Nucleon mass and pion-nucleon sigma term from a chiral analysis of lattice QCD world data
1 Instituto de Física Corpuscular (IFIC), Centro Mixto Universidad de Valencia-CSIC, Valencia, Spain
2 Departamento de Física Teórica and IFIC, Centro Mixto Universidad de Valencia-CSIC, Valencia, Spain
3 Department of Physics and Astronomy, University of Sussex, Brighton, UK
a e-mail: firstname.lastname@example.org
Published online: 9 June 2014
The chiral behavior of the nucleon mass is studied within the covariant SU(2) baryon chiral perturbation theory up to order p4. Lattice QCD data for the ensembles of 2 and 2 + 1 flavors are separately fitted, paying special attention to explicit Δ(1232) degrees of freedom, finite volume corrections and finite spacing effects. In the case of the 2 flavor ensemble, we fit simultaneously nucleon mass data together with new and updated data for the σπN term both in their dimensionless forms and determine a Sommer-scale of r0 = 0.493(23) fm. We obtain low-energy constants of natural size that are compatible with the rather linear pion-mass dependence observed in lattice QCD and report a preliminary updated value of σπN = 43(5)(4) MeV for the 2 flavor case and σπN = 52(3)(8) MeV for 2 + 1 flavor case.
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