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.
(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.
