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Help on QFT

  1. Aug 14, 2004 #1
    Hi, can anyone give me a clear definition of the following two things

    1) Wilson loop
    2) Spin network (invented by Penrose, right???)

    What do these quantities fysically mean???

    PS : can anyone explain me what the term LOOP means in Loop quantum gravity. To what does it refer ?

  2. jcsd
  3. Aug 15, 2004 #2
    Hey Marlon !

    Very intersting issues...that I don't want to pretend I undestand though :wink: But I want to advise you a very good paper on quantum gravity by Carlo Rovelli. This is an entire book, whose draft version is available at :

    Anything I could say would be more accurate in this paper. Enjoy ! :tongue2:
  4. Aug 15, 2004 #3
    grazie, humanino

    how is life out there in Paris???
  5. Aug 15, 2004 #4
    je vous en prie Marlon, c'est mon plaisir

    Another (shorter) paper
    where one can read :
    Should this move to another forum (LQG !!)?
  6. Aug 15, 2004 #5
    I took one week out of my thesis. Back to Switzerland Jura ! This is also how I come to have time to read useless things such as LQG :tongue2:

    Could someone elaborate on Penrose and spin network ? :confused:
  7. Aug 15, 2004 #6
    I give here the definition of the Wilson loop given by Zinn-Justin in his "QFT & Critical phenomena"

    section 33.3 "Wilson's loop and confinement" (p735)
    [tex]W(C)=\left\langle e^{-ie \oint_{C} A_\mu(s) ds_\mu } \right\rangle[/tex]
    with C a closed loop in space-time. This is a functional integral, and represents the parrallel transporter along the closed loop.

    As for spin network :
    Last edited: Aug 15, 2004
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