L. Adamczyk, AGH University of Science and Technology, Poland
James K. Adkins, University of KentuckyFollow
G. Agakishiev, Joint Institute for Nuclear Research, Russia
M. M. Aggarwal, Panjab University, India
Z. Ahammed, Variable Energy Cyclotron Centre, India
N. N. Ajitanand, State University of New York - Stony Brook
I. Alekseev, Alikhanov Institute for Theoretical and Experimental Physics, Russia
D. M. Anderson, Texas A & M University
R. Aoyama, University of Tsukuba, Japan
A. Aparin, Joint Institute for Nuclear Research, Russia
D. Arkhipkin, Brookhaven National Laboratory
E. C. Aschenauer, Brookhaven National Laboratory
M. U. Ashraf, Tsinghua University, China
A. Attri, Panjab University, India
G. S. Averichev, Joint Institute for Nuclear Research, Russia
X. Bai, Central China Normal University, China
V. Bairathi, National Institute of Science Education and Research, India
A. Behera, State University of New York - Stony Brook
R. Bellwied, University of Houston
A. Bhasin, University of Jammu, India
A. K. Bhati, Panjab University, India
P. Bhattarai, University of Texas at Austin
J. Bielcik, Czech Technical University in Prague, Czech Republic
J. Bielcikova, Nuclear Physics Institute AS CR, Czech Republic
L. C. Bland, Brookhaven National Laboratory
I. G. Bordyuzhin, Alikhanov Institute for Theoretical and Experimental Physics, Russia
J. Bouchet, Kent State University
J. D. Brandenburg, Rice University
A. V. Brandin, National Research Nuclear University MEPhI, Russia
D. Brown, Lehigh University
Renee H. Fatemi, University of KentuckyFollow
Suvarna Ramachandran, University of KentuckyFollow


The STAR Collaboration reports the measurement of semi-inclusive distributions of charged-particle jets recoiling from a high transverse momentum hadron trigger, in central and peripheral Au + Au collisions at √sNN = 200 GeV. Charged jets are reconstructed with the anti-kT algorithm for jet radii R between 0.2 and 0.5 and with low infrared cutoff of track constituents (pT > 0.2 GeV/c). A novel mixed-event technique is used to correct the large uncorrelated background present in heavy ion collisions. Corrected recoil jet distributions are reported at midrapidity, for charged-jet transverse momentum pchT,jet < GeV/c. Comparison is made to similar measurements for Pb + Pb collisions at √s = 2.76 TeV, to calculations for p + p collisions at √s = 200 GeV based on the PYTHIA Monte Carlo generator and on a next-to-leading order perturbative QCD approach, and to theoretical calculations incorporating jet quenching. The recoil jet yield is suppressed in central relative to peripheral collisions, with the magnitude of the suppression corresponding to medium-induced charged energy transport out of the jet cone of 2.8 ± 0.2(stat) ± 1.5(sys) GeV/c, for 10 < pchT,jet < 20 GeV/c and R = 0.5. No medium-induced change in jet shape is observed for R < 0.5. The azimuthal distribution of low-pchT,jet recoil jets may be enhanced at large azimuthal angles to the trigger axis, due to scattering off quasiparticles in the hot QCD medium. Measurement of this distribution gives a 90% statistical confidence upper limit to the yield enhancement at large deflection angles in central Au + Au collisions of 50 ± 30(sys)% of the large-angle yield in p + p collisions predicted by pythia.

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Published in Physical Review C, v. 96, issue 2, 024905, p. 1-25.

©2017 American Physical Society

The copyright holder has granted permission for posting the article here.

Due to the large number of authors, only the first 30 and the authors affiliated with the University of Kentucky are listed in the author section above. For the complete list of authors, please download this article or visit:

This group of authors is collectively known as the STAR Collaboration.

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