# Structure of the Roper Resonance from Lattice QCD Constraints

## TL;DR

This paper compares two models of the Roper resonance using lattice QCD data, finding that the resonance is best described as a dynamically generated state from meson-baryon interactions rather than a bare baryon state.

## Contribution

It provides a lattice QCD constrained analysis distinguishing between a meson-baryon dynamically generated resonance and a bare baryon component for the Roper resonance.

## Key findings

- The meson-baryon scattering scenario agrees with lattice QCD results.
- The bare baryon scenario is inconsistent with lattice QCD data.
- The Roper resonance is best described as a dynamically generated state.

## Abstract

Two different descriptions of the existing pion-nucleon scattering data in the region of the Roper resonance are constructed. Both descriptions fit the experimental data very well. In one scenario the resonance is the result of strong rescattering between coupled meson-baryon channels, while in the other scenario, the resonance has a large bare-baryon (or quark-model like) component. The predictions of these two scenarios are compared with the latest lattice QCD simulation results in this channel. Consideration of the finite volume spectra, the manner in which the states are excited from the vacuum in lattice QCD and the composition of the states in Hamiltonian effective field theory enable a discrimination of these two different descriptions. We find the second scenario is not consistent with lattice QCD results whereas the first agrees with the lattice QCD constraints. In this scenario, the mass of the quark-model like state is approximately 2 GeV and in the finite volume of the lattice is dressed to place the first radial excitation of the nucleon at 1.9 GeV. Within this description, the infinite-volume Roper resonance is best described as a resonance generated dynamically through strongly coupled meson-baryon channels.