How Can Point Particles Have Cross Sections?

In summary: I don't even know where to start. They have no spatial extent? If they didn't have cross sections, then they would simply fly past one another and not interact at all (i.e. the probability of an interaction would be infinitesimal). Is there any explanation as to how point particles like electrons or quarks or neutrinos can have non-zero cross sections?I don't know if standard particle physics is enough to answer this question. If concepts relating to QFT or other areas of physics are required, then the Mentors are free to move this thread to the appropriate forum.
  • #36
That's what I have shown. If you mean elastic scattering, then say that. Unfortunately that total cross section is infinite. If you ask for the differential cross section above some angle: That is finite, and so far it is simply falling with increasing energy as expected for point particles.
 
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  • #37
mfb said:
That's what I have shown. If you mean elastic scattering, then say that. Unfortunately that total cross section is infinite. If you ask for the differential cross section above some angle: That is finite, and so far it is simply falling with increasing energy as expected for point particles.
OK. Thanks. That is the most useful response so far and it answers my original query. Any 'bottom' of this potential well has not been found.
 

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