Quantum Chameleons

TL;DR

This paper develops a quantum framework for chameleon-like particles, revealing that quantum forces can surpass classical ones and significantly impact experimental constraints, especially in the context of the Eöt-Wash experiment.

Contribution

It introduces a quantum treatment of chameleon particles, deriving forces from the path integral and calculating the quantum pressure in layered materials, impacting experimental bounds.

Findings

Quantum force can dominate classical force by many orders of magnitude.

Quantum pressure interpolates between Casimir and Casimir-Polder limits.

Presence of shielding sheet enhances quantum pressure by two orders of magnitude.

Abstract

We initiate a quantum treatment of chameleon-like particles, deriving classical and quantum forces directly from the path integral. It is found that the quantum force can potentially dominate the classical one by many orders of magnitude. We calculate the quantum chameleon pressure between infinite plates, which is found to interpolate between the Casimir and the integrated Casimir-Polder pressures, respectively in the limits of full screening and no screening. To this end we calculate the chameleon propagator in the presence of an arbitrary number of one-dimensional layers of material. For the E\"ot-Wash experiment, the five-layer propagator is used to take into account the intermediate shielding sheet, and it is found that the presence of the sheet enhances the quantum pressure by two orders of magnitude. As an example of implication, we show that in both the standard chameleon and symmetron models, large and previously unconstrained regions of the parameter space are excluded once the quantum pressure is taken into account.