What is the value of the pion-nucleon coupling constant?

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Discussion Overview

The discussion revolves around the value of the pion-nucleon coupling constant, particularly in the context of using the Yukawa potential for modeling two-nucleon systems, such as the deuteron. Participants explore the challenges of finding appropriate values for the scaling constant used in the Yukawa potential and its implications for numerical solutions of the Schrödinger equation.

Discussion Character

  • Technical explanation
  • Homework-related
  • Exploratory

Main Points Raised

  • One participant expresses uncertainty about the value of the scaling constant in the Yukawa potential, noting discrepancies in sources regarding its notation and units.
  • Another participant suggests a specific source for numerical values of the coupling constant, indicating that it may help resolve the original poster's issue.
  • There is a request for guidance on how to properly cite the source provided, highlighting the importance of referencing in academic work.
  • A later reply acknowledges the request for citation assistance and mentions a vague recollection of similar values found in a book, but does not specify which book.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the value of the pion-nucleon coupling constant, and the discussion remains unresolved regarding the appropriate scaling constant for the Yukawa potential.

Contextual Notes

Participants note the lack of clarity regarding the natural units used in various sources, which complicates the determination of the coupling constant's value. There is also mention of the need for the potential function to yield correct energy units, indicating a dependency on the definitions and assumptions made in the calculations.

Phi6er
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Links for context:
1. https://en.wikipedia.org/wiki/Yukawa_potential
2. https://en.wikipedia.org/wiki/Yukawa_interaction#Classical_potential

I'm working on my BSc right now and I'm solving the energies of 2 nucleon systems (so basically just deuteron) by treating them as non-relativistic two particle systems where the potential only depends on distance. The 3D Schrödinger-equation reduces into a one dimensional one with an effective potential, which I then solve numerically.

But I need nuclear potentials to plug in, of course! I've already used a sort of square well type of potential, so I thought I'd plug in a Yukawa potential next. Here's where the problem arises: I don't know what to use as the value of the scaling constant. In link 1, the mystery constant is notated as g2 and in link 2 it is notated as g2/4π. The constant is apparently called the "gauge coupling constant" between the meson and fermion fields.

I've yet to find a single source that bothers to mention what kind of natural units they use, so all the numerical values I've found for the constant are useless to me. I know the units of the constant obviously have to be units of energy times units of length, as that way the potential function itself spits out units of energy. I've even tried to guess the units based on this, but every time I get a potential that is either way too deep or too shallow compared to the square well type of potential that I used and hence know is reasonably close to the truth.

So yeah, I have no idea where to find the value of this mysterious constant. Does anyone here know what it is?
 
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Phi6er said:
Links for context:
1. https://en.wikipedia.org/wiki/Yukawa_potential
2. https://en.wikipedia.org/wiki/Yukawa_interaction#Classical_potential

I'm working on my BSc right now and I'm solving the energies of 2 nucleon systems (so basically just deuteron) by treating them as non-relativistic two particle systems where the potential only depends on distance. The 3D Schrödinger-equation reduces into a one dimensional one with an effective potential, which I then solve numerically.

But I need nuclear potentials to plug in, of course! I've already used a sort of square well type of potential, so I thought I'd plug in a Yukawa potential next. Here's where the problem arises: I don't know what to use as the value of the scaling constant. In link 1, the mystery constant is notated as g2 and in link 2 it is notated as g2/4π. The constant is apparently called the "gauge coupling constant" between the meson and fermion fields.

I've yet to find a single source that bothers to mention what kind of natural units they use, so all the numerical values I've found for the constant are useless to me. I know the units of the constant obviously have to be units of energy times units of length, as that way the potential function itself spits out units of energy. I've even tried to guess the units based on this, but every time I get a potential that is either way too deep or too shallow compared to the square well type of potential that I used and hence know is reasonably close to the truth.

So yeah, I have no idea where to find the value of this mysterious constant. Does anyone here know what it is?

See for example page 3 of the following source for numerical values:

http://rickbradford.co.uk/CCC_AppF_StrongCouplinggs.pdf
 
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nrqed said:
See for example page 3 of the following source for numerical values:

http://rickbradford.co.uk/CCC_AppF_StrongCouplinggs.pdf

You're a damn hero. Thank you so much.

One more question though: how do I cite something like this? Can you throw me a link to whatever that is an appendix to? That would help me cite it.
 
Phi6er said:
You're a damn hero. Thank you so much.

One more question though: how do I cite something like this? Can you throw me a link to whatever that is an appendix to? That would help me cite it.

You are very welcome. Good question... I know that I have seen similar numbers in some book but I cannot remember which one, right now. I will try to find one and will get back to you.
 

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