This article is about bosons of a hypothetical new interaction. For mesons with the same names, see XYZ particle. X± and Y± bosonsComposition| 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 In particle physics, the X and Y bosons (sometimes collectively called "X bosons"[1]: 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). 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 Super-Kamiokande has put a lower bound on the proton's half-life as around 1034 years.[2] 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. ## Details[edit] An X boson would have the following two decay modes:[1]: 442 + -> L \+ + -> L \+ where the two decay products in each process have opposite chirality, is an up quark, is a down antiquark, and is a positron. A Y boson would have the following three decay modes:[1]: 442 + -> L \+ + -> L \+ + -> L \+ where is an up antiquark and e is an electron antineutrino. The first product of each decay has left-handed chirality and the second has right-handed chirality, which always produces one fermion with the same handedness that would be produced by the decay of a W boson, and one fermion with contrary handedness ("wrong handed"). Similar decay products exist for the other quark-lepton generations. In these reactions, neither the lepton number (L) nor the baryon number (B) is separately conserved, but the combination B − L is. Different branching ratios between the X boson and its antiparticle (as is the case with the K-meson) would explain baryogenesis. For instance, if an + / − pair is created out of energy, and they follow the two branches described above: + -> L \+ R , − -> L \+ R ; re-grouping the result ( ) + shows it to be a hydrogen atom. ### Origin[edit] The X± and Y± bosons are defined respectively as the six Q = ± 4/3 and the six Q = ± 1/3 components of the final two terms of the adjoint 24 representation of SU(5) as it transforms under the standard model's group: 24 -> ( 8 , 1 ) 0 ⊕ ( 1 , 3 ) 0 ⊕ ( 1 , 1 ) 0 ⊕ ( 3 , 2 ) − 5 6 ⊕ ( 3 ¯ , 2 ) 5 6 {\displaystyle \mathbf {24} \rightarrow (8,1)_{0}\oplus (1,3)_{0}\oplus (1,1)_{0}\oplus (3,2)_{-{\frac {5}{6}}}\oplus ({\bar {3}},2)_{\frac {5}{6}}} . The positively-charged X and Y carry anti-color charges (equivalent to having two different normal color charges), while the negatively-charged X and Y carry normal color charges, and the signs of the Y bosons' weak isospins are always opposite the signs of their electric charges. In terms of their action on C 5 , {\displaystyle \ \mathbb {C} ^{5}\ ,} X bosons rotate between a color index and the weak isospin-up index, while Y bosons rotate between a color index and the weak isospin-down index. ## See also[edit] * B − L * Grand unification theory * Leptoquark * Proton decay * W' and Z' bosons ## References[edit] 1. ^ a b c Ta-Pei Cheng; Ling-Fong Li (1983). Gauge Theory of Elementary Particle Physics. Oxford University Press. ISBN 0-19-851961-3. 2. ^ "Proton Decay Searches: Hyper-Kamiokande". www.hyper-k.org. 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