Divergences and Orientation in Spinfoams

TL;DR

This paper investigates how summing over orientations in spinfoam models causes divergences and shows that restricting to a single orientation removes these divergences in a simplified setting.

Contribution

It demonstrates that large divergences in spinfoam models are linked to summing over orientations and that restricting to one orientation can eliminate these divergences.

Findings

Divergences in spinfoam models are connected to orientation sums.

Restricting to a single orientation removes the spike divergence.

Simplified analysis confirms the role of orientation in divergences.

Abstract

We suggest that large radiative corrections appearing in the spinfoam framework might be tied to the implicit sum over orientations. Specifically, we show that in a suitably simplified context the characteristic "spike" divergence of the Ponzano-Regge model disappears when restricting the theory to just one of the two orientations appearing in the asymptotic limit of the vertex amplitude.