Title: Observation of Extra Photon Recoil in a Distorted Optical Field,
Abstract: Light carries momentum which induces on atoms a recoil for each photon
absorbed. In vacuum, for a monochromatic beam of frequency $\nu$, the global
momentum per photon is bounded by general principles and is smaller than $h
\nu/c$ leading to a limit on the recoil. However, locally this limit can be
broken. In this paper, we give a general formula to calculate the recoil in
vacuum. We show that in a laser beam with a distorted optical field, there are
regions where the recoil can be higher than this limit. Using atoms placed in
those regions we are able to measure directly the extra recoil.