Double Helicity Dependence of Jet Properties from Dihadrons in Longitudinally Polarized p+p Collisions at sqrt(s) = 200 GeV

TL;DR

This study measures the double-helicity dependence of dijet transverse momentum in polarized proton collisions, providing experimental insights into the potential role of orbital angular momentum in proton spin structure.

Contribution

First experimental measurement of the double-helicity dependence of dijet transverse momentum in polarized p+p collisions at 200 GeV.

Findings

No significant double-helicity dependence observed within uncertainties.

Results consistent with zero difference in dijet transverse momentum between helicity states.

Provides constraints on models of orbital angular momentum contributions to proton spin.

Abstract

It has been postulated that partonic orbital angular momentum can lead to a significant double-helicity dependence in the net transverse momentum of Drell-Yan dileptons produced in longitudinally polarized p+p collisions. Analogous effects are also expected for dijet production. If confirmed by experiment, this hypothesis, which is based on semi-classical arguments, could lead to a new approach for studying the contributions of orbital angular momentum to the proton spin. We report the first measurement of the double-helicity dependence of the dijet transverse momentum in longitudinally polarized p+p collisions at sqrt(s) = 200 GeV from data taken by the PHENIX experiment in 2005 and 2006. The analysis deduces the transverse momentum of the dijet from the widths of the near- and far-side peaks in the azimuthal correlation of the dihadrons. When averaged over the transverse momentum of the triggered particle, the difference of the root-mean-square of the dijet transverse momentum between like- and unlike-helicity collisions is found to be -37 +/- 88(stat) +/- 14(syst) MeV/c.