Searching anomalous polarization modes of stochastic gravitational wave
  background with LISA and Taiji
  The vector and scalar polarization modes of gravitational waves do not exist
in General Relativity, and their detection would have significant impacts on
fundamental physics. In this paper, we explored the detectability of these
anomalous polarization modes in a gravitational wave background around 1 mHz
with the future LISA-Taiji network. The inherent geometrical symmetry of the
network largely simplifies the correlation analysis. By taking a suitable
linear combination of the correlated outputs, the contribution of the standard
tensor modes can be canceled algebraically, and the anomalous modes can be
exclusively examined. We provide concise expressions for the signal-to-noise
ratios of the anomalous modes with this cancellation method. We also discuss
the possibility of separately estimating the amplitudes of the vector and
scalar modes, using the overall frequency dependence of the associated overlap
reduction functions.
