New constraints for CP-violating forces between nucleons in the range 1 micrometer to 1 centimeter

The range of nucleon interaction 10−4 cm-1 cm is interesting because it corresponds to the mass range of an intermediate particle within the so-called “axion window” that is not closed yet by experiment. Depolarization of ultracold neutrons (UCN) during their storage in material traps can be caused by CP-violating pseudo-magnetic precession of the neutron spin in the vicinity of an unpolarized matter surface. Using the experimental limits for UCN depolarization new constraints were set for the product gSgP of the dimensionless scalar and pseudo-scalar constants, and the parameter λPS=ℏ/mPSc, determining the range of the Yukawa-type interaction of the nucleon via a new pseudo-scalar boson (axion-like particle) with mass mPS:gSgPλPS2⩽2.96×10−21[cm2]for 10−3 cm<λPS<1 cm;gSgPλPS2⩽3.9×10−22[cm2]for 10−4 cm<λPS<10−3 cm. The previous limit on gSgP is improved by 4 to 5 orders of magnitude for λPS ranging from 0.1 cm to 1 cm. Prospects of increasing the accuracy in searching for CP-violating pseudo-magnetic precession are considered. Estimates of possible effects of pseudo-magnetic precession in the framework of theoretical models with CP-violation are discussed.