mfb said:
It's easy to make a heavier particle out of lighter particles:
* Atoms are made out of light electrons and the nucleus which is a bit lighter than the atom.
* Nuclei are made out of nucleons which are lighter than the nucleus.
* Nucleons are made out of quarks and gluons which are lighter than the nucleons. You can argue that the ~300 MeV scale of QCD is a better metric than quark masses but that's still lighter than nucleons.
Can this trend continue, quarks being made out of even lighter particles? No. Our accelerators would have enough energy to break this apart, create excited states and so on.
In principle you can create a light particle as bound state of two or more much heavier particles if the coupling has just the right binding energy to almost cancel the masses and at the same time reproduce all the values we expect for elementary particles, but that doesn't look like a very likely scenario.
There could be many new particles between the ones we know and the Planck scale. Doesn't mean that they have to be part of matter. We already know heavier particles that are not part of everyday matter, especially the whole second and third generation of quarks and leptons.
Unfortunately it's a bit more complicated than that, and the question, where the masses of particles come from is among the most complicated questions.
The question "how hard have they banged" is a pretty clever one. Not only that you need higher and higher energies to produce more and more massive instable particles but also to resolve smaller and smaller details. That's why in the history of particle and nuclear physics the resolution got finer and finer the higher the energies of collisions got with which we probe the constituents of matter.
At low energies what looks like "fundamental constituents of matter" seem to be protons, neutrons, and electrons. The protons and neutrons bind together to atomic nuclei with positive charges ##Z e##, where ##Z## is the number of protons within a nucleus and ##e## is the elementary charge. The positive nuclei bind together with the negatively charged electrons to form electrically neutral atoms. The nucleus in an atom comes with a mass ##m_{\text{Nuc}}##, which is given by the sum of the masses of protons and neutrons minus ##E_B/c^2##. The nucleus binds together with ##Z## electrons via the electromagnetic (Coulomb) force. Again the mass of the atom is ##m_{\text{atom}}=m_{\text{Nuc}}-E_B'/c^2##, where ##E_B'## is the electromagnetic binding energy between electrons and the nucleus.
With higher and higher energies more and more details about these particles could be revealed. By bombarding protons or atomic nuclei with high-energetic electrons in the 1960ies it turned out that the protons and neutrons themselves look like bound states of constituents, which were called "partons" in the beginning and then turned out to be the "quarks" of Gell-Mann's and Zweig's ordering scheme of hadrons (of which besides the proton and the neutron several more had been found in collision experiments too).
As could then be clarified in the early 1970ies concerning the strong interactions the elementary building blocks of the hadrons (coming as bound states of a quark-antiquark pair, the socalled mesons, which are bosons and bound states of three quarks, which are fermions) are quarks, carrying a so-called color charge. In analogy to the then well-known theory of the electromagnetic interactions, quantum electrodynamics, where electric charges are bound together by a massless vector field, the electromagnetic field, which in quantized version has the photons as elementary particle-like excitations, there were also vector fields binding together the quarks with color charges. The corresponding particle-like quanta were called gluons. The important difference between gluons and photons is that the gluons themselves also carry color charges, i.e., they are kinds of color-anticolor dipoles, and this makes a profound qualitative difference between the electromagnetic and the strong interaction: The coupling constant between color charges, parametrizing the interaction strength, gets larger and larger the smaller the energy in collisions of these color charges gets, and this leads to what's called "confinement", i.e., according to this theory of the strong interaction (Quantum Chromo Dynamics, QCD) it's impossible to ever observe objects carrying a non-zero net-color charge, and indeed there's never been seen a free quark, anti-quark or gluon yet. All we can find are a plethora of hadrons, which are all bound states of colored quarks and gluons, which have a net-color charge of zero.
Finally there's also the weak interaction. It has manifested itself first in terms of the ##\beta## decay of neutrons and corresponding decays of neutrons within radioactive nuclei. The weak interaction is pretty special too. In the mid 1960ies it came out that also the weak interaction is described by a quite similar theory as QED and QCD (so-called gauge theories), but again with somewhat different manifestations. It turned out that the vector fields which are analogous to the photons and gluons ("force carriers") in QED and QCD should correspond to massive particle-like quanta, and this was a big trouble for the theorists trying to describe the weak interaction, because when just writing down equations for such "massive gauge bosons" destroyed the entire mathematics of the model, i.e., it became meaningless and inconsistent. Famously Higgs (and some more physicists) around 1964 figured out how to get out of this dilemma: They evented a scheme, where the underlying mathematics (the socalled symmetries of the equations describing the fields and their interactions) was obeyed but the gauge bosons could get massive by coupling all the fields to another socalled scalar field, which should have a non-zero value even if no particles are present. The same mathematics also ruled that this socalled Higgs field "vacuum expectation value" must also be repsonsible for the masses of all the elementary particles in the so formed Standard Model (SM) of particle physics. As any field to the Higgs field there must be elementary particle-like excitations, and this is the famous Higgs boson, which was the last particle to be discoved in 2012 at the LHC at CERN.
According to this SM the elementary constituents of matter are
quarks and anti-quarks, which carry electric, color, and "weak" charges (in fact QED and the electroweak interaction are somewhat more close in the mathematics, i.e., the corresponding Quantum Flavor Dynamics describes in a kind of "unification" both electromagnetic an weak interactions and on a fundamental level one has the socalled weak hyper-charge and weak isospin). The quarks come in "3 families", each of contains a pair of quarks: (up,down), (charm,strange), (top,bottom) each carrying an electric charge of ##+2/3 e## and ##-1/3 e## as well as 3 color charges ("red", "green", "blue"). The corresponding anti-quarks carry just the opposite charges and are otherwise identical with the quarks.
leptons and anti-leptons: carry only electroweak charges and come also in three families (as the quarks), i.e., a charged lepton and a corresponding neutrino: ##(e,\nu_e)##, ##\mu,\nu_{\mu}##, ##\tau,\nu_{\tau})## and the corresponding anti-leptons. The charged leptons carry electric charge ##-e## and the neutrinos are all uncharged. Again the anti-leptons carry the opposite charges but are otherwise identical with the leptons.
Gluons: "force carriers" of the strong interaction. They come in 8 color-charges (a color-anticolor dipole, but one of the possible 9 combinations is strictly color neutral, and doesn't occur as a gluon). They are strictly massless.
Photons: "force carriers" of the electromagnetic interaction. They are uncharged and interact with particle carrying electric charges. They are strictly massless.
W- and Z-Bosons: "force carriers" of the weak interaction: The ##W##-bosons come as electrically charged carrying a positive charge ##+e## or ##-e##, and the Z-bosons are electrically neutral. They are all massive due to the Higgs mechanism.
Higgs boson(s): In the most simple variant of the SM in addition there's one Higgs boson, the elementary excitation of the Higgs field, whose vacuum-expectation value also delivers all the masses of the quarks and leptons.
Now the amazing thing is that the mass of the matter around us, i.e., the atomic nuclei is almost completely due to the strong interaction and the associated phenomenon of confinement. Only about 2% of the mass of the atoms building up our everyday matter, is due to the Higgs mechanism. The vast rest is due to the binding of quarks and gluons to hadrons. The problem is that we don't have a really intuitive picture of this "confinement" phenomenon. The best argument for this conclusion from the SM is that, when simulating QCD, the theory describing the strong interactions, on computers (the socalled "lattice gauge theory"), we can predict pretty well which hadrons should be found in nature and their masses.
A qualitative picture can be given in terms of the so-called "MIT bag model". The idea is that in the "vacuum of QCD" bags are formed, within which quarks and gluons are confined. In this picture a proton consists of three (valence) quarks (2 up-quarks and 1 down-quark with a total charge of ##2 \times 2/3 e +(-1/3 e)=+1 e## as it should be for a proton) which are confined in a small spherical hole in the vacuum with a radius of about 1 fm (1 fermi=1 femto meter=##10^{-15}m##). Now if you confine particles in such a small volume according to the uncertainty principle of quantum mechanics they must have a pretty high momentum uncertainty, i.e., the momenta of the quarks fluctuate around the average zero value for a proton at rest, and the corresponding kinetic energy of this motion leads to the mass of the proton. That's why with the quite light up and down quarks with masses of a few ##\text{MeV}/c^2## you get the quite large proton mass of ##938\; \text{MeV}/c^2##.
A more modern understanding is quite abstract and related to the so-called trace-anomaly of QCD and the formation of a quark condensate due to strong attractive interactions. The modern picture of the proton is also way more complicated than the simple bag model suggests: It consists not only of the 3 valence quarks but in addition also of "sea quarks and anti-quarks" as well as "gluons", i.e., of complicated field configurations of quark and gluon fields, and with ever higher energetic electrons one can try to resolve this structure of "partons" and in some sense also figure out, how the total mass and spin of the proton (and also other hadrons) are "distributed" over all these fields.
