Excited State Nucleon Spectrum with Two Flavors of Dynamical Fermions

Journal Article · Thu Jan 01 00:00:00 EST 2009 · Physical Review D

DOI:https://doi.org/10.1103/PhysRevD.79.034505· OSTI ID:956266

Bulava, John; Edwards, Robert; Engelson, Eric; Foley, Justin; Joo, Balint; Lichtl, Adam; Lin, Huey-Wen; Mathur, Nilmani; Morningstar, Colin; Richards, David; Wallace, Stephen

Excited states for isospin $$\frac{1}{2}$$ baryons are calculated using lattice QCD with two flavors of dynamical quarks. Anisotropic lattices are used with two pion masses, $$m_{\pi} = 416(36)$$~MeV and $578(29)$~MeV. A large number of baryon operators is developed. They are pruned to sets of 16 and a variational analysis is carried out for $$16\times 16$$ matrices of correlation functions. 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 $$24^3\times 64$$, spatial lattice spacing $$a_s \approx 0.11$$~fm and temporal lattice spacing $$a_t = \frac{1}{3} a_s$$. Clear evidence is found for a $$\frac{5}{2}^-$$ state in the pattern of negative-parity excited states. This agrees with the pattern of physical states and spin $$\frac{5}{2}$$ has been realized for the first time on the lattice.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Oak Ridge Leadership Computing Facility (OLCF); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: AC05-060R23177
• OSTI ID: 956266
• Report Number(s): JLAB-THY-08-929; arXiv:0901.0027; DOE/OR/23177-0573
• Journal Information: Physical Review D, Journal Name: Physical Review D
• Country of Publication: United States
• Language: English