Search

Very light particles with CP-violating couplings to ordinary matter, such as axions or axionlike particles, can mediate long-range forces between polarized and unpolarized fermions. We describe a new experimental search for such forces between unpolarized nucleons in two 250 kg Pb weights and polarized neutrons and electrons in a ³He-K comagnetometer located about 15 cm away. We place improved constraints on the products of scalar and pseudoscalar coupling constants, gpngsN<4.2×10-30 and gpegsN<1.7×10-30 (95% C.L.) for axionlike particle masses less than 10-6 eV, which represents an order of magnitude improvement over the best previous neutron laboratory limit. [ABSTRACT FROM AUTHOR]

We report the results of a new search for long-range spin-dependent interactions using a Rb-21Ne atomic comagnetometer and a rotatable electron spin source based on a SmCo5 magnet with an iron flux return. By looking for signal correlations with the orientation of the spin source we set new constraints on the product of the pseudoscalar electron and neutron couplings gepgnp/ℏc<1.7×10-14 and on the product of their axial couplings geAgnA/ℏc<5×10-42 to a new particle with a mass of less than about 1 μeV. Our measurements improve by about 2 orders of magnitude previous constraints on such spin-dependent interactions. [ABSTRACT FROM AUTHOR]

Very light particles with CP-violating couplings to ordinary matter, such as axions or axionlike particles, can mediate long-range forces between polarized and unpolarized fermions. We describe a new experimental search for such forces between unpolarized nucleons in two 250 kg Pb weights and polarized neutrons and electrons in a ^{3}He-K comagnetometer located about 15 cm away. We place improved constraints on the products of scalar and pseudoscalar coupling constants, g&#95;{p}^{n}g&#95;{s}^{N}<4.2×10^{-30} and g&#95;{p}^{e}g&#95;{s}^{N}<1.7×10^{-30} (95% C.L.) for axionlike particle masses less than 10^{-6}  eV, which represents an order of magnitude improvement over the best previous neutron laboratory limit.

Nuclear spin optical rotation (NSOR) arising from the Faraday effect constitutes a novel, advantageous method for detection of nuclear magnetic resonance, provided that a distinction is seen between different chemical surroundings of magnetic nuclei. Efficient first-principles calculations for isolated water, ethanol, nitromethane, and urea molecules at standard laser wavelengths reveal a range of NSOR for different molecules and inequivalent nuclei, indicating the existence of an optical chemical shift. 1H results for H2O(l) are in excellent agreement with recent pioneering experiments. We also evaluate, for the same systems, the Verdet constants of Faraday rotation due to an external magnetic field. Calculations of NSOR in ethanol and a 11-cis-retinal protonated Schiff base imply an enhanced chemical distinction between chromophores at laser wavelengths approaching optical resonance.