Constraining Disformally Coupled Scalar Fields

TL;DR

Disformally coupled scalar fields evade traditional fifth force constraints but can be constrained via their microscopic interactions with particles, with collider experiments providing the strongest bounds.

Contribution

This paper demonstrates how disformally coupled scalars can be studied through particle interactions and sets new experimental bounds on their coupling scale.

Findings

Mono-photon searches at LHC constrain the coupling scale to be greater than 100 GeV.

Disformally coupled scalars do not produce classical fifth force signals from static sources.

Microscopic interactions provide a viable way to probe disformal scalar fields.

Abstract

Light scalar fields can naturally couple disformally to matter fields. Static, non-relativistic sources do not generate a classical field profile for a disformally coupled scalar, and so such scalars are free from the constraints on the existence of fifth forces that are so restrictive for conformally coupled scalars. In this work we show that disformally coupled scalars can still be studied and constrained through their microscopic interactions with fermions and photons, both in terrestrial laboratories and from observations of stars. The strongest constraint on the coupling scale comes from mono-photon searches at the LHC and requires $M \gtrsim 10^2 \mbox{ GeV}$.