[gpderetta]

yes, and note that these are not fundamental particles (like the Higgs was for example), but composite particles of yet another combination of the fundamental quarks. The SM predicts the existence of hundreds (thousands?) of these.

[inlineint]

Actually it is even a one new particle (Omega_c baryon), but they observed five different excited energy states of it (like observing different excited states of a Hydrogen atom), so called resonances [1]. But the discovery is still exciting because it should have been really hard to find something that we don't really know how looks like in such large amount of noise.

The problem is that it is hard for us to predict masses/energies of new composite particles because although Standard Model provides hypothetical way to do it, it is infeasible computationally.

[1] http://physics.stackexchange.com/questions/64862/resonances-...

[nonbel]

>"it should have been really hard to find something that we don't really know how looks like in such large amount of noise."

But if there are thousands of different such "surprising-to find-particles" to possibly detect, is it actually surprising to observe one of them?

Edit:

Also, from the top answer at your link: "The first generation of elementary particles are by observation not composite and therefore not seen to decay...The Standard Model of elementary particles, with the three generations of matter, gauge bosons in the fourth column and the Higgs boson in the fifth."

From wikipedia: "In the Standard Model, the Higgs particle is a boson with no spin, electric charge, or colour charge. It is also very unstable, decaying into other particles almost immediately." https://en.wikipedia.org/wiki/Higgs_boson

So do elementary particles decay or not?

[inlineint]

> But if there are thousands of different such "surprising-to find-particles" to possibly detect, is it actually surprising to observe one of them?

It is hard to correctly identify what exactly particles from those possible thousands are observed in given data. The are two main problems: the properties of those not yet observed particles are not well known (because it is computationally hard to predict them from the standard model) and because the number of useful events is much much smaller than the number of events that correspond to already known events.

> So do elementary particles decay or not?

I don't see a contradiction here: the first generation of elementary particles does not decay (or has not been observed to decay yet), Higgs boson is not from then because the author of the answer are talking about the first generation of fermions and Higgs boson is not one of them.

[nonbel]

Thanks, I missed that "first generation" detail.