Related papers: Scheme Dependence at Small x
These notes develop aspects of perturbation theory of matrices related to so-called diagonalisation schemes. Primary focus is on constructive tools to derive asymptotic expansions for small/large parameters of eigenvalues and…
Theoretical description of the spin dependent structure function g_1(x,Q^2) in the region of low values of x and Q^2 is presented. It contains the Vector Meson Dominance contribution and the QCD improved parton model suitably extended to…
We explore several models of QCD evolution equations simplified by considering only the rapidity dependence of dipole scattering amplitudes, while provisionally neglecting their dependence on transverse coordinates. Our main focus is on the…
We study the dipole picture of high-energy virtual-photon-proton scattering. It is shown that different choices for the energy variable in the dipole cross section used in the literature are not related to each other by simple arguments…
The most general form of a marginal extended perturbation in a two-dimensional system is deduced from scaling considerations. It includes as particular cases extended perturbations decaying either from a surface, a line or a point for which…
The QCD corrections to the moments of the invariant mass distribution in the semileptonic $\tau$ decays are considered. The effect of the renormalization scheme dependence on the fitted values of alpha_s(m^2_tau) and the condensates is…
Using quantum electrodynamics as an example, a dependence of physical predictions of quantum field theory in a finite perturbation theory order on the choice of renormalization scheme is studied. It is shown that On-Mass-Shell…
We consider a new approach for taking into account the Q2 dependence of asymmetry A_1. This approach is based on the similarity of the Q2 behavior and the shape of the spin-dependent structure function g_1(x,Q^2) and spin averaged structure…
We present a dynamical study of the double parton distribution in impact parameter space, which enters into the double scattering cross section in hadronic collisions. This distribution is analogous to the generalized parton densities in…
Starting from a rewiev of DGLAP and BFKL evolution equations for small-x processes, a sistematic study is performed in order to understand the limits of both the formulations and to improve them in a unique framework, which aims to cover…
A possible scheme of q-deformation, which was recently developed by the present authors, is reviewed by stressing the starting idea.
The non-local dependence of the fermion determinant on the gauge field limits our ability of simulating Quantum Chromodynamics on the lattice. Here we present a factorization of the gauge field dependence of the fermion determinant based on…
We give predictions for the ratio RQ(x,Q2)=FLQ(x,Q2)/F2Q(x,Q2) at small values of Bjorken variable x in the first three orders of perturbation theory. We show an approximate x-independence of RQ(x,Q2) at low x and non-large Q2 values (Q2 <…
The spin structure function $g_1^p$ of the proton is studied in a two component framework, where the perturbative evolution of parton distributions and nonperturbative vector meson dominance model are used. We predict the $g_1^p$ asymmetric…
We examine the perturbative calculation of the inclusive semi-leptonic decay rate $\Gamma$ for the $b$-quark, using mass-independent renormalization. To finite order of perturbation theory the series for $\Gamma$ will depend on the…
We study the effect of optimising the renormalisation and factorisation scales on perturbative calculations of event shape means defined in the Breit frame of ep DIS. Unlike in the case of e^+e^- event shape means, this has only a small…
On the grounds of extension of the U-matrix unitarization to the off-shell scattering we consider virtual-photon induced scattering. We discuss behavior of the structure function F_2(x,Q^2) at low x and the total cross-section of…
This talk discusses recent progress in some topics relevant for deep inelastic scattering at small x. We discuss first differences and similarities between conventional collinear factorization and the dipole picture of deep inelastic…
We reconsider the choice of renormalization schemes in a differential-equation approach to aid the discussion of the renormalization of the unstable particles and the CKM matrix in the Standard Model. Certain mass dependent schemes do not…
We calculate the scale dependence of nonsinglet nucleon structure functions. Due to anomalous axial symmetry breaking a large flavour asymmetry of the quark--antiquark sea is generated nonperturbatively. This produces a strong scale…