Relaxion: A Landscape Without Anthropics
Ann Nelson, Chanda Prescod-Weinstein

TL;DR
The paper explores a relaxion mechanism during inflation that naturally addresses the hierarchy problem, the strong CP problem, and dark matter, by analyzing the axion-like field's behavior at different Hubble scales.
Contribution
It proposes a novel inflationary scenario with a specific Hubble scale range that allows the relaxion to solve multiple fundamental problems simultaneously.
Findings
Relaxion can resolve hierarchy and strong CP problems during inflation.
Hubble scale between weak scale and 3 GeV is optimal for the mechanism.
The model remains technically natural under the proposed conditions.
Abstract
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, dubbed the relaxion, whose expectation value determines the electroweak hierarchy as well as the QCD strong CP violating parameter. During an inflationary period, the Higgs mass squared is selected to be negative and hierarchically small in a theory which is consistent with 't Hooft's technical naturalness criteria. However, in the original model proposed by Graham, Kaplan and Rajendran (2015), the relaxion does not solve the strong CP problem, and in fact contributes to it, as the coupling of the relaxion to the Higgs field and the introduction of a linear potential for the relaxion produces large strong CP violation. We resolve this tension by considering inflation with a…
Peer Reviews
No public reviews on file for this paper yet. If you reviewed it on a platform where reviews are public (OpenReview, ICLR, NeurIPS, ICML), you can paste yours below so the community can read it here.
Videos
No videos yet. Explain this paper in a talk, walkthrough, or lecture? Add one.
