More on the open string pair production

Motivated by the recent work [1] one of present authors, we here report that there exist two new systems, namely, D3/(F, D1) and D3/(D3, (F, D1)), either which can give rise to a much larger sizable open string pair production rate at condition relaxed. Here D3 is taken as our own (1 + 3)-dimensional world while non-threshold bound state or (D3, D1)) placed parallel nearby in directions transverse both considered.