Understanding Particle Mass Shells

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SUMMARY

A particle is considered to be "on its mass shell" when it satisfies the equation E² = (pc)² + (mc²)², where E represents energy, p is momentum, and m is mass. This condition applies to all real particles, confirming their physical existence. In contrast, virtual particles, used in Feynman diagrams for calculations, do not adhere to this equation and are thus classified as "off-mass-shell." Understanding this distinction is crucial for grasping concepts in quantum field theory.

PREREQUISITES
  • Basic understanding of quantum mechanics
  • Familiarity with Feynman diagrams
  • Knowledge of relativistic energy-momentum relations
  • Concept of virtual particles in quantum field theory
NEXT STEPS
  • Study the derivation of the energy-momentum relation E² = (pc)² + (mc²)²
  • Explore the role of virtual particles in quantum field theory
  • Learn about Feynman diagrams and their applications in particle physics
  • Investigate the implications of mass shell conditions in particle interactions
USEFUL FOR

Physicists, students of quantum mechanics, and anyone interested in the fundamentals of particle physics and quantum field theory.

captain
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what does it mean when somebody says that a particle is on its mass shell? I have somewhat but not full understanding of that.
 
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captain said:
what does it mean when somebody says that a particle is on its mass shell? I have somewhat but not full understanding of that.

Ahoy there captain! :smile:

All real particles are on the mass shell.

Only pretend particles can be off-mass-shell … you use them in Feynman-type calculations, and then forget about them. :wink:
 
A particle is on mass shell if E^2 = (pc)^2 + (mc^2)^2 holds. Virtual particles are off mass shell.
 

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