Is the cosmological dark sector better modeled by a generalized Chaplygin gas or by a scalar field? Sergio del Campo, Júlio C. Fabris, Ramón Herrera and Winfried Zimdahl Eur. Phys. J. C, 77 7 (2017) 479 Published online: 18 July 2017 DOI: 10.1140/epjc/s10052-017-5051-y