Gauge boson

The conflict between this idea and experimental evidence that the weak and strong interactions have a very short range requires further theoretical insight.

This theory also predicts the existence of a scalar Higgs boson, which has been observed in experiments at the LHC.

The hypothetical X and Y bosons mediate interactions between quarks and leptons, hence violating conservation of baryon number and causing proton decay.

Analysis of data collected from such sources as the Super-Kamiokande neutrino detector has yielded no evidence of X and Y bosons.

[citation needed] The fourth fundamental interaction, gravity, may also be carried by a boson, called the graviton.

In the absence of experimental evidence and a mathematically coherent theory of quantum gravity, it is unknown whether this would be a gauge boson or not.