How do we know which is strong,weak force with considering Lagrangian?

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Discussion Overview

The discussion revolves around understanding the classification of fundamental forces (strong, weak, and electromagnetic) through the lens of their corresponding Lagrangians. Participants explore how coupling constants and the mass of force carrier bosons influence the strength and range of these interactions, while also considering the implications of renormalization group theory.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions how the strength of a force can be determined from its Lagrangian, noting that the coupling constant and the mass of the force carrier boson play significant roles in defining interaction ranges.
  • Another participant suggests that while all Lagrangians may share a similar form, it is unclear how this affects the intensity of the forces, implying that the characteristics of each interaction are self-consistent but not directly comparable in terms of strength.
  • A participant points out that the weak coupling constant for weak interactions is comparable to that of electromagnetic interactions, yet the weak force is significantly weaker, raising questions about the relationship between coupling constants and force strength.
  • One participant proposes that short-distance interactions should generally be associated with weak interactions at a macroscopic level, suggesting a connection between interaction range and force strength.
  • Another participant emphasizes that a large mass of the force carrier boson correlates with short-range interactions, further complicating the understanding of weak interactions.
  • It is noted that SU(3) symmetry may lead to a large coupling constant at large distances, indicating that strong interactions are characterized by their strength at those scales, while weak and electromagnetic interactions, despite having similar coupling constants, behave differently due to the mass of the bosons involved.

Areas of Agreement / Disagreement

Participants express differing views on how to interpret the relationship between Lagrangians, coupling constants, and the strength of interactions. There is no consensus on how these factors definitively classify the forces as strong or weak.

Contextual Notes

Participants acknowledge the complexity introduced by renormalization group theory, particularly regarding how the mass of bosons can change with transfer momentum, which may affect the interpretation of force strength.

ndung200790
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Please teach me this:
How do we know a force is strong,week or intermediate by considering the corresponding Lagrangian.It seem that the intensiveness depends on both coupling constant,the form of theory(form of Lagrangian).By the way, the mass of force carrier boson stipulates the range of the force. The greater mass the shorter distance of interaction.But there is an unclear for me,because the mass changes when we change transfer momentum as we know in renormalization group theory.
Thank you very much in advance.
 
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At the moment,I think that four types of interaction are discovered by experiment.Each type of interaction has many characteristics.And each theory is self-consistent with those characteristics.But it seem that we could not say any thing about the intensiveness of force basing on the Lagrangian,because all Lagrangian have same form:(coupling constant)(boson field)(current of fermion fields).Is that correct?
 
The week coupling constant g(of week interaction) has the same order as electromagnetic coupling constant(of QED),then I do not understand why the force of week interaction is very much weeker than electromagnetic force.
 
It seem to me that the short distant interaction in general speaking must be the week interaction(when we consider ''macroscopic" level).
 
With the meaning that the mass of force carrier boson is large.
 
It seem to me that the SU(3) symmetry leads to large coupling constant at large distance and long distance interaction.Then the interaction must be strong interaction.
The week and electromagnetic interactions have the same order of coupling constant,but the week interaction is short distance interaction because of massive boson,then the ''week interaction'' must be the week interaction when we consider ''macro'' level physics.
 

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