The spatial gauge-dependence of single-field inflationary bispectra
  In single-field inflationary models the bispectra are usually given in the
$\zeta$-gauge, because its temporal part leads to the super-horizon
conservation of fluctuations. However, this property is independent of the
choice of {\it spatial} gauge, so in this letter we explore this freedom. We
compute the variation of the bispectra under the most general spatial gauge
transformation that is globally defined and privileges no point, direction or
scale. In the squeezed configuration we then obtain a generalization of the
classic $\zeta$-gauge consistency relations, which we also derive through the
`large diffeomorphism' approach for all four bispectra. At leading order in the
long wave-number the transformation only affects the case where the long mode
is a scalar. The first effect is a shift of the tilt factor, so that one can
significantly reduce the amplitude of that contribution. Secondly, there is now
an extra term depending on the triangle shape, the same as in solid inflation,
which is due to the fact that the 3-metric has a scalar anisotropy in generic
spatial gauge. At next-to-leading order there is no variation, so the conformal
consistency relations of the $\zeta$-gauge are preserved.
