Speaker
Claudio Dappiaggi
Description
In the framework of the algebraic
approach to quantum field theory, the existence of
Hadamard states
allows for a thorough discussion of the regularization
and
renormalization freedoms of all observables. As a by-
product, we can
analyse rigorously the semiclassical Einstein?s equations
showing that
the renormalisation of the stress-energy tensor plays a
crucial
role. Furthermore, if we consider free scalar matter as
well as
homogeneous and isotropic solutions of the
semiclassical Einstein?s
equations, the system displays a de Sitter type
behaviour even without
a cosmological constant introduced a priori. We will show
that,
contrary to what often advocated, these solutions turn
out to be
stable and a comparison with experimental data is
possible.
