Related papers: Parton recombination effect in polarized parton di…
We investigate the positivity of double parton distributions with a non-trivial dependence on the parton colour. It turns out that positivity is not preserved by leading-order evolution from lower to higher scales, in contrast to the case…
We propose a unified and simple viewpoint to various evolution equations appropriate in different kinematic regions. We show that the resummation technique reduces to the Altarelli-Parisi equation, if the transverse degrees of freedom of a…
The importance of polarised gluons fragmenting into $\Lambda$ in the polarised $e^+ e^-$ annihilation is discussed using the Altarelli-Parisi evolution equations satisfied by the quark and gluon fragmentation functions. In this context, the…
In the high energy regime, the proton structure consists of a very large number of particles called partons (quarks and gluons) that interact with each other, according to the theory of strong interactions, Quantum Chromodynamics (QCD).…
The proton spin puzzle issue focused the attention on the parton spin and orbital angular momentum contributions to the proton spin. However, a complete characterization of the proton spin structure requires also the knowledge of the parton…
In this talk an introduction to generalized parton distributions is given. Recent developments are shortly reviewed, including non-perturbative calculations, phenomenological aspects and evaluation of higher order perturbative and power…
General properties of the differential cross section and of the polarization observables are derived for the $e^++e^-\to N+\bar N$ reaction, in presence of two--photon exchange. Polarization effects are investigated for longitudinally…
The extension of the method [arXiv:hep-ph/0503109] for solving the leading order evolution equation for Generalized Parton Distributions (GPDs) is presented. We obtain the solution of the evolution equation both for the flavor nonsinglet…
The lepton polarization asymmetry in the B\to\ell^{+}\ell^{-} decay, when one of the leptons is polarized, is investigated using the most general form of the effective Hamiltonian. The sensitivity of the asymmetry to the new Wilson…
We study the evolution behavior of generalized parton distributions at small longitudinal momentum fraction. Particular attention is paid to the ratio of a generalized parton distribution and its forward limit, to the mixing between quarks…
We give a brief overview of nuclear parton distributions. First, the EMC effect is discussed together with possible interpretations such as nuclear binding and $Q^2$ rescaling. Next, we explain shadowing descriptions:…
The hadron-energy evolution (Collins and Soper) equation for all the leading-twist transverse-momentum and spin dependent parton distributions is derived in the impact parameter space. Based on the result, we present resummation formulas…
The distribution of the spin of the nucleon among its constituents can be parametrized in the form of polarized parton distribution functions for quarks and gluons. Using all available data on the polarized structure function $g_1(x,Q^2)$,…
The polarized distribution functions of mesons, including pion, kaon and eta, using the proton structure function, are calculated. We are looking for a relationship between the polarized distribution of mesons and the polarized structure of…
The evolution of shower parton distributions in a jet is investigated in the framework of quark recombination model. The distributions are parameterized and the $Q^2$ dependence of the parameters is given by polynomials of $\ln Q^2$ for a…
We discuss our studies of polarized parton distributions which are related to the RHIC-Spin project. First, the parametrization of unpolarized parton distributions is explained as an introduction to general audience. Second, activities of…
We study parity-even and parity-odd polarization observables for the process $p \, p \to l^{\pm} \, X$, where the lepton comes from the decay of a $W$-boson. By using the collinear twist-3 factorization approach, we consider the case when…
Semiclassical expansion of the Wigner function for spin-1/2 fermions having an effective spacetime-dependent mass is used to analyze spin-polarization effects. The existing framework is reformulated to obtain a differential equation…
Based on a simple model which is compatible with the idea of the static quark model and the parton model, the polarized structure functions of proton and deuteron, two-spin asymmetries of $\pi ^0$ in polarized $pp$ reactions and inelastic…
The parton distributions in the proton are evaluated dynamically using a nonlinear QCD evolution equation - the DGLAP equation with twist-4 (the GLR-MQ-ZSR) corrections - starting from a low scale $\mu^2$, where the nucleon consists of…