Heavy Quark-Antiquark Annihilations

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SUMMARY

Charm-anticharm quark-antiquark annihilations in relative S-wave with spin-1 do not result in the emission of a single photon due to violations of total 4-momentum conservation. Instead, these annihilations can produce a virtual photon, leading to the creation of dilepton pairs such as electron-positron (e+ e-) or muon-antimuon (μ+ μ-). This phenomenon was pivotal in the discovery of the J/ψ meson, which played a significant role in confirming the existence of charm quarks as predicted by the GIM mechanism in electroweak theory.

PREREQUISITES
  • Quantum Chromodynamics (QCD)
  • Understanding of S-wave and spin states
  • Knowledge of particle physics terminology, specifically quark-antiquark interactions
  • Familiarity with the GIM mechanism in electroweak theory
NEXT STEPS
  • Study the properties and implications of the J/ψ meson in particle physics
  • Explore the GIM mechanism and its role in the electroweak theory
  • Research the concept of virtual particles and their significance in quantum field theory
  • Learn about dilepton production processes in high-energy physics experiments
USEFUL FOR

Particle physicists, researchers in quantum field theory, and students studying the interactions of quarks and the implications of the GIM mechanism.

Naeem Anwar
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Does Charm-Anticharm (in relative S-wave with spin-1) annihilates to a single photon? How does this vertex look like in QCD?
 
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That would violate total 4-momentum conservation.
 
It can, however, got to a "virtual photon", i.e., a "dilepton" which is an ##e^+ e^-## or ##\mu^+ \mu^-## pair. This lead to the discovery of the ##J/\psi## ("The November Revolution") and thus the discovery of charm (expected from the GIM mechanism in electroweak theory):

https://en.wikipedia.org/wiki/J/psi_meson
 

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