Double Spin Asymmetry of Electrons from Heavy Flavor Decays in p+p Collisions at sqrt(s)=200 GeV

TL;DR

This study measures the double-spin asymmetry of electrons from heavy flavor decays in polarized proton collisions at 200 GeV, providing constraints on the gluon polarization within the proton.

Contribution

First measurement of electron double-spin asymmetry from heavy flavor decays in polarized p+p collisions at this energy, constraining gluon polarization models.

Findings

Asymmetries are consistent with zero within errors.

Set a limit on gluon polarization: |Delta g/g|^2 < 0.033.

Results support small gluon polarization in the probed x-range.

Abstract

We report on the first measurement of double-spin asymmetry, A_LL, of electrons from the decays of hadrons containing heavy flavor in longitudinally polarized p+p collisions at sqrt(s)=200 GeV for p_T= 0.5 to 3.0 GeV/c. The asymmetry was measured at mid-rapidity (|eta|<0.35) with the PHENIX detector at the Relativistic Heavy Ion Collider. The measured asymmetries are consistent with zero within the statistical errors. We obtained a constraint for the polarized gluon distribution in the proton of |Delta g/g(log{_10}x= -1.6^+0.5_-0.4, {mu}=m_T^c)|^2 < 0.033 (1 sigma), based on a leading-order perturbative-quantum-chromodynamics model, using the measured asymmetry.