" These are either fermionic baryons composed of three quarks (the proton and neutron being the most familiar example) or bosonic mesons composed of a quark-antiquark pair (such as pions). The mass of such aggregates exceeds that of the components due to their binding energy . Tests and predictions The Standard Model predicted the existence of W and Z bosons, the gluon, the top quark and the charm quark before these particles had been observed. Their predicted properties were experimentally confirmed with good precision. The Large Electron-Positron collider at CERN tested various predictions about the decay of Z bosons, and found them confirmed. To get an idea of the success of the Standard Model a comparison between the measured and the predicted values of some quantities are shown in the following table: Quality Measured (GeV) SM prediction (GeV) Mass of W boson 80,4120±0,0420 80,3900±0,0180 Mass of Z boson 91,1874±0,0021 91,1874±0,0021 Challenges to the Standard Model Although the Standard Model has had great success in explaining experimental results, it has never been accepted as a complete theory of fundamental physics. This is because it has two important defects: The model contains 19 free parameters, such as particle masses, which must be determined experimentally (plus another 10 for neutrino masses). Beautiful Teenage Model These parameters cannot be independently calculated. The model does not describe the gravitational interaction. "

"784 GeV Tau neutrino ντ 0 2 +1/2 -1/2 1 < 70 MeV Anti-Tau τc 1 1 0 1 1 1. 784 GeV Tau antineutrino 0 1 0 0 1 < 70 MeV Top quark t +2/3 2 +1/2 +1/6 3 173 GeV Bottom quark b -1/3 2 -1/2 +1/6 3 ~4. 7 GeV Anti-top antiquark tc -2/3 1 0 -2/3 173 GeV Anti-bottom antiquark bc +1/3 1 0 +1/3 ~4. 7 GeV * - These are not ordinary Abelian charges which can be added together but labels of Group representations of Lie groups. ** - Mass is really a coupling between a left handed fermion and a right handed fermion. For example, the mass of an electron is really a coupling between a left handed electron and a right handed electron, which is the antiparticle of a left handed positron. Also neutrinos show large mixings in their mass coupling, so it's not accurate to talk about neutrino masses in the flavor basis or to suggest a left handed electron neutrino and a right handed electron neutrino have the same mass as this table seems to suggest. Beautiful Exposed Model Vip *** - What is actually measured experimentally are the masses of baryons and hadrons and various cross section rates. Since quarks can't be isolated because of QCD confinement, the quantity here is supposed to be the mass of the quark at the renormalization scale of the QCD phase transition. "