High-precision comparison of the antiproton-to-proton charge-to-mass ratio.
Invariance under the charge, parity, time-reversal (CPT) transformation is one of the fundamental symmetries of the standard model of particle physics. This CPT invariance implies that the fundamental properties of antiparticles and their matter-conjugates are identical, apart from signs. There is a deep link between CPT invariance and Lorentz symmetry--that is, the laws of nature seem to be invariant under the symmetry transformation of spacetime--although it is model dependent. A number of high-precision CPT and Lorentz invariance tests--using a co-magnetometer, a torsion pendulum and a maser, among others--have been performed, but only a few direct high-precision CPT tests that compare the fundamental properties of matter and antimatter are available. Here we report high-precision cyclotron frequency comparisons of a single antiproton and a negatively charged hydrogen ion (H(-)) carried out in a Penning trap system. From 13,000 frequency measurements we compare the charge-to-mass ratio for the antiproton (q/m)p- to that for the proton (q/m)p and obtain (q/m)p-/(q/m)p − 1 =1(69) × 10(-12). The measurements were performed at cyclotron frequencies of 29.6 megahertz, so our result shows that the CPT theorem holds at the atto-electronvolt scale. Our precision of 69 parts per trillion exceeds the energy resolution of previous antiproton-to-proton mass comparisons as well as the respective figure of merit of the standard model extension by a factor of four. In addition, we give a limit on sidereal variations in the measured ratio of <720 parts per trillion. By following the arguments of ref. 11, our result can be interpreted as a stringent test of the weak equivalence principle of general relativity using baryonic antimatter, and it sets a new limit on the gravitational anomaly parameter of |α − 1| < 8.7 × 10(-7).
RIKEN, Ulmer Initiative Research Unit, Wako, Saitama 351-0198, Japan.
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Ulmer
1] RIKEN, Ulmer Initiative Research Unit, Wako, Saitama 351-0198, Japan [2] CERN, CH-1211 Geneva, Switzerland.
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C
Smorra
RIKEN, Ulmer Initiative Research Unit, Wako, Saitama 351-0198, Japan.
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A
Mooser
1] RIKEN, Ulmer Initiative Research Unit, Wako, Saitama 351-0198, Japan [2] Max-Planck-Institut für Kernphysik, 69117 Heidelberg, Germany.
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Franke
1] RIKEN, Ulmer Initiative Research Unit, Wako, Saitama 351-0198, Japan [2] Graduate School of Arts and Sciences, University of Tokyo, Tokyo 153-8902, Japan.
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Nagahama
1] RIKEN, Ulmer Initiative Research Unit, Wako, Saitama 351-0198, Japan [2] Institut für Physik, Johannes Gutenberg-Universität, 55099 Mainz, Germany.
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G
Schneider
1] RIKEN, Ulmer Initiative Research Unit, Wako, Saitama 351-0198, Japan [2] Graduate School of Arts and Sciences, University of Tokyo, Tokyo 153-8902, Japan.
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Higuchi
RIKEN, Atomic Physics Laboratory, Wako, Saitama 351-0198, Japan.
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S
Van Gorp
Max-Planck-Institut für Kernphysik, 69117 Heidelberg, Germany.
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K
Blaum
Graduate School of Arts and Sciences, University of Tokyo, Tokyo 153-8902, Japan.
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Y
Matsuda
GSI-Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.
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Quint
1] Institut für Physik, Johannes Gutenberg-Universität, 55099 Mainz, Germany [2] Helmholtz Institut Mainz, 55099 Mainz, Germany.
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J
Walz
RIKEN, Atomic Physics Laboratory, Wako, Saitama 351-0198, Japan.
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Y
Yamazaki