3 ms·

> If it turns out to be true, the chart linked below showing the 17 known elementary particles would be expanded to show an 18th. no, actually the standard mod

by soheil 11y ago

> If it turns out to be true, the chart linked below showing the 17 known elementary particles would be expanded to show an 18th. no, actually the standard model would fundamentally break down. The math does not allow for such a heavy particle. No charts could save it.

gibybo 11y ago
How would it fundamentally break down? Admittedly I don't know enough to know how a particle with these particular properties would affect it, I was just trying to make the point that a new particle doesn't necessarily break the standard model. I'll try to edit my post for more accuracy.
- claudius 11y ago
  (It's been a while since I took this class, the following might well be wrong or grossly inaccurate) The particles of the standard model are assumed to correspond to the irreducible representations (irrep) of the groups associated to the symmetries of the strong, weak and electromagnetic interactions. These groups are SU(3) (strong) and SU(2)×U(1) electroweak. The currently known particles correspond to the first few irreps of these groups, with the dimensionality of the irrep nicely matching the number of “similar” particles, see e.g. [1]. This means that, if the above assumptions hold, finding a single new particle requires there to be yet another irrep[2] which would imply that there are even more new particles corresponding to the other dimensions of this irrep. [1] https://en.wikipedia.org/wiki/Standard_Model_%28mathematical_formulation%29#Field_content_in_detail https://en.wikipedia.org/wiki/Standard_Model_%28mathematical... [2] If this is even possible, I’m not quite sure, but SUSY does something similar I guess.
cshimmin 11y ago
That's not really the case. The standard model would need to be extended, sure (as the 750 GeV particle isn't predicted by the current SM). But there's no fundamental reason this can't be done; in fact in the weeks following this announcement by ATLAS/CMS, there were literally hundreds of theory models posted to the arXiv, claiming to extend the SM to account for the (potential) new resonance.
- AnimalMuppet 11y ago
  But the fact that there were hundreds of theory models posted means that there is no "standard model" for this new particle at the moment (if it is a real particle).

by soheil 11y ago

gibybo 11y ago

How would it fundamentally break down? Admittedly I don't know enough to know how a particle with these particular properties would affect it, I was just trying to make the point that a new particle doesn't necessarily break the standard model. I'll try to edit my post for more accuracy.

claudius 11y ago
(It's been a while since I took this class, the following might well be wrong or grossly inaccurate) The particles of the standard model are assumed to correspond to the irreducible representations (irrep) of the groups associated to the symmetries of the strong, weak and electromagnetic interactions. These groups are SU(3) (strong) and SU(2)×U(1) electroweak. The currently known particles correspond to the first few irreps of these groups, with the dimensionality of the irrep nicely matching the number of “similar” particles, see e.g. [1]. This means that, if the above assumptions hold, finding a single new particle requires there to be yet another irrep[2] which would imply that there are even more new particles corresponding to the other dimensions of this irrep. [1] https://en.wikipedia.org/wiki/Standard_Model_%28mathematical_formulation%29#Field_content_in_detail https://en.wikipedia.org/wiki/Standard_Model_%28mathematical... [2] If this is even possible, I’m not quite sure, but SUSY does something similar I guess.

cshimmin 11y ago

That's not really the case. The standard model would need to be extended, sure (as the 750 GeV particle isn't predicted by the current SM). But there's no fundamental reason this can't be done; in fact in the weeks following this announcement by ATLAS/CMS, there were literally hundreds of theory models posted to the arXiv, claiming to extend the SM to account for the (potential) new resonance.

AnimalMuppet 11y ago
But the fact that there were hundreds of theory models posted means that there is no "standard model" for this new particle at the moment (if it is a real particle).