Detecting solar chameleons through radiation pressure

TL;DR

This paper proposes a novel method to detect solar chameleon particles, a dark energy candidate, by measuring radiation pressure on a sensor, potentially exploring new parameter space in chameleon physics.

Contribution

It introduces a new experimental approach using radiation pressure to detect solar chameleons, expanding the search for these particles beyond previous methods.

Findings

Calculated the solar chameleon spectrum.

Estimated the experimental reach in parameter space.

Proposed a feasible detection setup at CERN.

Abstract

Light scalar fields can drive the accelerated expansion of the universe. Hence, they are obvious dark energy candidates. To make such models compatible with tests of General Relativity in the solar system and "fifth force" searches on Earth, one needs to screen them. One possibility is the so-called "chameleon" mechanism, which renders an effective mass depending on the local matter density. If chameleon particles exist, they can be produced in the sun and detected on Earth exploiting the equivalent of a radiation pressure. Since their effective mass scales with the local matter density, chameleons can be reflected by a dense medium if their effective mass becomes greater than their total energy. Thus, under appropriate conditions, a flux of solar chameleons may be sensed by detecting the total instantaneous momentum transferred to a suitable opto-mechanical force/pressure sensor. We calculate the solar chameleon spectrum and the reach in the chameleon parameter space of an experiment using the preliminary results from a force/pressure sensor, currently under development at INFN Trieste, to be mounted in the focal plane of one of the X-Ray telescopes of the CAST experiment at CERN. We show, that such an experiment signifies a pioneering effort probing uncharted chameleon parameter space.