https://doi.org/10.1140/epjd/s10053-023-00672-y
Regular Article – Atomic Physics
BASE—high-precision comparisons of the fundamental properties of protons and antiprotons
1
RIKEN, Ulmer Fundamental Symmetries Laboratory, 2-1 Hirosawa, 351-0198, Wako, Saitama, Japan
2
CERN, Esplanade des Particules 1, 1217, Meyrin, Switzerland
3
Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117, Heidelberg, Germany
4
GSI-Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, 64291, Darmstadt, Germany
5
Institut für Physik, Johannes Gutenberg-Universität, Staudinger Weg 7, 55099, Mainz, Germany
6
Graduate School of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, 153-0041, Meguro, Tokyo, Japan
7
Institut für Quantenoptik, Leibniz Universität, Welfengarten 1, 30167, Hannover, Germany
8
Eidgenössisch Technische Hochschule Zürich, Rämistrasse 101, 8092, Zürich, Switzerland
9
Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116, Braunschweig, Germany
10
Helmholtz-Institut Mainz, Johannes Gutenberg-Universität, Staudingerweg 18, 55128, Mainz, Germany
11
Heinrich-Heine Universität, Universitätsstraße 1, 40225, Düsseldorf, Germany
Received:
13
February
2023
Accepted:
1
May
2023
Published online:
5
June
2023
The BASE collaboration at the antiproton decelerator/ELENA facility of CERN compares the fundamental properties of protons and antiprotons with ultra-high precision. Using advanced Penning trap systems, we have measured the proton and antiproton magnetic moments with fractional uncertainties of 300 parts in a trillion (p.p.t.) and 1.5 parts in a billion (p.p.b.), respectively. The combined measurements improve the resolution of the previous best test in that sector by more than a factor of 3000. Very recently, we have compared the antiproton/proton charge-to-mass ratios with a fractional precision of 16 p.p.t., which improved the previous best measurement by a factor of 4.3. These results allowed us also to perform a differential matter/antimatter clock comparison test to limits better than 
%. Our measurements enable us to set limits on 22 coefficients of CPT- and Lorentz-violating standard model extensions (SME) and to search for potentially asymmetric interactions between antimatter and dark matter. In this article, we review some of the recent achievements and outline recent progress towards a planned improved measurement of the antiproton magnetic moment with an at least tenfold improved fractional accuracy.
© The Author(s) 2023
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