- #1

kloptok

- 188

- 0

As I understand it, when we use the MS-bar renormalization scheme, the parameters in the lagrangian no longer represent the physical parameters (for example, the m term is not the physical mass) and we can find equations that tell us how the lagrangian parameters vary with the fake parameter μ (any final answer can't depend on μ). This can also be done with the RG approach in a more formal way (as I understand it, the result is the same - we get a group of equations that tell us how the lagrangian parameters vary).

However, the next chapter on EFT:s I struggle to understand. I get that we have a cut-off [itex]\Lambda[/itex] for the momentum and that we can try to see what the theory tells us at momenta well below the cut-off but then a new cut-off [itex]\Lambda_0[/itex] is introduced and I must say I don't understand the difference between the two.

Something I would also like to get some help with is how Wilson's approach with EFT:s relates to renormalization. Why does the EFT approach remove the necessity for a theory to be renormalizable?

Any help and clarifications is highly appreciated!