Searcharxiv⌕ Search

arXiv subjects

R. Horsley

Publications and source records attributed to R. Horsley.

267 records · Page 15Linked to original sources
arXiv1995

Hadronic Coupling Constants in Lattice QCD

We calculate the hadronic coupling constants $g_{NNπ}$ and $g_{ρππ}$ in QCD, including dynamical quarks in the framework of staggered fermions in the lattice approach. For the nucleon--pion coupling we obtain $g_{NNπ} = 13.8 \pm 5.8$, to be compared with the experimental value $13.13 \pm 0.07$. The $ρππ$ coupling has been analysed for two different sets of operators with the averaged result $g_{ρππ} = 4.2 \pm 1.9$ which is to be compared with the experimental value $6.06 \pm 0.01$.

hep-lat↗
arXiv1995

Effective Yukawa Couplings in Noncompact Lattice QED

We investigate effective Yukawa couplings of mesons to the elementary fermions in noncompact lattice QED. The couplings are extracted from suitable fermion-antifermion-meson three-point functions calculated by Monte Carlo simulations with dynamical staggered fermions. The scaling behaviour is compatible with expectations from perturbation theory, thus indicating triviality of QED. The lines of constant Yukawa coupling are compared to flows of other quantities. Consistency is seen, at most, for weak coupling.

hep-lat↗
arXiv1994

Spectroscopy and Renormalisation Group Flow of a Lattice Nambu-Jona-Lasinio Model

We investigate a lattice Nambu--Jona-Lasinio model both by the Monte Carlo method and Schwinger-Dyson equations. A comparison allows the discussion of finite size effects and the extrapolation to infinite volume. We pay special attention to the identification of particles and resonances. This enables us to discuss renormalisation group flows in the neighbourhood of the critical coupling where the chiral symmetry breaking phase transition takes place. In no region of the bare parameter space do we find renormalisability for the model.

hep-lat↗
arXiv1994

Hadronic coupling constants in lattice QCD

We report on calculations of the hadronic coupling constants $g_{ρππ}$ and $g_{nnπ}$ based on lattice QCD with four flavors of dynamical staggered fermions. By computing 2--point and 3--point Green's functions we have been able to determine these coupling constants ab initio from QCD; the results are compatible with the experimental values.

hep-lat↗
arXiv1993

The present status of non-compact lattice QED

We give a 1993 update of non-compact lattice QED, in particular the chiral condensate, finite size effects and meson mass ratios. We compare descriptions of the phase transition. Our previous conclusions remain valid.

hep-lat↗
arXiv1993

Three-point functions in noncompact lattice QED

We calculate fermion-antifermion-"meson" three-point functions in noncompact lattice QED with dynamical staggered fermions and use them to extract effective Yukawa couplings. The results are consistent with the hypothesis that QED is trivial.

hep-lat↗
arXiv1993

The ``Spin'' Structure of the Nucleon - a lattice investigation

We will discuss here an indirect lattice evaluation of the baryon axial singlet current matrix element. This quantity may be related to the fraction of nucleon spin carried by the quarks. The appropriate structure function has recently been measured (EMC experiment). As in this experiment, we find that the quarks do not appear to carry a large component of the nucleon spin.

hep-lat↗
arXiv1992

The Spin Content of the Nucleon

The fraction of the nucleon spin that is carried by the quarks, $ΔΣ$, is computed in lattice QCD with dynamical staggered fermions. We obtain the value $ΔΣ= 0.18 \pm 0.02$.

hep-lat↗