Deutron is a boson


The title of this article is ambiguous. For the Swedish handball player, see Matilda Boson.
The standard model with the bosons in red (representation without the Higgs boson)

Bosons (after the Indian physicist Satyendranath Bose) in the standard model of particle physics all particles are that meet the Bose-Einstein statistics. According to the spin statistics theorem, they have an integer spin, i.e. $ 0 \! \, $, $ \ Hbar $, $ 2 \ hbar $ etc. Clearly speaking, bosons are those particles that control the forces between the fermions, the matter particles , convey.

The bosons include:

Bosons are differentiated from fermions, which satisfy the Fermi-Dirac statistics and, according to the spin statistics theorem, have a half-integer spin. An elementary particle in three spatial dimensions is always either a boson or a fermion.

In very thin layers, i.e. two-dimensional systems, there are bosons and fermions as well as so-called anyons, which have their own quantum statistics.

Classification according to the spin

Bosons are called differently depending on the spin. The basis of this designation is its transformation behavior under actually orthochronous Lorentz transformations.

Higher level tensors (i.e. bosons with a spin> 2) are physically less relevant because they only appear as composite particles.

Macroscopic quantum states

A special property of bosons is that the quantum mechanical wave function does not change when two identical bosons are exchanged (phase factor +1). In contrast, if two of the same ones are interchanged, the same changes Fermions the sign of the wave function. The reason for the invariance of the wave function in the case of boson swapping is based on the relatively complicated spin statistics theorem.

One consequence is that bosons of the same type can be in the same place (within the uncertainty relation) at the same time. Several bosons then assume the same quantum state, they form macroscopic quantum states. Examples are:

Compound particles

Fermionic or bosonic behavior of composite particles can only be observed from a greater distance (compared to the system under consideration). On closer inspection (on an order of magnitude in which the structure of the components becomes relevant) it becomes apparent that a composite particle behaves according to the properties (spins) of the components. For example, two helium-4 atoms (bosons) cannot occupy the same space if the space under consideration is comparable to the internal structure of the helium atom (~ 10-10 m) is because the components of the helium-4 atom are themselves fermions. As a result, liquid helium has a finite density just like an ordinary liquid.

Supersymmetric bosons

In the model of elementary particles expanded by supersymmetry, there are further elementary bosons. Mathematically, for every fermion there is a boson as a supersymmetrical partner particle, a so-called one Sfermionso that the spin differs by ± 1/2 in each case. The super partners of the fermions are generally preceded by an additional S- named, so is called z. B. then the corresponding boson to the electron Selektron.

Strictly speaking, in the interaction picture each fermionic field is first assigned a bosonic field as a super partner. In the mass image, the observable or predicted particles result as linear combinations of these fields. The number and the relative proportion of the components contributing to the mixtures on the side of the bosonic superpartners do not have to match the proportions on the original fermionic side. In the simplest case (with little or no mixture), however, a particular boson or sfermion (such as the selectron) can be assigned to a fermion (such as the electron).

In addition, the minimal supersymmetric standard model (MSSM), in contrast to the standard model (SM), already requires several bosonic Higgs fields including their super partners.

So far none of the postulated supersymmetric partner particles has been experimentally proven. They must therefore have such a high mass that they do not arise under normal conditions. It is hoped that the new generation of particle accelerators will be able to detect at least some of these bosons. There are indications that the lightest supersymmetric particle (LSP) is in the range of a few hundred GeV / c².

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 Wiktionary: Boson - Explanations of meanings, word origins, synonyms, translations