• Unphysical Goldstone bosons in SPheno

Dear Forum,

I've implemented the Scotogenic model in SARAH. I've based my implementation on the SM one and I've added the new odd particles. There is then a new scalar boson and the old H is now H1 = {H1p , H10}. So H1p and Ah should be unphysical Glodstone bosons and should be absorbed by W and Z.

The MakeSPheno command works fine. However, I have an issue with the Goldstone bosons ; they seem to be considered as physical states in SPheno even with the command "Goldstone->H1p" (same for Ah) in particles.m.

They appear at the end of the SPheno output as "H1p_1" and "Ah_1" :

Code: Select all

DECAY        21     0.00000000E+00   # VG
DECAY        22     0.00000000E+00   # VP
DECAY         0     0.00000000E+00   # H1p_1
DECAY         0     0.00000000E+00   # Ah_1

and also in the "H0" 3-body decays :

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DECAY      1001     5.99416253E-03   # H0
#    BR                NDA      ID1      ID2
#    BR                NDA      ID1      ID2       ID3
     5.55497876E-02    3            0       1016         11   # BR(H0 -> H1p Chi_3 Fe_1 )
     5.55497876E-02    3            0      -1016        -11   # BR(H0 -> H1p^* Chi_3^* Fe_1^* )

then giving wrong branching ratios.

I also provide my code in attachment and the SPheno output.

Could it be related to the new global Z2 symmetry, or to the declaration of the new scalar states (A0 and H0) in Definitions[EWSB][VEVs]? Or perhaps this is due to gauge fixing? Any ideas?

Many thanks,

Gaël A.

Hi,

non-physical states which should be ignored in the SPheno output must have PDG-Nr 0

Cheers,
Florian

Hi Florian,

I have corresponded privately with Gael about this. It's actually a genuine issue, SARAH will generate these decays for other models (e.g. the SM) if you turn 3-body scalar decays on. You see from Gael's output that he *did* set the PDG number to zero for the goldstones and the decay is not ignored. In the MSSM etc it's dealt with by "getGenSPhenoStart" being greater than 1, but there is no other check.

OTOH it's just a sign that the code is incomplete, because we don't allow three-body decays to vectors ... so I am not sure whether it is really worth artificially cutting out these processes.

Unphysical Goldstone bosons in SPheno

Unphysical Goldstone bosons in SPheno

Re: Unphysical Goldstone bosons in SPheno

Re: Unphysical Goldstone bosons in SPheno