On the different forms of the kinematical constraint in BFKL

Deák, Michal; Kutak, Krzysztof; Li, Wan-Chen; Staśto, Anna

doi:10.1140/epjc/s10052-019-7171-z

Cited by 13 publications

(19 citation statements)

References 64 publications

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“…In the Regge limit z n 1 one can put t −q 2 T 1 , but the latter approximation quickly degrades with an JHEP08(2020)055 increase of z n . In the kinematic constraint approach [52,53] to approximately take into account large collinearly-enhanced corrections to BFKL-evolution, one cuts-off the region of real-emission phase-space, where t −q 2 T 1 -approximation is no longer valid, i.e. one rejects the emissions with:…”

Section: Jhep08(2020)055mentioning

confidence: 99%

Towards stability of NLO corrections in high-energy factorization via modified multi-Regge kinematics approximation

Nefedov

2020

J. High Energ. Phys.

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The perturbatively-stable scheme of Next-to-Leading order (NLO) calculations of cross-sections for multi-scale hard-processes in DISlike kinematics is developed in the framework of High-Energy Factorization. The evolution equation for unintegrated PDF, which resums log 1/z-corrections to the coefficient function in the Leading Logarithmic approximation together with a certain subset of Next-to-Leading Logarithmic and Nextto-Leading Power corrections, necessary for the perturbative stability of the formalism, is formulated and solved in the Doubly-Logarithmic approximation. An example of DISlike process, induced by the operator tr [G µν G µν ], which is sensitive to gluon PDF already in the LO, is studied. Moderate (O(20%)) NLO corrections to the inclusive structure function are found at small x B < 10 −4 , while for the p T-spectrum of a leading jet in the considered process, NLO corrections are small (< O(20%)) and LO of k T-factorization is a good approximation. The approach can be straightforwardly extended to the case of multi-scale hard processes in pp-collisions at high energies.

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Section: Jhep08(2020)055mentioning

confidence: 99%

Towards stability of NLO corrections in high-energy factorization via modified multi-Regge kinematics approximation

Nefedov

2020

J. High Energ. Phys.

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“…which is the NLL term due to the scale changing transformation. At NNLL the scale changing transformation is much more complicated as it involves the NLL kernel as well [61,62]. Coming back to the NLL kernel, the well known problem that arises at NLL order in BFKL is due to the presence of double and triple collinear logarithms.…”

Section: Ll and Nll Bfkl Evolutionmentioning

confidence: 99%

“…There are also triple collinear poles which appear due to the kinematical constraints [28,29]. Such constraints were discussed in the BFKL context as originating from the improved kinematics, and more precisely by the requirement that the exchanged momenta are dominated by the transverse components [21,22], for more recent work on different forms of kinematical constraint see [62]. These contributions generate the double transverse logarithms and in the Mellin space they exhibit most singular behavior, the triple collinear poles…”

Section: Ll and Nll Bfkl Evolutionmentioning

confidence: 99%

“…To be precise, there are different versions of this constraint which appear in the literature, see [21,22,63]. It turns out that all versions are generating the same leading cubic poles in the Mellin space at NLL, they generate no double poles, and with the difference starting to appear in the single pole level, see [62]. The scale in the running coupling corresponds to the transverse momentum of the emitted gluon q 2 .…”

Section: Momentum Representationmentioning

confidence: 99%

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Taming of preasymptotic small x evolution within resummation framework

et al. 2020

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It is well understood that the leading logarithmic approximation for the amplitudes of high energy processes is insufficient and that the next-to-leading logarithmic effects are very large and lead to instability of the solution. The resummation at low x, which includes kinematical constraints and other corrections leads to stable result. Using previously established resummation procedure we study in detail the preasymptotic effects which occur in the solution to the resummed BFKL equation when the energy is not very large. We find that in addition to the well known reduction of the intercept, which governs the energy dependence of the gluon Green's function, resummation leads to the delay of the onset of its small x growth. Moreover the gluon Green's function develops a dip or a plateau in wide range of rapidities, which increases for large scales. The preasymptotic region in the gluon Green's function extends to about 8 units in rapidity for the transverse scales of the order of 30 − 100 GeV. To visualize the expected behavior of physical processes with two equal hard scales we calculate the cross section of the process γ * + γ * → X to be probed at future very high-energy electron-positron colliders. We find that at γ * γ * energies below 100 GeV the BFKL Pomeron leads to smaller value of the cross section than the Born approximation, and only starts to dominate at energies about 100 GeV. This pattern is significantly different from the one which we find using LL approximation. We also analyze the transverse momentum contributions to the cross section for different virtualities of the photons and find that the dominant contributions to the integral over the transverse momenta comes from lower values than the the external scales in the process under consideration.

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“…Such an implementation makes direct introduction of effects beyond the leading logarithmic approximation possible, e.g. conservation of energy and momentum without imposing kinematical constraints on the splitting kernel [34]. This makes the implementation attractive for estimation of basic quantities dominated by small x processes (e.g.…”

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confidence: 99%

Dipole evolution: perspectives for collectivity and γ*A collisions

Bierlich

Rasmussen

2019

J. High Energ. Phys.

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The transverse, spatial structure of protons is an area revealing fundamental properties of matter, and provides key input for deeper understanding of emerging collective phenomena in high energy collisions of protons, as well as collisions of heavy ions. In this paper eccentricities and eccentricity fluctuations are predicted using the dipole formulation of BFKL evolution. Furthermore, first steps are taken towards generation of fully exclusive final states of γ * A collisions, by assessing the importance of colour fluctuations in the initial state. Such steps are crucial for the preparation of event generators for a future electron-ion collider. Due to the connection between an impact parameter picture of the proton structure, and cross sections of ep and pp collisions, the model parameters can be fully determined by fits to such quantities, leaving results as real predictions of the model.

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On the different forms of the kinematical constraint in BFKL

Cited by 13 publications

References 64 publications

Towards stability of NLO corrections in high-energy factorization via modified multi-Regge kinematics approximation

Towards stability of NLO corrections in high-energy factorization via modified multi-Regge kinematics approximation

Taming of preasymptotic small x evolution within resummation framework

Dipole evolution: perspectives for collectivity and γ*A collisions

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