Tests of large-Nc QCD from hadronic tau decay
  We use the Aleph data on vector and axial-vector spectral functions to test simple duality properties of QCD in the large Nc limit, which emerge in the approximation of a minimal hadronic ansatz of a spectrum of narrow states. These duality properties relate the short- and long-distance behaviours of specific correlation functions, which are order parameters of spontaneous chiral symmetry breaking, in a way that we find well supported by the data. 
S. Peris (UAB), B. Phily (CPT) and E. de Rafael (CPT)