# 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.

## Key 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".