# Heidelberg 2015 – wissenschaftliches Programm

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# Q: Fachverband Quantenoptik und Photonik

## Q 42: Quantum Effects: QED II

### Q 42.4: Vortrag

### Mittwoch, 25. März 2015, 15:15–15:30, B/SR

**High-energy recollision processes of laser-generated electron-positron pairs** — •Sebastian Meuren, Karen Z. Hatsagortsyan, Christoph H. Keitel, and Antonino Di Piazza — Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg

By combining modern petawatt laser systems with highly energetic photon beams, the non-linear regime of QED becomes experimentally accessible with presently available technology [1]. In particular, the decay of a photon into a real electron-positron pair becomes feasible [2]. Once the pair is produced, the classical equations of motion predict that the electron and the positron are further accelerated by the laser field and – under certain circumstances – brought to a recollision [3]. We have shown rigorously for the first time that such recollision processes can be described in the realm of quantum field theory and that they are encoded in electron-positron loop Feynman diagrams [4]. By investigating the polarization operator in a plane-wave laser field, we have identified the contribution describing recollisions, which differs qualitatively and quantitatively from the one describing radiative corrections. As a consequence, recollision processes may significantly alter the tree-level predictions of QED in a strong laser field.

[1] A. Di Piazza, et al., Rev. Mod. Phys. **84**, 1177–1228 (2012)

S. Meuren et al., arXiv:**1406**.**7235** (2014)

M. Y. Kuchiev, Phys. Rev. Lett. **99**, 130404 (2007)

S. Meuren et al., arXiv:**1407**.**0188** (2014)