Quark and lepton flavor model with leptoquarks in a modular $$A_4$$ A 4 symmetry

Abstract We propose a quark-lepton model via leptoquarks and modular $$A_4$$ A 4 symmetry. Since the neutrino mass is induced at one-loop level mediated by down quarks as well as leptoquarks, we have to explain lepton and quark masses and mixings with a single modulus $$\tau $$ τ . Here, we find predictions for lepton and quark sectors with unified modulus $$\tau $$ τ , and show several constraints originating from leptoquarks.