Tübingen 2003 – scientific programme
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HK: Physik der Hadronen und Kerne
HK 46: Theorie VII
HK 46.9: Talk
Thursday, March 20, 2003, 18:45–19:00, D
Quark mass dependence of nucleon axial-vector coupling constant — •Massimiliano Procura1,2, Thomas Hemmert1, and Wolfram Weise1,2 — 1Physik-Department, Theoretische Physik T39, TU München, Germany — 2ECT*, Trento, Italy.
We analyse the quark mass expansion of the axial-vector coupling constant gA of the nucleon [1]. Since lattice data for this quantity are only available for quark masses heavier than 20 times the physical light quark masses, elaborating extrapolation schemes is necessary to bridge the gap between these data and the physical properties of the nucleon [2]. We compare two different approaches: one which includes pion and nucleon degrees of freedom only and an alternative one which incorporates the Δ(1232), with the Δ-N mass difference treated as a small scale. We have found that, in order to obtain a proper chiral extrapolation function, able to approach the physical value of gA, the inclusion of the explicit Δ degree of freedom is crucial. Work supported in part by DFG and BMBF.
- [1] T.R. Hemmert, M. Procura and W. Weise, in preparation.
- [2] W. Detmold, W. Melnitchouk and A.W. Thomas, Phys.Rev. D66 (2002) 054501.