In particle physics, the anomalous electric
dipole moment, or the electric dipole moment
of a particle in short, is the electric dipole
moment of a particle.
There is a symmetry, the CP symmetry, which
if exact and unbroken will predict an exactly
zero electric dipole moment for particles.
However, we know at least in the Yukawa sector
from neutral kaon oscillations that CP is
broken.
Experiments have been performed to measure
the electric dipole moment of various particles
like the electron and the neutron.
Many models beyond the standard model with
additional CP-violating terms generically
predict a nonzero electric dipole moment and
are hence sensitive to such new physics.
Instanton corrections from a nonzero θ term
in quantum chromodynamics predict a nonzero
electric dipole moment for the neutron (it
is easier to measure the electric dipole moment
in a neutral particle) which have not been
observed.
This is the strong CP problem and is a prediction
of chiral perturbation theory.
== See also ==
CP symmetry
anomalous magnetic dipole moment
