# Elastic Form Factors of Nucleon Excitations in Lattice QCD

## TL;DR

This paper demonstrates the use of lattice QCD and the PEVA technique to calculate electromagnetic form factors of nucleon excitations, revealing insights into their structure and the importance of advanced analysis methods.

## Contribution

It introduces the parity-expanded variational analysis (PEVA) technique for calculating form factors of baryon excitations in lattice QCD, highlighting its advantages over conventional methods.

## Key findings

- PEVA technique effectively isolates excited states in lattice QCD.
- Excitations at heavier quark masses resemble constituent quark model behavior.
- Form factors of the lowest-lying excitations are consistent with radial excitations.

## Abstract

First principles calculations of the form factors of baryon excitations are now becoming accessible through advances in Lattice QCD techniques. In this paper, we explore the utility of the parity-expanded variational analysis (PEVA) technique in calculating the Sachs electromagnetic form factors for excitations of the proton and neutron. We study the two lowest-lying odd-parity excitations and demonstrate that at heavier quark masses, these states are dominated by behaviour consistent with constituent quark models for the $N^*(1535)$ and $N^*(1650)$, respectively. We also study the lowest-lying localised even-parity excitation, and find that its form factors are consistent with a radial excitation of the ground state nucleon. A comparison of the results from the PEVA technique with those from a conventional variational analysis exposes the necessity of the PEVA approach in baryon excited-state studies.