EFFECTIVE POTENTIAL FOR D-BRANE IN CONSTANT ELECTROMAGNETIC-FIELD

We discuss the one-loop effective potential and static (large d) poten tial for toroidal D-brane described by DBI-action in constant magnetic and in constant electric fields. Explicit calculation is done for mem brane case (p = 2) for both types of external fields and in case of st atic potential for an arbitrary p. In the case of one-loop potential i t is found that the presence of magnetic background may stabilize D-br ane giving the possibility for non-pointlike ground state configuratio n. On the same time, constant electrical field acts against stabilizat ion and the correspondent one-loop potential is unbounded from below. The properties of static potential which also has stable minimum are d escribed in detail. The back-reaction of quantum gauge fields to one-l oop potential is also evaluated.