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Dirac delta to the fourth

  1. Jan 26, 2013 #1
    Please attached snapshot. Does the integral 7.9 equal to 0.5 [itex]\int[/itex]hμσ dzμ/dτ dzσ/dτdτ ?
    I'm confused as to the fourth power of Dirac's Delta. Then where does the derivative on x go ?
    For more on this, see MTW pg180

    Attached Files:

  2. jcsd
  3. Jan 26, 2013 #2


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    It's not a 4th power, it means a four-dimensional delta function. I.e. in Minkowski coordinates,

    δ4(x - x') = δ(x - x')δ(y - y')δ(z - z')δ(t - t')

    Ofttimes you would integrate this over all four dimensions. In this case there is only one integration, leaving three δ's, so it means that Tμν(x) is concentrated on the particle's worldline.
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