Kinds of hadrons about one hundred. That fact that hadrons exists hundreds, suggests an idea that hadrons - not elementary particles, and are constructed of smaller particles. All hadrons meet in two versions - electrically loaded and neutral. The most known and widespread such hadrons as neutron and proton.
If in the classical description electrons are presented in the form of a firm dot ball, in KED the electromagnetic field surrounding an electron is considered as a cloud of virtual photons which follows about an electron, surrounding it with energy quanta. Photons arise and disappear very quickly, and electrons move in space not on quite certain trajectories. Still it is possible to define one way or another initial final points of a way — before dispersion, but the way in an interval between the beginning and the end of the movement remains uncertain.
Now most of physicists considers quarks as originally elementary particles – dot, indivisible and not possessing internal structure. In this regard they remind leptons, but the deep interrelation has to exist families, similar on the structure. Thus, the most probable number of truly elementary particles for the end of the XX century is equal 4 Of them: leptons (6 * = 12 plus quarks (6 ** 2=3
In the middle of the XX century the theory of electromagnetic interaction — quantum electrodynamics (KE was created. It elaborately the smallest details and the theory of interaction equipped with perfect mathematical apparatus among themselves the loaded elementary particles (first of all, electrons or a positron by means of an exchange of photons. In KED for the description an electromagnet of interaction the concept of a virtual photon is used, the theory satisfies to the basic principles as quantum theory and theory of relativity.
Quarks can connect with each other one of two possible ways: either the three, or in couples a quark – an anti-quark. Rather heavy particles – consist of three quarks; the most known – a neutron and a proton. Lighter vapors a quark – an anti-quark form the particles which received the name of a mezona. For example, the proton consists of two "u" and one "d" of a quark (uud), and a neutron – of two "d" and one "u" of quarks. That this "trio" of quarks did not break up, force holding them, certain "glue" is necessary.
The main idea in creation of this theory consisted in the description of weak interaction in language of the concept of a calibration field according to which a key to understanding of the nature of interactions symmetry serves. One of fundamental ideas in physics of the second half of the XX century is a belief that all interactions exist only to support a certain set of abstract simmetriya in the nature. What relation symmetry has to fundamental interactions? After all, at first sight, the statement about existence of similar interrelation seems very paradoxical.