FCFADiracChainJoin failed with `Evaluation of isolated objects failed` error

[Turgon-Aran-Gondolin]

• Your Mathematica version

  12.3.1 for Linux x86 (64-bit) (June 24, 2021)

• Your FeynCalc version

  9.3.1

• Did you try to reinstall FeynCalc (stable version) using the automatic installer to make sure that you have the latest bugfixes?

  No, but this version should be up-to-date with the hot-fix-stable branch

• Does your Mathematica initialization file contain statements that might influence the behavior of FeynCalc? Sometimes external packages may modify `init.m` in unusual ways, causing troubles for other codes.

  No

• Please provide a minimal working example that illustrates the problem and works on a fresh kernel. The example should be provided either by writing the code (as `InputForm`!) directly in the issue text or by attaching a Mathematica notebook. Please do not post code samples as screenshots, PDF files etc.: Those essentially require us to retype everything by hand, which is annoying and also time consuming. Please explain the difference between the current behavior and the expected behavior.

    { DiracChain[Spinor[-Momentum[InMom1], mqu, 1], 
    DiracIndex[Dir1]] DiracChain[Spinor[-Momentum[InMom2], mqu, 1], 
    DiracIndex[Dir2]] DiracChain[
    mqu + DiracGamma[Momentum[InMom2 - OutMom3]], DiracIndex[Dir5], 
    DiracIndex[Dir6]] DiracChain[
    DiracGamma[Momentum[-OutMom1 - OutMom2]] . 
     DiracGamma[LorentzIndex[Lor2]] . DiracGamma[7], DiracIndex[Dir5],
     DiracIndex[Dir1]] DiracChain[
    DiracGamma[LorentzIndex[Lor1]] . DiracGamma[7], DiracIndex[Dir2], 
    DiracIndex[Dir6]]} // FCFADiracChainJoin

This will produce a Error! FCFADiracChainJoin has encountered a fatal problem and must abort the computation. The problem reads: "Evaluation of isolated objects failed.". However, reduce the number of gamma matrice in the block (Dir5,Dir1) will produce a result：

   { DiracChain[Spinor[-Momentum[InMom1], mqu, 1], 
    DiracIndex[Dir1]] DiracChain[Spinor[-Momentum[InMom2], mqu, 1], 
    DiracIndex[Dir2]] DiracChain[
    mqu + DiracGamma[Momentum[InMom2 - OutMom3]], DiracIndex[Dir5], 
    DiracIndex[Dir6]] DiracChain[
    DiracGamma[LorentzIndex[Lor2]] . DiracGamma[7], DiracIndex[Dir5], 
    DiracIndex[Dir1]] DiracChain[
    DiracGamma[LorentzIndex[Lor1]] . DiracGamma[7], DiracIndex[Dir2], 
    DiracIndex[Dir6]]} // FCFADiracChainJoin

[vsht]

Thanks for the bug report. This should be now fixed.

[Turgon-Aran-Gondolin]

Thanks! It works for me now.

[vsht]

Thanks for the feedback.