Low-energy sum rules and large- Nc consistency conditions

Abstract

The large- N c consistency conditions for axial-vector and isovector magnetic couplings of pions to baryons are discussed from the point of view of low-energy current-algebra sum rules (Adler-Weisberger, Cabibbo-Radicati). In particular, we show how the result that ratios of axial-vector and isovector magnetic coupling constants get corrections only at the order 1/ N c 2 follows from the N c-counting of appropriate cross sections. This counting is performed using various approaches at the quark and hadronic level. Other implications of our method are also presented.