Chemical potentials and parity breaking: the Nambu–Jona-Lasinio model A. A. Andrianov, D. Espriu and X. Planells Eur. Phys. J. C, 74 2 (2014) 2776 Published online: 19 February 2014 DOI: 10.1140/epjc/s10052-014-2776-8