title: Improved constraints on an axion-mediated force.
abstract: Low mass pseudoscalars, such as the axion, can mediate macroscopic parity and time-reversal symmetry-violating forces. We searched for such a force between polarized electrons and unpolarized atoms using a novel, magnetically unshielded torsion pendulum. We improved the laboratory bounds on this force by more than 10 orders of magnitude for pseudoscalars heavier than 1 meV and have constrained this force over a broad range of astrophysically interesting masses (10  μeV to 10 meV).
authors.affiliation: Center for Experimental Nuclear Physics and Astrophysics, University of Washington, Seattle, Washington 98195-4290, USA. sethh@uw.edu
authors.forename: S A
authors.initials: SA
authors.lastname: Hoedl
authors.forename: F
authors.initials: F
authors.lastname: Fleischer
authors.forename: E G
authors.initials: EG
authors.lastname: Adelberger
authors.forename: B R
authors.initials: BR
authors.lastname: Heckel