By 'singlet' I mean SU(2) singlet, i.e. a charged fermion without its partner. Is there any theoretical drawback? As I think, it will have no coupling with the Higgs, since Higgs is not needed to give mass to it. Will it be phenomenologically uninteresting?
So if I understand correctly, you propose something with nonzero U(1) hypercharge but no SU(2) weak charge, and therefore with nonzero electric charge. There are strong constraints on electrically charged particles, so presumably this is something heavy, ~TeV scale. Such particles would need to come in pairs with opposite hypercharges to cancel gauge anomalies. But what I don't see is what the point would be: why are you thinking about this sort of thing?
Already within the Standard Model there are charged singlets, namely the right-handed leptons. And they do couple to the Higgs and their left-handed partner, a coupling which results in the charged lepton masses.
@ David Schaich ...
Thank You for the reply. I didn't know about the experimental bounds. Actually I was wondering if LHC discovers a heavy charged lepton, then may be we can infer that there must be its partner also. There is no other serious issue..
Anyway, thanks all of you for your comments.
Jens, you are of course correct, but I believe the question proposed novel SU(2)-singlets *without* SU(2)-doublet partners.
Hi Salah, I don't know if you have continued along this line of research since this post is now getting a little old. In case you are still thinking about this problem I suggest that the publication listed below might be of interest when considering the contribution to the S, T, U parameters from heavy fermion representations.
Article The Effects on S, T and U from Higher-Dimensional Fermion Re...
- Badges
- Science topic
- Similar topics
- Physical Sciences
- Particle Physics
- Elementary Particle Physics