Are all of the quantum numbers of anti-particles opposite

In summary, the quantum numbers of antiparticles are generally opposite to those of their corresponding particles, including lepton numbers and electric charge. However, for other quantum numbers like strangeness, spin, and parity, the opposites are not always straightforward. Spin and spin projection remain the same, while parity is defined differently for fermions and bosons. Antiparticles have negative internal quantum numbers, while spacetime quantum numbers are the same for both particles and antiparticles.
  • #1
Radiohannah
49
0
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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  • #2


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:
  • #3


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...
 
  • #4


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

1. What are quantum numbers in physics?

Quantum numbers are a set of numerical values that describe the properties of a quantum system, such as the energy, spin, and angular momentum of a particle.

2. What is an anti-particle?

An anti-particle is the antiparticle counterpart to a particle, having the same mass and spin as the particle but opposite charge and other quantum numbers.

3. Are all of the quantum numbers of anti-particles opposite to those of particles?

Yes, all quantum numbers of anti-particles are opposite to those of particles. This includes charge, spin, lepton number, baryon number, and flavor quantum numbers.

4. Why are the quantum numbers of anti-particles opposite?

According to the CPT theorem in physics, the combined operation of charge conjugation (C), parity reversal (P), and time reversal (T) must leave the laws of physics unchanged. Therefore, the quantum numbers of anti-particles must be opposite to those of particles in order to maintain the balance of these operations.

5. What are the implications of opposite quantum numbers for anti-particles?

The opposite quantum numbers of anti-particles have significant implications in particle interactions and decays. It allows for the conservation of certain quantum numbers, such as the total charge and lepton number, in particle interactions and decays involving anti-particles. This also leads to the existence of antimatter, which plays a crucial role in our understanding of the universe.

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