Scheme dependence of NLO corrections to exclusive processes

Müller, Dieter

doi:10.1103/physrevd.59.116003

Cited by 15 publications

(4 citation statements)

References 73 publications

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“…, 200) to approximate the evolved distribution amplitude. It is important to stress that our results, obtained in the MS scheme of perturbative QCD for a fixed coupling, can be related to those derived before by Müller [21,23] in the conformally covariant subtraction (CS) scheme. More specifically, the solutions of the ERBL evolution equation in each scheme can be interlinked in the conformal limit (β = 0) on account of a finite refactorization [21].…”

Section: Rg Solution In the Case Of A Fixed Coupling Constantsupporting

confidence: 74%

“…More specifically, the solutions of the ERBL evolution equation in each scheme can be interlinked in the conformal limit (β = 0) on account of a finite refactorization [21]. This means that our solution (6.16a) in the MS scheme and Müller's corresponding results in the CS scheme [21,23] are connected by a RG transformation matrix determined by the special conformal anomaly [24].…”

Section: Rg Solution In the Case Of A Fixed Coupling Constantmentioning

confidence: 98%

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Renormalization-group improved evolution of the meson distribution amplitude at the two-loop level

Bakulev

Stefanis

2005

Nuclear Physics B

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We discuss the two-loop evolution of the flavor-nonsinglet meson distribution amplitude in perturbative QCD. After reviewing previous two-loop computations, we outline the incompatibility of these solutions with the group property of the renormalization-group transformations. To cure this deficiency, we compute a correction factor for the non-diagonal part of the meson evolution equation and prove that with this modification the two-loop solution conforms with the group properties of the renormalization-group transformations. The special case of a fixed strong coupling (no Q 2 dependence) is also discussed and comparison is given to previously obtained results.

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Section: Rg Solution In the Case Of A Fixed Coupling Constantsupporting

confidence: 74%

Section: Rg Solution In the Case Of A Fixed Coupling Constantmentioning

confidence: 98%

Renormalization-group improved evolution of the meson distribution amplitude at the two-loop level

Bakulev

Stefanis

2005

Nuclear Physics B

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“…To get a quantitative interpretation of such quantities in practice and compare them with experimental data, one has to get rid of the artificial Landau singularity at Q 2 = Λ 2 QCD (Λ QCD ≡ Λ in the following), where Q 2 is the large mass scale in the process. A proposal to solve this problem (in the spacelike region) without introducing exogenous infrared (IR) regulators, like an effective, or a dynamically generated, gluon mass [1] (see, for instance, [2,3,4,5,6,7,8,9,10] for such applications), was made by Shirkov and Solovtsov (SS) [11,12,13], based on general principles of local Quantum Field Theory. This theoretical framework-termed Analytic Perturbation Theory (APT)-was further expanded beyond the one-loop level of two-point functions to define an analytic 1 coupling and its powers in the timelike region [14,15,16,17,18,19,20,21], embracing previous attempts [22,23,24,25,26,27] in this direction.…”

Section: Introductionmentioning

confidence: 99%

Analyticity properties of three-point functions in QCD beyond leading order

Bakulev¹,

Karanikas

Stefanis

2005

Phys. Rev. D

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The removal of unphysical singularities in the perturbatively calculable part of the pion form factor-a classic example of a three-point function in QCD-is discussed. Different "analytization" procedures in the sense of Shirkov and Solovtsov are examined in comparison with standard QCD perturbation theory. We show that demanding the analyticity of the partonic amplitude as a whole, as proposed before by Karanikas and Stefanis, one can make infrared finite not only the strong running coupling and its powers, but also cure potentially large logarithms (that first appear at next-to-leading order) containing the factorization scale and modifying the discontinuity across the cut along the negative real axis. The scheme used here generalizes the Analytic Perturbation Theory of Shirkov and Solovtsov to non-integer powers of the strong coupling and diminishes the dependence of QCD hadronic quantities on all perturbative scheme and scale-setting parameters, including the factorization scale.

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“…This allows one to resolve mixing at given order of perturbation theory performing an additional calculation at one order less. This technique was used to compute the nonforward evolution kernels for the twist-two operators in QCD [4,5,6,7,8,9,10]. with two-loop accuracy.…”

Section: Introductionmentioning

confidence: 99%

Towards the three loop evolution equation for GPDs

Manashov¹

2017

Proceedings of QCD Evolution 2016 — PoS(QCDEV2016)

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QCD in d = 4 − 2ε dimensions and large number of flavors possesses a nontrivial infrared stable critical point. At the critical point the theory is invariant under the conformal transformations. It implies that the evolution kernel of leading-twist light-ray operators commutes with the generators of conformal transformations. Taking into account that the evolution kernels in the MS-scheme are not sensitive to the space-time dimensions one concludes that QCD evolution equations in MS-schemes have a hidden symmetry. Namely, the evolution kernel commutes with the generators of the conformal algebra. The explicit form of the generators differs from their canonical (classical) form and can be derived by studying conformal Ward identities. Invariance with respect to the conformal transformations imposes nontrivial constraints on the form of evolution kernels and allows one to restore the nonforward evolution kernels for the nonsinglet operators from the known NNLO anomalous dimensions. We present here the two loop expressions for the generators of conformal algebra.

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Scheme dependence of NLO corrections to exclusive processes

Cited by 15 publications

References 73 publications

Renormalization-group improved evolution of the meson distribution amplitude at the two-loop level

Renormalization-group improved evolution of the meson distribution amplitude at the two-loop level

Analyticity properties of three-point functions in QCD beyond leading order

Towards the three loop evolution equation for GPDs

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