We present a five-dimensional (5D) axion-neutrino model that explains the Standard Model fermion mass hierarchy and flavor structure, while simultaneously generating a high-quality axion. The axion and right-handed neutrinos transform under a 5D Peccei-Quinn gauge symmetry, and have highly suppressed profiles on the UV brane where the symmetry is explicitly broken. This setup allows neutrinos to be either Dirac or Majorana with hierarchically small sterile neutrino masses. The axion decay constant originates from the IR scale, which in the holographically dual four-dimensional description corresponds to the confinement scale of some new strong dynamics with a high-quality global Peccei-Quinn symmetry that produces a composite axion and light, composite sterile neutrinos. The sterile neutrinos could be observed in astrophysical or laboratory experiments, and the model predicts specific axion-neutrino couplings.
Bibliographical noteFunding Information:
The work of P. C. is supported by the Australian Government through the Australian Research Council. The work of T. G. and M. N. is supported in part by the Department of Energy under Grant No. DE-SC0011842 at the University of Minnesota, and T. G. is also supported by the Simons Foundation. T. G. acknowledges the Aspen Center for Physics which is supported by the National Science Foundation Grant No. PHY-1607611, where part of this work was done.
© 2022 authors. Published by the American Physical Society.