The strange and light quark contributions to the nucleon mass from lattice QCD

Roger Horsley, Gunnar Bali, Sara Collins, Meinulf Gockeler, Yoshifumi Nakamura, Andrea Nobile, Dirk Pleiter, Paul Rakow, Andreas Schafer, Gerrit Schierholz, Andrea Sternbeck, James Zanotti

Research output: Contribution to journalArticlepeer-review

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|qbar q|N> in lattice QCD, using the non-perturbatively 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 approx 0.073 fm. The renormalization of the matrix elements involves mixing between contributions from different quark flavours. 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_{T_s}=\sigma_s/m_N= 0.012(14)^{+10}_{-3} for the strangeness contribution at our larger than physical sea quark mass.
Original languageEnglish
Article number054502
Number of pages10
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Volume85
Issue number5
DOIs
Publication statusPublished - 1 Mar 2012

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