Contribution of the triangle graphs to the neutron electric dipole moment

Abstract

In the Kobayashi-Maskawa model we compute a new contribution to the neutron electric dipole moment induced byCP violating flavour-changing transitions of the typess→d+gluon+γ through heavy quark loops. This contribution, essentially given by the triangle anomaly graph, is by itself gauge invariant. We obtain from this mechanismDn/e=3.10−32 cm, one order of magnitude below our previous estimate from usual penguin diagram contributions.