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I'm just starting out using Mathematica and I'm trying to work through one of the examples given for FeynCalc, specifically the muon decay: https://github.com/FeynCalc/feyncalc/blob/master/FeynCalc/Examples/EW/Tree/Mu-ElAnelNmu.m

It seems to be working fine up until line 117,

diffDecayRate = 
  prefac d3q1/En[q1] d3q2/En[q2] d3k/En[k] delta4[q - q1 - q2] ampSquared[1] 

The output for this is

(16 d3k d3q1 d3q2 Subscript[G, F]^2 delta4[q - Subscript[q, 1] - 
    Subscript[q, 2]] tr[-(OverBar[k] "\[CenterDot]" OverBar[Subscript[q, 1]])] 
      tr[-(OverBar[p] "\[CenterDot]" OverBar[Subscript[q, 2]])])) /
  (En[k]*En[Subscript[q, 1]] En[Subscript[q, 2]])

that is:

enter image description here

which clearly isn't correct, and from there the integral cannot be evaluated. Has anyone else come across this, and is it immediately obvious what I might be doing wrong?

Please let me know if any more information is required.

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  • $\begingroup$ The examples from the master branch work only with the development version. If you install the stable version, only the examples shipped with it are guaranteed to work. $\endgroup$
    – vsht
    Feb 13 '19 at 16:30
  • $\begingroup$ Ah ok thank you! $\endgroup$
    – N Solomons
    Feb 13 '19 at 16:54

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