Photon Regeneration from Pseudoscalars at X-ray Laser Facilities

TL;DR

This work proposes a method of independently testing an anomalously large rotation of the polarization of light in the presence of a magnetic field in vacuum using a high-energy photon regeneration experiment using the synchrotron x rays from a free-electron laser.

Abstract

Recently, the PVLAS collaboration has reported an anomalously large rotation of the polarization of light in the presence of a magnetic field. As a possible explanation they consider the existence of a light pseudoscalar particle coupled to two photons. In this note, we propose a method of independently testing this result by using a high-energy photon regeneration experiment (the X-ray analogue of "invisible light shining through walls") using the synchrotron X-rays from a free-electron laser (FEL). With such an experiment the region of parameter space implied by PVLAS could be probed in a matter of minutes.

Figures (2)

• Figure 1: Schematic figure of the regeneration experiment.
• Figure 2: 95% confidence level exclusion region for different running times: 1 day and 1 year for two different magnets (a conventional magnet with $L=20$ m and $B=1$ T and a superconducting magnet with $L=10$ m and $B=10$ T). We have assumed efficient X-ray detection and an X-ray beam with $N_{0} = 10^{17}\ {\rm s}^{-1}$ and $\omega = 10$ keV.