Excited State Nucleon Spectrum with Two Flavors of Dynamical Fermions

TL;DR

This study computes highly excited isospin 1/2 baryon states using lattice QCD with two dynamical quark flavors, revealing the first lattice evidence for a spin 5/2^- state consistent with physical spectra.

Contribution

First lattice QCD calculation of highly excited isospin 1/2 baryon states with two dynamical flavors, including the first realization of spin 5/2 on the lattice.

Findings

Evidence for a 5/2^- state in negative-parity excited states.

Lowest energies reported for six irreducible representations at two pion masses.

Results agree with physical state patterns and demonstrate spin 5/2 realization.

Abstract

Highly excited states for isospin 1/2 baryons are calculated for the first time using lattice QCD with two flavors of dynamical quarks. Anisotropic lattices are used with two pion masses: 416(36) MeV and 578(29) MeV. The lowest four energies are reported in each of the six irreducible representations of the octahedral group at each pion mass. The lattices used have dimensions 24^3x64, spatial lattice spacing a_s = 0.11 fm and temporal lattice spacing a_t = 1/3 a_s. Clear evidence is found for a 5/2^-state in the pattern of negative-parity excited states. This agrees with the pattern of physical states and spin 5/2 has been realized for the first time on the lattice.