Various theories beyond the Standard Model predict new particles with masses in the sub-eV range with very weak couplings to ordinary matter. A P-odd and T-odd interaction between polarized and unpolarized matter proportional to s.r is one such possibility, where r is the distance between the two particles, and s is the spin of the polarized one. Such an interaction involving a scalar coupling gs at one vertex and a pseudoscalar coupling gp at the other vertex can be induced by the exchange of spin-0 particles between fermions. We show that measurements of the transverse spin relaxation rate Gamma_2 for polarized gas can be used to set limits on the product gs*gp for particle masses in the micro-electron volt to milli-electron volt range, corresponding to distances of the order of millimeters. We present limits from both a reanalysis of previous measurements of Gamma_2 in 3He spin exchange cells and from data in a test experiment searching for a change in Gamma_2 upon the motion of an unpolarized test mass. The outlook for more sensitive measurements using this technique is discussed.
Citation: Physical Review D (Particles, Fields, Gravitation and Cosmology)
Pub Type: Journals
He-3, monopole-dipole, polarized