Sliding Naturalness: New Solution to the Strong-CP and Electroweak-Hierarchy Problems.

Raffaele Tito D’Agnolo,Daniele Teresi

doi:10.1103/physrevlett.128.021803

Abstract

We present a novel framework to solve simultaneously the electroweak-hierarchy problem and the strong-CP problem. A small but finite Higgs vacuum expectation value and a small θ angle are selected after the QCD phase transition, without relying on the Peccei-Quinn mechanism or other traditional solutions. We predict a distinctive pattern of correlated signals at hadronic EDM, fuzzy dark matter, and axion experiments.

Highlights

Introduction.—Our whole understanding of physics is based on symmetry
A small but finite Higgs vacuum expectation value and a small θ angle are selected after the QCD phase transition, without relying on the Peccei-Quinn mechanism or other traditional solutions
The cosmological constant (CC) is coupled to gravity and determines the maximal observable size of the Universe. m2h is coupled to weak interactions, it determines their range and the mass of most known particles. θ is coupled to strong interactions and determines a series of properties of mesons and baryons, including the neutron electric dipole moment (EDM)

Summary

Featured in Physics

Sliding Naturalness: New Solution to the Strong-CP and Electroweak-Hierarchy Problems. A small but finite Higgs vacuum expectation value and a small θ angle are selected after the QCD phase transition, without relying on the Peccei-Quinn mechanism or other traditional solutions. In this Letter we present a novel framework that simultaneously explains the small observed value of m2h and θ, with the CC playing an important role in their selection. Other ideas of “cosmological naturalness” that select a small value for m2h in the early history of the Universe include Refs. A second metastable minimum for φÆ is generated only if both the Higgs vacuum expectation value (vev) hhi and the QCD θ angle are in specific ranges. In this minimum the CC can be tuned to zero, for instance, because of Weinberg’s argument on the existence of

Published by the American Physical Society

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