Enhancement of the CP-odd effect in the nuclear electric dipole moment of ${}^6$Li

Abstract

We calculate for the first time the electric dipole moment (EDM) of the ${}^6$Li nucleus within the alpha + p + n three-body cluster model using the Gaussian expansion method, assuming the one meson exchange P, CP-odd nuclear forces. It is found that the EDM of the ${}^6$Li is 2 times more sensitive on the isovector pion exchange P, CP-odd nuclear force than the deuteron EDM, due to the CP-odd interaction between the nucleons and the alpha cluster. The ${}^9$Be EDM is also calculated in the same framework as an alpha + alpha + n three-body system. We also test the ab initio calculation of the EDM of the deuteron, ${}^3$H and ${}^3$He nuclei using the realistic Argonne $v18$ nuclear force. In the ab initio calculations, good agreements with previous studies are obtained. We finally discuss the prospects for the new physics beyond the standard model.

Comments: 6 pages, 1 figure