Challenging Matter-Antimatter Symmetry: High-Precision Comparisons of the Fundamental Properties of the Antiproton and the Proton

According to the Standard Model of particle physics, which is the condensate of all human knowledge about the clockwork of nature, the Big Bang has produced equal amounts of matter and antimatter. On the other hand, cosmological observations imply that the visible part of the universe is entirely made out of matter. This striking inconsistency, one of the hottest topics of modern physics, inspires experiments to compare the fundamental properties of matter-antimatter conjugates at lowest energy and with great precision. The BASE collaboration at the CERN antiproton decelerator is performing such high-precision comparisons with protons and antiprotons. Using advanced, ultra-stable, cryogenic particle traps and superconducting detectors with single particle sensitivity, we have performed the most precise measurement of the proton-to-antiproton charge-to-mass ratio with a fractional precision of 11 significant digits [1]. In another measurement, we have invented a novel spectroscopy method, which allowed for the first ultra-high precision measurement of the antiproton magnetic moment with a fractional precision of 1.5 parts in a billion [2]. Together with our recent measurement of the proton magnetic moment [3] this improves the precision of previous experiments [4] by more than a factor of 3000. At the currently reached level of precision, our results support matter-antimatter symmetry.

In my talk I will review the recent achievements of BASE and will outline strategies to further improve our high-precision studies of matter-antimatter symmetry.


[1] S. Ulmer et al., Nature 524, 196 (2015).

[2] C. Smorra et al., Eur. Phys. Journ. Spec. Top. 224, 16 (2015).

[3] G. Schneider et al., Science 358, 1081 (2017).

[4] J. DiSciacca et al., Phys. Rev. Lett. 110, 130801 (2013).