" 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). Thai Beautiful Model These parameters cannot be independently calculated. The model does not describe the gravitational interaction. "

" One should not miss out the point that the original as well must be constituted in some way so it becomes accessible to the modeling individual I. IV. The term model is used in many communities with quite different traditions, commonly perceived problems, and purposes. To use the term properly therefore requires it being put into the right context. While this entry attempts to provide a general framework for talking about models it is not very likely that all communities would accept and use that framework. V. References [1] Stachowiak, H. Beautiful Arab Model; "Modell" (In German); In: Seiffert, H. Handlexikon zur Wissenschaftstheorie; Deutscher Taschenbuch Verlag; 1989; pp. "