Higgs particle elementary? The Higgs boson was observed in 2012 and is known to be a fundamental particle in the standard model, but it could be that it is not fundamental/or it consists of other particles? So my question is, if the LHC collides eg. protons then why is there no experiments (that i can see) at LHC where higgs bosons are collided into each other to see if another particle or more particles emerge that would tell us that the higgs is not fundamental? Also I have always wondered why the higgs field/particle needs to have spin 0? It has mass because the Lagrangian quadratic terms, so does this spin 0 arise mathematically or was it also measured at the lhc?
 A: The lifetime of the higgs boson is ridiculously small, of the order $\approx 10^{-22}\ \text{sec}$ and so it cannot be accelerated then collided to check for substructure. It would simply decay too quickly
to be able to do this. It also has zero charge. Protons have a lifetime more than sufficient (note that the proton in particular is thought to never decay by some). According to all experiments and theory, the higgs boson is likely to be an elementary particle.
As for your other questions, there seems to be a little confusion. The original procedure in a quantum field theory, where the adding of massive terms to a Lagrangian is done by the insertion of quadratic terms to the Lagrangian, does not work for the gauge bosons that participate in the weak interaction. The study of the weak interaction showed that the vector bosons $W^+$, $W^-$ and $Z$ were massive.  That is why the higgs mechanism was introduced. The higgs mechanism adds massive terms to a Lagrangian by introduction of the Higgs field.
This mechanism requires that the higgs field have a vacuum expectation value that is not zero anywhere. So at all point in space, the higgs field has a value and is never equal to zero. But at the same time, it is necessary that the higgs vacuum expectation value be Lorentz invariant. And if the higgs field (with a non zero VEV) had a non-zero spin like a vector or spinor field, then this would mean it has a preferred direction in space, breaking Lorentz invariance. Therefore, it must have no spin (a scalar field) and this was confirmed experimentally.
The spin zero nature of the higgs field was measured by looking at angular correlations between the particles the higgs boson decayed into. For more information about this, check this article by cern.
I also note that your question states that the higgs boson was observed. It was actually detected also by measuring characteristics of the bosons it decayed into.
