Vanishing of cosmological constant and fully localized gravity in a brane world with extra time(s)

We construct an intersecting brane configuration in six-dimensional space w ith one extra space-Eke and one extra time-like dimensions. With a certain additional symmetry imposed on the extra spacetime we have found that effec tive four-dimensional cosmological constant vanishes automatically, providi ng the static solution with gravity fully localized at the intersection reg ion as there are no propagating massive modes of graviton. In this way, the same symmetry allows us to eliminate tachyonic states of graviton from the spectrum of the effective four-dimensional theory, thus avoiding phenomeno logical difficulties coming from the matter instability usually induced in theories with extra time-like dimensions. (C) 2001 Elsevier Science B.V. Al l rights reserved.