How to Calculate the Partial Differential of 4 Momentum ? #260
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I found that the following code runs very well, but I don't know how to add it into FeynCalc. It is very troublesome to run this code before each calculation. } |
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FourDivergence should be sufficient
https://feyncalc.github.io/FeynCalcBookDev/FourDivergence.html
Am 10.04.24 um 12:54 schrieb Isaac Newton:
… I found that the following code runs very well, but I don't know how to
add it into FeynCalc. It is very troublesome to run this code before
each calculation.
{
pd[FV[p_, b_], p_, a_] := MT[a, b];
pd[GS[p_], p_, a_] := GA[a];
pd[SP[p_], p_, a_] := 2 FV[p, a];
pd[SP[p_, k_], p_, a_] := FV[k, a];
pd[f1_ + f2_, p_, a_] := pd[f1, p, a] + pd[f2, p, a];
pd[f_^n_, p_, a_] := n*f^(n - 1)*pd[f, p, a];
pd[f1_*f2_, p_, a_] := pd[f1, p, a]/f2 + f1/pd[f2, p, a];
pd[Dot[f1_, f2_], p_,
a_] := (Dot[pd[f1, p, a], f2] +
Dot[f1, pd[f2, p, a]]) /. {Dot[///, 0, /*] :> 0,
Dot[s*/, g/ + c/, h/__] :> Dot[s, g, h] + Dot[s, c, h]};
pd[f_, p_, a_] := If[FreeQ[f, p], 0, pd[f, p, a]];
}
Here is an example.
2024-04-10.185351.png (view on web)
<https://github.com/FeynCalc/feyncalc/assets/112673778/fab4fdff-1940-4952-9c2f-32b442558482>
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hello FeynCalc
Can we calculate the partial differential in the following figure ?
If this function does not exist, how to add some custom functions ?
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