I am trying to implement a simple extension of the SM to Feynrules, generating the Lagrangian in a Mathematica notebook file. I am wondering about the following:

  1. Is there a way to explicitly use the antiparticle fields in the Lagrangian? Say, in the SM.fr file there is a W-boson defined in the following way:

    V[3] == {
    ClassName        -> W,
    SelfConjugate    -> False,
    Mass             -> {MW, Internal},
    Width            -> {WW, 2.085},
    ParticleName     -> "W+",
    AntiParticleName -> "W-",
    QuantumNumbers   -> {Q -> 1},
    PDG              -> 24, 
    PropagatorLabel  -> "W",
    PropagatorType   -> Sine,
    PropagatorArrow  -> Forward,
    FullName         -> "W"},

Now if I write down a term using W[mu], will it be W+ (positively charged one)? If yes, how can I call W- field?

  1. Then if I want to add a new (Dirac) fermion to my theory, I initialize it as:

    F[102] == {
    ClassName   -> psi,
    SelfConjugate   -> False,
    Mass        -> {m,Internal},
    Width       -> {W,1},
    QuantumNumbers  -> {Q -> -1}, 
    PropagatorLabel -> "psiC",
    PropagatorType  -> Straight,
    PropagatorArrow -> True,
    ParticleName    -> "psimimus",
    AntiParticleName -> "psiplus",
    FullName        -> "psi"}

    If I then write down the kinetic term LNEWkin := I/2 psilbar.Ga[v].del[psil, v], would it include in fact 2 termc for psiminus and psiplus?

  2. Can I explicitly use psiminus (psimipusbar), psiplus (psiplusbar) in the Lagrangian?

I would be very grateful for the help.

  • $\begingroup$ Are you talking about this?feynrules.irmp.ucl.ac.be/attachment/wiki/StandardModel/SM.fr $\endgroup$ Jan 22 '19 at 16:46
  • $\begingroup$ Yes, so this is the SM.fr file I meant. After initializing field and parameters in the file, I upload it to the Mathematica notebook and write the Lagrangian in the *.nb file directly. $\endgroup$
    – UFO.newbie
    Jan 23 '19 at 14:20
  • $\begingroup$ This is the old code. It is necessary to rewrite it at least for 11.3. You can modify the code at your discretion. But you need to do an update. $\endgroup$ Jan 23 '19 at 18:02
  • $\begingroup$ So can I use the SM.fr file from the latest version of feynrules here feynrules.irmp.ucl.ac.be? Ok, now I see that I can call Wbar, so it probably gives me W-. I suspect that, in the same way, calling psi gives psiminus and calling psibar gives psiplus but is there a way to check the quantum numbers of the specific particle in Mathematica? For example, something like Charge[psi]? $\endgroup$
    – UFO.newbie
    Jan 24 '19 at 9:40
  • $\begingroup$ Everything is possible, but for this we need to test FeynCalc and SM.fr. $\endgroup$ Jan 24 '19 at 12:14

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