arXiv subjects
Publications and source records attributed to Laur Jarv.
We review recent results on the interplay between the five-dimensional space-time and the internal manifold in Calabi-Yau compactifications of M-theory. Black string, black hole and domain wall solutions as well as Kasner type cosmologies cannot develop a naked singularity as long as the moduli take values inside the Kahler cone.
We summarize our recent results of studying five-dimensional Kasner cosmologies in a time-dependent Calabi-Yau compactification of M-theory undergoing a topological flop transition. The dynamics of the additional states, which become massless at the transition point and give rise to a scalar potential, helps to stabilize the moduli and triggers short periods of accelerated cosmological expansion.
We study five-dimensional Kasner cosmologies in a time-dependent Calabi-Yau compactification of M-theory undergoing a flop transition. The dynamics of the additional states, which become massless at the transition point and give rise to a scalar potential, are taken into account using a recently constructed gauged supergravity action. Due to the dynamics of these states the moduli do not show the usual run-away behavior but oscillate around the transition region. Moreover, the solutions typically exhibit short periods of accelerated expansion. We also analyze the interplay between the geometries of moduli space and space-time.
We construct a family of five-dimensional gauged supergravity actions which describe flop transitions of M-theory compactified on Calabi-Yau threefolds. While the vector multiplet sector can be treated exactly, we use the Wolf spaces X(1+N) = U(1+N,2)/(U(1+N) x U(2)) to model the universal hypermultiplet together with N charged hypermultiplets corresponding to winding states of the M2-brane. The metric, the Killing vectors and the moment maps of these spaces are obtained explicitly by using the superconformal quotient construction of quaternion-Kahler manifolds. The inclusion of the extra hypermultiplets gives rise to a non-trivial scalar potential which is uniquely fixed by M-theory physics.
We reconsider supersymmetric five dimensional rotating charged black holes, and their description in terms of D-branes. By wrapping some of the branes on K3, we are able to explore the role of the enhancon mechanism in this system. We verify that enhancon loci protect the black hole from violations of the Second Law of Thermodynamics which would have been achieved by the addition of certain D-brane charges. The same charges can potentially result in the formation of closed time-like curves by adding them to holes initially free of them, and so the enhancon mechanism forbids this as well. Although this latter observation is encouraging, it is noted that this mechanism alone does not eliminate closed time-like curves from these systems, but is in accord with earlier suggestions that they may not be manufactured, in this context, by physical processes.
We present some results of studying certain axially symmetric supergravity geometries corresponding to a distribution of BPS D6-branes wrapped on K3, obtained as extremal limits of a rotating solution. The geometry's unphysical regions resulting from the wrapping can be repaired by the enhancon mechanism, with the result that there are two nested enhancon shells. For a range of parameters, the two shells merge into a single toroidal surface. Given the quite intricate nature of the geometry, it is an interesting system in which to test previous techniques that have been brought to bear in spherically symmetric situations. We are able to check the consistency of the construction using supergravity surgery techniques, and probe brane results. Implications for the Coulomb branch of (2+1)-dimensional pure SU(N) gauge theory are extracted from the geometry. Related results for wrapped D4- and D5-brane distributions are also discussed.
Supergravity solutions related to large N SU(N) pure gauge theories with eight supercharges have recently been shown to give rise to an ``enhancon'', a new type of hypersurface made of D-branes. We show that enhancons also arise in similar situations pertaining to SO(2N+1), USp(2N) and SO(2N) gauge theories, using orientifolds. Enhancons therefore appear to come in types A, B, C, and D. The latter three differ globally from type A by having an extra Z_2 identification, and are distinguished locally by their subleading behaviour in large N. We focus mainly on 2+1 dimensional gauge theory, where a relation to M-theory and the Atiyah-Hitchin and Taub-NUT manifolds enables the construction of the smooth supergravity solution and the study of some of the 1/N corrections. The role of the enhancon in eleven dimensional supergravity is also uncovered. There is a close relation to certain multi-monopole moduli space problems.