High-precision comparisons of the fundamental properties of matter/antimatter conjugates*

One of the hot topics of modern physics is the matter/antimatter asymmetry observed on cosmological scales, which is in contradiction to the charge-parity-time reversal invariance of the relativistic quantum field theories of the standard model of particle physics. This inspires comparisons of the fundamental properties of conjugate matter/antimatter systems at low energy and with great precision. Experiments at the antiproton decelerator of CERN contribute to this branch of physics, among them are high precision studies of the fundamental properties of protons and antiprotons by the BASE collaboration and measurements on the ground state hyperfine splitting of antihydrogen by the ASACUSA collaboration.

In BASE we measured the antiproton-to-proton charge-to-mass ratio with a fractional precision of 69 p.p.t., as well as the antiproton magnetic moment with fractional precisions of 0.8 p.p.m. and 1.5 p.p.b., respectively. The moment-measurements provide a baryon-magnetic-moment based CPT test gp / gpbar = 1.000 000 000 2 (15), which improves the uncertainty of previous experiments by more than a factor of 3000. In ASACUSA a beam of cold antihydrogen atoms was produced which constitutes a major step towards a measurement of the ground state hyperfine splitting in this composed antimatter system. In the future, a combination of precision measurements by both collaborations will allow first precise studies of antiproton sub-structure.

This talk will summarize the recent achievements made in BASE and ASACUSA and will give an outlook on future perspectives.