A combined analysis of PandaX, LUX, and XENON1T experiments within the
  framework of dark matter effective theory
  Weakly interacting massive particles are a widely well-probed dark matter
candidate by the dark matter direct detection experiments. Theoretically, there
are a large number of ultraviolet completed models that consist of a weakly
interacting massive particle dark matter. The variety of models makes the
comparison with the direct detection data complicated and often non-trivial. To
overcome this, in the non-relativistic limit, the effective theory was
developed in the literature which works very well to significantly reduce the
complexity of dark matter-nucleon interactions and to better study the nuclear
response functions. In the effective theory framework for a spin-1/2 dark
matter, we combine three independent likelihood functions from the latest
PandaX, LUX, and XENON1T data, and give a joint limit on each effective
coupling. The astrophysical uncertainties of the dark matter distribution are
also included in the likelihood. We further discuss the isospin violating cases
of the interactions. Finally, for both dimension-five and dimension-six
effective theories above the electroweak scale, we give updated limits of the
new physics mass scales.
