Improved chiral properties of FLIC fermions

The chiral properties of the fat-link irrelevant clover (FLIC) fermion action are examined. The improved chiral properties of fermion actions incorporating smoothed links are realized in the FLIC action where only the irrelevant operators of the fermion action are constructed with smoothed links. In particular, the histogram of the additive mass renormalization encountered in chiral-symmetry breaking Wilson-type fermion actions is seen to narrow upon introducing fat-links in the irrelevant operators. The exceptional configuration problem of quenched QCD is reduced, enabling access to the light quark mass regime of m_#pi#/m_#rho# #propor to# 0.35. In particular, quenched chiral non-analytic behavior is revealed in the light quark mass dependence of the #DELTA#-baryon mass. FLIC fermions offer a promising approach to revealing the properties of full QCD at light quark masses. (orig.)Available from TIB Hannover: RA 8919(2004-074) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Electromagnetic form factors wih FLIC fermions

The Fat-Link Irrelevant Clover (FLIC) fermion action provides a new form of nonperturbative #sigma#(a) improvement and allows efficient access to the light quark-mass regime. FLIC fermions enable the construction of the nonperturbatively #sigma#(a)-improved conserved vector current without the difficulties associated with the fine tuning of the improvement coefficients. The simulations are performed with an #sigma#(a"2) mean-field improved plaquette-plus-rectangle gluon action on a 20"3 x 40 lattice with a lattice spacing of 0.128 fm, enabling the first simulation of baryon form factors at light quark masses on a large volume lattice. Magnetic moments, electric charge radii and magnetic radii are extracted from these form factors, and show interesting chiral nonanalytic behavior in the light quark mass regime. (orig.)Available from TIB Hannover: RA 2999(03-210) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Hybrid meson spectrum from the FLIC action

The spectral properties of hybrid meson interpolating fields are investigated. The quantum numbers of the meson are carried by smeared-source fermion operators and highly-improved chromo-electric and -magnetic field operators composed with APE-smeared links. The effective masses of standard and hybrid operators indicate that the ground state meson is effectively isolated using both standard and hybrid interpolating fields. Focus is placed on interpolating fields in which the large spinor components of the quark and antiquark fields are merged. In particular, the effective mass of the exotic 1"-"+ meson is reported. Further, we report some values for excited mesonic states using a variational process. (orig.)Available from TIB Hannover: RA 2999(03-207) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

The strangeness magnetic moment of the nucleon from FLIC fermions

By imposing the constraints of charge symmetry we show that the strangeness magnetic moment of the nucleon can be expressed in terms of empirical magnetic moments and ratios of valence quark magnetic moments. The latter are determined using modern chiral extrapolation techniques and recent low mass lattice QCD simulations of the individual quark contributions to the magnetic moments of the nucleon octet. The result is a precise determination of G_M"s, namely -0.043 #+-# 0.013 #mu#N, which is consistent with the latest experimental measurements. (orig.)SIGLEAvailable from TIB Hannover: RA 2999(03-211) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Systematic uncertainties in the precise determination of the strangeness magnetic moment of the nucleon

Systematic uncertainties in the recent precise determination of the strangeness magnetic moment of the nucleon are identified and quantified. In summary, G_M"s=-0.046 #+-# 0.019 #mu#_N. (orig.)SIGLEAvailable from TIB Hannover: RA 2999(05-014) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Scaling of FLIC fermions

Hadron masses are calculated in quenched lattice QCD on a variety of lattices in order to probe the scaling behavior of the Fat-Link Irrelevant Clover (FLIC) fermion action, a fat-link clover fermion action in which the purely irrelevant operators of the fermion action are constructed using APE-smeared links. The scaling analysis indicates FLIC fermions provide a new form of nonperturbative O(a) improvement where near-continuum results are obtained at finite lattice spacing. (orig.)SIGLEAvailable from TIB Hannover: RA 2999(04-073) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Electromagnetic form factors with FLIC fermions

The fat-link irrelevant clover (FLIC) fermion action provides a new form of nonperturbative O(a) improvement and allows efficient access to the light quark-mass regime. FLIC fermions enable the construction of the nonperturbatively O(a)-improved conserved vector current without the difficulties associated with the fine tuning of the improvement coefficients. The simulations are performed with an O(a"2) mean-field improved plaquette-plus-rectangle gluon action on a 20"3 x 40 lattice with a lattice spacing of 0.128 fm, enabling the first simulation of baryon form factors at light quark masses on a large volume lattice. Magnetic moments, electric charge radii and magnetic radii are extracted from these form factors, and show interesting chiral nonanalytic behavior in the light quark mass regime. (orig.)SIGLEAvailable from TIB Hannover: RA 2999(03-157) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Hybrid mesons on the lattice with FLIC fermions

The spectral properties of hybrid meson interpolating fields are investigated. The quantum numbers of the meson are carried by smeared-source fermion operators and highly-improved chromo-electric and -magnetic field operators composed with APE-smeared links. The effective masses of standard and hybrid operators indicate that the ground state meson is effectively isolated using both standard and hybrid interpolating fields. Focus is placed on interpolating fields in which the large spinor components of the quark and antiquark fields are merged. In particular, the effective mass of the exotic 1"-"+ meson is reported. Further, we report some values for excited mesonic states using a variational process. (orig.)Available from TIB Hannover: RA 2999(03-208) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Precise determination of the strangeness magnetic moment of the nucleon

By combining the constraints of charge symmetry with new chiral extrapolation techniques and recent low mass lattice QCD simulations of the individual quark contributions to the magnetic moments of the nucleon octet, we obtain a precise determination of the strange magnetic moment of the proton. The result, namely G"s_M = -0.051 #+-# 0.021 #mu#_N, is consistent with the latest experimental measurements but an order of magnitude more precise. This poses a tremendous challenge for future experiments. (orig.)Available from TIB Hannover: RA 8919(04-075) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman