Ghost-free higher-order theories of gravity with torsion Álvaro de la Cruz-Dombriz, Francisco José Maldonado Torralba and Anupam Mazumdar Eur. Phys. J. C, 81 3 (2021) 240 Published online: 17 March 2021 DOI: 10.1140/epjc/s10052-021-09019-6