The exchange of massless spin-two particles

Abstract

The theory of gravity is considered from the little group viewpoint. This leads to a theory with a constraint, which is equivalent to general relativity with an arbitrary cosmological term. With this framework (i) the cosmological constant cannot be put into the Lagrangian but it appears as an integration constant. (ii) The gravitational Lagrangian automatically takes the form of a finite polynomial of the metric. (iii) The so-called conformal factor is fixed, which removes an apparent difficulty in carrying out path integrals.