Hidden in the light: Magnetically induced afterglow from trapped chameleon fields

We propose an afterglow phenomenon as a unique trace of chameleon fields in optical experiments. The vacuum interaction of a laser pulse with a magnetic field can lead to a production and subsequent trapping of chameleons in the vacuum chamber, owing to their mass dependence on the ambient matter density. Magnetically induced reconversion of the trapped chameleons into photons creates an afterglow over macroscopic timescales that can conveniently be searched for by current optical experiments. We show that the chameleon parameter range accessible to available laboratory technology is comparable to scales familiar from astrophysical stellar energy-loss arguments. We analyze quantitatively the afterglow properties for various experimental scenarios and discuss the role of potential background and systematic effects. We conclude that afterglow searches represent an ideal tool to aim at the production and detection of cosmologically relevant scalar fields in the laboratory.

Figure 1

Sensitivity limits for the scale $M$ specifying the inverse chameleon-photon coupling vs the chameleon mass for the BMV [13] (dotted line) and GammeV [20] (solid line) experiments as well as a hypothetical optimized experimental setup (dashed line); the experimental parameter values are detailed in the main text. The top left panel corresponds to an afterglow measurement with a duration $t_{\exp }$ of 1 d, the top right panel corresponds to 1 min and the lower figure to 1 s. The gain in sensitivity is less than an order of magnitude by waiting a day rather than a minute.