Asymptotic neutrino-nucleon cross section and saturation effects

In this paper we present a simple analytic expression for the (spin-averaged) neutrino-nucleon cross section for ultra-high energies at twist-2, obtained as the asymptotic limit of our previous findings. This expression gives values for the cross section in remarkable numerical agreement with the previous numerical evaluation in the energy region relevant for forthcoming neutrino experiments. Moreover, we discuss the role and the relevance of saturation and recombination effects in our approach, in comparison with other recent suggestions.Comment: 19 pages, 2 figure

The property of maximal transcendentality in the N=4 SYM

We show results for the universal anomalous dimension gamma_{uni}(j) of Wilson twist-2 operators in the N=4 Supersymmetric Yang-Mills theory in the first three orders of perturbation theory. These expressions are obtained by extracting the most complicated contributions from the corresponding anomalous dimensions in QCD.Comment: 6 pages, published in the Proceedings of International Bogolyubov Conference "Problems of Theoretical and Mathematical Physics" (dedicated to the 100th anniversary of the birth of N.N. Bogolyubov (1909-1992)), Dubna, Russia, August 21 - 27, 2009 (Phys.Part.Nucl. in press

Pomeron in the N=4 supersymmetric gauge model at strong couplings

We find the BFKL Pomeron intercept at N=4 supersymmetric gauge theory in the form of the inverse coupling expansion j0=2-2/lambda**(1/2)-1/lambda + 1/4 1/lambda**(3/2) + 2(1+3zeta3)/lambda**(2) + O(1/lambda**(5/2)) with the use of the AdS/CFT correspondence in terms of string energies calculated recently. The corresponding slope gamma'(2) of the anomalous dimension calculated directly up to the fifth order of perturbation theory turns out to be in an agreement with the closed expression obtained from the recent Basso results.Comment: 18 pages, 1 figure, fixed some typo

The Differential equation method: calculation of vertex-type diagrams with one non-zero mass

The differential equation method is applied to evaluate analytically two-loop vertex Feynman diagrams. Three on-shell infrared divergent planar two-loop diagrams with zero thresholds contributing to the processes Z --> bb bar (for zero b mass) and/or H --> gg are calculated in order to demonstrate a new application of this method.Comment: 12 pages, LATEX, uses axodray.st

Small x behavior of the slope dlnF_2/dln(1/x) in the framework of perturbative QCD

Using an analytical parameterization for the behavior of the x slope of the structure function F_2 at small x in perturbative QCD, at the leading twist approximation of the Wilson operator product expansion, and applying a flat initial condition in the DGLAP evolution equations, we found very good agreement with new precise deep inelastic scattering experimental data from HERA.Comment: 13 pages, 3 figures, late

Dressing and Wrapping

We prove that the validity of the recently proposed dressed, asymptotic Bethe ansatz for the planar AdS/CFT system is indeed limited at weak coupling by operator wrapping effects. This is done by comparing the Bethe ansatz predictions for the four-loop anomalous dimension of finite-spin twist-two operators to BFKL constraints from high-energy scattering amplitudes in N=4 gauge theory. We find disagreement, which means that the ansatz breaks down for length-two operators at four-loop order. Our method supplies precision tools for multiple all-loop tests of the veracity of any yet-to-be constructed set of exact spectral equations. Finally we present a conjecture for the exact four-loop anomalous dimension of the family of twist-two operators, which includes the Konishi field.Comment: 20 pages, 2 tables, no figures; v2: references added, conjecture on exact four-loop twist-two result state