Positive-parity excited states of the nucleon in quenched lattice QCD

Journal Article · Mon Nov 01 00:00:00 EDT 2010 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.82.094504· OSTI ID:21503812

Mahbub, M S ^[1]; Cais, Alan O ^[2]; Kamleh, Waseem; Leinweber, Derek B; Williams, Anthony G ^[2]

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1. Special Research Centre for the Subatomic Structure of Matter, Adelaide, South Australia 5005, Australia, and Department of Physics, University of Adelaide, South Australia 5005 (Australia)
2. Special Research Centre for the Subatomic Structure of Matter, Adelaide, South Australia 5005 (Australia) and Department of Physics, University of Adelaide, South Australia 5005 (Australia)

Positive-parity spin-(1/2) excitations of the nucleon are explored in lattice QCD. The variational method is used in this investigation and several correlation matrices are employed. As our focus is on the utility and methodology of the variational approach, we work in the quenched approximation to QCD. Various sweeps of Gaussian fermion-field smearing are applied at the source and at the sink of {chi}{sub 1{chi}1} and {chi}{sub 1{chi}2} correlation functions to obtain a large basis of operators. Using several different approaches for constructing basis interpolators, we demonstrate how improving the basis can split what otherwise might be interpreted as a single state into multiple eigenstates. Consistency of the extracted excited energy states are explored over various dimensions of the correlation matrices. The use of large correlation matrices is emphasized for the reliable extraction of the excited eigenstates of QCD.

• OSTI ID: 21503812
• Journal Information: Physical Review. D, Particles Fields, Vol. 82, Issue 9; Other Information: DOI: 10.1103/PhysRevD.82.094504; (c) 2010 American Institute of Physics; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
APPROXIMATIONS
CORRELATION FUNCTIONS
EIGENSTATES
EXCITATION
EXCITED STATES
EXTRACTION
LATTICE FIELD THEORY
NUCLEONS
PARITY
QUANTUM CHROMODYNAMICS
SPIN
ANGULAR MOMENTUM
BARYONS
CALCULATION METHODS
CONSTRUCTIVE FIELD THEORY
ELEMENTARY PARTICLES
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
FERMIONS
FIELD THEORIES
FUNCTIONS
HADRONS
PARTICLE PROPERTIES
QUANTUM FIELD THEORY
SEPARATION PROCESSES