Sub-ppm laser spectroscopy of antiprotonic helium and a CPT-violation limit on the antiprotonic charge and mass - art. no. 093401

Six laser-resonant transitions have been detected in metastable antiprotoni c helium atoms produced at the CERN Antiproton Decelerator. They include UV transitions from the last metastable states in the v = n - l - 1 = 0 and 1 cascades. Zero-density frequencies were obtained from measured pressure sh ifts with fractional precisions between 1.3 x 10(-7) and 1.6 x 10(-6). By c omparing these with QED calculations and the antiproton cyclotron frequency , we deduce that the antiproton and proton charges and masses agree to with in 6 x 10(-8) with a confidence level of 90%.