Ultralight dark matter searches with KAGRA gravitational wave telescope
  Among various dark matter candidates, bosonic ultralight fields with masses
below 1~eV are well motivated. Recently, a number of novel approaches have been
put forward to search for ultralight dark matter candidates using laser
interferometers at various scales. Those include our proposals to search for
axion-like particles (ALPs) and vector fields with laser interferometric
gravitational wave detectors. ALPs can be searched for by measuring the
oscillating polarization rotation of laser light. Massive vector fields weakly
coupled to the standard model sector can also be searched for by measuring the
oscillating forces acting on the suspended mirrors of the interferometers. In
this paper, the current status of the activities to search for such ultralight
dark matter candidates using a gravitational wave detector in Japan, KAGRA, is
reviewed. The analysis of data from KAGRA's observing run in 2020 to search for
vector dark matter, and the installation of polarization optics to the arm
cavity transmission ports of the interferometer to search for ALPs in future
observing runs are underway.
