# Vector boson

In particle physics, a vector boson is a boson with the spin equal to 1. The vector bosons regarded as elementary particles in the Standard Model are the gauge bosons, which are the force carriers of fundamental interactions: the photon of electromagnetism, the W and Z bosons of the weak interaction, and the gluons of the strong interaction. Some composite particles are vector bosons, for instance any vector meson (quark and antiquark). During the 1970s and '80s, intermediate vector bosons—vector bosons of "intermediate"[clarification needed] mass—drew much attention in particle physics.[citation needed]

## Vector bosons and the Higgs

Certain vector bosons, i.e. the Z and W particles, play a prominent role in the recently announced (July 4, 2012)[1] scalar boson (perhaps the Higgs boson), as shown by the attached Feynman diagram.

Feynman diagram of the fusion of two electroweak vector bosons to the scalar Higgs boson, which is a prominent process of the generation of Higgs bosons at particle accelerators.
(The symbol q means a quark particle, W and Z are the vector bosons of the electroweak interaction. H0 is the Higgs boson.)

## Explanation

The name vector boson arises from quantum field theory. The component of such a particle's spin along any axis has the three eigenvaluesħ, 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.[2]) The space of spin states therefore is a discrete degree of freedom consisting of three states, 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[citation needed] (the so named 3 representation of SU(2)). If the vector boson is taken to be the quantum of a field, the field is a vector field, hence the name.