Relativistic multireference Fock-space coupled-cluster calculation of the forbidden 6s2 1S0→6s5d 3D1 magnetic-dipole transition in ytterbium

We report the forbidden 6s(2) S-1(0)-> 6s5d D-3(1) magnetic-dipole transition amplitude computed using multireference Fock-space coupled-cluster theory. Our computed transition matrix element (1.34x10(-4))mu(B) is in excellent agreement with the experimental value (1.33x10(-4))mu(B). This value in combination with other known quantities will be helpful in determining the parity-nonconserving amplitude for the 6s(2) S-1(0)-> 6s5d D-3(1) transition in atomic Yb. To our knowledge, this calculation is the most accurate to date, and can be very important in the search for physics beyond the standard model. We further report the 6s6p P-3(0)-> 6s6p P-1(1) and 6s5d D-3(1)-> 6s6p P-3(0) transition matrix elements, which are also in good agreement with the earlier theoretical estimates.