# Spectroscopy with Local Multi-hadron Interpolators in Lattice QCD

## TL;DR

This study investigates the positive-parity nucleon spectrum in lattice QCD using both standard and novel five-quark interpolators to identify potential new low-lying states related to the Roper resonance.

## Contribution

Introduction of local five-quark meson-baryon operators based on phenomenological channels to explore missing states in nucleon spectrum studies.

## Key findings

- No new energy levels found near the Roper resonance region.
- Standard three-quark operators did not reveal additional states.
- Five-quark operators did not produce novel states despite their different structure.

## Abstract

The positive-parity nucleon spectrum is studied in 2 + 1 flavour lattice QCD in an attempt to discover novel low-lying energy eigenstates in the region of the Roper resonance. In this work, we employ standard three-quark interpolating fields and introduce new local five-quark meson-baryon operators that hold the possibility of revealing new states that have been missed in previous studies. Motivated by phenomenological arguments, five-quark interpolators based on the $\sigma{N}$, $\pi{N}$ and $a_0{N}$ channels are constructed. Despite the introduction of qualitatively different operators, no novel energy levels are extracted near the regime of the Roper resonance.