Schr\"odinger field theory in curved spacetime: In-In formalism and
  three-point function for inflationary background
  We review the Schr\"odinger picture of field theory in curved spacetime and
using this formalism, the power spectrum of massive non-interacting, minimally
coupled scalars in a fixed de Sitter background is obtained. To calculate the
N-point function in Schr\"odinger field theory, the "in-in" formalism is
extended in the Friedmann-Lema\^itre-Robertson-Walker (FLRW) universe. We
compute the three-point function for primordial scalar field fluctuation in the
single field inflation by this in-in formalism. The results are the same as the
three-point function in the Heisenberg picture.
