2018/09/04 by Amilkar Quintero, Quintero, Amilkar
Physics and Astronomy · #FOS: Physical sciences #High-Energy Particle Collisions Research #Nuclear Experiment (nucl-ex) #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions
paper · pdf · doi:10.48550/arxiv.1809.00923
openalex publication_date 2018/09/04 · openalex created_date 2022/08/03 · openalex updated_date 2026/07/28
The STAR experiment has been studying the spin structure of the proton, using\nthe unique high-energy polarized proton collider, the Relativistic Heavy Ion\nCollider (RHIC). The kinematic coverage at STAR allows accessing gluons because\nquark-gluon and gluon-gluon scatterings dominate particle production at low and\nmedium transverse momenta. The polarized gluon distribution function can be\nconstrained by measuring the longitudinal double-spin asymmetry (ALL) of\njet production and neutral pions. Global QCD analyses of polarized parton\ndistribution functions, which include the 2009 ALL STAR results for\ninclusive jet production at \√(s)=200 GeV, provide evidence of a non-zero\ngluon polarization in the measured range of partonic momentum fraction x >\n0.05. We present the status of the latest measurements of ALL at STAR,\nfor inclusive jet and dijet production at \√(s)=510 GeV and 200 GeV\ncollected in 2013 and 2015 respectively, both at mid-rapidity (|\η|<0.9).\nThe large data sample taken during these years will improve the precision of\nour knowledge about the proton spin structure while the increased center of\nmass energy allows probing the polarized gluon distribution function at smaller\npartonic momentum fraction. Furthermore, we present measurements of ALL\nfor neutral pions at forward rapidity (2.65<\η<3.9) collected during 2012\nand 2013 that also allow reaching lower partonic momentum fraction. We compare\nthese measurements with the latest global analyses.\n