Abstract
Based on conserved baryon number (or charge) and the generalized U(1b) symmetry, we discuss a new baryonic gauge field and its linear potential for two point-like baryon charges. The force between two baryons is repulsive, extremely weak, but independent of distance. However, the effective force between two baryon galaxies proportional to their distance. Only in the later stage of cosmic evolution, when the two baryon galaxies are separated by a large distance, the effective baryonic force can overcome their gravitational attractive force. Thus, this provides a gauge-field theoretic understanding of the late-time accelerated cosmic expansion.