B.I. Ermolaev

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

Abstract The explicit expressions for the non-singlet DIS structure functions F 1 and g 1 , 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.

Running coupling effects for the singlet structure function g1 at small x

Abstract The running of the QCD coupling is incorporated into the infrared evolution equations for the flavour structure function g1. The explicit expressions for g1 including the total resummation of the double-logarithmic contributions and accounting for the running coupling are obtained. We predict that asymptotically g1∼x−ΔS, with the intercept ΔS≈0.86, which is a factor of 2 larger than the non-singlet intercept ΔNS. The impact of the initial quark (δq) and gluon (δg) densities on the sign of g1 at x⪡1 is discussed and explicit expressions relating δq and δg are obtained.

Treatment of the QCD coupling in high energy processes

Abstract The treatment of the running QCD coupling in evolution equations is discussed. It is shown that the use of the virtuality of ladder (vertical) partons as the scale for QCD coupling in every rung of ladder graphs is an approximation that holds for DIS at large x only. On the contrary, in the small x region the coupling depends on the virtuality of s-channel (horizontal) gluons. This observation leads to different results for the Regge-like processes and DIS structure functions at small x.

Electroweak 2 → 2 amplitudes for electron-positron annihilation at TeV energies

The nonradiative scattering amplitudes for electron-positron annihilation into quark and lepton pairs in the TeV energy range are calculated in the double-logarithmic approximation. The expressions for the amplitudes are obtained using infrared evolution equations with different cutoffs for virtual photons and for W and Z bosons and compared with previous results obtained with a universal cutoff.

Forward-backward charge asymmetry ine+e−annihilation into hadrons at high energies

The forward-backward asymmetry in

Off-shell scattering amplitudes in the double-logarithmic approximation

{e}^{+}{e}^{\ensuremath{-}}

Production of electroweak bosons in e + e − annihilation at high energies

annihilation into a quark-antiquark pair is considered in the double-logarithmic approximation at energies much higher than the masses of the weak bosons. It is shown that after accounting for the exchange of virtual photons and

DEEP INELASTIC SPIN STRUCTURE FUNCTIONS AT SMALL x

W,Z

Infrared Evolution Equations: Method and Applications

bosons to all orders one is led to the following effect (asymmetry): quarks with positive electric charge (e.g., u,

Role of the singular factors in the standard fits for initial parton densities

\overline{d})