# Photon's antiparticle

1. Feb 3, 2012

### sreerajt

Photon's antiparticle!!!

It's said that photon is an antiparticle of itself. Also there are some particle following this property. How is this happening?

2. Feb 3, 2012

### Pengwuino

Re: Photon's antiparticle!!!

Who says everything has to have a separate, distinguishable anti-particle? There is no reason to assume such a thing must happen. I don't know any other particles that are their own anti-particles (although there are theories that neutrinos may be their own anti-particles but this has not been experimentally shown and is not currently an accepted idea).

3. Feb 3, 2012

### tom.stoer

Re: Photon's antiparticle!!!

the neutral pion π° is its own antiparticle

4. Feb 3, 2012

### sreerajt

Re: Photon's antiparticle!!!

i heard that force carrier's have this property.

5. Feb 3, 2012

### Staff: Mentor

Re: Photon's antiparticle!!!

Not all of them. The W+ and W- are antiparticles.

6. Feb 4, 2012

### VreemdeGozer

Re: Photon's antiparticle!!!

A particle that is it's own anti-particle is called a Majorana particle (and is elementary). (http://en.wikipedia.org/wiki/Majorana_particle)

Currently, only Majorana bosons are known to exist, although, the neutrino might be a Majorana fermion.

7. Feb 4, 2012

### clem

Re: Photon's antiparticle!!!

I have never seen (until now) the term 'Majorana bosons' used, because the Majorana equation applies only to fermions.

8. Feb 5, 2012

### thedemon13666

Re: Photon's antiparticle!!!

The photon can not be as it does not self-couple

9. Feb 5, 2012

### tom.stoer

Re: Photon's antiparticle!!!

For the classicfication of particles and antiparticles in terms of C, P- and T-symmetry this is irrelevant

10. Feb 6, 2012

### sreerajt

Re: Photon's antiparticle!!!

after all what is this c,p,t symmetry means?

11. Feb 7, 2012

### tom.stoer

Re: Photon's antiparticle!!!

C = Charge conjugation
P = Parity (space inversion)
T = Time inversion

You need them to classify particles and antiparticles mathematically

12. Feb 7, 2012

### ofirg

Re: Photon's antiparticle!!!

Hi,

The Z boson and gluon are also there own antiparticle, right?

Ofir

13. Feb 7, 2012

### clem

Re: Photon's antiparticle!!!

No. A gluon has a color combination, such Red-AntiBlue. Its antiparticle would be
AntiRed-Blue. The Z is its own antiparticle.

14. Feb 7, 2012

### ofirg

Re: Photon's antiparticle!!!

Hi,

I agree that a gluon with a specific color combination could have an antiparticle with a different color. However, the resulting color would be a linear combination of the colors of the gluons, with no need for antigluons. I believe that the gluon, as a color octet, is its own antiparticle.

For example, in supersymmetry, there is a hypothetical particle called the gluino. It has the same charges as the gluon but is spin half. It is treated as a majorana fermion, therefore its own antiparticle.

Ofir

15. Feb 7, 2012

### sreerajt

Re: Photon's antiparticle!!!

More than mathematics what is this symmetry?

16. Feb 8, 2012

### tom.stoer

Re: Photon's antiparticle!!!

what do you mean? which symmetry?

the symmetry of the quarks and gluons is called SU(3); it describes a rotation in a 3-dim. vector complex space; therefore when constructing this SU(3) one finds that there are 8 angles for rotations (instead of 3 as for rotations in a 3-dim. real vector space)

17. Feb 8, 2012

### Dickfore

Re: Photon's antiparticle!!!

the higgs boson is its own antiparticle.

18. Feb 8, 2012

### tom.stoer

Re: Photon's antiparticle!!!

in the simplest model - and iff it exists ;-)

19. Feb 8, 2012

### Dickfore

Re: Photon's antiparticle!!!

yes. i just wanted to point out that whenever your field is real, the antiparticle is the same as the particle.

Last edited: Feb 8, 2012
20. Feb 8, 2012

### tom.stoer

Re: Photon's antiparticle!!!

Good point; this is due to the fact that for a real scalar field the operator C for charge conjugation reduces obviously to the identity, i.e. C=1

21. Feb 8, 2012

### Dickfore

Re: Photon's antiparticle!!!

The photon is in the vector representation, being described by the 4-potential $A_\mu(x)$, but it is still real.

22. Feb 8, 2012

### tom.stoer

Re: Photon's antiparticle!!!

yes, but being real is not sufficient as you can see when looking at W±

23. Feb 8, 2012

### Dickfore

Re: Photon's antiparticle!!!

So, does it have to transform according to the trivial representation of the operation $\mathit{C}$?

24. Feb 8, 2012

### tom.stoer

Re: Photon's antiparticle!!!

I would say 'yes'