Collective T- and P-odd electromagnetic moments in nuclei with octupole deformations.

Parity and time invariance violating forces produce collective Pand Todd moments in nuclei with static octupole deformation. Collective Schiff moment, electric octupole and dipole and also magnetic quadrupole appear due to the mixing of rotational levels of opposite parity and can exceed singleparticle moments by more than a factor of 100. This enhancement is due to two factors, the collective nature of the intrinsic moments and the small energy separation between members of parity doublets. The above moments induce Tand Podd effects in atoms and molecules. Experiments with such systems may improve substantially the limits on time reversal violation. Parity and time invariance nonconserving nuclear moments induced by P-, Todd nuclear forces were discussed e.g. in Refs. [1–6]. These moments can be enhanced in nuclei which have close to the ground state (g.s.) levels of the same spin as the g.s. but opposite parity [3,4]. An interesting possibility to enhance the effect is to consider mechanisms producing collective T-, Podd moments. In Ref. [7] it was shown that the “spin hedgehog” mechanism produces a collective magnetic quadrupole. In the present paper we want to consider a different mechanism: mixing of opposite parity rotational levels (parity doublets) by T-, Podd interaction in the nuclei with octupole deformation. This deformation was demonstrated to exist in nuclei from the Ra-Th and Ba-Sm region and produces such effects as parity doublets, large dipole and octupole moments in the intrinsic frame of reference and enhanced E1 and E3 transitions (see review [8]). Let us start our consideration from the expression for the electrostatic potential of a nucleus screened by the electrons of the atom. If we consider only the dipole T-, Podd part of screening (Purcell-Ramsey-Schiff theorem [9]) one finds [4]: