Enhancement of theCP-odd effect in the nuclear electric dipole moment ofLi6

Abstract

We calculate for the first time the electric dipole moment (EDM) of the $^{6}\mathrm{Li}$ nucleus within the $\ensuremath{\alpha}+p+n$ 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 $^{6}\mathrm{Li}$ is 2 times more sensitive to the isovector pion exchange $P$, CP-odd nuclear force than the deuteron EDM because of the CP-odd interaction between the nucleons and the $\ensuremath{\alpha}$ cluster. The $^{9}\mathrm{Be}$ EDM is also calculated in the same framework as an $\ensuremath{\alpha}+\ensuremath{\alpha}+n$ three-body system. We also test the ab initio calculation of the EDM of the deuteron, $^{3}\mathrm{H}$, and $^{3}\mathrm{He}$ 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 new physics beyond the standard model.