Extracting $ΔG(x)$ from the $p⃗+p⃗→γ+jet+X$ reaction with the STAR detector at RHIC Available to Purchase

Two decades of polarized deep inelastic scattering experiments have revealed that the quarks within a proton carry only a small fraction of the proton’s spin, but provide few clues as to the source of the missing components. In particular, the role played by gluons remains largely unexplored. In this talk, I discuss an experimental program that will allow a direct extraction of the gluon helicity distribution function $ΔG(x),$ via a measurement of the spin correlation parameter $ALL$ in the reaction $p⃗+p⃗→γ+jet+X.$ Simulations indicate that a precise determination of the gluonic contribution to the proton’s spin, represented by the integral $ΔG,$ will require access to values of $xgluon$ as low as ∼0.01. I will show that this can be achieved using the STAR detector at RHIC, when equipped with suitable electromagnetic calorimetry extending to a pseudorapidity of $η=2.$