High-precision comparison of the antiproton-to-proton charge-to-mass ratio

• Autores: S. Ulmer, C. Smorra, A. Mooser, K. Franke, H. Nagahama, G. Schneider, T. Higuchi, S. Van Gorp, K. Blaum, Y. Matsuda, W. Quint, J. Walz, Y. Yamazaki
• Localización: Nature: International weekly journal of science, ISSN 0028-0836, Vol. 524, Nº 7564, 2015, págs. 196-199
• Idioma: inglés
• Texto completo no disponible (Saber más ...)
• Resumen

  • Invariance under the charge, parity, time-reversal (CPT) transformation1 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 dependent2. A number of high-precision CPT and Lorentz invariance tests—using a co-magnetometer, a torsion pendulum and a maser, among others—have been performed3, but only a few direct high-precision CPT tests that compare the fundamental properties of matter and antimatter are available4,5,6,7,8. 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 Symbol to that for the proton Symbol and obtain Symbol. 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 comparisons7,9 as well as the respective figure of merit of the standard model extension10 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 Symbol < 8.7 × 10-7.