In modern physics distinguish several types of interaction of particles: strong, weak and electromagnetic. For their description the Standard model of physics of elementary particles in which the quark acts as a fundamental particle is used.
Theory of quarks
The theory of quarks was developed to describe interaction of particles. It is important to note that in a free state not to meet a quark in the nature as the quark, strictly speaking, in itself is not a particle. It is a way of a configuration of an electromagnetic wave in a particle, and the particle usually includes not one such wave. The charge of a quark is equal to one third of a charge of an electron, and its scale is 0.5*10^-19 (10 in minus of the nineteenth degree), it is less than the size of a proton approximately in 20 thousand times. Hadrons (to which the proton and a neutron belongs) consist of quarks too.
On the present distinguish six types of quarks, as a rule, speak, "aromas". In addition, the quark also has one more characteristic important for distinction of type, it is color. It is obvious that this abstract division, the real quark, of course, has no colors, on aroma. But this theory is very convenient for calibration of quarks. To each type of a quark there corresponds the anti-quark – that is, "particle" which quantum numbers are opposite. Quantum numbers serve for the description of properties of a quark.
A story about how quarks received the name, is rather amusing. Gell-Mann, the scientist who for the first time assumed that hadrons consist of special particles borrowed this word from the novel by James Joyce "Finnegans Wakes" at which there are words: "Three quarks for Mr. Mark!". In general it is possible to call the theory of quarks in physics one of the most poetical. Here both history of the name, and characteristics of color and aroma, and types of quarks: true, charming, fascinated, strange … Each type of a quark is characterized by a charge and weight.
Role of quarks in physics
On the basis of quarks there are strong, weak and electromagnetic interactions. In strong interactions color of a quark, but not aroma can change. Weak interactions change aroma, but not color. In strong interaction one single quark cannot move away from other quarks on a little noticeable distance for this reason in a free look they cannot be observed. This phenomenon is called a konfaynment. But hadrons – "colourless" combinations of quarks – can already scatter from each other.
Whether quarks are real?
As because of the konfaynment it is impossible to see separate quarks, quite often nonspecialists ask: Whether "Quarks if we cannot observe them are real in general? Whether not mathematical it is abstraction?" Reasons of reality of the theory of quarks a little: - All hadrons, despite their large number, possess very small number of degrees of freedom. Originally the theory of quarks described these free parameters. - The Kvarkovy model appeared earlier, than many hadron particles became known, but all of them perfectly fitted into it. - The Kvarkovy model assumed some consequences which then were confirmed experimentally. For example, in hadron colliders it became possible "to beat out" quarks from protons at high-energy collisions, and results of these processes were observed in the form of streams. If the proton was an indivisible particle, no streams could exist. Certainly, despite experimental confirmations, the model of quarks still leaves to physics many questions.