  We investigate the signatures in the squeezed limit of the primordial scalar
bispectrum due to modifications of the standard theory at high energy. In
particular, we consider the cases of modified dispersion relations and/or
modified initial quantum state (both in the Boundary Effective Field Theory and
in the New Physics Hyper-Surface formulations). Using the in-in formalism we
study in details the squeezed limit of the contributions to the bispectrum from
all possible cubic couplings in the effective theory of single-field inflation.
We find general features such as enhancements and/or non-local shape of the
non-Gaussianities, which are relevant, for example, for measurements of the
halo bias and which distinguish these scenarios from the standard one (with
Bunch-Davies vacuum as initial state and standard kinetic terms). We find that
the signatures change according to the magnitude of the scale of new physics,
and therefore several pieces of information regarding high energy physics could
be obtained in case of detection of these signals, especially bounds on the
scales of new physics.
