Light quark contributions to Higgs decays

The literature establishes that the light fermions contributions to the decays $H\to Zγ$ and $H\toγγ$ are negligible since their coupling with the Higgs is proportional to $m_f$. In the present letter, we show that although such a conclusion is true for leptons, the light quark contributions are zero when we consider their non-perturbative effects.