Detailed Study of High-p_T Neutral Pion Suppression and Azimuthal Anisotropy in Au + Au Collisions at sqrt(s_NN) = 200 GeV

Journal Article · Mon Jan 01 00:00:00 EST 2007 · Physical Review C

DOI:https://doi.org/10.1103/PhysRevC.76.034904· OSTI ID:932005

Adler, S. S. ^[1]; Awes, Terry C ^[2]; Batsouli, Sotiria ^[3]; Cianciolo, Vince ^[2]; Efremenko, Yuri ^[3]; Read, Jr, Kenneth F ^[2]; Silvermyr, David O ^[2]; Sorensen, Soren P ^[4]; Stankus, Paul W ^[2]; Young, Glenn R ^[2]; Zhang, Chun ^[3]

---

1. Brookhaven National Laboratory (BNL)
2. ORNL
3. University of Tennessee, Knoxville (UTK) & Oak Ridge National Laboratory (ORNL)
4. University of Tennessee, Knoxville (UTK)

Measurements of neutral pion production at midrapidity in {radical}(s{sub NN}) = 200 GeV Au+Au collisions as a function of transverse momentum, p{sub T}, collision centrality, and angle with respect to reaction plane are presented. The data represent the final {pi}{sup 0} results from the PHENIX experiment for the first RHIC Au+Au run at design center-of-mass-energy. They include additional data obtained using the PHENIX Level-2 trigger with more than a factor of three increase in statistics over previously published results for p{sub T} > 6 GeV/c. We evaluate the suppression in the yield of high-p{sub T} {pi}{sup 0}'s relative to point-like scaling expectations using the nuclear modification factor R{sub AA}. We present the p{sub T} dependence of R{sub AA} for nine bins in collision centrality. We separately integrate R{sub AA} over larger p{sub T} bins to show more precisely the centrality dependence of the high-p{sub T} suppression. We then evaluate the dependence of the high-p{sub T} suppression on the emission angle {Delta}{phi} of the pions with respect to event reaction plane for 7 bins in collision centrality. We show that the yields of high-p{sub T} {pi}{sup 0}'s vary strongly with {Delta}{phi}, consistent with prior measurements. We show that this variation persists in the most peripheral bin accessible in this analysis. For the peripheral bins we observe no suppression for neutral pions produced aligned with the reaction plane while the yield of {pi}{sup 0}'s produced perpendicular to the reaction plane is suppressed by more than a factor of 2. We analyze the combined centrality and {Delta}{phi} dependence of the {pi}{sup 0} suppression in different p{sub T} bins using different possible descriptions of parton energy loss dependence on jet path-length averages to determine whether a single geometric picture can explain the observed suppression pattern.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: DE-AC05-00OR22725
• OSTI ID: 932005
• Journal Information: Physical Review C, Vol. 76, Issue 3; ISSN 0556-2813
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ANISOTROPY
DESIGN
MODIFICATIONS
PIONS
PRODUCTION
STATISTICS
TRANSVERSE MOMENTUM
GOLD