Longitudinal Double Spin Asymmetry in Inclusive Jet Production AtSTAR.

Longitudinal Double Spin Asymmetry in Inclusive Jet Production AtSTAR.
Author: STAR Collaboration
Publisher:
Total Pages:
Release: 2006
Genre:
ISBN:

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This contribution reports on the first measurement of the longitudinal double-spin asymmetry A{sub LL} for the inclusive production of jets in polarized proton-proton collisions at {radical}s = 200 GeV. The data were collected with STAR at RHIC in the years 2003 and 2004, and correspond to a sampled integrated luminosity of 0.3 pb{sup -1} with beam polarizations up to 45%. The results on A{sub LL} cover jet transverse momenta 5

Measurement of the Longitudinal Double Spin Asymmetry for Dijet Production in Polarized Proton+Proton Collisions at Sqrt(s)

Measurement of the Longitudinal Double Spin Asymmetry for Dijet Production in Polarized Proton+Proton Collisions at Sqrt(s)
Author: Daniel L. Olvitt
Publisher:
Total Pages: 147
Release: 2017
Genre:
ISBN:

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Understanding what contributes to the intrinsic angular momentum (spin) of the proton has been a major goal of the nuclear physics community. In the 1980s, it was discovered that quarks contribute 30% to the spin of the proton. This information led to a search to find other contributions to the spin of the proton. At STAR, the double spin asymmetry (ALL) is measured as it is sensitive to the polarized gluon distribution (Dg(x)). The STAR 2009 inclusive jet ALL at sqrt(s) = 200 GeV has been incorporated into two independent global fits. These fits show for the first time a statistically significant non-zero gluon contribution to the spin of the proton in the parton momentum fraction range x > 0.05. Dijet ALL is also measured at STAR. Dijets are advantageous since the parton momentum fraction (x) of the initial partons may be reconstructed to first order from final state measurements. In 2013 STAR collected an estimated 250 pb-1 of data at sqrt(s) = 510 GeV. The higher center of mass energy will allow STAR to probe Dg(x) at x values as low as 0.02. The large statistics will allow a reduction in the uncertainties. Once the data is incorporated into future global fits, it will allow for a more precise determination of Dg(x). The 2013 dijet ALL results will be presented. The results show good agreement with both global fits and previous STAR results dijet measurements.

UNIQUE DESCRIPTION FOR SINGLE TRANSVERSE SPIN ASYMMETRIES IN DIS AND HADRONIC COLLISIONS.

UNIQUE DESCRIPTION FOR SINGLE TRANSVERSE SPIN ASYMMETRIES IN DIS AND HADRONIC COLLISIONS.
Author: F. YUAN
Publisher:
Total Pages: 4
Release: 2006
Genre:
ISBN:

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We derive a unique formula for the single-transverse-spin asymmetry in semi-inclusive hadron production in deep inelastic scattering, valid for all transverse momentum region. Based on this, we further study the integrated asymmetry weighted with transverse-momentum. They can be evaluated in terms of the twist-three quark-gluon correlation functions, which are responsible for the single spin asymmetry in single inclusive hadron production in hadronic collisions. By using the fitted twist-three functions from the hadronic collision data, we find a consistent description for SSAs in deep inelastic scattering. This demonstrates that we have a unique picture for SSAs in these two processes, and shall provide important guidelines for future studies.

Proceedings of the 17th International Spin Physics Symposium

Proceedings of the 17th International Spin Physics Symposium
Author: Kenichi Imai
Publisher: American Inst. of Physics
Total Pages: 1196
Release: 2007-07-02
Genre: Science
ISBN:

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Getting down to the bottom line is what this proceedings digest is all about, as any physicist will tell you: spin is the fundamental concept in physics. The applications are pretty universal due to the fact that, using spin-related phenomena, physicists are trying to reveal the fundamental principles of nature – and things don’t come much more bottom-line than that. This volume is the proceedings of the 17th International Spin Physics Symposium which is a forum to discuss spin physics and related topics.

Spin Physics

Spin Physics
Author: Donald G. Crabb
Publisher: American Inst. of Physics
Total Pages: 1236
Release: 2009-08-25
Genre: Science
ISBN: 9780735406865

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The topics covered in the conference ranged from the physics that can be done with polarized beams of particles (protons, electrons, gamma-rays, etc.) to the techniques and instrumentation necessary to achieve this. Topics included: nucleon structure measurements (from where does the spin of the proton and neutron come), the acceleration, storage and polarization of particle beams and the polarized targets and sources necessary for mounting the experiments.