QCD axion and neutrino physics induced by hidden flavor structure

Abstract

We study the reasonable requirements of two anomalous U(1)s in a flavored-axion framework for the anomaly cancellations of both U(1)-mixed gravity and U(1)Y×[U(1)]2 which in turn determine the U(1)Y charges where U(1)Y is the hypercharge gauge symmetry of the standard model. We argue that, with a flavor symmetry group, axion-induced topology in symmetry-broken phases plays crucial roles in describing how quarks and leptons are organized at a fundamental level and make deep connections with each other. A unified model, as an example, is then proposed in a simple way to describe a whole spectrum of particles where both flavored-axion interactions with normal matter and the masses and mixings of fermions emerge from the spontaneous breaking of a given symmetry group. Once a scale of active neutrino mass defined at a seesaw scale is fixed by the commensurate U(1) flavored-PQ charge of fermions, that of QCD axion decay constant FA is determined. In turn, fundamental physical parameters complementary to each other are predicted with the help of precision flavor experiments. Model predictions are extracted on the characteristics of neutrino and flavored-axion: FA=3.57−1.53+1.52×1010 GeV (consequently, QCD axion mass ma=1.52−0.46+1.14×10−4 eV, axion to photon coupling |gaγγ|=2.15−0.64+1.61×10−14GeV−1, axion to electron coupling gAee=3.29−0.98+2.47×10−14, etc.); atmospheric mixing angle θ23, Dirac CP phase δCP, and 0νββ-decay rate for normal mass ordering and inverted one by taking quantum corrections into account. © 2020 The Author(s)