Gauged e-mu extension

[Amin]

Hi Florian,

I was wondering if implementing a U(1)_L(e)-L(mu) gauge symmetry extension of the SM is easy in SARAH. Also, can one add a non-chiral fermion field?

Thank you,
Amin

[Amin]

For the non-chiral fermion case, I was thinking of writing something as:

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FermionFields[[1]] = {XL, 1, xL, 0, 1,  1, -1}; 
FermionFields[[2]] = {XR, 1, conj[xR], 0, 1,  1, -1}; 

and

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DEFINITION[EWSB][DiracSpinors]={
FX ->{ xL, xR} }

Does SARAH understand this as a non-chiral field?

Best,
Amin

[FStaub]

Yes, that should work.

[Amin]

Thanks Florian.
What about implementing a U(1) L(e)-L(mu) extension to the SM? Is it doable with SARAH?

Best,
Amin

[Amin]

Hi again,

To implement the U(1) e-mu model, the tau field must be uncharged under the new U(1). So I can define the e, mu and tau fermion fields separately which can be done in SARAH, apparently. Would something like this work?

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FermionFields[[1]]={l, 2, {vL0, eL0}, -1/2,2,1,1}
FermionFields[[2]]={lt, 1, {tvL0, tlL0}, -1/2,2,1,0}

DEFINITION[EWSB][Flavors]= {
 {FvL0, {FveL,FvmL}},
 {FeL0, {FeL, FmL}},
 {FtvL0, {FvtL}},
 {FtlL0, {FtauL}}
 }

I have kept the tau but gave it zero charge under U(1)_X in hopes that SPheno would work. Does that sound reasonable?

Thank you,
Amin

[FStaub]

Yes, that's the way you need to do it.

[Amin]

Thanks Florian.
I guess I also need to modify the Yukawa couplings accordingly.

Best,
Amin

[FStaub]

Yes, you must treat the fields in the entire model as different particles.