Troubleshooting

MATCHA only produces zeros for the HEFT coefficients

Currently, MATCHA works only at tree level at LO in HEFT. If the user’s model does not produce a non-decoupling contribution to the LO HEFT Lagrangian and its first contributions appear at NLO, MATCHA is not yet able to obtain the NLO HEFT coefficients.

MATCHA provides HEFT coefficients dependent on positive powers of the heavy masses

Check that the UV parameters are chosen consistently in the large-mass limit. In particular, three-particle vertices that are part of the UV input should not diverge when the heavy masses are taken large.

In some cases, in order to simplify the expressions, the UV model may be written in terms of parameters that are not independent, such as a sine and a cosine. In that situation, a dependence on the heavy masses can be spurious and should disappear once the relation between those parameters is imposed.

Inspect the diagrams used in the matching to check whether all relevant fields have been included. See the example in the Command Reference.

FeynArts or FormCalc cannot be found

Check that the paths defined in Config.m point to the local installations of FeynArts and FormCalc. The folders should correspond to the versions used by MATCHA, for example FeynArts 3.11 and FormCalc 9.8.

The model files are not detected

Make sure that the .mod and .gen files generated by FeynRules are located in the directory specified by ModelPath. The model name passed to MATCHA should match the name of the FeynArts model files.

The model files do not show the expected heavy-mass dependence

When generating the FeynRules output, it is recommended to use

CouplingRename -> False

This keeps the dependence on the heavy masses explicit in the generated FeynArts model files.

MATCHA says that a field key is invalid

Check that SetSMFields uses the current field keys: "Higgs", "GaugeCharged", "GaugeNeutral", "GoldstoneCharged", "GoldstoneNeutral", and "Quark". Use "Quark", not "Top", and "QuarkMass", not "TopMass".

Output files are not written

Check that OutputDirectory in Config.m points to a location that Mathematica can create and write to.