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Lattice QCD analysis of the strangeness magnetic moment of the nucleon

2000; American Physical Society; Volume: 62; Issue: 7 Linguagem: Inglês

10.1103/physrevd.62.074505

1538-4500

Derek B. Leinweber, A. W. Thomas,

High-pressure geophysics and materials

The outcome of the SAMPLE Experiment suggests that the strange-quark contribution to the nucleon magnetic moment, G_M^s(0), may be greater than zero. This result is very difficult to reconcile with expectations based on the successful baryon magnetic-moment phenomenology of the constituent quark model. We show that careful consideration of chiral symmetry reveals some rather unexpected properties of QCD. In particular, it is found that the valence u-quark contribution to the magnetic moment of the neutron can differ by more than 50% from its contribution to the Xi^0 magnetic moment. This hitherto unforeseen result leads to the value G_M^s(0) = -0.16 +/- 0.18 with a systematic error, arising from the relatively large strange quark mass used in existing lattice calculations, that would tend to shift G_M^s(0) towards small positive values.