Refraction of light by light in vacuumXavier Sarazin, François Couchot, Arache Djannati-Ataï, Olivier Guilbaud, Sophie Kazamias, Moana Pittman and Marcel UrbanEur. Phys. J. D, 70 1 (2016) 13DOI: https://doi.org/10.1140/epjd/e2015-60428-5