# Alternative flow equation for the functional renormalization group

## TL;DR

This paper introduces a new flow equation for the functional renormalization group derived via the 2PI effective action, offering an alternative to the standard Wetterich equation, with potential implications for theoretical physics.

## Contribution

It presents a novel flow equation based on the 2PI effective action and external sources, differing from the traditional approach.

## Key findings

- Derivation of an alternative flow equation using 2PI effective action.
- Establishment of a consistent link between two-point sources and the RG regulator.
- Demonstration of differences from the standard Wetterich-based flow equation.

## Abstract

We derive an alternative to the Wetterich-Morris-Ellwanger equation by means of the two-particle irreducible (2PI) effective action, exploiting the method of external sources due to Garbrecht and Millington. The latter allows the two-point source of the 2PI effective action to be associated consistently with the regulator of the renormalization group flow. We show that this procedure leads to a flow equation that differs from that obtained in the standard approach based on the average one-particle irreducible effective action.