Large and infinite extra dimensions

The emphasis in the developmet of theories with more than three spatial dimensions has recently shifted towards ``brane world'' picture, which assumes that ordinary matter (with possible exceptions of gravitons and other, hypothetic, particles which interact very weakly with matter) is trapped to a three-dimensional submanifold --- brane --- embedded in fundamental multi-dimensional space. In the brane world scenario, extra dimensions may be large, and even infinite; they may have effects, directly observable in current or fothcoming experiments. On the basis of simple field-theoretic models, various ideas in this direction are exposed at a non-expert level.Comment: 55 pages, 10 figures Several references and figures added. Journal version, to appear in Uspekhi Fiz. Nau

Cosmology

In these lectures we first concentrate on the cosmological problems which, hopefully, have to do with the new physics to be probed at the LHC: the nature and origin of dark matter and generation of matter-antimatter asymmetry. We give several examples showing the LHC cosmological potential. These are WIMPs as cold dark matter, gravitinos as warm dark matter, and electroweak baryogenesis as a mechanism for generating matter-antimatter asymmetry. In the remaining part of the lectures we discuss the cosmological perturbations as a tool for studying the epoch preceeding the conventional hot stage of the cosmological evolution.Comment: 47 pages, set of lectures given at the 2011 European School of High-Energy Physics, Cheile Gradistei, Romania, 7-20 Sep 2011, edited by C. Grojean, M. Mulder

More about wormholes in generalized Galileon theories

We consider a class of generalized Galileon theories within General Relativity in space-times of more than two spatial dimensions. We show that these theories do not admit stable, static, spherically symmetric, asymptotically flat and traversable Lorentzian wormholes.Comment: 7 pages, refinement of arXiv:1509.08808 [hep-th

Galileon bounce after ekpyrotic contraction

We consider a simple cosmological model that includes a long ekpyrotic contraction stage and smooth bounce after it. Ekpyrotic behavior is due to a scalar field with a negative exponential potential, whereas the Galileon field produces bounce. We give an analytical picture of how the bounce occurs within the weak gravity regime, and then perform numerical analysis to extend our results to a non-perturbative regime.Comment: 15 pages, 5 picture