## Automatic index contraction gives errors with term (SU(2) triplet)³ × (singlet)

Question how to implement a model or how to change a model implementation
Socob
Posts: 29
Joined: 7. Dec 2017, 16:18

### Automatic index contraction gives errors with term (SU(2) triplet)³ × (singlet)

Automatic index contraction doesn’t seem to work properly for a term of the form trip.trip.trip.sing, where “trip” is a real scalar SU(2) triplet and “sing” is a real scalar singlet. For example, when I add a real scalar triplet to the built-in model “SM+Triplet/Real”:

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`ScalarFields[[2]] = {trip, 1, {{T0/Sqrt[2], conj[Tm]}, {Tm, -T0/Sqrt[2]}}, 0, 3, 1};ScalarFields[[3]] = {sing, 1, ss, 0, 1, 1};RealScalars = {T0, sing};`

and the following term to the Lagrangian:

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`LagNoHC = ... - LT3 trip.trip.trip.sing;`

I get the following Mathematica errors after running Start[...]:

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`...Evolve States: GaugeESAdding terms to the Lagrangian:  ... adding: Yu H.u.q-Yd conj[H].d.q-Ye conj[H].e.l (All Done) ... adding: -(1/2) MT trip.trip-mu2 conj[H].H-KHT conj[H].trip.H-LT3 trip.trip.trip.sing+1/2 LT Delta[lef1,lef4b] Delta[lef1b,lef2] Delta[lef2b,lef3] Delta[lef3b,lef4] trip.trip.trip.trip+1/2 LHT conj[H].H.trip.trip+1/2 LH conj[H].H.conj[H].H (All Done)! Part::partw: Part 1 of {} does not exist.! Take::take: Cannot take positions 1 through 3 in {}[[1]].! Part::partw: Part 1 of {} does not exist.! Take::take: Cannot take positions 1 through 3 in {}[[1]].Rotate Lagrangian: 14/14Derive ghost terms:   ... generate gauge fixing terms: 3/3 (All Done)  ... calculate Ghost interactionsCalc Mixings of Matter FieldsSave information (All Done)...`

FStaub
Posts: 752
Joined: 13. Apr 2016, 14:05

### Re: Automatic index contraction gives errors with term (SU(2) triplet)³ × (singlet)

Looks like a problem with interfacing Susyno. I need to check once I'm back to work...

FStaub
Posts: 752
Joined: 13. Apr 2016, 14:05

### Re: Automatic index contraction gives errors with term (SU(2) triplet)³ × (singlet)

It seems that this is not necessarily a "problem". The coupling you are writing down vanishes exactly. I was checking with a non-zero coupling (conj[H].trip.H.sing) and got no error messages. I catch now this special case and print a warning.

Cheers,
Florian