2006/12/11 by H. Leutwyler · 2 citations
Physics and Astronomy · #Lattice QCD #Particle physics #Particle physics theoretical and experimental studies #Physics #Physics of Superconductivity and Magnetism #Pion #Quantum Chromodynamics and Particle Interactions #Quantum chromodynamics #Quantum electrodynamics #Quantum field theory #Quantum mechanics #Quark #Scattering #Scattering amplitude #Theoretical physics #hep-ph
paper · pdf · doi:10.1142/9789812790804_0002
Contribution to the proceedings of the workshop "Chiral Dynamics, Theory & Experiment", Durham/Chapel Hill, NC, USA, September 2006
arxiv created 2006/12/11 · openalex publication_date 2007/10/01 · openalex created_date 2016/06/24 · arxiv updated 2017/08/23 · openalex updated_date 2026/08/05
Recent work in low energy pion physics is reviewed. One of the exciting new developments in this field is that simulations of QCD on a lattice now start providing information about the low energy structure of the continuum theory, for physical values of the quark masses. Although the various sources of systematic error yet need to be explored more thoroughly, the results obtained for the correlation function of the axial current with the quantum numbers of the pion already have important implications for the effective Lagrangian of QCD. The consequences for ππ scattering are discussed in some detail. The second part of the report briefly reviews recent developments in the dispersion theory of the scattering amplitude. One of the important results here is that the position of the lowest resonances of QCD can now be determined in a model independent manner and rather precisely. Beyond any doubt, the partial wave with I=ℓ=0 contains a pole on the second sheet, not far from the threshold: the lowest resonance of QCD carries the quantum numbers of the vacuum.