vector boson

In particle physics, a vector boson is a boson with the spin quantum number equal to 1.

The vector bosons considered to be elementary particles are the gauge bosons or, the force carriers of fundamental interactions: the photon of electromagnetism, the W and Z bosons of the weak interaction, and the gluon of the strong interaction. There also exist composite particles that are vector bosons, such as the vector mesons, made of a quark and antiquark. For some time, through the 1970s and '80s, intermediate vector bosons, vector bosons of "intermediate" mass, was a major topic in high energy physics.^{[citation needed]}

Explanation

The name vector boson arises from quantum field theory. The component of such a particle's spin along any axis has the three eigenvalues −ħ, 0, and +ħ (where ħ is the reduced Planck constant), meaning that any measurement of it can only yield one of these values. (This is, at least, true for massive vector bosons; the situation is a bit different for massless particles such as the photon, for reasons beyond the scope of this article.^{[citation needed]}) The space of spin states therefore has three degrees of freedom, the same as the number of components of a vector in three-dimensional space. Quantum superpositions of these states can be taken such that they transform under rotations just like the spatial components of a rotating vector. If the vector boson is taken to be the quantum of a field, the field is a vector field, hence the name.

See also

• Pseudovector meson
• Scalar boson

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