# Continuum Behaviour of Lattice QED, Discretized with One-Sided Lattice Differences, in One-Loop Order

## TL;DR

This paper investigates a lattice QED formulation using one-sided differences, revealing that only the vacuum polarization tensor correctly approaches the continuum limit, and proposes averaging over difference choices to restore covariance.

## Contribution

It systematically analyzes one-loop corrections in lattice QED with one-sided differences and introduces a method to eliminate non-covariant artifacts by averaging over all difference choices.

## Key findings

- Only vacuum polarization tensor has the correct continuum limit.
- Fermion self energy and vertex function have non-covariant contributions.
- Averaging over all difference choices restores covariance.

## Abstract

A lattice action for QED is considered, where the derivatives in the Dirac operator are replaced by one-sided lattice differences. A systematic expansion in the lattice spacing of the one-loop contribution to the fermion self energy, vacuum polarization tensor and vertex function is carried out for an arbitrary choice of one-sided lattice differences. It is shown that only the vacuum polarization tensor possesses the correct continuum limit, while the fermion self energy and vertex function receive non-covariant contributions. A lattice action, discretized with a fixed choice of one-sided lattice differences therefore does not define a renormalizable field theory. The non-covariant contributions can however be eliminated by averaging the expressions over all possible choices of one-sided lattice differences.