Related papers: Gluon orbital angular momentum at small-$x$
We present a calculation of Wigner distributions for gluons in light-front dressed quark model. We calculate the kinetic and canonical gluon orbital angular momentum and spin-orbit correlation of the gluons in this model.
Although the matrix element of the gluon spin operator in nucleon helicity states is known to be independent of some special choices of gauge, we show that it is not invariant under a general gauge transformation. We find that there exists…
Using a novel analysis technique, the gluon polarisation in the nucleon is re-evaluated using the longitudinal double-spin asymmetry measured in the cross section of semi-inclusive single-hadron muoproduction with photon virtuality…
Linear polarization of gluons inside unpolarized hadrons affects the transverse momentum distribution of produced spin-0 particles, such as of the Higgs or (pseudo-)scalar quarkonium states at LHC. Despite the currently unknown amount of…
We compute the contribution of the gluonic component of the energy-momentum tensor (EMT) to the angular momentum density in various decompositions. We use the light-front Hamiltonian technique, and a two-component formalism in light-front…
The quark orbital angular momentum (OAM) has been recognized as an important piece of the proton spin puzzle. A lot of effort has been invested in trying to extract it quantitatively from the generalized parton distributions (GPDs) and the…
We show that the gluon distribution function for very large nuclei may be computed for small transverse momentum as correlation functions of an ultraviolet finite two dimensional Euclidean field theory. This computation is valid to all…
It is well-known that the back-to-back (correlation) limit of inclusive quark-antiquark dijet production in unpolarized high energy electron-proton collisions can probe the Weizs\"{a}cker-Williams (WW) gluon transverse momentum-dependent…
We compute the gluon distribution in deep inelastic scattering at small x by solving numerically the angular ordering evolution equation. The leading order contribution, obtained by neglecting angular ordering, satisfies the BFKL equation.…
We derive the first-ever small-$x$ expression for the inclusive gluon production cross section in the central rapidity region of the longitudinally polarized proton-proton collisions. The cross section depends on the polarizations of both…
We study spin asymmetries in diffractive $Q \bar Q$ and vector meson production which are sensitive to the spin-dependent part of the two-gluon-nucleon coupling. It is found that the $A_{ll}$ and $A_{lT}$ asymmetry in diffractive reactions…
We consider the interaction of the partonic fluctuation of a scalar ``photon'' with an external color field to calculate the leading and next-to-leading order gluon distribution of the proton following the work done by…
A major controversy has arisen in QCD as to how to split the total angular momentum into separate quark and gluon contributions, and as to whether the gluon angular momentum can itself be split, in a gauge invariant way, into a spin and…
This talk consists of four parts. In part one, I give an elementary discussion on constructing a Lorentz-invariant spin sum rule for the nucleon. In part two, I discuss a gauge-dependent spin sum rule, explore its relation with the…
We present measurements of the longitudinal spin asymmetry, $A_{LL}$, for the inclusive jet signal at STAR. The data presented here are mid-rapidity jets in the transverse momentum range of $5<pT<35$ GeV/c and come from polarized…
In a series of papers, we have established the existence of two gauge-invariant decompositions of the nucleon spin, which are physically nonequivalent. The orbital angular momenta of quarks and gluons appearing in these two decompositions…
We study the Collins effect in the azimuthal asymmetric distribution of hadrons inside a high energy jet in the single transverse polarized proton proton scattering. From the detailed analysis of one-gluon and two-gluon exchange diagrams…
We discuss the impact of recent high-statistics RHIC data on the determination of the gluon polarization in the proton in the context of a global QCD analysis of polarized parton distributions. We find clear evidence for a non-vanishing…
The nucleon spin problem raises experimental and theoretical questions regarding the contribution of the orbital angular momentum of the quarks to the total spin of the nucleon. In this article we examine the commutation relationships of…
The Wigner distributions for u and d quarks in a proton are calculated using the light front wave functions (LFWFs) of the scalar quark-diquark model for nucleon constructed from the soft-wall AdS/QCD correspondence. We present a detail…