Mediation of the electromagnetic force

In summary, the authors show that any spin mediating the exchange of photons has an effect on the force between like charges.
  • #1
einKI
10
0
Hi

I have some problem to get insight into the mediation of the electromagnetic
force and hope someone here is able to help me.

If you look at the Standard Model there is the photon which acts on
electrically charged particles like electrons and quarks.
The electromagnetic force is pushing and pulling particles (compared to
gravity which only pulls).

But how is this pull/push information transmitted? The photon is
neutral charged. Is there any additional property that determines how
a photon acts on a negatively/positively charged particle?

Or I'm completely on the wrong path and the whole push/pull is only
a mechanism of the electromagnetic field not a single photon?

by
 
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  • #2
Has anybody thought about that ? I did not find an explanation which would satisfy me. Any hint, anybody ?
 
  • #3
A photon has no charge, but it does have momentum, so absorption or emission of ("virtual") photons by particles gives rise to a force (speaking very loosely) that may either be attractive or repulsive.

http://math.ucr.edu/home/baez/physics/Quantum/virtual_particles.html" is an explanation.
 
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  • #4
George Jones said:
A photon has no charge, but it does have momentum, so absorption or emission of ("virtual") photons by particles gives rise to a force (speaking very loosely) that may either be attractive or repulsive.
Thank you for the response. I will go to Baez's site. I have the feeling that the problem is due to the assimilation of a Feynman diagram as a real process. The sign in the calculation appears at the vertices. The photon itself, with its propagator, does not "carry" information on the charge.

But diagrams are not real processes, so we must not worry about the minutes of those calculations...

Well, I do not find the answer completely satisfactory. I'll go read Baez :-) Thanks again !
 
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  • #5
Well, thank you very much for pointing me to Baez's site. The answer is totally satisfying. As you said, the paradox lies in the fact that virtual particle exchange can lead to attraction, contrary to the classical picture. Although it is not stated exactly in this manner, I still think the OP should be advised not to think of Feynman diagrams as real processes. Read the link is definitely the best advice in any case.
 
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  • #6
Hi

the link is indeed very good to understand the attractive force in QED.
thx you for that.

by
 
  • #7
If you do not want to go through Baez's discussion, the point I recall from it is the following : the information on +/- or -/- charges is not carried by the photon. In the calculation, it appears in the interference between the amplitudes at first order (one photon exchange) and zeroth order (no interaction). If you just look at the Feynman diagram, you only have one photon exchange and you can not get the attraction or repulsion.

It is very important from time to time to ask basic questions :smile:
 
  • #8
I found an article tackling the problem for any spin of the exchanged boson :

Attraction/repulsion between like charges and the spin of the classical mediating field
Phys. Rev. D 33, 2475 - 2477 (1986)
 

What is the electromagnetic force?

The electromagnetic force is a fundamental force of nature that describes the interaction between electrically charged particles. It is responsible for the attraction and repulsion between charged particles, and it also governs the behavior of electric and magnetic fields.

How is the electromagnetic force mediated?

The electromagnetic force is mediated by particles called photons. Photons are massless particles that carry the electromagnetic force between charged particles. They act as the "force carriers" of the electromagnetic force.

What is the role of the electromagnetic force in everyday life?

The electromagnetic force plays a crucial role in everyday life. It is responsible for the functioning of electronic devices, such as computers and smartphones, as well as the transmission of electricity through power lines. It also governs the behavior of light and other electromagnetic waves, which are essential for vision and communication.

How does the strength of the electromagnetic force compare to other fundamental forces?

The strength of the electromagnetic force is significantly stronger than the other fundamental forces, such as gravity and the weak and strong nuclear forces. It is approximately 10^36 times stronger than the force of gravity.

Can the strength of the electromagnetic force be altered?

Yes, the strength of the electromagnetic force can be altered by changing the charge or distance between charged particles. For example, increasing the charge of a particle will increase the strength of the electromagnetic force between it and other charged particles. Additionally, changing the distance between charged particles can also affect the strength of the force, as it follows an inverse-square law.

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