Electric dipole moment from QCD and how it vanishes for mixed states A. P. Balachandran, T. R. Govindarajan and A. R. de Queiroz Eur. Phys. J. Plus, 127 10 (2012) 118 Published online: 04 October 2012 DOI: 10.1140/epjp/i2012-12118-7