Title:

Longitudinal double spin asymmetry for inclusive jet and dijet production in proton-proton collisions at \sqrt{s} = 510 GeV

PAs:

Zilong Chang, Renee Fatemi, Carl Gagliardi, Suvarna Ramachandran

Target Journal:

Physical Review D 

Abstract:

We report the first measurement of the midrapidity inclusive jet and dijet longitudinal double-spin asymmetry A_LL in polarized proton-proton collisions at center-of-mass energy sqrt{s} = 510 GeV. The inclusive jet A_LL measurement provides sensitivity to the gluon helicity distribution down to a Bjorken-x of 0.02, while the dijet measurements, binned in four jet-pair topologies, will allow for tighter constraints on the x dependence. Both results are consistent with previous measurements made at sqrt{s}= 200 GeV and show excellent agreement with predictions from recent next-to-leading order global analyses. 

Figures:

Figure 1: jet spectrum divided by triggers, ratio = (data-simu)/data.

Figure 2: charged hadron jT.

Figure 3: charged hadron z.

Figure 4:  jet NEF.

Figure 5: underlying event dpT asymmetry with a constant fit.

Figure 6:  underlying event dpT vs underlying event corrected detector jet pT

Figure 7:  underlying event charged pT distribution (similar plot for underlying event tower pT distribution not shown here).

Figure 8: sampled xg distribution will aLL weighting, points: triggered detector jets vs. histograms: all parton jets (minbias).

Figure 9:  run12 inclusive jet ALL vs. parton jet pT.

Figure 10: run12 inclusive jet ALL with predictions from 100 NNPDF pol1.1 replica.

Figure 11: run12 inclusive jet ALL with run9 inclusive jet ALL vs. xT.

Dijet A_LL Plots

Figure 12: Dijet Invariant Mass spectrum

Figure 13: Dijet Delta Phi Spectrum

Figure 14: Run 12 dijet ALL for Forward - Forward Bin

Figure 15: Run 12 Dijet ALL Forward - Middle Bin

Figure 16: Run12 Dijet ALL Forward - Backward Bin

Figure 17: Run 12 Dijet ALL Middle - Middle Bin