  Field theory in de Sitter space admits a one-parameter family of vacua
determined by a superselection parameter alpha. Of these vacua, the Euclidean
vacuum uniquely extrapolates to the vacuum of flat Minkowski space. States
which resemble the alpha-vacua can be constructed as excitations above the
Euclidean vacuum. Such states have modes alpha(k) which decay faster that
k^{(1-d)/2}. Fields in such states exhibit non-local correlations when examined
from the perspective of fields in the Euclidean vacuum. The dynamics of such
entangled states are fully consistent. If an alpha-state with properties that
interpolate between an alpha-vacuum and the Euclidean vacuum were the initial
condition for inflation, a signature for this may be found in a momentum
dependent correction to the inflationary power spectrum. The functional
formalism, which provides the tool for examining physics in an alpha-state,
extends to fields of other spin. In particular, the extension to spin-2 may
proffer a new class of infrared modifications to gravitational interactions.
The implications of superselection sectors for the landscape of string vacua
are briefly discussed.
