General relativity effects in precision spin experimental tests of fundamental symmetries

Abstract

A search for the $P$- and $CP(T)$-violating electric dipole moments (EDM) of atoms, particles and nuclei with sensitivity up to $10^{-15}$ in units of magnetic dipole moments, allowed by all discrete symmetries, is one of the topical problems of modern physics. According to Sakharov, $CP$-violation is one of the three key criteria of baryogenesis in generally accepted paradigm of the Big Bang cosmology. All three criteria are supported by the Standard Model (SM), but it fails to describe the observed baryon asymmetry of the Universe. This is regarded a strong argument in favor of existence of $CP$-symmetry breaking mechanisms beyond minimal SM, which can lead to measurable EDMs of atoms, particles and nuclei. Direct searches for EDM of charged particles and nuclei are possible only in storage rings (COSY, NICA). After successful studies by the JEDI collaboration at the COSY synchrotron, at the forefront is a search for the proton EDM in an electrostatic storage ring with the proton spin frozen at the magic energy with projected sensitivity $d_p\sim 10^{-29}\,e\cdot$cm. Following a brief introduction to the $CP$-violation physics and the baryogenesis, the review presents a detailed discussion of significant contributions to the spin dynamics from the terrestrial gravity along with the new effects of Earth's rotation in ultrasensitive searches for the EDM of charged particles and neutrons. Quite remarkably, for the projected sensitivity to the proton EDM, these false EDM effects can by one to two orders of magnitude exceed the signal of the proton EDM, and become comparable to an EDM contribution in experiments with ultracold neutrons. We also discuss the role of a precessing spin as a detector of the axion-like dark matter, and consider applications of the quantum gravitational anomalies to the dense matter hydrodynamics and the spin phenomena in the non-central nuclear collisions.