Are all of the quantum numbers of anti-particles opposite

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Discussion Overview

The discussion centers on the quantum numbers of anti-particles in relation to their corresponding particles. Participants explore whether various quantum numbers, such as strangeness, spin, and parity, are opposite for anti-particles compared to particles. The scope includes theoretical considerations of particle physics.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant questions if all quantum numbers of anti-particles are opposite to those of particles, specifically mentioning lepton numbers and charge.
  • Another participant asserts that strangeness is opposite for anti-particles, while spin and its projection do not change. They also note that parity is defined for the particle-antiparticle pair for fermions and that the parity of an antiboson is the same as that of the boson.
  • A third participant suggests that a more accurate statement would be that "antiparticles have negative INTERNAL quantum numbers," distinguishing between internal quantum numbers (like electric charge and strangeness) and spacetime quantum numbers (like mass and momentum).

Areas of Agreement / Disagreement

Participants express differing views on the nature of quantum numbers, with some agreeing on specific oppositional relationships (like strangeness) while others introduce distinctions between internal and spacetime quantum numbers. The discussion remains unresolved regarding the broader implications of these distinctions.

Contextual Notes

Participants do not fully resolve the definitions of internal versus spacetime quantum numbers, leaving some assumptions about the implications of these classifications unaddressed.

Radiohannah
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Hey

Just wondering-

Are all of the quantum numbers of anti-particles opposite to their corresponding particle quantum numbers?

I know that lepton numbers are opposite for particles and anti particles
As is charge...

But what about the quantum numbers like strangeness, spin, parity etc etc?

Are they opposite too?

Cheers
 
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Radiohannah said:
Hey
But what about the quantum numbers like strangeness, spin, parity etc etc?
S is opposite.
Spin and spin projection doesn't change.
Parity is defined for the particle-antiparticle pair for fermions.
It is negative for fermion-antifermion,
Parity of an antiboson is the same as for the boson.
 
Last edited by a moderator:


i suppose the correct statement would be "antiparticles have negative INTERNAL quantum numbers". Here, the word "INTERNAL" means not spacetime.

Examples of "internal QN": electric charge, strangeness, baryon number...

Examples of "spacetime QN": mass, momentum, helicity...
 


that's cleared a lot up, thanks guys :-)
 

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