title: Comment on "Collimated multi-MeV ion beams from high-intensity laser interactions with underdense plasma".
authors.affiliation: Kansai Photon Science Institute Japan Atomic Energy Agency Umemidai 8-1, Kizu, Kyoto 619-0215, Japan.
authors.forename: S V
authors.initials: SV
authors.lastname: Bulanov
authors.forename: T Zh
authors.initials: TZh
authors.lastname: Esirkepov