We used a torsion pendulum and rotating attractor with 20-pole electron-spin distributions to probe dipole-dipole interactions mediated by exotic pseudo-Goldstone bosons with mb≤500μeV and coupling strengths up to 14 orders of magnitude weaker than electromagnetism. This corresponds to symmetry-breaking scales F≤70 TeV, the highest reached in any laboratory experiment. We used an attractor with a 20-pole unpolarized mass distribution to improve laboratory bounds on CP-violating monopole-dipole interactions with 1.5μeV<mb<400μeV by a factor of up to 1000.
@article{arxiv.1508.02463,
title = {Short-range spin-dependent interactions of electrons: a probe for exotic pseudo-Goldstone bosons},
author = {W. A. Terrano and E. G. Adelberger and J. G. Lee and B. R. Heckel},
journal= {arXiv preprint arXiv:1508.02463},
year = {2015}
}