Confronting Inflation Models with the Coming Observations on Primordial
  Gravitational Waves
  The recent observations from CMB have imposed a very stringent upper-limit on
the tensor/scalar ratio $r$ of inflation models, $r < 0.064$, which indicates
that the primordial gravitational waves (PGW), even though possible to be
detected, should have a power spectrum of a tiny amplitude. However, current
experiments on PGW is ambitious to detect such a signal by improving the
accuracy to an even higher level. Whatever their results are, it will give us
much information about the early Universe, not only from the astrophysical side
but also from the theoretical side, such as model building for the early
Universe. In this paper, we are interested in analyzing what kind of inflation
models can be favored by future observations, starting with a kind of general
action offered by the effective field theory (EFT) approach. We show a general
form of $r$ that can be reduced to various models, and more importantly, we
show how the accuracy of future observations can put constraints on model
parameters by plotting the contours in their parameter spaces.
