R. Altmeyer

Hadronic coupling constants in lattice QCD

We calculate the hadronic coupling constantsgNNπ andgϱππ in QCD, including dynamical quarks in the framework of staggered fermions in the lattice approach. For the nucleon-pion coupling we obtaingNNπ=13.8±5.8, to be compared with the experimental value 13.13±0.07 [1]. The ϱππ coupling has been analysed for two different sets of operators with the averaged resultgϱππ=4.2±1.9 which is to be compared with the experimental value 6.06±0.01 [2].

The πN sigma term — an evaluation using staggered fermions☆☆☆

Abstract A lattice calculation of the πN sigma term iis described using dynamical staggered fermions. Preliminary results give a sea term comparable in magnitude to the valence term.A lattice calculation of the πN sigma term iis described using dynamical staggered fermions. Preliminary results give a sea term comparable in magnitude to the valence term.

Renormalisation of lattice currents and the calculation of decay constants for dynamical staggered fermions

A numerical calculation of the lattice staggered renormalisation constants at beta = 5.35, m = 0.01 is presented. It is seen that there are considerable non-perturbative effects present. As an application the vector decay constant f(rho) is estimated.

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.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.

The spin content of the nucleon

Abstract 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 ± 0.02.