Abstract
Exotic spin-dependent interactions between fermions have recently attracted attention in relation to theories beyond the Standard Model. The exotic interactions can be mediated by hypothetical fundamental bosons which may explain several unsolved mysteries in physics. Here we expand this area of research by probing an exotic parity-odd spin- and velocity-dependent interaction between the axial-vector electron coupling and the vector nucleon coupling for polarized electrons. This experiment utilizes a high-sensitivity atomic magnetometer, based on an optically polarized vapor that is a source of polarized electrons, and a solid-state mass containing unpolarized nucleons. The atomic magnetometer can detect an effective magnetic field induced by the exotic interaction between unpolarized nucleons and polarized electrons. We set an experimental limit on the electron-nucleon coupling g_{mathrm{A}}^{mathrm{e}}g_{mathrm{V}}^{mathrm{N}} , < , 10^{ - 30} at the mediator boson mass below 10−4 eV, significantly improving the current limit by up to 17 orders of magnitude.
Highlights
Exotic spin-dependent interactions between fermions have recently attracted attention in relation to theories beyond the Standard Model
We investigated the interaction between polarized electrons and unpolarized nucleons based on a spin-exchange relaxation-free (SERF) atomic magnetometer: V ðbσi ; rÞ
H 8π ð2bσi where ħ is Planck’s constant, bσi is the ith spin unit vector of the polarized electron, r is the separation vector in the direction between the polarized electron and the unpolarized nucleon, r = |r|, v is their relative velocity vector, and λ = ħ(mbc)−1 is the interaction range with mb being the boson mass and c being the speed of light in vacuum. gAe gVN is the interaction coupling assuming no difference between electron-neutron and electron-proton couplings, and ignoring electron-electron couplings
Summary
The exotic interactions can be mediated by hypothetical fundamental bosons which may explain several unsolved mysteries in physics We expand this area of research by probing an exotic parity-odd spin- and velocitydependent interaction between the axial-vector electron coupling and the vector nucleon coupling for polarized electrons. In the present study we investigate an exotic parity-odd spin- and velocity-dependent interaction of electrons wiÀth axiaÁlvector electron coupling and vector nucleon coupling gAe gVN 3, where A, V, e, and N stand for the axial-vector coupling, the vector coupling, the electron, and the nucleon, respectively This interaction can be generated by massive spin-1 boson exchange[29], for example, from spontaneous breaking with two or more Higgs doublets. While the parity-even spin- and velocity-dependent interaction for electrons has been experimentally investigated[20,33,34,35,36], to the best of our knowledge, the parity-odd spin- and velocitydependent interaction of electrons has been explored by few laboratory experiments such as electron-spin polarized torsionpendulum experiments[33,34] using the Sun and the Moon as a unpolarized test mass
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