Scalar boson
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A scalar boson is a boson whose spin equals zero.
[edit] Explanation
The name "scalar boson" arises from quantum field theory. The spin component of such a particle along any axis will always have only one possible value: 0. The space of spin states therefore has one degree of freedom. Now a mathematical scalar has one dimension. If the scalar boson is taken to be the quantum of a field, the field is a scalar field; hence the name.
Examples of scalar bosons include certain mesons, and most famously, the Higgs boson, the only elementary particle predicted by the Standard Model that has eluded detection to date (March 2009). Most mesons, such as the pion, are pseudoscalar bosons.

