Loopless neutron EDM and charm CP violation: The Standard Model and beyond
It is pointed out that the electric dipole moment of the neutron in the Standard Model is generated already at tree level to the second order in the weak interactions due to bound-state effects. The related contribution has a regular nonvanishing chiral limit and does not depend on the mass splitting between s and d quarks. We estimate it to be about 10^(-31)e*cm. The CP asymmetry in D-> K^+K^- / pi^+pi^- recently reported by LHCb and CDF is argued to be too large to naturally fit the SM. If so, a new source of CP violation is implied in the Delta C=1 sector with a `milliweak' strength, about 10 times that of the SM. Its product with the SM Delta C=-1 amplitude would then yield an enhanced contribution to d_n originating at the charm mass scale, 30 to 100 times larger than in the SM, or even higher in certain model yet not quite natural examples.