2006/12/28 by M. Sarsour
Physics and Astronomy · #High-Energy Particle Collisions Research #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #hep-ex
paper · pdf · doi:10.1088/1742-6596/69/1/012033
published as J.Phys.Conf.Ser.69:012033,2007 · 4 pages, 5 figures, presented at GHP06 conference
arxiv created 2006/12/28 · openalex publication_date 2007/05/01 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/29
Abstract. The STAR experiment uses polarized p+p collisions at RHIC to determine the contributions to the spin of the proton from gluon spin and from orbital angular momentum of the quarks and gluons. Selective STAR measurements of the longitudinal double spin asymmetry for inclusive jet and inclusive hadron production are presented here. In addition, we report measurements of the transverse spin asymmetry for di-jet production at mid-rapidity and the transverse single-spin asymmetry for forward π ◦ production. The quark and anti-quark contributions to the spin of the proton measured with polarized deep-inelastic scattering (DIS) fixed target experiments amount to only ≤ 30 % [1]. Consequently, the rest of the spin of the proton must come from the gluons and the orbital angular momentum of both quarks and gluons. However, the gluon polarization, ∆g, is poorly constrained from scaling violations in the DIS data [2], and more precise and direct measurements are needed. Polarized p+p collisions at the Relativistic Heavy Ion Collider (RHIC) provide a very suitable environment, rich with strongly interacting probes, to measure ∆g directly and precisely. There are many processes where the gluon participates directly. In addition, the high c.m. energy, √ s = 200 GeV, and high pT make next-to-leading order (NLO) perturbative Quantum Chromodynamics