Moments of isovector quark distributions in lattice QCD
Department of Physics, University of Washington, Box 351560, WA 98195, Seattle, USA
2 Special Research Centre for the Subatomic Structure of Matter, University of Adelaide, SA 5005, Adelaide, Australia
3 Jefferson Lab, 12000 Jefferson Avenue, VA 23606, Newport News, USA
* e-mail: email@example.com
We investigate the connection of lattice calculations of moments of isovector parton distributions to the physical regime through extrapolations in the quark mass. We consider the one-pion loop renormalisation of the nucleon matrix elements of the corresponding operators and thereby develop formulae with which to extrapolate the moments of the unpolarised, helicity and transversity distributions. These formulae are consistent with chiral perturbation theory in chiral limit and incorporate the correct heavy-quark limits. In the polarised cases, the inclusion of intermediate states involving the -isobar is found to be very important. The results of our extrapolations are in general agreement with the phenomenological values of these moments where they are known, and for the first time we make reliable predictions for the low moments of the isovector transversity distribution.
© Società Italiana di Fisica and Springer-Verlag, 2003