Extracting Bigravity from String Theory

Abstract

Given the success of constructing quantum field theories for vector spin-1 theories numerous attempts have been made to do the same for theories involving spin-2 theories. The most successful of these attempts is String theory which, gives a consistent frame work to create a Hilbert space that includes a mssless spin-2. However, there are other issues to be addressed involving spin-2 theories it has been shown that there exists a unique way to couple a massive spin-2 to a gravity theory (massless spin-2) which is known as Bimetric gravity. Therefore, the natural question to ask is whether or not this theory comes from a string theory construct i.e. can one find a massive spin-2 state in string theory whose low energy limit coupled to massless case gives the Bimetric gravity? In the following, we will discuss our attempt to find such a state and the subtleties involving the construction of effective action.