Naturally light scalar particles: a generic and simple mechanism

TL;DR

This paper presents a simple scalar model mechanism that naturally produces light scalar particles, addressing the hierarchy problem by leveraging symmetry breaking and quantum fluctuations without fine-tuning.

Contribution

It introduces a scalar model with a non-renormalizable term that breaks symmetry, enabling naturally light scalars through quantum effects, offering a new approach to the hierarchy problem.

Findings

Pseudo-Goldstone masses are driven by quantum fluctuations to small, natural values.

The mechanism does not require fine-tuning to keep scalar masses light.

The model provides a generic framework for naturally light scalars in scalar theories.

Abstract

The hierarchy problem in the Standard Model is usually understood as both a technical problem of stability of the calculation of the quantum corrections to the masses of the Higgs sector and of the unnatural difference between the Planck and gauge breaking scales. Leaving aside the gauge sector, we implement on a purely scalar model a mechanism for generating naturally light scalar particles where both of these issues are solved. In this model, on top of terms invariant under a continuous symmetry, a highly non-renormalizable term is added to the action that explicitly breaks this symmetry down to a discrete one. In the spontaneously broken phase, the mass of the pseudo-Goldstone is then driven by quantum fluctuations to values that are non-vanishing but that are generically, that is, without fine-tuning, orders of magnitude smaller than the UV scale.