Is the Photon Really Its Own Antiparticle?

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Discussion Overview

The discussion revolves around the concept of whether the photon is its own antiparticle, exploring related properties of other particles and the implications of particle-antiparticle relationships in theoretical physics. The scope includes theoretical considerations, particle classification, and symmetry principles.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants assert that the photon is an antiparticle of itself, questioning the necessity of distinct antiparticles for all particles.
  • Others argue that not all force carriers share this property, citing the W+ and W- bosons as examples of particles that are distinct from their antiparticles.
  • A participant mentions that the neutral pion (π°) is its own antiparticle.
  • There is a discussion about Majorana particles, with some stating that only Majorana bosons are known, while others suggest that neutrinos might be Majorana fermions.
  • Concerns are raised about the photon’s inability to self-couple, which some argue is relevant to its classification as an antiparticle.
  • Participants discuss the role of C, P, and T symmetries in classifying particles and antiparticles, with some seeking clarification on these concepts.
  • There is a debate regarding whether gluons are their own antiparticles, with differing views on their color combinations and the implications for particle classification.
  • The Higgs boson is mentioned as potentially being its own antiparticle, though this is noted to depend on the model and assumptions about its existence.
  • Some participants highlight that for real scalar fields, the particle and antiparticle can be the same, while others point out that being real is not a sufficient condition for this property.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the photon and other particles being their own antiparticles, with no consensus reached on the implications of self-coupling or the role of symmetries in this classification.

Contextual Notes

There are unresolved mathematical steps and assumptions regarding the classification of particles and antiparticles, particularly concerning the implications of symmetry operations and the nature of specific particles like gluons and the Higgs boson.

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

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).
 


the neutral pion π° is its own antiparticle
 


i heard that force carrier's have this property.
 


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


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.
 


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


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


thedemon13666 said:
The photon can not be as it does not self-couple
For the classicfication of particles and antiparticles in terms of C, P- and T-symmetry this is irrelevant
 
  • #10


after all what is this c,p,t symmetry means?
 
  • #11


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

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

You need them to classify particles and antiparticles mathematically
 
  • #12


Hi,

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

Ofir
 
  • #13


No. A gluon has a color combination, such Red-AntiBlue. Its antiparticle would be
AntiRed-Blue. The Z is its own antiparticle.
 
  • #14


Hi,

Thanks for your reply

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


More than mathematics what is this symmetry?
 
  • #16


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


the higgs boson is its own antiparticle.
 
  • #18


in the simplest model - and iff it exists ;-)
 
  • #19


yes. i just wanted to point out that whenever your field is real, the antiparticle is the same as the particle.
 
Last edited:
  • #20


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


The photon is in the vector representation, being described by the 4-potential A_\mu(x), but it is still real.
 
  • #22


yes, but being real is not sufficient as you can see when looking at W±
 
  • #23


tom.stoer said:
yes, but being real is not sufficient as you can see when looking at W+ and W-

So, does it have to transform according to the trivial representation of the operation \mathit{C}?
 
  • #24


I would say 'yes'
 

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