Is a classical description of stable non-BPS D-branes possible?

We study the classical geometry produced by a stack of stable (i.e., tachyon-free) non-BPS D-branes present in K3 compactifications of type IT string theory. This classical representation is derived by solving the equations of motion describing the low-energy dynamics of the supergravity fields which couple to the non-BPS state. Differently from what expected, this configuration displays a singular behaviour: the space-time geometry has a repulson-like singularity This fact suggests that the simplest setting, namely a set of coinciding non-interacting D-branes, is not acceptable. We finally discuss the possible existence of other acceptable configurations corresponding to more complicated bound states of these non-BPS branes. (C) 2000 Elsevier Science B.V. All rights reserved.