Distinguishing axions from generic light scalars using electric dipole moment and fifth-force experiments
We derive electric dipole moment (EDM) constraints on possible new macroscopic time-reversal and parity-violating (TVPV) spin-dependent forces. These constraints are compared to those derived from direct searches in fifth-force experiments and from combining laboratory searches with astrophysical bounds on stellar energy loss. For axion-mediated TVPV spin-dependent forces, EDM constraints dominate over fifth-force limits by several orders of magnitude. However, we show that for a generic light scalar, unrelated to the strong CP problem, present bounds from direct fifth-force searches are more stringent than those inferred from EDM limits for the interaction ranges explored by fifth-force experiments. Thus, correlating observations in EDM and fifth-force experiments could help distinguish axions from more generic light scalar scenarios.
Additional Information© 2014 American Physical Society. Received 11 March 2014; published 16 September 2014. We acknowledge fruitful discussions with H. Abele, P. Chu, H. Gao, and T. G. Walker. This work was supported in part by U.S. Department of Energy Contracts No. DEAC02- 06CH11357 (M. P.), No. DE-FG02-08ER41531 (M. P. and M. J. R.-M.), and No. DE-SC0011095 (M. J. R.-M.), the Wisconsin Alumni Research Foundation (M. P. and M. J. R.-M.), Northwestern University (S. M.), and the theoretical program on Contract No. I689-N16 by the Austrian Fonds zur Förderung der Wissenschaftlichen Forschung (M. P.).
Published - PhysRevD.90.054016.pdf
Submitted - 1401.7339v2.pdf