相关论文: Effect of Orbital Angular Momentum on Valence-Quar…
We investigate the quark angular momentum in a model with the nucleon being a quark and a spectator. Both scalar and axial-vector spectators are included. We perform the calculations in the light-cone formalism where the parton concept is…
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…
We study the connection between the quark orbital angular momentum and the pretzelosity transverse-momentum dependent parton distribution function. We discuss the origin of this relation in quark models, identifying as key ingredient for…
We present a detailed investigation of the skewness dependence of quark Wigner distributions within the light-front dressed quark model. While previous studies have largely focused on the forward limit, we explore the impact of nonzero…
We derive simple relations between the polarized and unpolarized valence quark distributions in a light-cone SU(6) quark-spectator model for nucleons. The explicit x-dependent Wigner rotation effect for the light-flavor quarks is…
I deduce an inequality between the helicity and the transversity distribution of a quark in a nucleon, at small energy scales. Then I establish, thanks to the positivity constraint, a rigorous bound on longitudinally polarized valence quark…
We investigate the different decompositions of the angular momentum in QCD for a relativistic spin $1/2$ composite state, namely a quark dressed with a gluon. We use light-front Hamiltonian perturbation theory, and in the light-front gauge,…
In this letter, we report the results for the isovector polarized quark quasi-distribution functions $\Delta u(x,v) - \Delta d(x,v)$ in the large $N_c$, calculated within the chiral quark-soliton model. It is shown that the polarized quark…
We present a recent calculation of the Wigner distributions of quarks and gluons in a perturbative model. We also present the results for the orbital angular momentum and the spin-orbit correlations.
We consider the role of chirally odd wave functions in hard exclusive reactions. Such wave functions have the quarks oriented in the opposite helicity configuration from those assumed in the short-distance limit and are generally associated…
Valence quark distributions in pion, polarizied $\rho$ mesons and nucleon in the region of intermediate $x$ are obtained by generalizied QCD sum rules. It is shown, that polarization effects are very significant. The strong suppression of…
We report on the first global analysis of transverse momentum dependent helicity distributions of the proton. The analysis is performed at next-to-leading order with the evolution factor at next-to-next-to-leading-logarithmic accuracy.…
We demonstrate that a nonzero strangeness contribution to the spacelike electromagnetic form factor of the nucleon is evidence for a strange-antistrange asymmetry in the nucleon's light-front wave function, thus implying different…
In this letter, we investigate the nucleon quasi-parton distribution functions in the chiral quark soliton model. We derive a set of sum-rules depending on the velocity of the nucleon and on the Dirac matrix defining the distribution…
The quark orbital angular momentum component of proton spin, $L_q$, can be defined in QCD as the integral of a Wigner phase space distribution weighting the cross product of the quark's transverse position and momentum. It can also be…
We report the first calculation of the simplest but most fundamental transverse momentum dependent (TMD) distribution of quarks in the nucleon, i.e. the time-reversal-even unpolarized TMD quark and antiquark distribution with isoscalar…
We present a measurement of semi-inclusive spin asymmetries for positively and negatively charged hadrons from deep inelastic scattering of polarised muons on polarised protons and deuterons in the range $0.003<x<0.7$ and $Q^2>$1 GeV$^2$.…
The evolution of orbital angular momentum distributions within the radiative parton model is studied. We use different scenarios for the helicity weighted parton distributions and consider a broad range of input distributions for orbital…
The momentum and helicity density distributions of the strange quark sea in the nucleon are obtained in leading order from charged-kaon production in deep-inelastic scattering on the deuteron. The distributions are extracted from…
We calculate the Wigner functions for a quark target dressed with a gluon. These give a combined position and momentum space information of the quark distributions and are related to both generalized parton distributions (GPDs) and…