Unimodular gravity and general relativity from graviton self-interactions

Understand

It is commonly accepted that general relativity is the only solution to the consistency problem that appears when trying to build a theory of interacting gravitons (massless spin-2 particles).

• Padmanabhan's 2008 thought-provoking analysis raised some concerns that are having resonance in the community.
• In this work we present the self-coupling problem in detail and explicitly solve the infinite-iterations scheme associated with it for the simplest theory of a graviton field, which corresponds to an irreducible spin-2 representation of the Poincar\'e group.
• We make explicit the non-uniqueness problem by finding an entire family of solutions to the self-coupling problem.