Using Geoelectrons to Search for Velocity-Dependent Spin-Spin Interactions

Abstract

We use the recently developed model of the electron spins within the Earth to investigate all of the six possible long-range velocity-dependent spin-spin interactions associated with the exchange of an intermediate vector boson. Several laboratory experiments have established upper limits on the energy associated with various fermion-spin orientations relative to the Earth. We combine the results from three of these experiments with the geoelectron-spin model to obtain bounds on the velocity-dependent interactions that couple electron spin to the spins of electrons, neutrons and protons. Five of the six possible potentials investigated were previously unbounded. The bound achieved on V 8 is about 30 orders of magnitude more restrictive in the long-range limit than the only previously established constraint.Recently, there has been renewed interest in exploring possible anomalous spin-spin interactions mediated by new particles [1][2][3][4][5][6][7]. Observation of such an interaction would constitute the discovery of a new force in nature and suggest physics beyond the standard model of particle physics. Non electromagnetic spin-spin forces created through the exchange of a scalar boson (like the axion) were first suggested by Moody and Wilcek [8]. Dobrescu and Mocioiu enumerated nine possible spin-spin interactions associated with the exchange of a vector boson (like the z') that are compatible with rotational invariance [9]. Stringent limits have now been placed on the three velocity-independent interactions both at long range [1,4,5,10 ] and at atomic scales [2,3,7]. The remaining six interactions (numbered as in Ref.[9]) depend not only on the spins (�) and relative positions (r) of the two fermions, but also on their relative velocity (v).

Prospects for electron spin-dependent short-range force experiments with rare earth iron garnet test masses

“…For the case of electrons, these interactions appear to be unconstrained in this range. At λ = 1 km, the lower limit of the range analyzed in [6], the constraints on electron interactions range from 10 −32 -10 −22 for the case of V 14…”

Constraints on exotic spin-dependent interactions between electrons from helium fine-structure spectroscopy

“…This difference comes from the fact that the velocity-dependent potentials in Refs. [2,54] are in fact presented in a "mixed" representation (not a position representation, as stated). We discuss this further in the Appendix B.…”

“…3. Constraints for V 8 electron coupling constant were obtained earlier using geoelectron experiments [54], which considered boson masses less than 10 −10 eV, yielding constraints g The V 2 potential does not split energy levels of different J and the same L and S, but only shifts such levels by the same amount. This means that in order to experimentally observe the shifts, we need another reference state outside the fine-structure manifold.…”

Searching for new spin-dependent interactions withSmCo5spin sources and a spin-exchange-relaxation-free comagnetometer

“…2, we take the effective magnetic field for electron as B can be improved by over 10 orders of magnitude in λ < 1000 m compared with the current best limits [29]. For the constrains of the possible new "dipoledipole interaction" f (en) 3 and f (en) 6+7 , this proposal could be more than 7 orders of magnitude better than the current records [29,30] at around λ = 1000 m. For the limits of f 9+10 and f (en) 2 , this proposal could be more than over 3 orders of magnitude better than other proposals [17,27]. For other terms of the SVDFs for electron-electron (ee) and electron-nucleon (en) couplings, the proposed method can also be several orders of magnitude better than other corresponding best limits up to date.…”