Do anti-particles have opposite parity?

  • Thread starter johne1618
  • Start date
  • #1
370
0
Hi,

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

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

John
 

Answers and Replies

  • #2
xts
882
0
Anti-particles have not only charge, but all their conservation numbers, among them charge and parity, opposite to their "normal" particles.
 
  • #3
370
0
Thanks!
 
  • #4
370
0
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
xts
882
0
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
Bill_K
Science Advisor
Insights Author
4,157
201
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
Meir Achuz
Science Advisor
Homework Helper
Gold Member
3,533
114
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
Meir Achuz
Science Advisor
Homework Helper
Gold Member
3,533
114
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
Meir Achuz
Science Advisor
Homework Helper
Gold Member
3,533
114
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.
 

Related Threads on Do anti-particles have opposite parity?

  • Last Post
Replies
6
Views
14K
Replies
3
Views
2K
Replies
8
Views
2K
  • Last Post
Replies
2
Views
4K
  • Last Post
Replies
2
Views
4K
Replies
4
Views
3K
Replies
2
Views
794
  • Last Post
Replies
8
Views
1K
  • Last Post
Replies
22
Views
5K
  • Last Post
Replies
15
Views
2K
Top