Renormalized vertex functions in terms of bare ones

In summary, the study discusses the relationship between renormalized vertex functions and their bare counterparts within quantum field theory. It highlights how renormalization addresses divergences by relating these functions through specific transformations and counterterms. The analysis emphasizes the importance of understanding these connections for accurate predictions in particle interactions and the overall consistency of the theory.
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Siupa
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Let ##\Gamma[\varphi] = \Gamma_0[\sqrt{Z}\varphi ] = \Gamma_0[\varphi_0]## be the generating functional for proper vertex functions for a massless ##\phi##-##4## theory. The ##0## subscripts refer to bare quantities, while the quantities without are renormalized. Then
$$\tilde{\Gamma}^{(n)}(p_i, \mu, \lambda) = Z^{\frac{n}{2}}\left( \tfrac{\Lambda}{\mu}, \lambda\right) \tilde{\Gamma}_0^{(n)}(p_i, \Lambda, \lambda_0)$$
Where the ##\tilde{\Gamma}^{(n)}## are the ##n##-point proper vertex functions in Fourier space (bare and renormalized), ##\Lambda## is the Pauli-Villars cutoff, ##\mu## an arbitrary scale, ##p_i## external momenta, ##\lambda## the ##\phi##-##4## couplings (bare and renormalized). How does one show this?
 

FAQ: Renormalized vertex functions in terms of bare ones

What is the purpose of renormalizing vertex functions?

Renormalizing vertex functions helps to remove infinities that arise in quantum field theory calculations, making the theory predictive and consistent with experimental results. It allows us to relate physical (renormalized) quantities to the theoretically calculated (bare) ones.

How do bare vertex functions differ from renormalized vertex functions?

Bare vertex functions are the original, unadjusted quantities in a quantum field theory, which often contain divergences. Renormalized vertex functions are the adjusted quantities where these divergences have been systematically removed, making them finite and physically meaningful.

What role do counterterms play in the renormalization process?

Counterterms are added to the original Lagrangian to cancel out the infinities that appear in the bare vertex functions. These counterterms are specifically chosen to ensure that the renormalized vertex functions are finite and match experimental observations.

How are renormalized vertex functions calculated from bare ones?

Renormalized vertex functions are calculated from bare ones by introducing renormalization constants, which are determined through a renormalization scheme. These constants are used to relate the bare parameters (like coupling constants and masses) to their renormalized counterparts, effectively absorbing the infinities.

What are the common renormalization schemes used in practice?

Common renormalization schemes include the on-shell scheme, where physical masses and coupling constants are fixed to their experimental values, and the minimal subtraction (MS) and modified minimal subtraction (MS-bar) schemes, which systematically subtract divergences using dimensional regularization.

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