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We present a determination of the gluon polarization Delta G/G in the nucleon, based on the helicity asymmetry of quasi-real photoproduction events, Q^2<1(GeV/c)^2, with a pair of large transverse-momentum hadrons in the final state. The…

High Energy Physics - Experiment · Physics 2008-11-26 COMPASS Collaboration , E. S. Ageev

We consider the production and decay of the $\chi_2$ charmonium state in polarized and unpolarized $pp$ collisions at RHIC in the framework of an effective theory based on the QCD multipole expansion. We find that the angular distribution…

High Energy Physics - Phenomenology · Physics 2011-03-23 R. L. Jaffe , D. Kharzeev

One of the goals of COMPASS experiment is the determination of the gluon polarisation, \Delta G/G, for a deep understanding of the spin structure of the nucleon. The gluon polarisation can be measured via the Photon-Gluon-Fusion (PGF)…

High Energy Physics - Experiment · Physics 2019-08-13 Luís Silva

A complete expression for the p_T-distribution of the gluon production rate in the homogeneous chromoelectric field has been obtained. Our result contains a new additional term proportional to the singular function \delta(p_T^2). We…

High Energy Physics - Theory · Physics 2008-11-26 D. G. Pak

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…

High Energy Physics - Phenomenology · Physics 2007-05-23 J. Bartelski , S. Tatur

We present a possible direct measurement of the polarised gluon density $\Delta G(x)$ in LO from di-jet production in polarised deep inelastic ep scattering, assuming the kinematics of the HERA collider. We show the sensitivity to the…

High Energy Physics - Phenomenology · Physics 2007-05-23 G. Radel , A. De Roeck , M. Maul

Gluon production on two scattering centers is studied in the formalism of reggeized gluons. Different contributions to the inclusive cross-section are derived with the help of the Lipatov effective action. The AGK relations between these…

High Energy Physics - Phenomenology · Physics 2015-06-16 M. A. Braun , S. S. Pozdnyakov , M. Yu. Salykin , M. I. Vyazovsky

We study the polarization of hyperon in different processes in singly polarized $pp$ collisions, in particular its relation to the polarized parton distributions. We show that by measuring hyperon polarization in particularly chosen…

High Energy Physics - Phenomenology · Physics 2009-11-10 Qing-hua Xu , Zuo-tang Liang

Little information is known about the polarization of gluons inside a longitudinally polarized proton. We investigate the sensitivity of photoproduction experiments with both beam and target longitudinally polarized to the polarization of…

High Energy Physics - Phenomenology · Physics 2010-11-01 S. Keller , J. F. Owens

A new preliminary result of a gluon polarisation \Delta G/G obtained selecting high transverse momentum hadron pairs in DIS events with Q^2>1 (GeV/c)^2 is presented. Data has been collected by COMPASS at CERN during the 2002-2004 years. In…

High Energy Physics - Experiment · Physics 2019-08-13 L. Silva

A recent global QCD analysis of jet production and other polarized scattering data has found the presence of negative solutions for the gluon helicity distribution in the proton, $\Delta g$, along with the traditional $\Delta g > 0$…

High Energy Physics - Phenomenology · Physics 2026-05-04 R. M. Whitehill , Yiyu Zhou , N. Sato , W. Melnitchouk

The utility of prompt photon plus associated jet production for constraining the size and shape of the polarized gluon density of the proton $\Delta G$ is examined at $\sqrt{S}=40$ GeV, appropriate for the proposed HERA-$\vec{N}$ polarized…

High Energy Physics - Phenomenology · Physics 2014-11-17 L. E. Gordon

We study various conceivable photoproduction reactions in a polarized ep collider mode of HERA with respect to their sensitivity to the proton's polarized gluon distribution. A special emphasis is put on the `resolved' part of the cross…

High Energy Physics - Phenomenology · Physics 2007-05-23 J. M. Butterworth , N. Goodman , M. Stratmann , W. Vogelsang

The STAR Collaboration has measured the longitudinal double-spin asymmetry for inclusive jet production in polarized p+p collisions at sqrt{s} = 200 GeV. The results set significant new constraints on the gluon polarization within the…

High Energy Physics - Experiment · Physics 2019-08-13 C. A. Gagliardi

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…

High Energy Physics - Phenomenology · Physics 2023-03-29 Bheemsehan Gurjar , Chandan Mondal , Dipankar Chakrabarti

Longitudinal double-spin asymmetries of charged hadrons with high transverse momentum $p_T$ have been measured in electroproduction using the \hermes\ detector at \hera. Processes involving gluons in the nucleon have been enhanced relative…

High Energy Physics - Experiment · Physics 2012-08-03 The HERMES Collaboration , A. Airapetian

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…

High Energy Physics - Experiment · Physics 2019-08-14 Matthew Walker

The proton spin structure is not understood yet and there has remained large uncertainty on Delta g, the gluon spin contribution to the proton. Double helicity asymmetry (A_LL) of pi0 production in polarized pp collisions is used to…

High Energy Physics - Experiment · Physics 2019-08-13 K. Aoki

The double spin asymmetry for exclusive $J/\psi$ pair production in the polarized $p-p$ collisions at RHIC is investigated. Our study shows that the asymmetry in this process is measurable at RHIC-SPIN experiments in the near future, and,…

High Energy Physics - Phenomenology · Physics 2011-03-23 Jiro Kodaira , Cong-Feng Qiao

We propose to utilize the polarization information of the $Z$ bosons in $ZZ$ production, via the gluon-gluon fusion process $gg\to ZZ$, to probe the $Zt\bar{t}$ gauge coupling. The contribution of longitudinally polarized $Z$ bosons is…

High Energy Physics - Phenomenology · Physics 2020-09-23 Qing-Hong Cao , Bin Yan , C. -P. Yuan , Ya Zhang