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Phys. Rev. Lett. 87, 093401 (2001) [4 pages]

Sub-ppm Laser Spectroscopy of Antiprotonic Helium and a CPT-Violation Limit on the Antiprotonic Charge and Mass

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M. Hori1, J. Eades1, R. S. Hayano2, T. Ishikawa2, J. Sakaguchi2, E. Widmann2, H. Yamaguchi2, H. A. Torii3, B. Juhász4, D. Horváth5, and T. Yamazaki6
1CERN, CH-1211 Geneva 23, Switzerland
2Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
3Institute of Physics, University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8902, Japan
4Institute of Nuclear Research of the Hungarian Academy of Sciences, H-4001 Debrecen, Hungary
5KFKI Research Institute for Particle and Nuclear Physics, H-1525 Budapest, Hungary
6RI Beam Science Laboratory, RIKEN, Wako, Saitama 351-0198, Japan

Received 28 March 2001; published 9 August 2001

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 1.3×10-7 and 1.6×10-6. By comparing these with QED calculations and the antiproton cyclotron frequency, we deduce that the antiproton and proton charges and masses agree to within 6×10-8 with a confidence level of 90%.

© 2001 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevLett.87.093401
DOI:
10.1103/PhysRevLett.87.093401
PACS:
36.10.-k, 14.20.Dh, 32.70.Jz
 
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