The CPT-violating effects on neutrons’ gravitational bound state

Abstract

In this work, the CPT-violating (CPTV) interactions on neutrons’ gravitational bound state are studied. With simple analytical solutions, we provide a preliminary investigation into the Lorentz-violation (LV)-induced spin precession due to the and couplings, where and represent LV coefficients. The helicity-dependent couplings can induce unusual phase evolutions with position and momentum dependence. As varies with time due to the Earth’s motion, the spin polarization also shows a sidereal time dependence, and it may be enhanced with time for an ultra-stable polarized state of neutrons. The inseparability of the spin-momentum coupling of the term can also lead to a motional-dependent polarization state. With precisely measured transition frequency between different gravitational bound states, we get a rough bound GeV for unpolarized neutrons. If the spin-flip transition frequency can reach comparable precision in the future, the bound could be improved to the level of 10−24 GeV. The test of weak equivalence principle with polarized atoms may also improve it significantly.