[seminar] [DANAS] I.L. Shapiro, 13.7. (četvrtak) 11h (s.t.), seminar ZTF-a

[Anđelo Samsarov]

         SEMINAR  TEORIJSKE  FIZIKE


    (Zajednički seminari Fizičkog odsjeka PMF-a te Zavoda za teorijsku
     fiziku i Zavoda za eksperimentalnu fiziku IRB-a)

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    Do we have a chance for renormalizable and unitary quantum gravity?


     Ilya L. Shapiro
     Universidade Federal de Juiz de Fora,
     MG, Brazil


    Datum:  četvrtak, 13. srpnja 2017.
    Vrijeme: 11 sati s.t. (TOČNO)
    Mjesto: IRB, predavaona I krila


   Sažetak:

  The main difficulty of perturbative quantum gravity (QG) in D=4 is
the conflict between renormalizability and unitarity of the theory.
The simplest version of QG is based on General Relativity and is
non-renormalizable. One can construct renormalizable and even
superrenormalizable versions of QG by introducing higher derivatives,
but then we meet the unphysical higher-derivative massive ghosts. The
non-polynomial models of QG have no ghosts at the tree level, but
taking loop corrections into account one meets infinite amount of
ghost-like complex states. The same is true for the string-induced
gravitational action, which requires an infinite amount of fine-tuning
to remain free of ghosts. We descrive the recent proposal of the
polynomial superrenormalizable versions of QG with complex poles.
These models have an attractive feature to be unitary within the
Lee-Wick approach, at both tree and perturbative quantum levels.
Furthermore, these theories have unambiguous and exactly calculable
beta-functions and even can be made finite. One of the interesting
open question is whether these theories can be tested experimentally.
Another (and in fact related) important aspect is to understand what
remains from the quantum corrections in these theories in the IR.

Voditelj seminara: Anđelo Samsarov (asamsarov at irb.hr)

http://thphys.irb.hr/Seminar/list.htm
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