Tübingen 2003 – scientific programme

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HK: Physik der Hadronen und Kerne

HK 19: Theorie II

HK 19.9: Talk

Tuesday, March 18, 2003, 18:15–18:30, D

Chiral Magnetism of the Nucleon — •Thomas R. Hemmert¹ and Wolfram Weise^1,2 — ¹Theoretische Physik T39, Physik Department, TU München, Germany — ²ECT*, Villa Tambosi, Trento, Italy

We study [1] the quark mass expansion of the magnetic moments of the nucleon in a chiral effective field theory including nucleons, pions and delta resonances as explicit degrees of freedom. We point out that the usual powercounting applied so far to this problem misses important quark mass structures generated via an intermediate isovector M1 nucleon-delta transition. We propose a modified powercounting and compare the resulting chiral extrapolation function to available (quenched) lattice data. The extrapolation is found to work surprisingly well, given that the lattice data result from rather large quark masses. Our calculation raises the hope that extrapolations of lattice data utilizing chiral effective field theory might be applicable over a wider range in quark masses than previously thought, and we discuss recent extensions of this scheme to lattice studies of nucleon formfactors [2].

Work supported in part by DFG and BMBF.

• [1] T. R. Hemmert, W. Weise, [hep-lat/0204005], EPJA(2002) in press.
• [2] QCDSF collabortion, in preparartion.