[seminar] Ilya L. Shapiro, 20. sijecnja 2011. (cetvrtak) u 11:00 tocno, IRB, dvorana I krila

[Hrvoje Nikolic]

       INSTITUT Rudjer Boskovic
       ZAVOD ZA TEORIJSKU FIZIKU
       Bijenicka c. 54, Zagreb, Hrvatska


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                      SEMINAR ZAVODA ZA TEORIJSKU  FIZIKU
             (Zajednicki seminari Zavoda za teorijsku fiziku i
                 Zavoda za eksperimentalnu fiziku IRB-a i
                 Zavoda za teorijsku fiziku PMF-a)

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         Ilya L. Shapiro, Departamento de Fisica, ICE, Universidade Federal
                          de Juiz de Fora, Brazil


     "One-loop form factors, multiplicative anomaly and galaxy rotation
      curves"

       Vrijeme:  20. sijecnja 2011. (cetvrtak), 11:00 tocno

       Mjesto:  Institut Rudjer Boskovic, dvorana I krila

       Sazetak:
We report on some recent results on the evaluation of quantum
corrections to the classical actions of gravity and electromagnetic
fields. In the last case we consider the one-loop QED in curved
space time and find that the effective action in the
electromagnetic sector possess an ambiguity, which can be
characterized as the
nonlocal multiplicative anomaly. Moreover, by analyzing different
space-time dimensions we come to the understanding of the real
origin of this theoretical phenomenon which should probably take
place also in other theories. The mentionded ambiguity may concern
the exact form of the Appelquist and Carazzone theorem, but the
general form of the decopuling rule remains the same. In gravity,
Appelquist and Carazzone theorem can be also derived explicitly,
but only for the higher derivative terms in the action. It is
remarkable that the assumption of a standard quadratic decoupling
for the Newton constant leads to the very good prediction for the
rotation curve for a sample of nine different spiral galaxies.



      Voditelj seminara:
      Hrvoje Nikolic (hrvoje at thphys.irb.hr)


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