Large

We perform an ab initio calculation of the $$N_c$$ scaling of the low-energy couplings of the chiral Lagrangian of low-energy strong interactions, extracted from the mass dependence of meson masses and decay constants. We compute these observables on the lattice with four degenerate fermions, $$N_f=4$$, and varying number of colours, $$N_c=3$$–6, at a lattice spacing of $$a\simeq 0.075$$ fm. We find good agreement with the expected $$N_c$$ scaling and measure the coefficients of the leading and subleading terms in the large $$N_c$$ expansion. From the subleading $$N_c$$ corrections, we can also infer the $$N_f$$ dependence, that we use to extract the value of the low-energy couplings for different values of $$N_f$$. We find agreement with previous determinations at $$N_c=3$$ and $$N_f=2, 3$$ and also, our results support a strong paramagnetic suppression of the chiral condensate in moving from $$N_f=2$$ to $$N_f=3$$