JOURNAL OF ENGINEERING SCIENCES-UKRAINE, cilt.10, sa.1, ss.1-7, 2023 (Scopus)
Motivated by the recent work \cite{Lu:2019ynq} by one of the present authors, we here report that there exist two new systems, namely, D3/(F, D1) and D3/(D3, (F, D1)), either of which can give rise to a much larger sizable open string pair production rate at a condition much relaxed. Here the D3 is taken as our own (1 + 3)-dimensional world while the non-threshold bound state (F, D1) or (D3, (F, D1)) is placed parallel nearby in the directions transverse to both our D3 world and the non-threshold bound state considered.