Fat-link Clover Fermion Action Research Articles

Scaling of fat-link irrelevant-clover 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.

Spin-3/2 baryons in lattice QCD

We present first results for masses ofspin-3/2 baryons in lattice QCD, using a novel fat-link clover fermion action in which only the irrelevant operators are constructed using fat links. In theisospin-1/2 sector; we observe, after appropriate spin and parity projection, a strong signal for the J P =3/2 − state, and find good agreement between the½ + mass and earlier nucleon mass simulations with aspin-½ interpolating field. For theisospin-3/2 Δ states, clear mass splittings are observed between the various½ ±and3/2 ± channels, with the calculated level orderings in good agreement with those observed empirically.

Excited baryons from the FLIC fermion action

Masses of positive and negative parity excited nucleons and hyperons are calculated in quenched lattice QCD using anO( a 2) improved gluon action and a fat-link clover fermion action in which only the irrelevant operators are constructed with fat links. The results are in agreement with earlier N * simulations with improved actions, and exhibit a clear mass splitting between the nucleon and its parity partner, as well as a small mass splitting between the two low-lying J P =½ − N * states. Study of different A interpolating fields suggests a similar splitting between the lowest two½ −Λ * states, although the empirical mass suppression of theΛ * (1405) is not seen.

Light quark simulations with FLIC fermions

Hadron masses are calculated in quenched lattice QCD in order to probe the scaling behavior of a novel fat-link clover fermion action in which only the irrelevant operators of the fermion action are constructed using APEsmeared links. Light quark masses providing am π/m p mass ratio of 0.35 are considered to assess the exceptional configuration problem of clover-fermion actions. This Fat-Link Irrelevant Clover (FLIC) fermion action provides scaling which is superior to mean-field improvement and offers advantages over non-perturbative improvement including a reduced exceptional configuration problem.

Novel fat-link fermion actions

The hadron mass spectrum is calculated in lattice QCD using a novel fat-link clover fermion action in which only the irrelevant operators of the fermion action are constructed using smeared links. The simulations are performed on a 16 3 × 32 lattice with a lattice spacing of a = 0.125 fm. We compare actions with n = 4 and 12 smearing sweeps with a smearing fraction of 0.7. The n = 4 Fat-Link Irrelevant Clover (FLIC) action provides scaling which is superior to mean-field improvement, and offers advantages over nonperturbative O ( a) improvement.

Hadron masses from novel fat-link fermion actions

The hadron mass spectrum is calculated in lattice QCD using a novel fat-link clover fermion action in which only the irrelevant operators in the fermion action are constructed using smeared links. The simulations are performed on a 16{sup 3} x 32 lattice with a lattice spacing of a=0.125 fm. We compare actions with n=4 and 12 smearing sweeps with a smearing fraction of 0.7. The n=4 Fat-Link Irrelevant Clover (FLIC) action provides scaling which is superior to mean-field improvement, and offers advantages over nonperturbative 0(a) improvement, including a reduced exceptional configuration problem.