[seminar] Ivica Dadić, 09.03. (srijeda) 14h (c.t.), predavaona III krila IRB
Kornelija Passek-Kumericki
passek at irb.hr
Fri Mar 4 09:38:41 CET 2016
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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Renormalization in Finite-Time-Path Out-of-Equilibrium $\phi^3$ QFT
Ivica Dadic
Zavod za teorijsku fiziku, IRB
Datum: srijeda, 09. ozujak 2016.
Vrijeme: 14 sati c.t.
Mjesto: IRB, predavaona III krila
Sazetak:
This talk is based on work with Prof. Dr. D. Klabucar.
We formulate the perturbative renormalization for the
out-of-equilibrium $g \phi^3$ quantum field theory in the
formalism with the finite time path. We use the
retarded/advanced basis of
out-of-equilibrium Green functions.
We use the dimensional regularization method and find the
correspondence of diverging contributions in the Feynman
diagrams and their counterparts in R/A basis.
1. The tadpole contributions
are only partially eliminated by renormalization condition.
But, finite tadpole contributions are vanishing as $t\rightarrow \infty $,
in a good agreement with the renormalization condition $<0|\phi|0>=0$
of the S-Matrix theory.
2. Renormalized finite part of retarded (advanced) self-energy
$\Sigma_{\infty,R(A)}(p_0)$ is not retarded (i.e. not causal),
as it is not vanishing when $|p_0|\rightarrow\infty $.
The same happens in S-matrix theory, where $\Sigma_{\infty,F}(p_0)$
cannot be split into its retarded and advanced component.
The problem is ``avoided '' by considering self-energy with legs
$G_F(p_0)\Sigma_{\infty,F}(p_0)G_F(p_0)$, which can be split to
R and A components. The same works in the Glaser-Epstein renormalisation
approach. In the finite-time-path approach $G_R*\Sigma_R*G_R$
should be calculated at $D\neq 4$.
Voditeljica seminara: Kornelija Passek-Kumericki (passek at irb dot hr)
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