相关论文: Spin Structure Function of the Virtual Photon Beyo…

In this work we study the renormalization of the electrodynamics of spin 1/2 fermions in the Poincar\'e projector formalism which is second order in the derivatives of the fields. We analyze the superficial degree of divergence of the…

Nucleon spin structure has been an active and exciting subject of interest for the last three decades. Recent precision spin-structure data from Jefferson Lab have significantly advanced our knowledge of nucleon structure in the valence…

We evolve virtual photon parton densities up to the SUSY threshold and higher using coupled inhomogeneous DGLAP differential equations. Reliable input parameterizations were available from the c-quark threshold. Limited $P^2$ ( target…

Numerical simulations of the quarkonium spin splittings are done in the framework of lattice nonrelativistic quantum chromodynamics (NRQCD). At leading order in the velocity expansion the spin splittings are of $O(M_Q v^4)$, where $M_Q$ is…

I present an introduction to the field of Quantum Chromodynamics (QCD) with emphasis on nucleon spin structure and perturbative methods. After a somewhat comprehensive overview of perturbative QCD, including the systematics of…

Factorization scheme analysis of $F_2^{\gamma}(x,Q^2)$ in the next-to-leading order QCD is revisited. It is emphasized that the presence of the inhomogeneous term in the evolution equations for quark distribution functions of the photon…

We present a measurement of the deuteron spin-dependent structure function g1d based on the data collected by the COMPASS experiment at CERN during the years 2002-2004. The data provide an accurate evaluation for Gamma_1^d, the first moment…

The spin-dependent structure functions $g_1(x)$, $g_2(x)$, ${g}_2^{WW}(x)$ and ${\bar g}_2(x)$ and their moments are studied in the CM bag model. The results show that (i) $\int_0^1g_2(x)dx=0$, i.e. the Burkhardt-Cottingham sum rule holds,…

We perform a systematic study on the spin decomposition of an electron in QED at one-loop order. It is found that the electron orbital angular momentum defined in Jaffe-Manohar and Ji spin sum rules agrees with each other, and the so-called…

We propose a new approach for taking into account the Q^2 dependence of measured asymmetry A1. This approach is based on the similarity of the Q2 behaviour and the shape of the spin-dependent structure function g1(x,Q^2) and spin averaged…

We study the nonperturbative and higher order perturbative corrections on the electromagnetic ($F_{1p,2p}^\gamma$) and electromagnetic-weak interference ($F_{1p,2p,3p}^{\gamma Z}$) structure functions and their impact on the parity…

We use the covariant current formalism to derive the general form of the 2-photon correlation function for fully chaotic sources. Motivated by the recent discussion in the literature we concentrate on the effects from the photon spin on the…

We analyse the available data on the polarized asymmetries $A_1$ for proton, neutron and deuteron targets. We use a homogeneous and updated set of unpolarized structure functions to derive $g_1$ from $A_1$, and we accurately correct for the…

We extend the QCD sum rule analysis of the \gamma^*\gamma^* -->\pi^o form factor into the region where one of the photons has small virtuality: q^2 << Q^2 > 1 GeV^2. In this kinematics, one should perform an additional factorization of…

Predictions for the spin dependent structure function $g_1$ of the nucleon are presented. We use an unified approach incorporating the LO DGLAP evolution and the resummation of double logarithmic terms $ln^2(x)$. We show, that the singular…

Inter-band photo-excitation of electron states with the twisted photons in GaAs, a direct band-gap bulk semiconductor, is considered theoretically. Assuming linearity of the quantum transition amplitudes and applying Wigner-Eckart theorem,…

A leading order QCD analysis of spin asymmetries in polarized deep inelastic lepton nucleon scattering is presented within the framework of the radiative parton model. Two resulting sets of plausible leading order spin dependent parton…

We have measured the spin structure functions g2p and g2d and the virtual photon asymmetries A2p and A2d over the kinematic range 0.02 < x < 0.8 and 1.0 < Q^2 < 30(GeV/c)^2 by scattering 38.8 GeV longitudinally polarized electrons from…

We study the transition of non-perturbative to perturbative QCD in situations with possible violations of scaling limits. To this end we consider the singly- and doubly-virtual pion transition form factor $\pi^0\to\gamma\gamma$ at all…

We present a novel approach for investigating the spin structure of hadrons based on the two-point function in quantum field theory. In a rotating frame, we derive two independent expressions of the two-point function and identify their…