arXiv:2112.14358·v2·High Energy Physics — Phenomenology
Implication of two-baryon azimuthal correlations in collisions at LHC energies on the QGP
Liuyao Zhang (1)🇨🇳 · Jinhui Chen (1)🇨🇳 · Wei Li (2)🇺🇸 · Zi-Wei Lin (3) ((1) Key Laboratory of Nuclear Physics and Ion-beam Application (MOE), Institute of Modern Physics, Fudan University, Shanghai, China, (2) T.W. Bonner Nuclear Laboratory, Rice University, Houston, Texas, USA, (3) Department of Physics, East Carolina University, Greenville, North Carolina, USA)🇺🇸
Abstract
The near-side depression in two-proton or two-antiproton azimuthal correlations in collisions at 7 TeV has been observed experimentally and then qualitatively reproduced in our earlier studies with a multi-phase transport model. In this study, we further investigate the origin of the depression feature in two-baryon correlations in small collision systems. We find that the initial parton-level spatial correlation, a finite expansion in the parton stage, and quark coalescence are important ingredients leading to the near-side depression. In particular, we find that a finite expansion of the parton system leads to a finite space-momentum correlation at hadronization, which then converts the near-side depression in the coordinate space to that in the momentum space. These results suggest that a partonic matter with a finite lifetime is formed in the pp collisions. Further studies are needed to determine whether the partonic matter is near local equilibrium and can thus be called a QGP or far away from local equilibrium.
Comments: 7 pages, 4 figures