[seminar] [DANAS] Ivica Dadić, 09.03. (srijeda) 14h (c.t.), predavaona III krila IRB

[Kornelija Passek-Kumericki]

                       SEMINAR  TEORIJSKE  FIZIKE


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

----------------------------------------------------------------------


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)
-------------- next part --------------
A non-text attachment was scrubbed...
Name: sem20160309-Dadic.pdf
Type: application/pdf
Size: 76587 bytes
Desc: 
URL: <http://www.phy.pmf.unizg.hr/pipermail/seminar/attachments/20160309/6717f60a/attachment-0001.pdf>