New CP-violation and preferred-frame tests with polarized electrons

Abstract

We used a torsion pendulum containing $\sim 9\times 10^{22}$ polarized electrons to search for CP-violating interactions between the pendulum's electrons and unpolarized matter in the laboratory's surroundings or the sun, and to test for preferred-frame effects that would precess the electrons about a direction fixed in inertial space. We find $|g_{\mathrm{P}}^e{g}_{\mathrm{S}}^N|/(\hslash c)<1.7\times 10^{-36}$ and $|g_{\mathrm{A}}^e{g}_{\mathrm{V}}^N|/(\hslash c)<4.8\times 10^{-56}$ for $\lambda >1$AU. Our preferred-frame constraints, interpreted in the Kostelecký framework, set an upper limit on the parameter $|{\tilde{\mathbf{b}}}^e|\le 5.0\times 10^{-21}$ eV that should be compared to the benchmark value $m_e^2/M_{\mathrm{Planck}}=2\times 10^{-17}$ eV.

Comments: 4 figures, accepted for publication in Physical Review Letters