On the spinfoam expansion in cosmology

TL;DR

This paper explores a technique to generate spinfoam sums from Hamiltonian theories, aiming to find the generalized projector for constraints in quantum cosmology without deparametrization, and applies it to dipole cosmology.

Contribution

It demonstrates how to use a recent method to construct spinfoam expansions directly from Hamiltonian constraints in cosmological models.

Findings

The technique can produce spinfoam expansions for simple models.

Infinities in the calculations can be managed effectively.

The approach is applied successfully to dipole cosmology.

Abstract

We consider the technique introduced in a recent work by Ashtekar, Campiglia and Henderson, which generate a spinfoam-like sum from a Hamiltonian theory. We study the possibility of using it for finding the generalized projector of a constraint on physical states, without first deparametrising the system. We illustrate this technique in the context of a very simple example. We discuss the infinities that appear in the calculation, and argue that they can be appropriately controlled. We apply these ideas to write a spinfoam expansion for the "dipole cosmology".