A. Czarnecki et B. Krause, NEUTRON ELECTRIC-DIPOLE MOMENT IN THE STANDARD MODEL - COMPLETE 3-LOOP CALCULATION OF THE VALENCE QUARK CONTRIBUTIONS, Physical review letters, 78(23), 1997, pp. 4339-4342
We present a complete three-loop calculation of the electric dipole mo
ment of the u and d quarks in the standard model. For the d quark, mor
e relevant for the experimentally important neutron electric dipole mo
ment, we find cancellations which lead to an order of magnitude suppre
ssion compared with previous estimates.