How diverse elementary particles are so diverse and their characteristics.It is based on the characteristics and the classification of elementary particles.
One of the most important indicators - is the weight.It is important to take into account is the rest mass of the particle motion at the moment because, especially at high speeds, it is greatly increased.Sometimes, without taking into account this fact, some scientists announce the discovery of new particles, but had to deal with the long-known.The unit of reference is considered to be a rest mass of the electron, as it is the easiest of them.In our time, classification of particles according to their rest masses as follows:
- photons that have no rest mass, because they are constantly moving with the speed of light;
- light particles - leptons, which include electrons and neutrinos;
- medium particles that weigh from one to a thousand electron mass;
- heavy - baryons, having a mass of more than a thousand of mass of the electron, which include neutrons, protons, Hyperion.
following characteristics that established the classification of elementary particles - their electrical charge.He is a multiple of the charge of an electron (-1) always.According to this characteristic of all particles are divided into positively charged, negatively charged, and zero charge.It is also the existence of particles with fractional charge.
Another characteristic for which established the classification of elementary particles - their life:
- stable particles, to which relate the electron neutrino, photon and proton, neutron is stable as long as there is a part of the nucleus of the atom, andin a free state it disintegrates within 15 minutes;
- unstable particles - all others.Life time at which 10 (-10) - 10 (-24) seconds, and the particles with the shortest life span - resonances collapsing even before time to leave the atom or atomic nucleus.They live 10 (-25) - 10 (-26) seconds.Although the existence of such particles is calculated theoretically, but practically no one is registered.The human life is the most important role to play, of course, stable particles, after all of them, and built all the macroscopic body.
following classification characteristic - the type of interaction:
- leptons - particles that participate only in weak and electromagnetic interactions;
- hadrons - particles is that, in addition to the above, and even take part in strong interactions.
But the most important characteristics of elementary particles - is the spin (the description of the particle momentum).This value in classical mechanics describes the characteristics of rotation of the body.But physics, considering the properties of elementary particles, the spin is characterized differently - as the internal degrees of freedom of the particles.He can only take positive values, which are proportional to Planck's constant, in contrast to the spin mechanics that can take any value.The coefficient expresses its proportionality is called the spin quantum number.For some particles, it can have integer (0, 1, 2), while the other - the half-integer (1/2, 3/2) values.Particles having a 0-tion spin, looks the same when you turn it from any angle, spin per unit - takes the same view after turning it 360 degrees, and from the back to 2 - After turning 180 degrees with a spin in ½ -720 degrees.All particles with a non-integer values of spin are called - fermions.These are all commonly known particles, such as protons, electrons and neutrons.Their backs is 1/2.And with integer - bosons.These substances, in fact, are quanta of fields, but even with particle properties, still serve as the fields in the classical limit.A striking example of bosons is the photon, in which the spin is 1, and mesons with zero spin.
