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arXiv · 1304.0483

The nucleon mass and pion-nucleon sigma term from a chiral analysis of lattice QCD world data

L. Alvarez-Ruso·T. Ledwig·J. Martin Camalich·M. J. Vicente-Vacas
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Abstract

The pion-mass dependence of the nucleon mass within the covariant SU(2) baryon chiral perturbation theory both without and with explicit Delta(1232) degrees of freedom up to order p^4 is investigated. By fitting to lattice QCD data in 2 and 2+1 flavors from several collaborations, for pion masses M_pi < 420 MeV, we obtain low energy constants of natural size and compatible with pion nucleon scattering data. Our results are consistent with the rather linear pion-mass dependence showed by lattice QCD. In the 2 flavor case we have also performed simultaneous fits to the nucleon mass and pion-nucleon sigma-term data. As a result of our analysis, which encompasses the study of finite volume corrections and discretization effects, we report a value for the pion-nucleon sigma-term of 41(5)(4) MeV in the 2 flavor case and 52(3)(8) MeV for 2+1 flavors, where the inclusion of the Delta(1232) resonance changes the results by around 9 MeV. In the 2 flavor case we are able to set independently the scale for lQCD data, given by a Sommer scale of r_0=0.493(23) fm.

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L. Alvarez-Ruso, T. Ledwig, J. Martin Camalich, M. J. Vicente-Vacas. 2013-10-17. The nucleon mass and pion-nucleon sigma term from a chiral analysis of lattice QCD world data. https://doi.org/10.1103/physrevd.88.054507

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