Preliminary Results - Longitudinal double-spin asymmetry for inclusive jet production at √s=200 GeV (2015 dataset)

Longitudinal double-spin asymmetries of inclusive jet production at 200 GeV from the 2015 dataset

The results were planned to be shown during the DIS2020 conference, March, 2020, NYC, USA as a part of the following oral presentation:

DIS2020 Abstract

The Solenoidal Tracker at the Relativistic Heavy Ion Collider (STAR) experiment probes the gluon helicity distribution ∆G(x) using collisions of longitudinally polarized protons at sqrt s = 200 GeV and sqrt s = 510 GeV. Access to ∆G(x) is possible through the double spin asymmetries A LL in gluon-dominated hard scattering processes of inclusive jet and di-jet production. Previously published results on inclusive jet processes at sqrt s = 200 GeV and |η jet | < 1 are based on data collected in 2009, which correspond to an integrated luminosity L of 20 pb −1 with an average beam polarization P of 57%. When included in perturbative QCD analysis of global data, they provide evidence for positive gluon polarization for a momentum fraction x > 0.05 at a hard perturbative scale Q2 = 10 GeV2 .  Additional data were collected in 2015 with an approximately twice larger figure of merit LP4 . This contribution will cover the status of the analysis of 2015 inclusive jet and di-jet data, as well as, the jet measurements based on the most recent high-luminosity 510 GeV data collected in 2013, which will further constrain ∆G(x) at lower x. 


STAR Collaboration Meeting, 12th March, 2020

Update to PWG List, 18th March 2020
Spin PWG Meeting, 4th March, 2020

Preliminary Results Note

Blog posts

Preliminary plots

The plots below show the longitudinal double-spin asymmetry for inclusive jet production for the 2015 data set for the jet eta region |eta| < 1.0. The results from the 2009 data set are shown with blue points. The ALL from NNPDF1.1 and DSSV'14 theoretical analysis are also presented. The plots have been prepared in 3 different versions: with 2019 data and theory curves, with 2009 data, and without any additional results.


The plot below shows the longitudinal double-spin asymmetry for inclusive jet production for the 2015 data set for 2 different jet eta regions |eta| < 0.5 (top panel) and 0.5 < |eta| <1.0 (bottom panel). The results from the 2009 data set are shown with blue points.

The plot below shows false asymmetries: blue beam single spin asymmetry, yellow beam single spin asymmetry, like-sign double spin asymmetry, and unlike-sign double spin asymmetry for the 2015 longitudinal  data with constant function fit.

Results for |eta| < 1.0

Bin xT xT syst. ALL ALL syst. ALL stat.
1 6.43E-02 2.20E-03 1.56E-04 3.45E-04 9.63E-04
2 7.91E-02 2.57E-03 3.32E-03 1.33E-03 8.16E-04
3 9.38E-02 3.15E-03 2.63E-03 8.45E-04 7.45E-04
4 1.12E-01 3.30E-03 3.87E-03 9.77E-04 8.72E-04
5 1.33E-01 3.39E-03 5.48E-03 9.72E-04 1.11E-03
6 1.57E-01 3.51E-03 3.50E-03 7.41E-04 1.51E-03
7 1.84E-01 3.67E-03 1.53E-02 5.63E-04 2.22E-03
8 2.15E-01 4.13E-03 1.86E-02 1.22E-03 3.41E-03
9 2.50E-01 4.80E-03 2.06E-02 9.90E-04 5.72E-03
10 2.91E-01 5.47E-03 3.99E-02 1.25E-03 1.02E-02
11 3.35E-01 7.38E-03 4.11E-02 1.31E-03 1.94E-02

Results for |eta| < 0.5

Bin xT xT syst. ALL ALL syst. ALL stat.
1 6.39E-02 2.25E-03 6.32E-04 4.36E-04 1.24E-03
2 7.85E-02 2.53E-03 2.29E-03 1.21E-03 1.05E-03
3 9.41E-02 3.30E-03 3.46E-03 8.34E-04 9.69E-04
4 1.12E-01 3.22E-03 4.11E-03 9.28E-04 1.12E-03
5 1.33E-01 3.46E-03 7.57E-03 9.72E-04 1.43E-03
6 1.59E-01 3.44E-03 4.81E-03 7.32E-04 1.92E-03
7 1.85E-01 3.74E-03 1.80E-02 5.62E-04 2.79E-03
8 2.16E-01 4.23E-03 2.22E-02 1.27E-03 4.25E-03
9 2.52E-01 4.96E-03 1.99E-02 1.03E-03 7.04E-03
10 2.93E-01 5.55E-03 3.44E-02 1.34E-03 1.23E-02
11 3.37E-01 8.44E-03 4.89E-02 1.55E-03 2.32E-02

Results for 0.5 < |eta| < 1.0

Bin xT xT syst. ALL ALL syst. ALL stat.
1 6.50E-02 2.23E-03 -5.89E-04 3.45E-04 1.53E-03
2 7.99E-02 2.81E-03 4.86E-03 1.77E-03 1.29E-03
3 9.34E-02 3.03E-03 1.43E-03 8.17E-04 1.17E-03
4 1.12E-01 3.51E-03 3.51E-03 1.09E-03 1.38E-03
5 1.32E-01 3.34E-03 2.28E-03 9.69E-04 1.78E-03
6 1.54E-01 3.84E-03 1.48E-03 7.60E-04 2.46E-03
7 1.82E-01 3.60E-03 1.08E-02 6.27E-04 3.67E-03
8 2.13E-01 4.01E-03 1.23E-02 1.18E-03 5.73E-03
9 2.46E-01 4.61E-03 2.24E-02 1.06E-03 9.80E-03
10 2.85E-01 5.41E-03 5.18E-02 1.32E-03 1.78E-02
11 3.31E-01 6.07E-03 2.31E-02 1.27E-03 3.55E-02

Code repository 

Temporarly, the code to the analysis is stored locally at /star/u/zurek/ but will be uploaded to the official repository