Related papers: Uncertainty of polarized gluon distribution from p…
The STAR Collaboration reports measurements of the longitudinal double-spin asymmetry, $A_{LL}$, for neutral pions produced at forward directions in polarized proton-proton collisions, at a center-of-mass energy of $510$ GeV. Results are…
The longitudinally polarized gluon density is probed sensitively in hard collisions of polarized protons under the condition that the dominant dynamics are perturbative and of leading twist origin. First data have recently been presented by…
We investigate the polarized parton distribution functions (PDFs) and their uncertainties by using the world data on the spin asymmetry A_1. The uncertainties of the polarized PDFs are estimated by the Hessian method. The up and down…
We report on recent results of the longitudinal double-spin asymmetry A_LL from the STAR and PHENIX experiments. Data were collected in longitudinally polarized proton-proton collisions at a center-of-mass energy of 200 GeV. The results…
The physics scope of a possible future experiment utilizing an internal polarized nucleon target in the HERA proton beam is discussed. By measuring single spin asymmetries in inclusive particle production at 820~GeV beam energy the…
A longitudinal double spin asymmetry for \pi^0 production has been measured by the PHENIX collaboration. The asymmetry is sensitive to the polarized gluon distribution and is indicated to be positive by theoretical predictions. We study a…
The recent high precision SMC data on polarized $\mu p$ scatterings have again confirmed that very little of the proton spin is carried by quarks. To unravel the mystery of the proton spin structure, it is quite important to know the…
We calculate polarization asymmetries in photoproduction of high transverse momentum mesons, focusing on charged pions, considering the direct, fragmentation, and resolved photon processes. The results at very high meson momentum measure…
The STAR Collaboration reports precise measurements of the longitudinal double-spin asymmetry, $A_{LL}$, for dijet production with at least one jet at intermediate pseudorapidity $0.8 < \eta_{\rm jet} < 1.8$ in polarized proton-proton…
We report global analysis results for polarized parton distribution functions in the nucleon. The optimum distributions are determined by using spin asymmetry data on polarized lepton scattering on proton, neutron, and deuteron. Their…
Production of large-p_T hadron pairs by polarized photon on a longitudinally polarized proton towards probing the polarized gluon distribution is studied. Resolved photon contributions and the effect of changing the scales are taken into…
We obtain the gluon parton distribution functions (PDFs) in the proton within the extended light-front holographic QCD framework, where the proton couples with the spin-two Pomeron in Anti-de Sitter space, together with constraints imposed…
These proceedings show the preliminary results of the dijet longitudinal double spin asymmetry $A_{LL}$ in polarized proton-proton collisions at $\sqrt{s} = 200$ GeV for the pseudorapidity range $|\eta| \le 0.8$. The integrated luminosity…
In order to understand the gluon contribution to the nucleon spin, some experiments can study the production of hadrons at high transverse momemtum from lepton-nucleon or nucleon-nucleon scattering. RHIC has recently measured such double…
In order to determine polarized parton densities in nucleon we have made fits using all experimental data on spin asymmetries measured in the deep inelastic scattering on different nucleon targets. We have used in our analysis next to…
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 $g_1(x,Q^2)$,…
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…
We analyze the capability of prompt photon production in pp and pp(bar) collisions to constrain the gluon distribution of the proton, considering data from fixed-target experiments as well as collider measurements. Combined fits are…
We present preliminary results for the first measurements of the double longitudinal spin asymmetry A_LL in inclusive jet production at mid-rapidity in polarized proton-proton collisions at sqrt(s) = 200 GeV. The data amount to ~ 0.5 pb-1…
There have been many versions of spin-dependent parton distributions in the literature. Although most agree with present data within uncertainties, they are based upon different physical assumptions. Some physical models are discussed and…