We investigate the possible influence of very-high-energy physics on
inflationary predictions focussing on whether effective field theories can
allow effects which are parametrically larger than order H^2/M^2, where M is
the scale of heavy physics and H is the Hubble scale at horizon exit. By
investigating supersymmetric hybrid inflation models, we show that decoupling
does not preclude heavy-physics having effects for the CMB with observable size
even if H^2/M^2 << O(1%), although their presence can only be inferred from
observations given some a priori assumptions about the inflationary mechanism.
Our analysis differs from the results of hep-th/0210233, in which other kinds
of heavy-physics effects were found which could alter inflationary predictions
for CMB fluctuations, inasmuch as the heavy-physics can be integrated out here
to produce an effective field theory description of low-energy physics. We
argue, as in hep-th/0210233, that the potential presence of heavy-physics
effects in the CMB does not alter the predictions of inflation for generic
models, but does make the search for deviations from standard predictions
worthwhile.Comment: 19 pages, LaTeX, no figures, uses JHEP
