"Asymptotic safety of gravity coupled to matter"
Relatore: Dott. Roberto Percacci- SISSA Trieste
10 Giugno 2003 ore 16.30
|Nonperturbative treatments of the UV limit of pure gravity
suggest that it admits a stable fixed point with positive
Newton's constant and cosmological constant.
This result is stable under the addition of
a scalar field with a generic potential
and nonminimal couplings to the scalar curvature.
There is a fixed point where the mass
and all nonminimal scalar interactions vanish while
the gravitational couplings have values which are almost
identical to the pure gravity case.
We discuss the linearized flow around this fixed point
and find that the critical surface is four--dimensional.
In the presence of other, arbitrary, massless minimally
coupled matter fields, the existence of the fixed point,
the sign of the cosmological constant and the dimension of the
critical surface depend on the type and number of fields.
In particular, for some matter content,
there exist polynomial asymptotically
free scalar potentials, suggesting a gravitational
solution to the well-known problem of triviality.