New Limits on Anomalous Spin-Spin Interactions.

We report the results of a new search for long-range spin-dependent interactions using a Rb-^{21}Ne atomic comagnetometer and a rotatable electron spin source based on a SmCo_{5} magnet with an iron flux return. By looking for signal correlations with the orientation of the spin source we set new constraints on the product of the pseudoscalar electron and neutron couplings g_{p}^{e}g_{p}^{n}/ℏc<1.7×10^{-14} and on the product of their axial couplings g_{A}^{e}g_{A}^{n}/ℏc<5×10^{-42} to a new particle with a mass of less than about 1  μeV.

Improved Limits on Spin-Mass Interactions.

Very light particles with CP-violating couplings to ordinary matter, such as axions or axionlike particles, can mediate long-range forces between polarized and unpolarized fermions. We describe a new experimental search for such forces between unpolarized nucleons in two 250 kg Pb weights and polarized neutrons and electrons in a ^{3}He-K comagnetometer located about 15 cm away. We place improved constraints on the products of scalar and pseudoscalar coupling constants, g_{p}^{n}g_{s}^{N}<4.

^{3}He-^{129}Xe Comagnetometery using ^{87}Rb Detection and Decoupling.

We describe a ^{3}He-^{129}Xe comagnetometer using ^{87}Rb atoms for noble-gas spin polarization and detection. We use a train of ^{87}Rb π pulses and σ^{+}/σ^{-} optical pumping to realize a finite-field Rb magnetometer with suppression of spin-exchange relaxation. We suppress frequency shifts from polarized Rb by measuring the ^{3}He and ^{129}Xe spin precession frequencies in the dark, while applying π pulses along two directions to depolarize Rb atoms.

Nuclear Matrix Elements for Tests of Local Lorentz Invariance Violation.

The nuclear matrix elements for the spin operator and the momentum quadrupole operator are important for the interpretation of precision atomic physics experiments that search for violations of local Lorentz and CPT symmetry and for new spin-dependent forces. We use the configuration-interaction nuclear shell model and self-consistent mean-field theory to calculate the momentum matrix elements for ^{21}Ne, ^{23}Na, ^{133}Cs, ^{173}Yb, and ^{201}Hg. We show that these momentum matrix are strongly suppressed by the many-body correlations, in contrast to the well-known enhancement of the spatial quadrupole nuclear matrix elements.

Publisher's Note: Limits on Lorentz Invariance Violation from Coulomb Interactions in Nuclei and Atoms [Phys. Rev. Lett. 118, 142501 (2017)].

This corrects the article DOI: 10.1103/PhysRevLett.118.