Difference between coupling constant and strength parameter

In summary, the conversation discusses the confusion between the coupling constant g_W and the strength parameter \alpha_W in the weak interaction. It is mentioned that both quantities indicate the strength of the interaction, but the difference between them is not fully understood. It is also noted that \alpha_W is referred to as the (running) coupling constant. It is clarified that there is no difference between the two quantities and \alpha_W is calculated by dividing g_W squared by 4 pi. The conversation also mentions that g_W is used to indicate the coupling strength between fields in the Lagrangian, while \alpha_W is used in Feynman diagrams when there are two vertices.
  • #1
Daaavde
30
0
Hello to everyone,

I got a little bit confused between the coupling constant [itex]g_W[/itex] and the strength parameter [itex]\alpha_W[/itex] in the weak interaction. For what I know they should both give an idea of the strength of the interaction but I miss to understand what's the difference between them.
 
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  • #2
If I understand your quantities well...alpha is called the (running) coupling constant too.
There is no difference between the one or the other...
[itex] \alpha_{W}= \frac{g_{W}^{2}}{4 \pi}[/itex]

The one appears on the Lagrangian as the coupling strength between the fields on vertices.
The other appears in the Feynman diagrams of interactions when you have two vertices.
 
  • #3
Thank you for the answer!
 

What is the difference between coupling constant and strength parameter?

The coupling constant and strength parameter are both ways to describe the strength of the interaction between two objects in a physical system. However, they are used in different contexts and have different mathematical definitions.

How is coupling constant defined?

The coupling constant is a dimensionless value that represents the strength of the interaction between two particles in a quantum field theory. It is typically denoted by the symbol g and is used to calculate the strength of interactions in particle physics.

What is the strength parameter used for?

The strength parameter is a measure of the strength of the interaction between two objects in a classical system. It is typically denoted by the symbol k and is used in fields such as chemistry, biology, and engineering to describe the strength of bonds or forces between molecules or objects.

Can the coupling constant and strength parameter be directly compared?

No, the coupling constant and strength parameter cannot be directly compared because they are used in different contexts and have different mathematical definitions. They are also based on different physical theories, with the coupling constant being used in quantum field theory and the strength parameter being used in classical mechanics.

How do the coupling constant and strength parameter affect physical systems?

The values of the coupling constant and strength parameter can significantly impact the behavior of physical systems. A higher value for the coupling constant may result in a stronger interaction between particles in a quantum field theory, while a higher strength parameter may result in stronger bonds between molecules in a chemical reaction. Furthermore, changes in these values can lead to different physical phenomena and outcomes in a system.

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