Masses of Light Quarks in the 1/Nc Chiral Perturbation Theory

The mass formulas obtained for pseudoscalar $${{\\pi }^{ \\pm }},{{K}^{ \\pm }},{{K}^{0}}({{\\bar {K}}^{0}})$$ mesons in the NLO approximation of combined expansion in momenta, quark masses $${{m}_{{\\text{q}}}}$$ , and $$1{\\kern 1pt} /{\\kern 1pt} {{N}_{{\\text{c}}}}$$ allow us to conclude that the ratios $${{m}_{u}}{\\kern 1pt} /{\\kern 1pt} {{m}_{d}}$$ and $${{m}_{s}}{\\kern 1pt} /{\\kern 1pt} {{m}_{d}}$$ belong to a third-order algebraic curve. It is shown that the inclusion of higher-order corrections does not affect the shape of the curve. The data on the effective Lagrangian constants found from lattice calculations allow us to determine the quark masses.