Vector dark matter production from inflation with symmetry breaking
  We present a scenario of vector dark matter production from symmetry breaking
at the end of inflation. In this model, the accumulated energy density
associated with the quantum fluctuations of the dark photon accounts for the
present energy density of dark matter. The inflaton is a real scalar field
while a heavy complex scalar field, such as the waterfall of hybrid inflation,
is charged under the dark gauge field. After the heavy field becomes tachyonic
at the end of inflation, rolling rapidly towards its global minimum, the dark
photon acquires mass via the Higgs mechanism. To prevent the decay of the
vector field energy density during inflation, we introduce couplings between
the inflaton and the gauge field such that the energy is pumped to the dark
sector. The setup can generate the observed dark matter abundance for a wide
range of the dark photon's mass and with the reheat temperature around
$10^{12}$ GeV. The model predicts the formation of cosmic strings at the end of
inflation with the tensions which are consistent with the CMB upper bounds.
