# Quark-photon vertex from lattice QCD in Landau gauge

## TL;DR

This paper investigates the nonperturbative quark-photon vertex in Landau gauge using lattice QCD, comparing the form factors with continuum Bethe-Salpeter solutions to understand their similarities and differences.

## Contribution

It provides the first detailed lattice QCD extraction of all form factors of the quark-photon vertex in Landau gauge for two off-shell kinematics.

## Key findings

- Lattice results show both similarities and differences with continuum Bethe-Salpeter solutions.
- All longitudinal and transverse form factors are extracted from lattice data.
- The momentum dependence of form factors is systematically compared to continuum predictions.

## Abstract

We study the nonperturbative structure of the quark-photon vertex in Landau gauge. To this end, we utilize lattice QCD data for the vector current for two mass-degenerate quark flavours and extract all longitudinal and transverse form factors of the underlying vertex for two off-shell kinematics. The momentum dependence of the form factors is compared to the solution of the inhomogeneous Bethe-Salpeter equation for the vertex in the rainbow-ladder approximation. Differences but also similarities are seen between our lattice and the truncated continuum results.