ar X iv : g r - qc / 0 00 10 31 v 1 1 1 Ja n 20 00 4 d neutral dilatonic black holes and ( 4 + p ) dimensional nondilatonic black p - branes

4d neutral dilatonic black holes and (4 + p) dimensional nondilatonic black p-branes Abstract It is shown that, in contrast to the case of extreme 4d dilatonic black holes, 4d neutral dilatonic black holes with horizon singularities can not be interpreted as nonsingular nondilatonic black p-branes in (4 + p) dimensions, regardless of the number of extra dimensions p. That is, extra dimensions do not remove naked singularities of 4d neutral dilatonic black holes. It has been pointed out by Gibbons, Horowitz, and Townsend[1] that for certain values of the dilaton coupling α = p/(p + 2), where p is an odd integer, the horizon singularities of extreme 4d dilaton black holes[2] can be removed by extra dimensions. That is, for certain numbers of extra dimensions (p = odd) the extreme 4d dilaton black hole can be viewed from a (4 + p) dimensional perspective as a singularity free nondilatonic black p-brane. It can be inferred that this result may not hold for the case of nonextreme dilaton black holes. In fact, Wesson and de Leon[3] have investigated 1