1212.5055 (C. B. Lang et al.)

Scattering in the pion-nucleon negative parity channel in lattice QCD    [PDF]

C. B. Lang, V. Verduci

We study the coupled nucleon-pion system (negative parity, isospin 1/2) based on a lattice QCD simulation for n_f=2 mass degenerate light quarks. Both, standard 3-quarks baryon operators as well as meson-baryon (4+1)-quark operators are included. Using the distillation method and variational analysis we determine energy levels of the lowest eigenstates. Comparison with the results of simple 3-quark correlation studies exhibits drastic differences: there appears a new level and the old ones move to different positions. A clearer picture of the negative parity nucleon spectrum emerges. For the parameters of the simulation (pion mass of 266 MeV) we may assume elastic s-wave scattering and can derive values of the phase shift.

View original: http://arxiv.org/abs/1212.5055