Spin, torsion and violation of null energy condition in traversable wormholes Elisabetta Di Grezia, Emmanuele Battista, Mattia Manfredonia and Gennaro Miele Eur. Phys. J. Plus, 132 12 (2017) 537 Published online: 22 December 2017 DOI: 10.1140/epjp/i2017-11799-6