CPT

[paper] Sixfold improved single particle measurement of the magnetic moment of the antiproton

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

H. Nagahama et al.

doi: 10.1038/ncomms14084

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 g(antiproton)=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(proton)=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.

[paper] Demonstration of the double Penning Trap technique with a single proton

Demonstration of the double Penning Trap technique with a single proton

A. Mooser et al.

doi: 10.1016/j.physletb.2013.05.012

Spin flips of a single proton were driven in a Penning trap with a homogeneous magnetic field.
For the spin-state analysis the proton was transported into a second Penning trap with
a superimposed magnetic bottle, and the continuous Stern–Gerlach effect was applied.
This first demonstration of the double Penning trap technique with a single proton suggests
that the antiproton magnetic moment measurement can potentially be improved by three
orders of magnitude or more.