Remarks on Dp and Dp−2 with each carrying a flux

We explore various properties of interaction between Dp and Dp′ with each carrying a world-volume flux and with the p′-branes placed along p′ spatial world-volume directions of the p-branes at a separation when p−p′=2. Carefully analyzing the annulus amplitudes calculated via the boundary state approach, we find that many features of amplitudes remain similar to those studied when p=p′ such as the nature of force on the brane separation, the onset of various instabilities when the brane-separation is on the order of string scale and the occurrence of pair production of open strings when there is a relevant electric flux present. In addition, we have also found many new features of interaction which don't appear in the absence of fluxes or when p=p′ in the presence of fluxes, for example, the nature of interaction can be repulsive and there is no onset of tachyonic instability under certain conditions. Even in the absence of a magnetic flux, we can have an exponential enhancement of the rate of pair production of open strings in certain cases, which may be significant enough to give observational consequences.