  We consider the stringy interaction between two parallel stacks of D3 branes
placed at a separation. Each stack of D3 branes in a similar fashion carry an
electric flux and a magnetic flux with the two sharing no common field strength
index. The interaction amplitude has an imaginary part, giving rise to the
Schwinger-like pair production of open strings. We find a significantly
enhanced rate of this production when the two electric fluxes are almost
identical and the brane separation is on the order of string scale. This
enhancement will be largest if the two magnetic fluxes are opposite in
direction. This novel enhancement results from the interplay of the
non-perturbative Schwinger-type pair production due to the electric flux and
the stringy tachyon due to the magnetic flux, and may have realistic physical
applications.
