System Size and Energy Dependence of Jet-Induced Hadron Pair Correlation Shapes inCu+CuandAu+AuCollisions ats

Abstract

We present azimuthal angle correlations of intermediate transverse momentum (1-4 GeV/c) hadrons from dijets in Cu+Cu and Au+Au collisions at square root sNN=62.4 and 200 GeV. The away-side dijet induced azimuthal correlation is broadened, non-Gaussian, and peaked away from Delta phi=pi in central and semicentral collisions in all the systems. The broadening and peak location are found to depend upon the number of participants in the collision, but not on the collision energy or beam nuclei. These results are consistent with sound or shock wave models, but pose challenges to Cherenkov gluon radiation models.

Collectivity in Small Collision Systems: An Initial-State Perspective

“…The current debate of collectivity in small systems was triggered by the discovery of ridge like correlations that extend over a long range in rapidity in high multiplicity p+p collisions by the CMS collaboration [5]. Such long range structure of azimuthal correlations was previously seen in heavy ion collisions at RHIC [44][45][46] and LHC [47] and generally attributed to the nearly boost invariance structure of the azimuthal correlations driven by hydrodynamic flow. At the same time causality arguments suggest [48] that such correlations must develop at the very early stages of the collisions, indicating the strong influence of initial state dynamics on such observable.…”

Measurement of two-particle correlations with respect to second- and third-order event planes in Au + Au collisions at sNN=200 GeV

“…Under the two-source (flow + jet) model assumption [44], this underlying event is directly subtracted to obtain the jet contributions. In our previous measurements and most RHIC A + A results, the subtracted flow modulations of the underlying event were limited to contributions of v 2 and the fourth-order harmonic component with respect to the second-order event plane v 4 { 2 } [15,16,20,23,28,[44][45][46][47][48]. Only the recent STAR measurement [49] took into account contributions from v 3 and the fourth-order harmonic component uncorrelated to the second-order event-plane in addition to v 4 { 2 }.…”

“…Only the recent STAR measurement [49] took into account contributions from v 3 and the fourth-order harmonic component uncorrelated to the second-order event-plane in addition to v 4 { 2 }. At low-to-intermediate p T in two-particle correlations, intricate features appear such as the near-side long-range rapidity correlations called the "ridge" [45,50] and the away-side "double-humped" structures [28,44,[46][47][48][49]51,52]. Across the large rapidity ranges available at the Large Hadron Collider, the rapidity-independence and hence the likely geometrical origin of most of these structures have been established.…”

Centrality dependence of forward-backward multiplicity correlation in Au+Au collisions atsNN=200GeV

“…Abundant experimental data have been reported [3][4][5][6] that require urgent study. A lot of theoretical investigations have been reported as well [7][8][9][10][11][12][13][14].…”