\DeclareRobustCommand{ \pbar}{ \HepAntiParticle{ p}{ }{ }\xspace} \DeclareRobustCommand{ \p}{ \HepParticle{ p}{ }{ }\xspace} \DeclareRobustCommand{ \mup}{ $\mu_{ p}${ }{ }\xspace} \DeclareRobustCommand{ \mupbar}{ $\mu_{ \pbar}${ }{ }\xspace} \DeclareRobustCommand{ \muN}{ $\mu_N${ }{ }\xspace For the first time a single trapped \pbar is used to measure the \pbar magnetic moment ${ \bm\mu}_{ \pbar}$. The moment ${ \bm\mu}_{ \pbar} = \mu_{ \pbar} { \bm S}/(\hbar/2)$ is given in terms of its spin ${ \bm S}$ and the nuclear magneton (\muN) by $\mu_{ \pbar}/\mu_N = -2.792\,845 \pm 0.000\,012$. The 4.4 parts per million (ppm) uncertainty is 680 times smaller than previously realized. Comparing to the proton moment measured using the same method and trap electrodes gives $\mu_{ \pbar}/\mu_p = -1.000\,000 \pm 0.000\,005$ to 5 ppm, for a proton moment ${ \bm{ \mu}}_{ p} = \mu_{ p} { \bm S}/(\hbar/2)$, consistent with the prediction of the CPT theorem.
Categories: physics.atom-ph