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Q: Fachverband Quantenoptik und Photonik

Q 11: Quanteneffekte (QED)

Q 11.5: Talk

Monday, March 19, 2007, 15:15–15:30, 5E

Light-by-light diffraction — •Antonino Di Piazza, Karen Z. Hatsagortsyan, and Christoph H. Keitel — Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg

The influence of a strong optical standing wave into the propagation of an x-ray probe is calculated in the framework of nonlinear quantum electrodynamics. It is shown that the procedure usually followed, to assign to vacuum a refractive index different from unit due to vacuum polarization effects, is a too crude approximation because of the tight focusing of the strong field. After the interaction a linearly polarized x-ray probe becomes elliptically polarized with the main axis of the ellipse rotated with respect to the initial polarization direction. The obtained ellipticity and the polarization rotation angle are shown to be in principle measurable [1].

[1] A. Di Piazza, K. Z. Hatsagortsyan, and C. H. Keitel, Phys. Rev. Lett. 97, 083603 (2006). See also hep-ph/0602039.