A new avenue in the search for CP violation: Moessbauer spectroscopy of 227-Ac

Abstract

This work proposes a new avenue in the search for CP-violating odd-electric and even-magnetic nuclear moments. A promising candidate to find such moments in the ground state is the quadrupole-deformed and octupole-correlated nucleus 227-actinium. In this nucleus, the 27.4-keV $E1$~transition that connects the $3/2^{+}$ parity-doublet partner and the $3/2^{-}$ ground state is perfectly suited to apply the sensitive technique of recoil-free selfabsorption, commonly known as Mössbauer spectroscopy. In this experimental approach, the lifetime of the $3/2^{+}$ upper parity-doublet partner allows an estimate of the lower limit of $\Delta E=2\cdot {\Gamma }_{\gamma }$= $23.7(1)\times 10^{-9}$ eV for the achievable energy resolution to be made. This resolution must be exceeded by the interaction of a CP-violating moment and the corresponding multipole moment of the field distribution in the lattice. This work presents the first ideas for patterns caused by CP-violating moments on the expected quadrupole splitting and nuclear Zeeman effect.

Comments: 9 pages, 4 figures