What is the difference between photons from annihilation and normal photons?

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In summary, When an electron and a positron collide, they can produce a pair of photons, muons, tauons, or even transmute into each other. These end products are considered real particles, regardless of whether they are photons or other particles. The difference between a virtual and a real particle is that virtual particles are hypothesized to exist in order to explain interactions, but cannot be observed directly. Additionally, while a real photon can be produced in a weak interaction, a single real photon cannot be produced in an electron-positron collision due to momentum conservation. However, it is possible for two photons to be produced through a t-channel process.
  • #1
guapig
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:confused: when an electron meets a positron, both the electron and the positron cease to exist, and pure light comes flying out,and then the photon(light) will decay into a [tex]\mu^- \mu^+[/tex] .

MY question is what is the difference between the photon that comes from the annihilation and a normal photon which will not decay at all.

Thanks.
GUAPIG: any reply would be greatly appreciated.
 
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  • #2
You have things a little muddled. Electron-positron collisions produce a pair of photons, OR a pair of muons, OR - if you're lucky - a pair of tauons, or you can even get the two to transmute into one another. I believe the intermediate between all these is a virtual weak boson, but I could be misremembering.

The answer to your actual question is that there is no difference between the end products and an actual photon - because the end products ARE unambiguously real photons, or muons, or whatever.

If you're asking what the difference is between a virtual weak boson and a 'real' weak boson, there isn't as such. Virtual particles are those which are not observed but are hypothesised to exist in order to carry out interactions such as these, and as such vanish too quickly to observe.
 
  • #3
Sorry,my English is bad,I could not express my idea clearly.But I really THank you Sojourner01.

maybe it is like this.When an electron-positron collision is occurring,we may get something as you said,but it is just possibility.

but I still have something unsure.I will try to work out.
THANKS AGAIN
 
  • #4
I assume you are talking about the s-channel process.

Indeed a phonton could appear in the Feymann diagram as an intermediate line, however it is a virtual photon instead of a real one. This is the case in QED.
As for weak interaction, the intermediate particle could also be a Z boson. Sometimes you will hear people talk about "on-shell" decay which means a real Z boson is created then decays. "off-shell" decay can also happen, where the Z is no longer phisical but "virtual".

Actually e+e- can not collider together can produce a single real photon. Just write the 4-momentum conservation and you can easily see that. As for a massive boson, Z in this case, such a process is possible.

However the e+e- -> 2 photon is possible through t-channel,as sojourner explained. Or check it out here
http://en.wikipedia.org/wiki/Electron-positron_annihilation
 

1. What is a photon?

A photon is a unit of light, also known as an elementary particle. It is the smallest possible unit of light and has properties of both a wave and a particle.

2. How do we detect photons?

Photons can be detected using specialized instruments such as photomultiplier tubes or photodiodes. These instruments are designed to convert light energy into electrical signals that can be measured and recorded.

3. Do all photons have the same energy?

No, not all photons have the same energy. The energy of a photon is directly related to its frequency, so photons with different frequencies will have different energies. This can be observed in the different colors of light, each corresponding to a different frequency and energy.

4. Can we create or destroy photons?

Photons cannot be created or destroyed, but they can be converted into other forms of energy. For example, when a photon is absorbed by an atom, it can cause an electron to move to a higher energy level. When the electron returns to its original level, it releases a new photon with the same energy as the original one.

5. Do all photons travel at the same speed?

Yes, all photons travel at the speed of light in a vacuum, which is approximately 299,792,458 meters per second. This is a fundamental constant in the universe and is the maximum speed at which anything can travel.

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