Solving Scattering Problem: Get Help with Phase Shift Delta

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Discussion Overview

The discussion revolves around a problem in scattering theory, specifically related to the phase shift \(\delta\) in the context of scattering by a square well potential. Participants are exploring discrepancies between expected and derived behaviors of the phase shift as a function of particle energy, particularly at small energies.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant expresses confusion regarding their derivation of the phase shift \(\delta\) and requests hints to resolve the issue.
  • Another participant suggests that the phase shift may have jumped by \(\pi\) at the energy where a bound state appears, indicating a potential source of the discrepancy.
  • A participant notes that the figure does not display the expected behavior at small energies and seeks further insights into their derivation.
  • One participant questions the clarity of another's statements regarding their derivation and suggests that the figure aligns with expected textbook results.
  • Another participant acknowledges that while the figure appears textbook-like, the process of deriving it is challenging.

Areas of Agreement / Disagreement

Participants express differing views on the correctness of the derivation and the behavior of the phase shift at small energies. There is no consensus on the source of the discrepancies or the correctness of the derivations presented.

Contextual Notes

Participants have not resolved the assumptions underlying the derivations, and there are unresolved mathematical steps regarding the behavior of the phase shift at small energies.

ftft
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hi all,

I am facing a confusing problem with scattering theory and any hint would be greatly appreciated..
In the famous scattering by a square well problem the phase shift\delta is a smooth curve in the particle energy... but what I get from my own derivation is not exactly as it should be (see attached file)...

any hint?

 

Attachments

  • delta0at50.jpeg
    delta0at50.jpeg
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Your phase shift has jumped by pi, probably at the energy where a bound state appears.
The bound state pulls the wave function in, changing the phase by pi.
 
Thank you.. however the figure doesn't show the expected behaviour at small energies...
I attached a pdf file showing what I did exactly, hoping that somebody will discover what the problem is in my derivation..
I am really desperate to know..
 

Attachments

Last edited:
"I couldn't get the correct behavior of the curve at small energies E at any
value of the potential.
I think my derivation is correct and also my variable…. So why doesn't it
give me the supposed figures? Where is the error?"

I don't know what you mean by the above statements.
Your figure in the thumbnail looks like what I would expect.
I can't (won't) go through your steps in detail, but they seem like what I have seen in textbooks.
 
exactly, it seems like is given in textbooks.. but getting through it is another thing
 

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