We discuss the determination of the strong coupling αMS(mZ) or, equivalently, the QCD Λ parameter. Its determination requires the use of perturbation theory in αs(μ) in some scheme s and at some energy scale μ. The higher the scale μ, the more accurate perturbation theory becomes, owing to asymptotic freedom. As one step in our computation of the Λ parameter in three-flavor QCD, we perform lattice computations in a scheme that allows us to nonperturbatively reach very high energies, corresponding to αs=0.1 and below. We find that (continuum) perturbation theory is very accurate there, yielding a 3% error in the Λ parameter, while data around αs≈0.2 are clearly insufficient to quote such a precision. It is important to realize that these findings are expected to be generic, as our scheme has advantageous properties regarding the applicability of perturbation theory.

Dalla Brida, M., Fritzsch, P., Korzec, T., Ramos, A., Sint, S., Sommer, R. (2016). Determination of the QCD Λ Parameter and the Accuracy of Perturbation Theory at High Energies. PHYSICAL REVIEW LETTERS, 117(18) [10.1103/PhysRevLett.117.182001].

Determination of the QCD Λ Parameter and the Accuracy of Perturbation Theory at High Energies

Dalla Brida, M;
2016

Abstract

We discuss the determination of the strong coupling αMS(mZ) or, equivalently, the QCD Λ parameter. Its determination requires the use of perturbation theory in αs(μ) in some scheme s and at some energy scale μ. The higher the scale μ, the more accurate perturbation theory becomes, owing to asymptotic freedom. As one step in our computation of the Λ parameter in three-flavor QCD, we perform lattice computations in a scheme that allows us to nonperturbatively reach very high energies, corresponding to αs=0.1 and below. We find that (continuum) perturbation theory is very accurate there, yielding a 3% error in the Λ parameter, while data around αs≈0.2 are clearly insufficient to quote such a precision. It is important to realize that these findings are expected to be generic, as our scheme has advantageous properties regarding the applicability of perturbation theory.
Articolo in rivista - Articolo scientifico
Lattice QCD; QCD coupling; Perturbation theory;
English
2016
117
18
182001
reserved
Dalla Brida, M., Fritzsch, P., Korzec, T., Ramos, A., Sint, S., Sommer, R. (2016). Determination of the QCD Λ Parameter and the Accuracy of Perturbation Theory at High Energies. PHYSICAL REVIEW LETTERS, 117(18) [10.1103/PhysRevLett.117.182001].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/183259
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