Title: Measurement of the longitudinal double-spin asymmetry for dijet production in polarized proton-proton collision at $\sqrt{s} = 200$ GeV

PA: Matthew Walker, Joseph Seele, Bernd Surrow

Proposed Target Journal: Physical Review Letters

Abstract:

We report the measurement of the longitudinal double-spin asymmetry for dijet production at midrapidity in longitudinally polarized proton-proton collisions at $sqrt{s} = 200$ GeV by the STAR experiment at RHIC. STAR is able to measure dijet production in different pseudorapidity acceptances for the first time, which allows constraints to be placed on the shape of the polarized gluon distribution function, $\Delta g(x)$.

Summary:

 In summary, we report the measurement of the longitudinal double-spin asymmetry for dijet production at midrapidity in longitudinally polarized proton-proton collisions at $sqrt{s} = 200$ GeV by the STAR experiment at RHIC. This measurement is the first analysis to use multiple pseudorapidity acceptances to provide sensitivity to the shape of $\Delta g(x)$. This measurement also provides strong constraints on the value of $\Delta G$.

Rough Timeline:

• Paper Proposal to Spin PWG
• Paper Proposal to PWGC (04/24/2012)
• Presentation of Final Result
• Paper Draft circulated to Spin PWG
• Paper in GPC
• Release of Paper to Collaboration
• Paper submitted to Journal

Documentation:

• Spin PWG presentations
  • Dijet Filter for Simulation
  • Dijet Filter Performance
  • Dijet Simulation Request
  • 2009 Analysis Overview
• Technical Note
  
  • Analysis Note

Figures:

• Fig 1: Agreement between Data and Simulation

• Fig 2: $A_{LL}$ for East-East and West-West, East-West, and the full acceptance

• Fig 3: $x_1$ and $x_2$ distributions for East-East, East-West, and the Full acceptance

or linear:

• Fig 4: Comparison of asymmetry to various values of $\Delta G$ in GRSV (Tentative, need additional grid files from GRSV)

Chi2 values and CL