Speaker
Description
We consider a massive vector field as a model for early Universe
dark matter. Assuming that the massive vector field interacts with
the Standard Model matter very weakly and is produced
non-thermally, we study the evolution of this field in early
Universe during the radiation dominated epoch. We show that this
field may be naturally created with the equation of state of
radiation (w=1/3), but at some time a transition happens and the
field behaves as cold dark matter (w=0). If a small fraction of
dark matter is described by such massive vector fields, the
expansion rate of the Universe is slightly enhanced at early time
and, thus, the value of the sound horizon of baryon acoustic
oscillations (standard ruler) is reduced. As a result, in this
model the value of the Hubble constant appears to be larger than
that in the standard LambdaCDM model. We show that for certain
values of the parameters of mass and density of the massive vector
field the Hubble tension problem may be naturally revolved.
