Why must the mediator of the strong force be heavy?

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Discussion Overview

The discussion revolves around the nature of the mediator of the strong force, particularly focusing on why a heavy particle is necessary for this force, as proposed by Yukawa. The scope includes theoretical considerations and conceptual clarifications related to particle physics.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant references Griffith's text, questioning the intuition behind the requirement for a heavy mediator in the context of the strong force.
  • Another participant explains that a massless mediator results in a long-range Coulomb potential, while a massive mediator leads to a Yukawa potential, which is associated with shorter ranges.
  • A further contribution highlights the negative exponential in the Yukawa potential, indicating that larger masses suppress the potential, thereby affecting the range.
  • Another participant notes that the strong force is mediated by massless gluons, but the residual strong force is mediated by pions, and confinement prevents the emergence of a Coulomb potential at lower energies.
  • One participant expresses confusion and seeks further clarification regarding the statements made, particularly referencing a problem in Griffith's text.

Areas of Agreement / Disagreement

Participants present various viewpoints on the nature of the strong force and its mediators, with some agreeing on the implications of mass on the range of the force, while others raise questions that indicate a lack of consensus on the underlying intuition.

Contextual Notes

The discussion touches on complex concepts such as the Yukawa potential and confinement, which may depend on specific definitions and assumptions that are not fully explored in the thread.

Phys12
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I'm reading Griffith's Introduction to Elementary Particles and it says that when Yukawa proposed his theory of the strong force, it was an indication that the meadiator of that force must be a heavy particle since the force is a short ranged force. Why is that the case? I cannot get the intuition behind it
 
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A massless mediator leads to a Coulomb potential - it has a long range. A massive mediator leads to a Yukawa potential, where larger masses lead to shorter ranges.
 
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Look at the (negative!) exponential in the yukawa potential. It surpresses the potential if the mass of the mediator gets larger.
 
Also note that this is the residual strong force mediated by pions. The strong force itself is mediated by massless gluons. The reason that this does not lead to a Coulomb potential is confinement, i.e., that only colourless states exist at lower energies.
 
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Phys12 said:
Why is that the case?

You know how right after he writes that, Griffiths says "See Problem 1.2"? You should see problem 1.2.
 

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