X and Y bosons

X and Y bosons

Composition	Elementary particle
Statistics	Bosonic
Status	Hypothetical
Types	12
Mass	≈ 10^15 GeV/c^2
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	5/3
B − L	2/3

In particle physics, the X and Y bosons (sometimes collectively called "X bosons"^[1]) are hypothetical elementary particles analogous to the W and Z bosons, but corresponding to a new type of force predicted by the Georgi–Glashow model, a grand unified theory.

Details

The X and Y bosons couple quarks to leptons, allowing violation of the conservation of baryon number, and thus permitting proton decay.

An X boson would have the following decay modes:^[2]

X
→
u
+
u

X
→
e+
+
d

where the two decay products in each process have opposite chirality,
u
is an up quark,
d
is a down quark and
e+
is a positron.

A Y boson would have the following decay modes:^[2]

Y
→
e+
+
u

Y
→
d
+
u

Y
→
d
+
ν
e

where the first decay product in each process has left-handed chirality and the second has right-handed chirality and
ν
e is an electron antineutrino.

Similar decay products exist for the other quark-lepton generations

In these reactions, neither the lepton number (L) nor the baryon number (B) is conserved, but B − L is. Different branching ratios between the X boson and its antiparticle (as is the case with the K-meson) would explain baryogenesis.

See also

• B − L
• Grand unification theory
• Proton decay
• W' and Z' bosons
• Leptoquark

References

1. Ta-Pei Cheng; Ling-Fong Li (1983). Gauge Theory of Elementary Particle Physics. Oxford University Press. p. 437. ISBN 0-19-851961-3.
2. Ta-Pei Cheng; Ling-Fong Li (1983). Gauge Theory of Elementary Particle Physics. Oxford University Press. p. 442. ISBN 0-19-851961-3.