Constraints on Fractionally Charged Particles from CDMSlite

While the Standard Model does not anticipate the existence of free particles with a fractional electric charge, fractionally charged particles (FCPs) have not been experimentally excluded. The Standard Model of particle physics does have quarks and antiquarks with $\pm\,2e$/3 and $\pm\,e$/3 charges, but their strong interaction binds them inside unit-charged hadrons. Free fractionally charged particles are a feature of viable extensions to the Standard Model with extra U(1) gauge symmetries. I report the results of an analysis of CDMSlite Run 2 Period 1 data resulting in the first direct detection limits on cosmogenic FCPs with an electric charge as small as $e/10^8$ and the most stringent limit on vertical intensity for FCPs with an electric charge $\leq$$e/160$. This analysis is also the first to consider cosmogenic FCPs with a wide range of masses (5 MeV/c$^2$ - 100 TeV/c$^2$) and velocities ($\beta\gamma$ = 0.1 - 10$^6$).