2016/09/30 by ALICE Collaboration, J. Adam, D. Adamová +98 · 1 citation
Mathematics · Physics and Astronomy · #Atomic physics #Azimuth #Charged particle #High-Energy Particle Collisions Research #Jet (fluid) #Nuclear physics #Optics #Order (exchange) #Particle physics #Particle physics theoretical and experimental studies #Physics #Pseudorapidity #Quantum mechanics #Range (aeronautics) #Statistical Methods and Bayesian Inference #hep-ex #nucl-ex
paper · pdf · doi:10.1103/physrevc.96.034904
published as Phys. Rev. C 96, 034904 (2017) · 26 pages, 10 captioned figures, 3 tables, authors from page 21, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/3146
openalex created_date 2016/10/07 · openalex publication_date 2017/09/08 · arxiv created 2017/12/18 · arxiv updated 2017/12/19 · openalex updated_date 2026/08/05
In two-particle angular correlation measurements, jets give rise to a near-side peak, formed by particles associated to a higher-pT trigger particle. Measurements of these correlations as a function of pseudorapidity (\mathrm\ensuremathΔ\ensuremathη) and azimuthal (\mathrm\ensuremathΔ\ensuremathφ) differences are used to extract the centrality and pT dependence of the shape of the near-side peak in the pT range 1<pT<8 GeV/c in Pb-Pb and pp collisions at √sNN = 2.76 TeV. A combined fit of the near-side peak and long-range correlations is applied to the data and the peak shape is quantified by the variance of the distributions. While the width of the peak in the \mathrm\ensuremathΔ\ensuremathφ direction is almost independent of centrality, a significant broadening in the \mathrm\ensuremathΔ\ensuremathη direction is found from peripheral to central collisions. This feature is prominent for the low-pT region and vanishes above 4 GeV/c. The widths measured in peripheral collisions are equal to those in pp collisions in the \mathrm\ensuremathΔ\ensuremathφ direction and above 3 GeV/c in the \mathrm\ensuremathΔ\ensuremathη direction. Furthermore, for the 10% most central collisions and 1<pT,assoc< 2 GeV/c, 1<pT,trig< 3 GeV/c, a departure from a Gaussian shape is found: a depletion develops around the center of the peak. The results are compared to A Multi-Phase Transport (AMPT) model simulation as well as other theoretical calculations indicating that the broadening and the development of the depletion are connected to the strength of radial and longitudinal flow.