to the question “where does the mass come from?"

The clue to the origin of the mass of quarks and leptons, the truly fundamental issue, will probably be revealed in the coming years, perhaps at LHC/CERN. What we are concerned with here is the issue – perhaps less fundamental – we can address with what we already have at our disposal and will have in the near future and deals with strongly interacting matter when it is heated to several hundred MeV in temperature or is compressed to several times the density of the nuclear matter.

The Origin of Hadron Mass
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Let us take the proton as a typical hadron. The argument goes in a similar way for, say, the $\rho$ meson mass which is currently a hot topic of experimental efforts. The simplest way to proceed is to think in terms of constituent quarks whose masses are dynamically generated by the complex vacuum.

In QCD, the proton is made up of three light (“chiral") quarks, the total mass of which is tiny, a few MeV, compared with the proton mass which is $\sim$ 1000 MeV. It is believed - and the evidence is strong - that most of 