  We investigate the potential of observations of anisotropies in the cosmic
microwave background (CMB) and large-scale structure in the Universe to detect
possible modifications of standard inflationary models by physics beyond the
Planck scale. A generic model of primordial density fluctuations is
investigated, and we derive constraints on its parameters from current data. We
conclude that the currently available data do not put very stringent
constraints on this model. Furthermore, we use simulated power spectra from the
Sloan Digital Sky Survey (SDSS) and the Planck satellite to show that it is
unlikely that a trans-Planckian signature of this type can be detected in CMB
and large-scale structure data.

Astrophysics;High Energy Physics - Phenomenology;High Energy Physics - Theory