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Evidence for Nonlinear Gluon Effects in QCD and Their Mass Number Dependence at STAR

Journal Article · · Physical Review Letters
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  1. American Univ. in Cairo, New Cairo (Egypt); STAR Collaboration et al.
The STAR Collaboration reports measurements of back-to-back azimuthal correlations of di-π0s produced at forward pseudorapidities (2.6<η<4.0) in p+p, p+Al, and p+Au collisions at a center-of-mass energy of 200 GeV. We observe a clear suppression of the correlated yields of back-to-back π0 pairs in p+Al and p+Au collisions compared to the p+p data. The observed suppression of back-to-back pairs as a function of transverse momentum suggests nonlinear gluon dynamics arising at high parton densities. Furthermore, the larger suppression found in p+Au relative to p+Al collisions exhibits a dependence of the saturation scale $$Q^{2}_{s}$$ on the mass number A . A linear scaling of the suppression with A1/3 is observed with a slope of -0.09±0.01.
Research Organization:
Argonne National Laboratory (ANL), Argonne, IL (United States); Brookhaven National Laboratory (BNL), Upton, NY (United States); Texas A & M Univ., College Station, TX (United States); Univ. of California, Los Angeles, CA (United States)
Sponsoring Organization:
Bundesanstalt fur Materialforschung und prufung (BAM); Chinese Academy of Sciences (CAS); Croatian Ministry of Science, Education and Sports; Czech Science Foundation (GACR); Government of India, Department of Atomic Energy; Government of India, Department of Science and Technology; Helmholtz Association of German Research Centres; Japan Society for the Promotion of Science (JSPS); Ministry of Education, Culture, Sports, Science and Technology (MEXT); Ministry of Science and Technology of the People's Republic of China; National Natural Science Foundation of China (NSFC); National Research Foundation (NRF) of Korea; National Science Centre of Poland (NCN); National Science Foundation (NSF); Rosatom State Atomic Energy Corporation; Russian Federation, Ministry of Education and Science; USDOE Office of Science (SC), Nuclear Physics (NP)
Contributing Organization:
STAR Collaboration
Grant/Contract Number:
AC02-06CH11357; FG02-88ER40424; SC0012704; SC0017982
OSTI ID:
1889856
Alternate ID(s):
OSTI ID: 1903271
OSTI ID: 1903336
OSTI ID: 1903339
OSTI ID: 1905073
Report Number(s):
BNL-223208-2022-JAAM
Journal Information:
Physical Review Letters, Journal Name: Physical Review Letters Journal Issue: 9 Vol. 129; ISSN 0031-9007
Publisher:
American Physical Society (APS)Copyright Statement
Country of Publication:
United States
Language:
English

References (40)

Semihard processes in QCD journal November 1983
Gluon recombination and shadowing at small values of x journal May 1986
Operator expansion for high-energy scattering journal March 1996
STAR detector overview
  • Ackermann, K. H.; Adams, N.; Adler, C.
  • Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 499, Issue 2-3 https://doi.org/10.1016/S0168-9002(02)01960-5
journal March 2003
Initial state parton broadening and energy loss probed in d+Au at RHIC journal June 2003
Jet azimuthal correlations and parton saturation in the color glass condensate journal February 2005
Forward inclusive dijet production and azimuthal correlations in pA collisions journal November 2007
Rapidity and centrality dependence of azimuthal correlations in deuteron–Gold collisions at RHIC journal November 2010
Forward dihadron correlations in deuteron–gold collisions with a Gaussian approximation of JIMWLK journal June 2013
Observations on dA scattering at forward rapidities journal December 2004
Energy losses in the black disc regime and correlation effects in the STAR forward pion production in dAu collisions journal February 2007
Back-to-back correlations of di-hadrons in dAu collisions at RHIC journal October 2012
On the dihadron angular correlations in forward pA collisions journal September 2018
Gluon saturation and initial conditions for relativistic heavy ion collisions journal May 2014
Quantum Chromodynamics at High Energy book September 2012
The Beam-Beam Counter: A Local Polarimeter at STAR conference January 2008
High gluon densities in heavy ion collisions journal February 2017
Dijet azimuthal correlations and conditional yields in p p and p + Pb collisions at s N N = 5.02 TeV with the ATLAS detector journal September 2019
Forward production ind+Aucollisions by parton recombination journal February 2005
Non-Abelian energy loss in cold nuclear matter journal June 2007
Comparison of transverse single-spin asymmetries for forward π 0 production in polarized p p , p Al and p Au collisions at nucleon pair c.m. energy s NN = 200     GeV journal April 2021
Measurement of transverse single-spin asymmetries of π 0 and electromagnetic jets at forward rapidity in 200 and 500 GeV transversely polarized proton-proton collisions journal May 2021
Computing quark and gluon distribution functions for very large nuclei journal March 1994
Gluon distribution functions for very large nuclei at small transverse momentum journal April 1994
Saturation effects in deep inelastic scattering at low Q 2 and its implications on diffraction journal November 1998
Small- x F 2 structure function of a nucleus including multiple Pomeron exchanges journal June 1999
Multiple parton interactions and forward double pion production in p p and d A scattering journal February 2011
Dihadron momentum imbalance and correlations in d + Au collisions journal March 2012
Probing gluon saturation through dihadron correlations at an electron-ion collider journal April 2014
Longitudinal double-spin asymmetries for π 0 s in the forward direction for 510 GeV polarized p p collisions journal August 2018
Forward dihadron back-to-back correlations in p A collisions journal January 2019
Azimuthal Correlations of Forward Dihadrons in d + Au Collisions at RHIC in the Color Glass Condensate journal October 2010
Suppression of Back-to-Back Hadron Pairs at Forward Rapidity in d + Au Collisions at s N N = 200     GeV journal October 2011
Transverse-Momentum Spectra in A u + A u and d + A u Collisions at s N N = 200     G e V and the Pseudorapidity Dependence of High- p T Suppression journal August 2003
Evolution of the Nuclear Modification Factors with Rapidity and Centrality in d + A u Collisions at N N S = 200     G e V journal December 2004
Relating High-Energy Lepton-Hadron, Proton-Nucleus, and Nucleus-Nucleus Collisions through Geometric Scaling journal January 2005
Nuclear Modification Factors for Hadrons at Forward and Backward Rapidities in Deuteron-Gold Collisions at s N N = 200     G e V journal March 2005
Forward Neutral Pion Production in p + p and d + Au Collisions at s N N = 200     GeV journal October 2006
The Color Glass Condensate journal November 2010
Mining for Gluon Saturation at Colliders journal August 2021