Title:
Jet-hadron correlations with respect to the event plane in \sNN = 200 GeV Au+Au collisions in STAR

Abstract:
We present the dependence of azimuthal angular correlations of charged tracks with the axis of a reconstructed jet relative to second order event plane for Au-Au collisions at \sNN = 200 GeV in STAR.  Partonic interactions are dependent upon the path-length traversed through the medium, so medium modifications to a jet should be path-length dependent.  Studying jets differentially to the event plane allows for a path-length dependent measurement of these medium modifications.  The event plane is the experimental estimate of the reaction plane defined as the plane formed by the impact parameter and the beam direction.  The reaction place fit (RPF) method is implemented to remove the flow modulated background.  Associated track yields and gaussian width calculations are performed in three angular bins of the jet axis relative to the event plane.   Results from the 20-50% most central events for 15 < p_T^jet < 20 and 20 < p_T^jet < 40 GeV/c are shown by the track yields in EP bins. Potential effects are further quantified by taking ratios of the track yields in EP bins.  No dependence on the results is seen within uncertainties for jets with transverse momentum ranging from 15 to 40 GeV/c.   This finding is consistent with the observation from ALICE at \sNN = 2.76 TeV.

Conclusion:
The measurement of jet-hadron correlations relative to the event plane for the 20-50% most central events for Au+Au collisions at \sNN = 200 GeV in STAR is reported.  Partonic interactions are directly related to the distance traversed in the medium, so the expectation is any modifications via the medium to the jet should be path-length dependent.  The angle of the jet measured with respect to the event plane is correlated on average with the jets' path-length through the medium.  In this analysis, the average path-length of away-side jets is maximized by the surface bias of the near-side trigger jet.  This work utilizes the RPF background subtraction method to remove the event plane dependent background, while reducing uncertainties and assumptions associated with prior background subtraction techniques.  Associated yields, their ratios, and jet peak widths are extracted for each event plane orientation and compared for different average path-lengths and to JEWEL model calculations.   JEWEL predicts that despite the path-length dependence of partonic energy loss, the impact of jet-by-jet fluctuations to the partonic energy loss dominates over that of the path-length dependence, while the path-length dependence is seen to be well below the systematic uncertainty in the measurement.  It was also reported in a di-jet asymmetry measurement relative to the event plane with JEWEL \cite{Milhano:2015mng} that not only energy loss fluctuations, but also hard fluctuations which do not arise from jet-medium interactions play a more important role than path-length dependence \cite{Milhano:2015mng}.  

With the current statistics of this measurement at 200 GeV, the associated yields and jet peak widths show no event plane dependence.  The ratios taken of the associated yields attempt to quantify the differences, but they do not deviate significantly from 1.0.  For the 20-40 GeV/c sample there are small hints to potential modifications when looking at the inclusive bin of 1.0-10.0 GeV/c.  The uncertainties are large, however, and there are various effects occurring throughout the included momentum range.  We note that the consistency with no event plane dependence is still compatible with a non-zero v₂^jet, as found by the non-zero v₂^jet values extracted in 20-50% semi-central collisions from the Reaction Plane Fit.  Furthermore, the results presented here are consistent with the conclusions seen in jet-hadron and h-h correlations by \cite{Nattrass:2016cln}, and jet-hadron correlations by ALICE Experiment \cite{PhysRevC.101.064901} at \sNN = 2.76 TeV energies.  The lack of an event plane dependence in data therefore indicates that any dependence of these modifications on the average path-length is less than our experimental uncertainties.  Alternatively, the initial geometry within specific centrality bins may be fluctuating at a larger magnitude than any possible event plane dependence \cite{Noronha-Hostler-RAAv2,PhysRevLett.116.252301}.  The possibility of this occurrence can be studied through event shape engineering by looking at the initial configuration and selecting on low and high ellipticity events by  using the q_n flow vector found within a selected centrality range.

PA's:
Joel Mazer, Rutgers
Tanmay Pani, Rutgers
Sevil Salur, Rutgers

Target Journal:
PRC

GPC:

2022, November 10th - Compare JEWEL curves to each other and data, Random Cone study
2022, November 17th - using Random Cone study for JES systematics (showing iterative process)
2022, November 28th - adding JEWEL integrated-EP angle calculations to associated yields, peak widths, and removed JEWEL from yield ratios; update some aesthetics

Paper drafts after submission:
v0 (first submission): 
JHC_Paper_v12_23_06_14.pdf

v1 (round 1 editor comments, current): 
STAR-jethadron_paper.pdf
diff: drupal.star.bnl.gov/STAR/system/files/diff_1_0.pdf
responses: drupal.star.bnl.gov/STAR/system/files/responseToEditor.pdf

v2(comments from production team):
Bigger text size in plots: drupal.star.bnl.gov/STAR/system/files/STAR-jethadron_paper_0.pdf

Paper with author list: drupal.star.bnl.gov/STAR/system/files/STAR-jethadron_paper_1.pdf

Paper draft, internal iterations: 
v2
v2.1_21-04-09
v2.3b_21-04-20
v2.4_21-04-30
v2.5_21-05-26
v3.0_22_02-16
v4.0_22_04_18
v5.0_22_10_18
v6.0_22_12_05
v7.0_23-02-01

v8_23_03_31

v9.0_23_04_19

JHC_Paper_v10_23_04_26

Compare_Report_JHC_Paper_v12_23_06_14.pdf
drupal.star.bnl.gov/STAR/system/files/Compare_Report_JHC_Paper_v12_23_06_14.pdf
Analysis Note:
v1.0
v1.1_21-04-30
v2.0_21_08_18
v3.0_22_04_18
v6.0_22_12_05

Response to GPC comments:
COMMENTS from GPC_ paperdraft v6_0.pdf

Analysis Code:
The paper's code repository is at:
$CVSROOT/offline/paper/psn0788/

online viewer:
https://www.star.bnl.gov/cgi-bin/protected/viewvc.cgi/cvsroot/offline/paper/psn0788/

github pages:
1) https://github.com/joelmazer/star-jetframework
2) https://github.com/joelmazer/Centrality


Presentation to JetCorr (Preview):
April 1, 2021

Presentation to PWGC (Preview):
Friday - April 23rd, 2021

Responses to PWGC (preview) questions/comments:
PWGC-preview-comments-questions-replies (21-04-30)

JetCorr updates:
November 2, 2017 - STAR Analysis Meeting
January 25, 2018 - STAR Analysis Meeting,  .....  Method Summary
July 18, 2018
July 30, 2018
August 14, 2018
August 15, 2018 - Bulk Corr Meeting
August 21, 2018
August 31, 2018
December 10, 2021 - Jet Hadron update on P20a Run14 Picos
February 4, 2021 - Mixed Event Weights
March 4, 2021 - STAR Collaboration Meeting - Jet Had correlations update
April 1, 2021 - jet-corr paper preview
April 23, 2021 - PWGC jet-hadron correlation paper preview
May 13, 2021 - JEWEL studies for Jet-hadron correlation

July 22, 2021 - Embedding study follow-up I
      - Tanmay embedding: slides
August 19, 2021 - Embedding study follow-up II
      - Tanmay embedding: slides II

September 17, 2021 - STAR Analysis Meeting - Jet-had vs EP update
      - Tanmay update: slides
December 16, 2021
      - Tanmay update: slides - Embedding update

February 16, 2022 - STAR Collaboration Meeting - Jet-had vs EP paper update and status + Emb systematics
      -Tanmay update: slides - Embedding - Trk Eff in/out cone

March 3, 2022 - Jet-Corr Meeting: Embedding closure test update: remove EP dependence, bug fix

April 18, 2022 - Minor pending follow-up on 6-10 GeV closure bin of 20-40 GeV jets

Public Presentations:
  - Jet Workshop - June 27, 2018 - talk presentation: "Jet-hadron correlations and the need for a precise background subtraction method"

  - Hot Quarks, September 2018 - talk presentation:  "Jet-hadron correlations relative to the event plane at RHIC with STAR"

  - 13th International Workshop on High-pt Physics in the RHIC/LHC era - March 2019 - talk presentation:  "Event plane dependence of jet quenching studied via azimuthal correlations and differential jet shape in Au+Au collisions at \sqrt{s_{NN}} GeV with the STAR detector at RHIC"

  - 13th International Workshop on High-pt Physics in the RHIC/LHC era - March 2019 - proceedings: "Event plane dependence of jet quenching studied via azimuthal correlations and differential jet shape in Au+Au collisions at \sqrt{s_{NN}} GeV with the STAR detector at RHIC"

Preliminary Plots
   - preliminary plots page