Sub-ppm laser spectroscopy of antiprotonic helium and a CPT-violation limit on the antiprotonic charge and mass.
Six laser-resonant transitions have been detected in metastable antiprotonic 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 shifts with fractional precisions between 1.3 x 10(-7) and 1.6 x 10(-6). By comparing these with QED calculations and the antiproton cyclotron frequency, we deduce that the antiproton and proton charges and masses agree to within 6 x 10(-8) with a confidence level of 90%.
Hori
M
M
CERN, CH-1211 Geneva 23, Switzerland.
Eades
J
J
Hayano
R S
RS
Ishikawa
T
T
Sakaguchi
J
J
Widmann
E
E
Yamaguchi
H
H
Torii
H A
HA
Juhász
B
B
Horváth
D
D
Yamazaki
T
T