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- Aspects of non-perturbative unitarity in Quantum Field Theory

According to the Asymptotic Safety conjecture, a (non-perturbatively)

renormalizable quantum field theory of gravity could be constructed

based on the existence of a non-trivial fixed point of the

renormalization group flow.

The existence of this fixed point can be established, e.g., via the

non-perturbative methods of the functional renormalization group (FRG).

In practice, the use of the FRG methods requires to work within

truncations of the gravitational action, and higher-derivative operators

naturally lead to the presence of several poles in the propagator. The

question is whether these poles represent a real problem for the

unitarity of the theory.

Using QED as a working example, in this talk I will discuss some aspects

of non-perturbative unitarity in Quantum Field Theory. I will show that

the inclusion of quantum effects at all scales is of crucial importance

to assess unitarity of field theories. In particular, poles appearing in

truncations of the action could correspond to fake degrees of freedom of

the theory. Possible conditions to determine, within truncations,

whether a pole represents a fake or a genuine degree of freedom of the

theory will also be discussed.

Collection/Series:

Event Type:

Seminar

Scientific Area(s):

Speaker(s):

Event Date:

Mercredi, Décembre 4, 2019 - 15:30 to 17:00

Location:

Sky Room

Room #:

394

©2012 Institut Périmètre de Physique Théorique