QCD does not violate the CP-symmetry as easily as the electroweak theory ; unlike the electroweak theory in which the gauge fields couple to chiral currents constructed from the fermionic fields, the gluons couple to vector currents. Experiments do not indicate any CP violation in the QCD sector. For example, a generic CP violation in the strongly interacting sector would create the electric dipole moment of the neutron which would be comparable to 10 e ·m while the experimental upper bound is roughly one trillionth that size.