Bounds on the light quark masses O

The corrections to the current algebra mass formulae for the pseudoscalar mesons are analyzed by means of a simultaneous expansion in powers of the light quark masses and powers of 1Nc. The relative magnitude of the two expansion parameters is related to the mass ratio Mη2Mη′2, which represents a quantity of order Ncms. A set of mass formulae is derived, including an inequality, which leads to bounds for the ratios mumd and msmd.