X and Y bosons
In particle physics, the X and Y bosons (sometimes collectively called "X bosons": 437 ) are hypothetical elementary particles analogous to the W and Z bosons, but corresponding to a unified force predicted by the Georgi–Glashow model, a grand unified theory (GUT).
| Composition | Elementary particle |
|---|---|
| Statistics | Bosonic |
| Family | Gauge boson |
| Status | Hypothetical |
| Types | 12 |
| Mass | ≈ 1015 GeV/c2 |
| Decays into | X: two quarks, or one antiquark and one charged antilepton Y: two quarks, or one antiquark and one charged antilepton, or one antiquark and one antineutrino |
| Electric charge | X: ±4/3 e Y: ±1/3 e |
| Color charge | triplet or antitriplet |
| Spin | 1 |
| Spin states | 3 |
| Weak isospin projection | X: ±1/2 Y: ∓1/2 |
| Weak hypercharge | ±5/6 |
| B − L | ±2/3 |
| X | 0 |
Since the X and Y boson mediate the grand unified force, they would have unusual high mass, which requires more energy to create than the reach of any current particle collider experiment. Significantly, the X and Y bosons couple quarks (constituents of protons and others) to leptons (such as positrons), allowing violation of the conservation of baryon number thus permitting proton decay.
However, the Hyper-Kamiokande has put a lower bound on the proton's half-life as around 1034 years. Since some grand unified theories such as the Georgi–Glashow model predict a half-life less than this, then the existence of X and Y bosons, as formulated by this particular model, remain hypothetical.