Flavor Singlet Axial Coupling of the Proton An Updated Analysis.pdf

1 Flavor Singlet Axial Coupling of the Proton – An Updated Analysis ∗ J. Viehoffa for the SESAMa,b Collaboration aNIC c/o Forschungszentrum J¨ulich, D-52425 J¨ulich, and DESY, D-22603 Hamburg, Germany. bPhysics Department, University of Wuppertal, D-42097 Wuppertal, Germany. 9 We present a combined analysis of SESAM and T χL data for the flavor singlet axial coupling G1 of the proton, A 9 which is very helpful to stabilize the disconnected signals at small quark masses. From connected and disconnected 9 contributions we use the tadpole improved renormalization constant ZA and obtain G1 = 0.21(12). 1 A t c O 1. Introduction 2. Lattice techniques 1 The flavor singlet axial coupling of the proton On the lattice both connected and disconnected 1 is defined as diagrams for GA (see figure 1) can be calculated 1 from ratios of correlation functions [4]. v s G1 ¯ = P |uγ¯ γ u + dγ γ d + sγ¯ γ s|P , (1) 1 A 5 5 5 0 where s denotes the components of the proton qq 0 0 polarization vector. In the naive parton model jµ jµ