相关论文: Analyticity properties of three-point functions in…
We present an investigation of the pion's electromagnetic form factor F_{\pi}(Q^2) in the spacelike region utilizing two new ingredients: (i) a double-humped, endpoint-suppressed pion distribution amplitude derived before via QCD sum rules…
We apply analytic perturbation theory to the QCD analysis of the xF_3 structure function data of the CCFR collaboration. We use different approaches for the leading order Q^2 evolution of the xF_3 structure function and compare the…
We work out and discuss the Minkowski version of Fractional Analytic Perturbation Theory (FAPT) for QCD observables, recently developed and presented by us for the Euclidean region. The original analytic approach to QCD, initiated by…
We perform perturbative QCD factorization of infrared radiations associated with an energetic $b$ quark from a polarized top quark decay, taking the semi-leptonic channel as an example. The resultant formula is expressed as a convolution of…
We study the factorization of soft and collinear singularities in dimensionally-regularized fixed-angle scattering amplitudes in massless gauge theories. Our factorization is based on replacing the hard massless partons by light-like Wilson…
A formula for the two-loop infrared singularities of dimensionally regularized QCD scattering amplitudes with an arbitrary number of massive and massless legs is derived. The singularities are obtained from the solution of a…
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…
Solving the QCD renormalization group equation at the 2-loop and 3-loop orders we obtain explicit expressions for the coupling as a function of the scale in terms of the Lambert W function. We study the nature of the ``Landau…
In quantum theory, physical amplitudes are usually presented in the form of Feynman perturbation series in powers of coupling constant $\al .$ However, it is known that these amplitudes are not regular functions at $\alpha=0 .$ For QCD, we…
The aim of this topical article is to outline the fundamental ideas underlying the recently developed Fractional Analytic Perturbation Theory (FAPT) of QCD and present its main calculational tools together with key applications. For this,…
We discuss the structure of infrared and ultraviolet singularities in on-shell QCD and supersymmetric QCD amplitudes at one-loop order. Previous results, valid for massless partons, are extended to the case of massive partons. Using…
The subject of the first section-lecture is concerned with the strength and the weakness of the perturbation theory (PT) approach, that is expansion in powers of a small parameter $\alpha$, in Quantum Theory. We start with outlining a…
We summarize recent results on the evolution of unpolarized parton densities and deep-inelastic structure functions in massless perturbative QCD. Due to last year's extension of the integer-moment calculations of the three-loop splitting…
The analytization procedure which allows one to remove nonphysical singularities of the QCD running coupling constant $\bar\alpha_s(q^2)$ in the infrared region is applied to standard as well as to iterative solutions of the two-loop…
We recalculate the proton Dirac form factor based on the perturbative QCD factorization theorem which includes Sudakov suppression. The evolution scale of the proton wave functions and the infrared cutoffs for the Sudakov resummation are…
In this paper we show that, as in the spacelike case, the inverse logarithmic expansion is applicable for all values of the argument of the analytic coupling constant. We present two different approaches, one of which is based primarily on…
In this work, we give a detailed discussion for QCD factorization involved the complete chirally enhanced power corrections for B decays to two light pseudoscalar mesons, and present some detailed calculations of radiative corrections at…
We present the analytic form of all leading-color two-loop five-parton helicity amplitudes in QCD. The results are analytically reconstructed from exact numerical evaluations over finite fields. Combining a judicious choice of variables…
Scattering amplitudes of partons in QCD contain infrared divergences which can be resummed to all orders in terms of an anomalous dimension. Independently, in the limit of high-energy forward scattering, large logarithms of the energy can…
We show that the controversies on the gauge dependence and the infrared singularity emerged in the generalized factorization approach for nonleptonic heavy meson decays within the framework of the operator product expansion can be resolved…