Abstract
We present the first measurements of the longitudinal double-spin asymmetry $A_{LL}$ for dijets with at least one jet reconstructed within the pseudorapidity range $0.8 < \eta < 1.8$. The dijets were measured in polarized $pp$ collisions at a center-of-mass energy $\sqrt{s}$ = 200 GeV. Values for $A_{LL}$ are determined for several distinct event topologies, defined by the jet pseudorapidities, and span a range of parton momentum fraction $x$ down to $x \sim$ 0.01. The measured asymmetries are found to be consistent with the predictions of global analyses that incorporate the results of previous RHIC measurements. They will provide new constraints on $\Delta g(x)$ in this poorly constrained region when included in future global analyses.
Highlights
AND MOTIVATIONUnderstanding the internal spin structure of the proton is a fundamental goal in strong interaction physics
We present the first measurements of the longitudinal double-spin asymmetry ALL for dijets with at least one jet reconstructed within the pseudorappiffidffi ity range 0.8 < η < 1.8
We report the first measurements of the longitudinal double-spin asymmetry, ALL, for dijet production at intermediate pseudorapidities, where at least one of the jets was detected pinffiffi The data were taken at s the range of 0.8 < η 1⁄4 200 GeV in 2009
Summary
Understanding the internal spin structure of the proton is a fundamental goal in strong interaction physics. The addition of the most recent STAR inclusive jet results [7] shows, for the first time, a positive gluon polarization in the region of sensitivity, x > 0.05. At lower values of the momentum fraction x, the magnitude and shape of the gluon helicity distribution are still poorly constrained Correlation observables, such as those from dijet production, capture more information about the initial state kinematics of the hard scattering, and may lead to tighter constraints on the shape of ΔgðxÞ. We report the first measurements of the longitudinal double-spin asymmetry, ALL, for dijet production at intermediate pseudorapidities, where at least one of the jets was detected pinffiffi The data were taken at s the range of 0.8 < η 1⁄4 200 GeV in 2009.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
