Gauge theory with calculable neutron-proton-quark mass difference

Abstract

A gauge theory of weak and electromagnetic interactions is presented, in which the neutron-proton-quark mass difference is finite and calculable. The model is a generalization to include strange particles of an $\mathrm{SU}{(2)}_{L}\ifmmode\times\else\texttimes\fi{}\mathrm{SU}{(2)}_{R}\ifmmode\times\else\texttimes\fi{}\mathrm{U}(1)$ model suggested by Weinberg; neutral strangeness-changing processes are suppressed using the Glashow-Iliopoulos-Maiani mechanism, which introduces a fourth "charmed" quark ${\mathcal{P}}^{\ensuremath{'}}$, in addition to the usual $\mathcal{P}$, $\mathfrak{N}$, $\ensuremath{\lambda}$. Universality of semileptonic and leptonic weak interactions can easily, though not naturally, be achieved, and the model has the interesting prediction that the effective hadronic neutral current is purely vector. By imposing an additional discrete symmetry, a solution is obtained in which weak universality is natural, and the neutron-quark and proton-quark masses vanish in zero order.