Antiproton–to–electron mass ratio determined by two-photon laser spectroscopy of antiprotonic helium atoms

Abstract

Abstract. The ASACUSA collaboration of CERN has recently carried out two-photon laser spectroscopy of antiprotonic helium atoms. Three transition frequencies were determined with fractional precisions of 2.3-5 parts in 10 9 . By comparing the results with three-body QED calculations, the antiproton-to-electron mass ratio was determined as 1836.1526736(23).