A lattice study of the strangeness content of the nucleon
Abstract
We determine the quark contributions to the nucleon spin Delta s, Delta u and Delta d as well as their contributions to the nucleon mass, the sigma-terms. This is done by computing both, the quark line connected and disconnected contributions to the respective matrix elements, 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 = 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 value sigma_{piN}=38(12) MeV at the physical point and the strangeness fraction f_{Ts}=sigma_s/m_N=0.012(14)(+10-3) at our larger than physical sea quark mass. For the strangeness contribution to the nucleon spin we obtain in the MSbar scheme at the renormalization scale of 2.71 GeV Delta s = -0.020(10)(2).
Keywords
Cite
@article{arxiv.1112.0024,
title = {A lattice study of the strangeness content of the nucleon},
author = {G. S. Bali and S. Collins and M. Gockeler and R. Horsley and Y. Nakamura and A. Nobile and D. Pleiter and P. E. L. Rakow and A. Sternbeck and A. Schafer and G. Schierholz and J. M. Zanotti},
journal= {arXiv preprint arXiv:1112.0024},
year = {2015}
}
Comments
7 pages, 3 figures, Invited Talk at the 33rd Erice School on Nuclear Physics, Erice, 16-24 September 2011, Italy