Nucleon excitation mass spectrum

J. Bulava et al., Phys. Rev. D 79, 034505 (2009)

• Solid boxes show the masses of the nucleon stationary states in a cubic box having periodic boundary conditions. Vertical extents indicate statistical uncertainties from the Monte Carlo computations. Hollow boxes show thresholds above which multi-hadron states are expected.
• N_f=2 flavors of light quarks on a 24³ by 64 lattice using an anisotropic clover fermion action, with spatial lattice spacing a_s~0.11 fm and anisotropy a_s/a_t~3.
• Left panel: light quark masses are such that the pion mass is 580 MeV.
• Right panel: light quark masses are such that pion mass is 420 MeV.