Effective Potential for D-brane in Constant Electromagnetic Field

We discuss the one-loop effective potential and static (large $d$) potential for toroidal D-brane described by DBI-action in constant magnetic and in constant electric fields. Explicit calculation is done for membrane case ($p=2$) for both types of external fields and in case of static potential for an arbitrary $p$. In the case of one-loop potential it is found that the presence of magnetic background may stabilize D-brane giving the possibility for non-pointlike ground state configuration. On the same time, constant electrical field acts against stabilization and the correspondent one-loop potential is unbounded from below. The properties of static potential which also has stable minimum are described in detail. The back-reaction of quantum gauge fields to one-loop potential is also evaluated.Comment: LaTeX file,17 pages, few misprints and mistakes are correcte

Braneworld Cosmology in (Anti)--de Sitter Einstein--Gauss--Bonnet--Maxwell Gravity

Braneworld cosmology for a domain wall embedded in the charged (Anti)-de Sitter-Schwarzschildblack hole of the five--dimensional Einstein-Gauss-Bonnet-Maxwell theory is considered. The effective Friedmann equation for the brane is derived by introducing the necessary surface counterterms required for a well-defined variational principlein the Gauss--Bonnet theory and for the finiteness of the bulk space. The asymptotic dynamics of the brane cosmology is determined and it is found that solutions with vanishingly small spatial volume are unphysical. The finiteness of the bulk action is related to the vanishing of the effective cosmological constant on the brane. An analogy between the Friedmann equation and a generalized Cardy--Verlinde formula is drawn.Comment: LaTex file 28 pages, typos corrected, one reference is adde

Dark energy problem: from phantom theory to modified Gauss-Bonnet gravity

The solution of dark energy problem in the models without scalars is presented. It is shown that late-time accelerating cosmology may be generated by the ideal fluid with some implicit equation of state. The universe evolution within modified Gauss-Bonnet gravity is considered. It is demonstrated that such gravitational approach may predict the (quintessential, cosmological constant or transient phantom) acceleration of the late-time universe with natural transiton from deceleration to acceleration (or from non-phantom to phantom era in the last case).Comment: LaTeX 8 pages, prepared for the Proceedings of QFEXT'05, minor correctons, references adde

Translating the genomics revolution: the need for an international gene therapy consortium for monogenic diseases

Letter to the Edito