Updated Bounds on Milli-Charged Particles

Abstract

We update the bounds on fermions with electric charge $ϵe$ and mass $m_{ϵ}$. For $m_{ϵ}\text{lsim}{m}_e$ we find $10^{-15}\text{lsim}ϵ<1$ is excluded by laboratory experiments, astrophysics and cosmology. For larger masses, the limits are less restrictive and depend on $m_{ϵ}$. For milli-charged neutrinos, the limits are stronger, especially if the different flavors mix as suggested by current experimental evidence.

Comments: 15 pages, 1 figure, minor changes, matches version to be published in JHEP