Treatment of the QCD coupling in high energy processes

Ermolaev, B. I.; Greco, Mario; Troyan, S. I.

doi:10.1016/s0370-2693(01)01252-7

Cited by 25 publications

(33 citation statements)

References 19 publications

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“…However, as shown in Ref. [8], our approach and DGLAP converge when x ∼ 1 where the factorization does hold. The parametrization of α s (k 2 ) in the form of Eq.…”

Section: Comparison Between Dglap and Our Approachsupporting

confidence: 56%

“…As shown in Ref. [8], this parametrization differs from the DGLAP one, α s = α s (k 2 ⊥ ), at small x, though both parameterizations coincide when x is large. The main point is that the factorization of the phase space into transverse and longitudinal spaces used in DGLAP is a good approximation for large x only.…”

Section: Implementation Of Dglap With Our Higher-loop Contributionsmentioning

confidence: 60%

“…In the present paper we use our previous results [7,8] to show that the impact of the high-order corrections on the Q 2 and x -evolutions of the non-singlet structure functions is indeed quite sizable at available values of x. We also show that the reason for the success of phenomenological analysis of the data based on DGLAP at x < 10 −2 is related to the sharp x -dependence assumed for the initial parton densities, which is able to mimic the role of high-order corrections.…”

Section: Introductionmentioning

confidence: 99%

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Non-singlet structure functions: Combining the leading logarithms resummation at small-x with DGLAP

Ermolaev

Greco²,

Troyan

2005

Physics Letters B

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The explicit expressions for the non-singlet DIS structure functions F1 and g1, obtained at small x by resumming the leading logarithmic contributions to all orders, are discussed and compared in detail with the DGLAP evolution for different values of x and Q 2 . The role played by the DGLAP inputs for the initial parton densities on the small-x behavior of the non-singlet structure functions is discussed. It is shown that the singular factors included into the fits ensure the Regge asymptotics of the non-singlet structure functions and mimic the impact of the total resummation of the leading logarithms found explicitly in our approach. Explicit expressions are presented which implement the NLO DGLAP contributions with our small -x results.

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“…However, as shown in Ref. [8], our approach and DGLAP converge when x ∼ 1 where the factorization does hold. The parametrization of α s (k 2 ) in the form of Eq.…”

Section: Comparison Between Dglap and Our Approachsupporting

confidence: 56%

Section: Implementation Of Dglap With Our Higher-loop Contributionsmentioning

confidence: 60%

Section: Introductionmentioning

confidence: 99%

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Non-singlet structure functions: Combining the leading logarithms resummation at small-x with DGLAP

Ermolaev

Greco²,

Troyan

2005

Physics Letters B

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“…In this paper we present a model for next-to-leading order (NLO) resummed form factors based on the time-like coupling recently introduced by B. Ermolaev, M. Greco and S. Troyan in [6] in the framework of small x physics (see also [7]). The usual expression for resummed threshold form factors in N -space is [3,4,5]:…”

Section: Introductionmentioning

confidence: 99%

“…Absorptive effects, i.e. the −iπ terms in gluon polarization functions, are usually neglected in literature: by taking them into account, one enforces that all gluons participating to the cascade are unstable particles [6]. They are analogous to the quasi-particles of statistical physics, possessing in lowest order -non interacting quasi-particles -a non-zero width [13].…”

Section: Introductionmentioning

confidence: 99%

Model for next-to-leading order threshold resummed form factors

Aglietti

Ricciardi

2004

Phys. Rev. D

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We present a model for next-to-leading order resummed threshold form factors based on a time-like coupling recently introduced in the framework of small x physics. Improved expressions for the form factors in N -space are obtained which are not plagued by Landau-pole singularities, as the included absorptive effects -usually neglected -act as regulators. The physical reason is that, because of faster decay of gluon jets, there is not enough resolution time to observe the Landau pole. Our form factors reduce to the standard ones when the absorptive parts related to the coupling are neglected. The inverse transform from N -space to x-space can be done directly without any prescription and we obtain analytical expressions for the form factors, which are well defined in all x-space.

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Modelling non-perturbative corrections to bottom-quark fragmentation

2007

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We describe B-hadron production in e(+)e(-) annihilation at the Z(0) pole by means of a model including non-perturbative corrections to b-quark fragmentation as originating, via multiple soft emissions, from an effective QCD coupling constant, which does not exhibit the Landau pole any longer and includes absorptive effects due to parton branching. We work in the framework of perturbative fragmentation functions at NLO, with NLL DGLAP evolution and NNLL large-x resummation in both coefficient function and initial condition of the perturbative fragmentation function. We include hadronization corrections via the effective coupling constant in the NNLO approximation and do not add any further non-perturbative fragmentation function. As part of our model, we perform the Mellin transforms of our resummed expressions exactly. We present results on the energy distribution of b-flavored hadrons, which we compare with LEP and SLD data, in both x- and N-spaces. We find that, within the theoretical uncertainties on our calculation, our model is able to reasonably reproduce the data at x less than or similar to 0.92 and the first five moments of the B cross section. (C) 2007 Elsevier B.V. All rights reserved

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Treatment of the QCD coupling in high energy processes

Cited by 25 publications

References 19 publications

Non-singlet structure functions: Combining the leading logarithms resummation at small-x with DGLAP

Non-singlet structure functions: Combining the leading logarithms resummation at small-x with DGLAP

Model for next-to-leading order threshold resummed form factors

Modelling non-perturbative corrections to bottom-quark fragmentation

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