion: A Landscape Without Anthropics
The relaxion mechanism provides a potentially elegant solution to the hierarchy problem without resorting to anthropic or other fine-tuning arguments. This mechanism introduces an axion-like field,Expand
Dynamics of relaxed inflation
A bstractThe cosmological relaxation of the electroweak scale has been proposed as a mechanism to address the hierarchy problem of the Standard Model. A field, the relaxion, rolls down its potentialExpand
Constraints on relaxion windows
A bstractWe examine the low energy phenomenology of the relaxion solution to the weak scale hierarchy problem. Assuming that the Hubble friction is responsible for a dissipation of the relaxionExpand
Naturalizing supersymmetry with a two-field relaxion mechanism
A bstractWe present a supersymmetric version of a two-field relaxion model that naturalizes tuned versions of supersymmetry. This arises from a relaxion mechanism that does not depend on QCD dynamicsExpand
Dynamical relaxation in 2HDM models
The dynamical relaxation provides an interesting solution to the hierarchy problem in face of the missing signatures of any new physics in recent experiments. Through a dynamical process taking placeExpand
Constraints on the relaxion mechanism with strongly interacting vector-fermions
A bstractWe study the experimental constraints on strongly interacting vector-fermions compatible with the relaxion mechanism and investigate any possible tuning. The focus is on a minimal model andExpand
Expectations for inflationary observables: simple or natural?
We describe the general inflationary dynamics that can arise with a single, canonically coupled field where the inflaton potential is a 4-th order polynomial. This scenario yields a wide range ofExpand
Gravitational tests of electroweak relaxation
Abstract We consider a scenario in which the electroweak scale is stabilized via the relaxion mechanism during inflation, focussing on the case in which the back-reaction potential is generated byExpand
Bayesian naturalness, simplicity, and testability applied to the $B-L$ MSSM GUT using GPU Monte Carlo
The lack of decisive experimental results to settle fundamental questions in physics has led to increasing reliance upon intuitive criteria such as naturalness, simplicity, and testability. We argueExpand
Naturalness made easy: two-loop naturalness bounds on minimal SM extensions
A bstractThe main result of this paper is a collection of conservative naturalness bounds on minimal extensions of the Standard Model by (vector-like) fermionic or scalar gauge multiplets. Within, weExpand


Relaxion Cosmology and the Price of Fine-Tuning
The relaxion scenario presents an intriguing extension of the standard model in which the particle introduced to solve to the strong CP problem, the axion, also achieves the dynamical relaxation ofExpand
Relaxing the electroweak scale: the role of broken dS symmetry
A bstractRecently, a novel mechanism to address the hierarchy problem has been proposed [1], where the hierarchy between weak scale physics and any putative ‘cutoff’ M is translated into aExpand
Is the relaxion an axion?
A bstractWe consider the recently proposed cosmological relaxation mechanism where the hierarchy problem is ameliorated, and the electroweak (EW) scale is dynamically selected by a slowly rollingExpand
Naturalizing supersymmetry with a two-field relaxion mechanism
A bstractWe present a supersymmetric version of a two-field relaxion model that naturalizes tuned versions of supersymmetry. This arises from a relaxion mechanism that does not depend on QCD dynamicsExpand
Musings on cosmological relaxation and the hierarchy problem
Recently Graham, Kaplan and Rajendran [1] proposed cosmological relaxation as a mechanism for generating a hierarchically small Higgs vacuum expectation value. Inspired by this we collect someExpand
Global fits of the nonuniversal Higgs model
We carry out global fits to the nonuniversal Higgs Model (NUHM), applying all relevant present-day constraints. We present global probability maps for the NUHM parameters and observables (includingExpand
Compatibility of planck and BICEP2 results in light of inflation
We investigate the implications for inflation of the detection of B-modes polarization in the cosmic microwave background by BICEP2. We show that the hypothesis of the primordial origin of theExpand
Bayesian approach and naturalness in MSSM analyses for the LHC
The start of LHC has motivated an effort to determine the relative probability of the different regions of the MSSM parameter space, taking into account the present, theoretical and experimental,Expand
Natural priors, CMSSM fits and LHC weather forecasts
Previous LHC forecasts for the constrained minimal supersymmetric standard model (CMSSM), based on current astrophysical and laboratory measurements, have used priors that are flat in the parameterExpand
CMSSM, naturalness and the "fine-tuning price" of the Very Large Hadron Collider
The absence of supersymmetry or other new physics at the Large Hadron Collider (LHC) has lead many to question naturalness arguments. With Bayesian statistics, we argue that natural models are mostExpand