sarah is hosted by Hepforge, IPPP Durham

Frequently Asked Questions

  • Can I give SPheno.spc.MODEL as param_card to MadGraph 5 using UFO models files created by SARAH?
    Yes, just make sure not to include the HiggsBounds-blocks in the spectrum files. Those can't be read by MadGraph and create an error messsage. To switch them off, set SPHENOINPUT(520) = 0 in the LesHouches-input file
  • When I load a model in MadGraph I get the message:

    X particles with pdg code xxxxxx is in conflict with MG convention name for particle Y

    You have to load the model via

    import model MODEL -modelname

    to use the naming conventions of the UFO file.
  • Can I read SPheno.spc.MODEL with CalcHep model files created by SARAH?
    Yes, by default SARAH writes the CalcHep model files to support the SLHA+ functionality. However, since CalcHep can't handle complex mixing matrices, make sure to set SPHENOINPUT(50) = 0 in the LesHouches input file.
  • When I try to compile SPheno, I get an error message that the SPheno version is not compatible. How can I fix that?
    Make sure to use the SPheno version (or newer) stated by SARAH when running MakeSPheno[]. In addiiton, it is not possible to compile the code from the new sub-directory where the new code is located by, one has to use in the root-directory of the SPheno installation:

  • I get the following syntax error when I try to compile SPheno under MacOS:

    expr: syntax error

    Try to change the following line in the Makefile:

    cVersion =$(shell expr $(version) \>= $(minV))


    cVersion =minV
  • Why is SPheno using 1 TeV as scale to write the output and not the average of the stop masses?
    That happens when you use SPA conventions. To switch them off, use in your Les Houches input file:

    Block SPhenoInput # SPheno specific input
    2 0 # SPA conventions
  • I get the error message

    (PYCTTR:) colour tag tracing failed

    when I pass events from MG to phythia.

    That happens if pythia 6 doesn't support the color structure (e.g. 3x3x3 like in UDD operators in RpV). You should try pythia 8. Thank to L. Mitzka for pointing this out.

  • When I run SPheno, I get the error message "-1006"
    You are working most likely with a model in which some masses have to be calculated with quadruple-precision, but SPheno was just compiled with double-precision. To change this, edit src/Makefile and change
    Afterwards, run make cleanall and recompile everything.