Vacuum phenomenology of the chiral partner of the nucleon in a linear sigma model with vector mesons

Jul, 2009
16 pages
Published in:
  • Phys.Rev.D 82 (2010) 014004
e-Print:

Citations per year

20092013201720212025051015
Abstract: (arXiv)
We investigate a linear sigma model with global chiral U(2)R×U(2)LU(2)_{R} \times U(2)_{L} symmetry. The mesonic degrees of freedom are the standard scalar and pseudoscalar mesons and the vector and axial-vector mesons. The baryonic degrees of freedom are the nucleon, NN, and its chiral partner, NN^{*}, which is usually identified with N(1535). The chiral partner is incorporated in the so-called mirror assignment, where the nucleon mass is not solely generated by the chiral condensate but also by a chirally invariant mass term, m0m_{0}. The presence of (axial-) vector fields modifies the expressions for the axial coupling constants of the nucleon, gANg_{A}^{N}, and its partner, gANg_{A}^{N^{*}}. Using experimental data for the decays NNπN^{*} \to N \pi and a1πγa_{1} \to\pi\gamma, as well as lattice results for gANg_{A}^{N^{*}} we infer m0500m_{0}\sim500 MeV, i.e., an appreciable amount of the nucleon mass originates from sources other than the chiral condensate. We test our model by evaluating the decay NNηN^{*} \to N \eta and the s-wave nucleon-pion scattering lengths a0(±)a_{0}^{(\pm)}.
Note:
  • 16 pages, 2 figures. To appear in Phys. Rev. D
  • 12.39.Fe
  • 13.75.Gx
  • 12.39.Mk
  • quantum chromodynamics
  • symmetry: chiral
  • symmetry: U(2) x U(2)
  • nucleon: mass
  • N(1535): hadronic decay
  • N(1535): width
  • coupling constant: axial