Generally covariant geometric momentum, gauge potential and a Dirac fermion on a two-dimensional sphereQ. H. Liu, Z. Li, X. Y. Zhou, Z. Q. Yang and W. K. DuEur. Phys. J. C, 79 8 (2019) 712DOI: https://doi.org/10.1140/epjc/s10052-019-7231-4