composite Higgs and technicolor

When physicists worry that the Higgs boson is suspiciously light, one escape is to say it is not really a fundamental, indivisible particle at all. The proton looks like one object but is actually three quarks glued together; perhaps the Higgs is the same — a tightly bound clump of more basic ingredients, only revealing its structure if you hit it hard enough. Composite-Higgs and technicolor are families of theories built on exactly that move: make the Higgs (or its job) a bound state rather than an elementary point.

Technicolor was the bolder original version. It proposed a brand-new strong force, like the strong force that binds quarks but operating at much higher energy, with new 'techni-quarks'. Their binding would break the electroweak symmetry and give the W and Z bosons their mass, with no fundamental Higgs needed at all. Composite Higgs is the modern, gentler descendant: it keeps a Higgs-like particle but makes it a composite object held together by a new strong interaction, so its lightness is natural in the same way the pion is naturally much lighter than other hadrons.

These ideas matter as rivals to supersymmetry for solving the hierarchy problem — different answers to why the Higgs is light. The honest verdict is harsh for the original technicolor: the 2012 discovery that the Higgs behaves remarkably like a simple, elementary particle, plus precision electroweak measurements, ruled out the plain versions. Modern composite-Higgs models survive by predicting only small deviations, which experiments are still hunting for. So far every measured Higgs property looks point-like, with no sign of internal structure.