München 2006 – wissenschaftliches Programm
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HK: Physik der Hadronen und Kerne
HK 30: Theorie
HK 30.6: Vortrag
Mittwoch, 22. März 2006, 15:15–15:30, B
Improved QCD sum rule analysis for the nucleon — •Bernhard Langwallner, Norbert Kaiser, and Wolfram Weise — Inst. f. Theoretische Physik, TU Muenchen, 85747 Garching
We extend the QCD sum rule analysis for the nucleon to higher orders in the quark mass. This procedure allows us to determine the nucleon mass as a function of varying light quark mass mq (or equivalently, as a function of varying pion mass mπ2 ∼ mq). With one basic input parameter, the chiral condensate ⟨ 0|q q |0⟩, we are able to reproduce results of QCD lattice simulations over the large range 0 < mπ2 < 0.6 GeV2 together with the physical point MN,phys = 939 MeV. In our QCD sum rule analysis we employ the commonly used spin-1/2 interpolating 3-quark field as well as a spin-3/2 variant introduced by Leinweber. Such a combined analysis allows us to quantify the deviations from factorization (i.e. vacuum saturation) for the 4-quark condensates. We find that the corrections to factorization increase strongly with decreasing quark mass mq. Finally, we estimate the contributions to the 4-quark condensates arising from one- and two-pion intermediate states.
Work supported in part by BMBF.