QCD running coupling effects for the non-singlet structure function at small x

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

doi:10.1016/s0550-3213(99)00812-3

Cited by 24 publications

(19 citation statements)

References 17 publications

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“…Obviously, such procedure can be repeated as many times as one needs, allowing to describe processes with arbitrary number of external kinematic invariants. We suppose that the amplitudes A on γγ ðρÞ;Ã γγ ðρ; y 1 Þ; A γγ ðρ; y 1 ; y 2 Þ are related to the conjugated Mellin amplitudes f γγ ðωÞ;F γγ ðω; y 1 Þ; F γγ ðω; y 1 ; y 2 Þ by the Mellin transform (22).…”

Section: Photon-photon Amplitudes In Dlamentioning

confidence: 99%

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Elastic scattering of virtual photons via a quark loop in the double-logarithmic approximation

2018

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We calculate the amplitude of elastic photon-photon scattering via a single quark loop in the doublelogarithmic approximation, presuming all external photons to be off-shell and unpolarized. At the same time we account for the running coupling effects. We consider this process in the forward kinematics at arbitrary relations between t and the external photon virtualities. We obtain explicit expressions for the photon-photon scattering amplitudes in all double-logarithmic kinematic regions. Then we calculate the small-x asymptotics of the obtained amplitudes and compare them with the parent amplitudes, thereby fixing the applicability regions of the asymptotics, i.e., fixing the applicability region for the nonvacuum Reggeons. We find that these Reggeons should be used at x < 10 −8 only.

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Section: Photon-photon Amplitudes In Dlamentioning

confidence: 99%

“…[4] and, in contrast, we account for the running α s effects, using the results of Ref. [22]. In our approach α s runs in every rung of each involved Feynman ladder graph.…”

Section: Introductionmentioning

confidence: 99%

Elastic scattering of virtual photons via a quark loop in the double-logarithmic approximation

2018

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“…x was considered before for the t-channel quark exchange amplitudes [21][22][23][24][25][26][27]. For helicity evolution it was first applied by Bartels, Ermolaev and Ryskin (BER) in [28,29] (see also [30][31][32][33]). (The DLA parameter α s ln 2 1…”

mentioning

confidence: 99%

Small-x asymptotics of the gluon helicity distribution

Kovchegov

Pitonyak

Sievert

2017

J. High Energ. Phys.

232

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Abstract:We determine the small-x asymptotics of the gluon helicity distribution in a proton at leading order in perturbative QCD at large N c . To achieve this, we begin by evaluating the dipole gluon helicity TMD at small x. In the process we obtain an interesting new result: in contrast to the unpolarized dipole gluon TMD case, the operator governing the small-x behavior of the dipole gluon helicity TMD is different from the operator corresponding to the polarized dipole scattering amplitude (used in our previous work to determine the small-x asymptotics of the quark helicity distribution). We then construct and solve novel small-x large-N c evolution equations for the operator related to the dipole gluon helicity TMD. Our main result is the small-x asymptotics for the gluon helicity distribution: ∆G ∼

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“…It accounts for the total resummation of the leading double-logarithmic contributions and running QCD coupling effects (see Ref. [34,35] and the overview [36] for details).…”

Section: Appendix B: Projection Operators For Forward Compton Amplitudesmentioning

confidence: 99%

Factorization model for distributions of quarks in hadrons

2015

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We consider distributions of unpolarized (polarized) quarks in unpolarized (polarized) hadrons. Our approach is based on QCD factorization. We begin with a study of the basic factorization for the parton-hadron scattering amplitudes in the forward kinematics and suggest a model for non-perturbative contributions to such amplitudes. This model is based on this simple observation: after emitting an active quark by the initial hadron, the remaining set of quarks and gluons becomes unstable, so a description of this colored state can approximately be done in terms of resonances, which leads to expressions of the Breit-Wigner type. Then we reduce these formulas to obtain explicit expressions for the quark-hadron scattering amplitudes and quark distributions in K T -and collinear factorizations.

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QCD running coupling effects for the non-singlet structure function at small x

Cited by 24 publications

References 17 publications

Elastic scattering of virtual photons via a quark loop in the double-logarithmic approximation

Elastic scattering of virtual photons via a quark loop in the double-logarithmic approximation

Small-x asymptotics of the gluon helicity distribution

Factorization model for distributions of quarks in hadrons

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