“…Again, since there does not exist any soliton after the formation of NPDL at the acoustic speed, there does not exist any negative potential supersoliton at the acoustic speed for p > 0. But for p = 0, i.e., if there is no positrons in the system, Das et al 25 found the existence of NPDLs and most importantly, the existence of negative potential supersolitons at the acoustic speed. Now, in the present work, if we consider p = 0, i.e., the positron concentration in the system is zero, then the present plasma system reduces to the exactly same system of Das et al 25 Figure 8 is the existence domain with respect to µ at p = 0 when σ ie = 0.9.…”