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Paper webpage: Measurement of direct photon+jet and pi0+jet azimuthal correlation in Au+Au and p+p collisions at 200 GeV

Updated on Thu, 2024-12-19 09:07. Originally created by nihar on 2023-05-27 01:50.

  Title:  Measurement of medium-induced acoplanarity in central Au + Au and p + p collisions at sNN=200 GeV using γdir+jet and π0+jet correlation

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PAs: Nihar Ranjan Sahoo [PA Rep] , Derek Anderson, Saskia Mioduszewski, and Peter Jacobs

Target Journal:   PRL

Abstract:

We present measurements of azimuthal correlations between direct photon (γ) and neutral pion (π0) coincident with recoil jets in central Au+Au and p+p collisions at   = 200 GeV. Recoil-charged jets are measured with transverse momentum ( ) range of 10 <   < 15 GeV/c using jet resolution parameter R = 0.2 and 0.5, with trigger transverse energy for γ and π0 between 11 and 15 GeV. The recoil jet yield, as a function of the azimuthal angle difference ( ) between trigger particles and recoil jets, is measured over a range of  . We observe a significant excess recoil jet yield with R=0.5 towards   in 0-15% central Au+Au collisions, compared with p+p baseline, for both trigger cases. This observation is absent in recoil jets with R=0.2. These findings provide the first evidence of a novel manifestation of jet-medium interaction in heavy-ion collisions at RHIC.
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Analysis Note:  Link

Paper Draft:

Version-1 : link 
Version-2 : link
Version-3 : link
Version-4 : link
Version-5 : link

Figure-1

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Figure-2

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Figure-3

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Summary and conclusion:

  • STAR reports the jet acoplanarity measurement between direct photon (γ) and neutral pion (π0) coincident with recoil jets in 0-15% central Au+Au and p+p collisions at  sqrt(sNN) = 200 GeV. 
  • We observe excess recoil jet yield with R=0.5 towards pi/2 in 0-15% central Au+Au collisions relative to p+p date for both γ and π0
  • This observation is absent in recoil jets with R=0.2. 
  • This is the first observation of jet acoplanarity due to jet-medium interaction in heavy-ion collisions at RHIC

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Additional documents:

HP-pwg paper proposal: https://drupal.star.bnl.gov/STAR/blog/nihar/Jet-acoplanarity-paper-proposal-follow-discussion

PWG comments: link

 STAR Note : PSN0841 



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