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HK: Physik der Hadronen und Kerne

HK 46: Theorie VII

HK 46.9: Vortrag

Donnerstag, 20. März 2003, 18:45–19:00, D

Quark mass dependence of nucleon axial-vector coupling constant — •Massimiliano Procura^1,2, Thomas Hemmert¹, and Wolfram Weise^1,2 — ¹Physik-Department, Theoretische Physik T39, TU München, Germany — ²ECT*, Trento, Italy.

We analyse the quark mass expansion of the axial-vector coupling constant g_A 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 g_A, 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.