1206.7034 (G. S. Bali et al.)

Nucleon mass and sigma term from lattice QCD with two light fermion
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G. S. Bali, P. C. Bruns, S. Collins, M. Deka, B. Gläßle, M. Göckeler, L. Greil, T. R. Hemmert, R. Horsley, J. Najjar, Y. Nakamura, A. Nobile, D. Pleiter, P. E. L. Rakow, A. Schäfer, R. Schiel, G. Schierholz, A. Sternbeck, J. Zanotti

We analyze Nf=2 nucleon mass data with respect to their dependence on the pion mass down to mpi = 157 MeV and compare it with predictions from covariant baryon chiral perturbation theory (BChPT). A novel feature of our approach is that we fit the nucleon mass data simultaneously with the directly obtained pion-nucleon sigma-term. Our lattice data below mpi = 435 MeV is well described by O(p^4) BChPT and we find sigma=37(8)(6) MeV for the sigma-term at the physical point. Using the nucleon mass to set the scale we obtain a Sommer parameter of r_0=0.501(10)(11) fm.

View original: http://arxiv.org/abs/1206.7034