Do anti-particles have opposite parity?

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In summary, the conversation discussed the relationship between anti-particles and particles, specifically in terms of their charge and parity. It was mentioned that anti-particles have opposite charge and parity to their corresponding particles. However, it was clarified that this is not always the case for mesons, as their spin-parity includes contributions from both intrinsic properties and orbital wavefunctions. It was also noted that gauge bosons and fermions have different rules for determining parity. Finally, the concept of charge conjugation and its effects on parity were discussed.
  • #1
johne1618
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Hi,

I understand that anti-particles have the opposite charge to particles.

Do anti-particles have the opposite parity to particles as well?

John
 
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  • #2
Anti-particles have not only charge, but all their conservation numbers, among them charge and parity, opposite to their "normal" particles.
 
  • #3
Thanks!
 
  • #4
Actually, is that right?

I looked on hyperphysics and it said only the "internal" quantum numbers are reversed under charge conjugation not the spatial coordinates.

John
 
  • #5
johne1618 said:
I looked on hyperphysics and it said only the "internal" quantum numbers are reversed under charge conjugation not the spatial coordinates.
Sure! You're right. I gave too quick answer...
Parity of compound particle (e.g. hadrons) is composed (multiplicatively) of internal parities of quarks and the parity of their relative geometry. The last do not differ from particle to anti-particle.
So both mesons and their anti-mesons have same parity ([itex]-1^{spin+1}[/itex]). Baryons, as composed of 3 quarks, have parity +1, while their counterparts have -1.
 
  • #6
So both mesons and their anti-mesons have same parity (−1)spin+1
Still too quick. There are plenty of mesons that obey this rule, and plenty more that do not. The spin-parity of a meson includes contributions from both the intrinsic properties of the quarks and the orbital wavefunction as well. Take a look at a list of the charmonium and bottomonium states.
 
  • #7
The parity of meson considered as q-qbar bound states is (-1)^L+1.
The spin of the meson equals L if the q-qbar are in a spin zero state, but can be different if the q-qbar are in a spin 1 state. Gauge bosons have negative intrinsic parity.
The parity of a boson antiparticle is the same as the particle.
 
  • #8
Fermions have only relative parity. For instance, the intrinsic relative parity of the proton and antiproton is negative.
 
  • #9
So, when in texts it refers to applying charge conjuction (C) as replacing a particle with its antiparticle... this isn't strictly true? As particles whose antiparticle has opposite parity, would need you to apply CP to the particle to get the antiparticle?
 
  • #10
An antimeson has the same parity as the corresponding meson.
A fermion.s only has relative parity with another fermion or its antifermion.
The relative parity of the proton and antiproton is negative.
The relative parity of the nucleon and the and the Delta is positive.
Relative parity of a nucleon and the Lambda cannot be defined because parity is not conserved in Lambda decay.
 

1. What are anti-particles?

Anti-particles are particles that have the same mass and spin as their corresponding particles, but with opposite electric charge. They are the mirror image of particles and have the same properties except for their opposite charge.

2. What is parity in physics?

Parity in physics refers to the symmetry of a physical system under spatial inversion. In other words, if the system is flipped or reflected, its properties remain the same. Parity is a fundamental property of particles and is used to classify them as either even or odd.

3. How do anti-particles have opposite parity?

Anti-particles have opposite parity because they are mirror images of particles. This means that if a particle has even parity, its anti-particle will have odd parity and vice versa. This is due to the fact that they have opposite electric charge, which is a property that is affected by spatial inversion.

4. Why is the concept of opposite parity important?

The concept of opposite parity is important because it plays a crucial role in the conservation laws of particle physics. The conservation of parity states that the total parity of a system must remain the same before and after a particle interaction. This helps to explain certain phenomena, such as the decay of particles, and is fundamental in understanding the behavior of particles and anti-particles.

5. How is the opposite parity of anti-particles experimentally observed?

The opposite parity of anti-particles can be experimentally observed through various methods, such as particle accelerators and detectors. By studying the trajectory and interactions of particles and anti-particles, scientists can determine their properties, including their parity. Additionally, certain particle interactions, such as the decay of a particle into its anti-particle, can also demonstrate the opposite parity of anti-particles.

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