Interaction of Moving Branes with Background Massless and Tachyon Fields in Superstring Theory

Using the boundary state formalism we study a moving D$p$-brane in a partially compact spacetime in the presence of the background fields: Kalb-Ramond $B_{\mu \nu }$, a U(1) gauge field $A_{\alpha }$ and the tachyon field. The boundary state enables us to obtain interaction amplitude of two branes with above background fields. The branes are parallel or perpendicular to each other. Presence of the background fields, compactification of some directions of the spacetime, motion of the branes and arbitrariness of the branes’ dimensions give a general feature to the system. Due to the tachyon fields and velocities of the branes, the behavior of the interaction amplitude reveals obvious differences from what is conventional.