Journal Article

Sixfold improved single particle measurement of the magnetic moment of the antiproton

Ulmer, S., Tanaka, T., Higuchi, T., Smorra, C., Sellner, S., Walz, J., Ospelkaus, C., Nagahama, H., Yamazaki, Y., Mooser, A., Schneider, G., Matsuda, Y., Borchert, M. J., Harrington, J., Besirli, M., Blaum, K., Quint, W.

2017

Overview

Our current understanding of the Universe comes, among others, from particle physics and cosmology. In particle physics an almost perfect symmetry between matter and antimatter exists. On cosmological scales, however, a striking matter/antimatter imbalance is observed. This contradiction inspires comparisons of the fundamental properties of particles and antiparticles with high precision. Here we report on a measurement of the g -factor of the antiproton with a fractional precision of 0.8 parts per million at 95% confidence level. Our value /2=2.7928465(23) outperforms the previous best measurement by a factor of 6. The result is consistent with our proton g -factor measurement g p /2=2.792847350(9), and therefore agrees with the fundamental charge, parity, time (CPT) invariance of the Standard Model of particle physics. Additionally, our result improves coefficients of the standard model extension which discusses the sensitivity of experiments with respect to CPT violation by up to a factor of 20. High-precision measurements could disclose fundamental dissimilarities between matter and antimatter, which are found imbalanced in the Universe. Here, the authors measure the magnetic moment of the antiproton with six-fold higher accuracy than before, finding it consistent with that of the proton.

• Publisher: Nature Publishing Group UK,Nature Publishing Group,Nature Portfolio
• Subject: 639/766/36 / 639/766/483/640 / Charged particles / Electrodes / Humanities and Social Sciences / multidisciplinary / Particle physics / Physics / Science / Science (multidisciplinary)