Possible dynamical origin of fermion mass differences within SO(10) unifying symmetry

Abstract

I explore the possibility that all fermions of a given generation have equal masses at momenta where unifying SO(10) symmetry is manifest. Subsequent breakdown through intermediate SU(5) and SU(3)×SU(2)×U(1) levels of symmetry is shown to provide a mechanism by which $c$ and $t$ running masses grow heavier than $s$ and $b$ running masses, respectively. The hierarchy also preserves mass relations between $b$, $s$, $\tau$, and $\mu$ obtained from the SU(5) model. Compatibility with present estimates of ${{sin}^2\theta }_W$ and $m_c$ is shown to constrain neutrino masses to be 100-500 times lighter than those of corresponding charged leptons.