Constraints on Light Hidden Sector Gauge Bosons from Supernova Cooling
  We derive new bounds on hidden sector gauge bosons which could produce new
energy loss mechanisms in supernovae, enlarging the excluded region in
mass-coupling space by a significant factor compared to earlier estimates. Both
considerations of trapping and possible decay of these particles need to be
incorporated when determining such bounds, as does scattering on both neutrons
and protons. For masses and couplings near the region which saturates current
bounds, a significant background of such gauge bosons may also be produced due
to the cumulative effects of all supernovae over cosmic history.
