title: Spectroscopy of antiprotonic helium atoms and its contribution to the fundamental physical constants.
abstract: Antiprotonic helium atom, a metastable neutral system consisting of an antiproton, an electron and a helium nucleus, was serendipitously discovered, and has been studied at CERN's antiproton decelerator facility. Its transition frequencies have recently been measured to nine digits of precision by laser spectroscopy. By comparing these experimental results with three-body QED calculations, the antiproton-to-electron massratio was determined as 1836.152674(5). This result contributed to the CODATA recommended values of the fundamental physical constants
authors.affiliation: Department of Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyoku,Tokyo, Japan. hayano@phys.s.u-tokyo.ac.jp
authors.forename: Ryugo S
authors.initials: RS
authors.lastname: Hayano
mesh_terms: D006371:Helium / Q000737:chemistry*; D007834:Lasers; D055620:Optical Phenomena; D055585:Physical Phenomena; D011522:Protons; D013057:Spectrum Analysis / Q000379:methods*
chemical_list: D011522:Protons; D006371:Helium