NLO evolution of color dipoles

The small-$x$ deep inelastic scattering in the saturation region is governed by the non-linear evolution of Wilson-line operators. In the leading logarithmic approximation it is given by the BK equation for the evolution of color dipoles. In the next-to-leading order the BK equation gets contributions from quark and gluon loops as well as from the tree gluon diagrams with quadratic and cubic nonlinearities. We calculate the gluon contribution to small-x evolution of Wilson lines (the quark part was obtained earlier).Comment: 43 pages, 12 figure

Photon impact factor and kTk_T-factorization for DIS in the next-to-leading order

The photon impact factor for the BFKL pomeron is calculated in the next-to-leading order (NLO) approximation using the operator expansion in Wilson lines. The result is represented as a NLO $k_T$-factorization formula for the structure functions of small-$x$ deep inelastic scattering.Comment: 13 pages, 4 figures, typos corrected. arXiv admin note: substantial text overlap with arXiv:1009.472

Gluon TMD in particle production from low to moderate x

We study the rapidity evolution of gluon transverse momentum dependent distributions appearing in processes of particle production and show how this evolution changes from small to moderate Bjorken x.Comment: 36 pages, 3 figures. arXiv admin note: text overlap with arXiv:1505.0215

Photon impact factor in the next-to-leading order

An analytic coordinate-space expression for the next-to-leading order photon impact factor for small-$x$ deep inelastic scattering is calculated using the operator expansion in Wilson lines.Comment: 5 pages, 3 figure

Rapidity evolution of gluon TMD from low to moderate x

We study how the rapidity evolution of gluon transverse momentum dependent distribution changes from nonlinear evolution at small $x \ll 1$ to linear evolution at moderate $x \sim 1$.Comment: 70 pages, 7 figures, published versio

Power corrections to TMD factorization for Z-boson production

A typical factorization formula for production of a particle with a small transverse momentum in hadron-hadron collisions is given by a convolution of two leading-twist TMD parton densities with cross section of production of the final particle by the two partons. For practical applications at a given transverse momentum, though, one should estimate at what momenta the power corrections to TMD factorization formula due to higher-twist operators become essential. In this paper we calculate the first power corrections to TMD factorization formula for Z-boson production and Drell-Yan process in high-energy hadron-hadron collisions. At the leading order in $N_c$ power corrections are expressed in terms of leading-twist TMDs by QCD equations of motion.Comment: 44 pages, 3 figures. v2: text changes. arXiv admin note: text overlap with arXiv:1706.0141

Properties of inclusive hadron production in Deep Inelastic Scattering on heavy nuclei at low x

In this paper we present a comprehensive study of inclusive hadron production in DIS at low $x$. Properties of the hadron spectrum are different in different kinematic regions formed by three relevant momentum scales: photon virtuality $Q^2$, hadron transverse momentum $k_T$ and the saturation momentum $Q_s(x)$. We investigate each kinematic region and derive the corresponding asymptotic formulas for the cross section at the leading logarithmic order. We also analyze the next-leading-order (NLO) corrections to the BFKL kernel that are responsible for the momentum conservation. In particular, we establish the asymptotic behavior of the forward elastic dipole--nucleus scattering amplitude at high energies deeply in the saturation regime and a modification of the pomeron intercept. We study the nuclear effect on the inclusive cross section using the nuclear modification factor and its logarithmic derivative. We argue that the later is proportional to the difference between the anomalous dimension of the gluon distribution in nucleus and in proton and thus is a direct measure of the coherence effects. To augment our arguments and present quantitative results we performed numerical calculations in the kinematic region that may be accessible by the future DIS experiments.Comment: 29 pages, 8 figure

Light-cone Distribution Amplitudes of Xi and their Applications

We present the light-cone distribution amplitudes of the Xi baryons up to twist six on the basis of QCD conformal partial wave expansion to the leading order conformal spin accuracy. The nonperturbative parameters relevant to the DAs are determined in the framework of the QCD sum rule. The light-cone QCD sum rule approach is used to investigate both the electromagnetic form factors of Xi and the exclusive semileptonic decay of Xi_c as applications. Our estimations on the magnetic moments are $\mu_{\Xi^0}=-(1.92\pm0.34)\mu_N$ and $\mu_{\Xi^-}=-(1.19\pm0.03)\mu_N$. The decay width of the process Xi_c->Xi e^+\nu_e is evaluated to be $\Gamma=8.73\times10^{-14}{GeV}$, which is in accordance with the experimental measurements and other theoretical approaches.Comment: 23 pages, 8 figures, version to appear in Phys. Rev.

NLO evolution of 3-quark Wilson loop operator

It is well known that high-energy scattering of a meson from some hadronic target can be described by the interaction of that target with a color dipole formed by two Wilson lines corresponding to fast quark-antiquark pair. Moreover, the energy dependence of the scattering amplitude is governed by the evolution equation of this color dipole with respect to rapidity. Similarly, the energy dependence of scattering of a baryon can be described in terms of evolution of a three-Wilson-lines operator with respect to the rapidity of the Wilson lines. We calculate the evolution of the 3-quark Wilson loop operator in the next-to-leading order (NLO) and present a quasi-conformal evolution equation for a composite 3-Wilson-lines operator. We also obtain the linearized version of that evolution equation describing the amplitude of the odderon exchange at high energies

Analyticity and crossing symmetry of the eikonal amplitudes in gauge theories

After a brief review and a more refined analysis of some relevant analyticity properties (when going from Minkowskian to Euclidean theory) of the high-energy parton-parton and hadron-hadron scattering amplitudes in gauge theories, described nonperturbatively, in the eikonal approximation, by certain correlation functions of two Wilson lines or two Wilson loops near the light cone, we shall see how these same properties lead to a nice geometrical interpretation of the crossing symmetry between quark-quark and quark-antiquark eikonal amplitudes and also between loop-loop eikonal amplitudes. This relation between Minkowskian-to-Euclidean analyticity properties and crossing symmetry is discussed in detail and explicitly tested in the first orders of perturbation theory. Some nonperturbative examples existing in the literature are also discussed.Comment: Completely revised version with new comments, new references and new figures; 37 pages + 5 figure