1997/06/04 by Silas R. Beane, Beane, Silas R.
Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #High Energy Physics - Theory (hep-th) #hep-ph #hep-th
paper · pdf · doi:10.48550/arxiv.hep-ph/9706250
9 pages TeX, uses mtexsis.tex
arxiv created 1997/06/04 · arxiv updated 2009/11/30
We study a 2N-flavor effective theory of N-flavor QCD. With the axial anomaly accounted for in the effective theory by a 't Hooft interaction, only QCD conserved currents survive. However, there is a residual discrete symmetry with interesting properties. With non-vanishing quark masses, this S2 symmetry is broken unless θ=0 or pi. We further show that there is a sense in which hadrons in the effective theory fall into S2 multiplets. Surprisingly, predictions of this multiplet structure in the four-flavor effective theory are in good agreement with experiment and have been found previously by imposing Regge asymptotic constraints on pion-hadron scattering amplitudes.