Strange and light quark contributions to the nucleon mass from lattice QCD

Bali, G.S.; Horsley, R.; Sternbeck, A.; Pleiter, D.; Zanotti, J.M.; Rakow, P.E.L.; Nobile, A.; Nakamura, Y.; Göckeler, M.; Collins, S.; Schierholz, G.; Schäfer, A.

doi:10.1103/PhysRevD.85.054502

Journal Article

PreJuSER-19009

Strange and light quark contributions to the nucleon mass from lattice QCD

Bali, G. S. ; Collins, S. ; Göckeler, M. ; Horsley, R. ; Nakamura, Y. ; Nobile, A. ; Pleiter, D.FZJ* ; Rakow, P. E. L. ; Schäfer, A. ; Schierholz, G. ; Sternbeck, A. ; Zanotti, J. M.

2012
Soc. [S.l.]

Physical review / D 85(5), 054502 (2012) [10.1103/PhysRevD.85.054502]

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Please use a persistent id in citations: http://hdl.handle.net/2128/11137 doi:10.1103/PhysRevD.85.054502

Abstract: We determine the strangeness and light quark fractions of the nucleon mass by computing the quark line connected and disconnected contributions to the matrix elements m(q)< N vertical bar(q) over barq vertical bar N > in lattice QCD, using the nonperturbatively improved Sheikholeslami-Wohlert Wilson fermionic action. We simulate n(F) = 2 mass degenerate sea quarks with a pion mass of about 285 MeV and a lattice spacing a approximate to 0.073 fm. The renormalization of the matrix elements involves mixing between contributions from different quark flavors. The pion-nucleon sigma term is extrapolated to physical quark masses exploiting the sea quark mass dependence of the nucleon mass. We obtain the renormalized values sigma(pi N) = (38 +/- 12) MeV at the physical point and f(Ts) = sigma(s)/m(N) = 0.012(14)(-3)(+10) for the strangeness contribution at our larger than physical sea quark mass.

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Note: We thank Peter Bruns and Ludwig Greil for discussion. This work was supported by the European Union under Grant No. 238353 (ITN STRONGnet) and by the Deutsche Forschungsgemeinschaft SFB/Transregio 55. Sara Collins acknowledges support from the Claussen-Simon-Foundation (Stifterverband fur die Deutsche Wissenschaft). Andre Sternbeck was supported by the EU International Reintegration Grant (IRG) No. 256594. James Zanotti was supported by the Australian Research Council under Grant No. FT100100005 and previously by the Science and Technology Facilities Council under Grant No. ST/F009658/1. Computations were performed on the SFB/TR55 QPACE supercomputers, the BlueGene/P (JuGene) and the Nehalem Cluster (JuRoPA) of the Julich Supercomputer Center, the IBM BlueGene/L at the EPCC (Edinburgh), the SGI Altix ICE machines at HLRN (Berlin/Hannover), and Regensburg's Athene HPC cluster. We thank the support staffs of these institutions. The Chroma software suite [38] was used extensively in this work and gauge configurations were generated using the BQCD code [39] on QPACE and BlueGenes.

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