Speaker
Description
We investigate the invariability of the Gauss-Bonnet action term in 4D in the case where gravitational instatons appear in the quantum foam level. The key hypotheses of Euclidean Quantum Gravity, that produce instaton solutions of distinct topology, are encapsulated effectively into the quantum field fluctuations. Therefore, under the Effective Topological Variation Conjecture (ETVC) the variation of the Gauss-Bonnet term need not be zero and in the semiclassical approach yields a novel effective dark energy sector of topological origin. The effective cosmological constant $\protect\Lambda_{eff}$ is interpreted as the density of wormholes thus exhibiting a dynamical nature. We examine the case of Nariai instatons and Euclidean Wormholes leading to arbitrary sign of dark energy. The theoretical values of $\Lambda_{eff}$ support our models candidacy for explaining the late time acceleration.
