Preferred-frame and CP-violation tests with polarized electrons

We used a torsion pendulum containing ≈10²³ polarized electrons to search new interactions that couple to electron spin. We limit CP-violating interactions between the pendulum’s electrons and unpolarized matter in the Earth or the Sun, test for rotation and boost-dependent preferred-frame effects using the Earth’s rotation and velocity with respect to the entire cosmos, and search for exotic velocity-dependent potentials between polarized electrons and unpolarized matter in the Sun and Moon. We find CP-violating parameters |g_P^eg_S^N|/(ℏc)<9.4×10^-37 and |g_A^eg_V^N|/(ℏc)<1.2×10^-56 for λ>1AU. We test for preferred-frame interactions of the form V=-σ^e·A, V=-Bσ^e·v/c, or V=-∑σ_i^eC_ijv_j/c, where v is the velocity of the Earth with respect to the cosmic microwave background restframe and i, j represent the equatorial inertial coordinates X, Y, and Z. We constrain all 3 components of A, obtaining 1σ upper limits |A_X,Y|≤1.5×10^-22eV and |A_Z|≤4.4×10^-21eV that may be compared to the benchmark value m_e²/M_Planck=2×10^-17eV. Interpreting our constraint on A in terms of noncommutative geometry, we obtain an upper bound of (355l_GUT)² on the minimum observable area, where l_GUT=ℏc/(10¹⁶GeV) is the grand unification length. We find that |B|≤1.2×10^-19eV. All 9 components of C are constrained at the 10^-17 to 10^-18eV level. We determine 9 linear combinations of parameters of the standard model extension; rotational-noninvariant and boost-noninvariant terms are limited at roughly the 10^-31GeV and 10^-27GeV levels, respectively. Finally, we find that the gravitational mass of an electron spinning toward the galactic center differs by less than about 1 part in 10²¹ from an electron spinning in the opposite direction. As a byproduct of this work, the density of polarized electrons in SmCo₅ was measured to be (4.19±0.19)×10²²cm^-3 at a field of 9.6 kG.