Dark energy from the gravity vacuum

  title={Dark energy from the gravity vacuum},
  author={Sandipan Sengupta},
  journal={Classical and Quantum Gravity},
We propose a new solution to the cosmological constant problem building on a nonperturbative quantum theory of gravity with torsional instantons. These pseudoparticles, which were recently found to exist in a first order formulation of Giddings–Strominger axionic gravity, carry nontrivial Nieh–Yan topological charge. The nonperturbative ground state as generated due to tunneling effects is shown to be stable under quantum fluctuations. Within this framework, the associated vacuum angle, namely… 



Classification of Gravitational Instanton symmetries

We classify the action of one parameter isometry groups of Gravitational Instantons, complete non singular positive definite solutions of the Einstein equations with or without Λ term. The fixed

The Cosmological Constant Problem

Astronomical observations indicate that the cosmological constant is many orders of magnitude smaller than estimated in modern theories of elementary particles. After a brief review of the history of