The Energy of Asymptotically de Sitter Spacetimes in Kaluza—Klein Theory

We use a Hamiltonian approach to derive a general expression for 5D Kaluza—Klein metrics which depend on the extra coordinate but whose 4D embedded spacetimes are asymptotically de Sitter. This enables us to better understand the nature of the cosmological constant and the role played by the dimension in inducing 4D matter from 5D geometry.     

An improved result for a class of Klein–Gordon–Maxwell system with quasicritical potential vanishing at infinity

The following kind of Klein–Gordon–Maxwell system is investigated where $\omega >0$ is a parameter, and V is vanishing potential. By using some suitable conditions on K and f, we obtain a Palais–Smale sequence by using Pohožaev equality and prove the ground-state solution for this system by employing variational methods. Our result improves the related one in the literature.