Chameleon vector bosons

Abstract

We show that for a force mediated by a vector particle coupled to a conserved $U(1)$ charge, the apparent range and strength can depend on the size and density of the source, and the proximity to other sources. This chameleon effect is due to screening from a light charged scalar. Such screening can weaken astrophysical constraints on new gauge bosons. As an example we consider the constraints on chameleonic gauged $B\ensuremath{-}L$. We show that although Casimir measurements greatly constrain any $B\ensuremath{-}L$ force much stronger than gravity with range longer than $0.1\text{ }\text{ }\ensuremath{\mu}\mathrm{m}$, there remains an experimental window for a long-range chameleonic $B\ensuremath{-}L$ force. Such a force could be much stronger than gravity, and long or infinite range in vacuum, but have an effective range near the surface of the earth which is less than a micron.