相关论文: Transverse spin effects and higher twist in the si…
We derive the analog of the Wandzura-Wilczek relation for the light-cone distributions of polarized gluons in a transversely polarized nucleon. The short distance cross-section is entirely due to the intrinsic transverse momenta of gluon in…
The distribution of longitudinal gluons in a nucleon, introduced earlier by Gorsky and Ioffe, is estimated from below by making use of the positivity of density matrix and the analogue of the Wandzura-Wilczek relation for the light-cone…
The transverse nucleon spin can be transferred to the quarks and gluons in several ways. In the factorizing, hard scattering processes to be considered, these are parameterized at leading twist by the transversity distribution function and…
We derive exact relations among the polarized gluon and three-gluon distributions in the transversely polarized nucleon which are relevant to single and double spin asymmetries in various hard processes. We also discuss the partonic…
We extend the study of quark spin-orbit correlations in the nucleon to the case of transverse polarization. At the leading-twist level, this completes the spin structure of the quark kinetic energy-momentum tensor. In particular, we revisit…
We investigate the transverse quark spin densities of the nucleon with the lowest moment within the framework of the SU(3) chiral quark-soliton model, emphasizing the strange quark spin density. Based on previous results of the vector and…
We show how generalized quark distributions in the nucleon describe the density of polarized quarks in the impact parameter plane, both for longitudinal and transverse polarization of the quark and the nucleon. This density representation…
Accounting for transverse momenta of the quarks, a longitudinal quark spin asymmetry exists in a transversely polarized nucleon target. The relevant leading quark distribution $g_{1T}(x,k_T^2)$ can be measured in the semi-inclusive…
I review what is known about the quark and gluon spin distributions in the nucleon. I discuss in some detail (a) the existence of sum rules for angular momentum; (b) the interpretation and possible measurement of the nucleon's transversity…
A first empirical extraction of the transversity distributions for the $u$- and $d$-quarks has been done by Anselmino {\it et al.} based on the combined global analysis of the measured azimuthal asymmetries in semi-inclusive deep inelastic…
The specificities of transverse polarization with respect to helicity of ultrarelativistic fermions are pointed out. For massless fermions, a covariant transversity four-vector is defined, up to a kind of gauge transformation. The…
The twist-four quark and gluon distributions in a transversely polarized nucleon are identified and relations among them are discussed by using QCD equations of motion. Their contribution, at the order of ${\cal O} \left( 1/Q^2 \right)$, to…
In recent decades, the spin and transverse momentum of quarks and gluons were found to play integral roles in the structure of the nucleon. Simultaneously, the onset of gluon saturation in hadrons and nuclei at high energies was predicted…
The spin structure of nucleon at twist 2 and 3 levels is analyzed. The contribution of quark and gluon spins to nucleon spin are Lorentz invariant, while it is not sure for orbital angular momentum. The conserved fractional moments of…
We derive the gradient expansion for the exchange energy of a spin-polarized electron gas by perturbing the uniformly spin polarized state and thus inducing a small non-collinearity that is slowly varying in space. We show that the…
In the past few years, a lot of evidences have been accumulated, which indicate that the gluon polarization inside the nucleon is likely to be small at least at the low renormalization scales. On the other hand, the recent lattice QCD…
The complete knowledge of the nucleon spin structure at leading twist requires also addressing the transverse spin distribution of quarks, or transversity, which is yet unexplored because of its chiral-odd nature. Elaborating strategies to…
Significant differences between transverse and longitudinal polarized parton distributions are found at low energies within a light-front covariant quark model of the nucleon. These differences are due to relativistic spin effects…
We investigate the evolution of transverse spin in tightly focused circularly polarized beams of light, where spin-orbit coupling causes a local rotation of the polarization ellipses upon propagation through the focal volume. The effect can…
We investigate the gluon Wigner distributions for unpolarized, longitudinally polarized and transversely polarized target state. Instead of a nucleon, we take the target state to be a quark dressed with a gluon at one loop and investigate…