Group Theoretical Construction of Nucleon Operators using All-to-All Quark Propagators

摘要

We describe a method to construct irreducible baryon operators usingall-to-all quark propagators. It was demonstrated earlier that a large basis ofextended baryon operators on anisotropic, quenched lattices can be used toreliably extract the masses of 5 or more excited states in the nucleon channel.All-to-all quark propagators are expected to be needed when studying theseexcited states on light, dynamical configurations because contributions frommulti-particle states are expected to be significant. The dilution method isused to approximate the all-to-all quark propagators. Low-lying eigenmodes canalso be used if necessary. For efficient computation of matrix elements of theinterpolating operators, the algorithms should exploit the fact that manyextended baryon operators can be obtained from the different linearcombinations of three-quark colour-singlet operators. The sparseness of thediluted noise vectors also afford several computation simplifications. Somepreliminary results are presented for nucleon effective masses.