Recently, the research group led by Prof. Bowen Xiao and Prof. Guangyou Qin from the College of Physical Science and Technology of CCNU, in cooperation with the Center for Theoretical Physics (CPHT) of École Polytechnique, by using the effective theory of quantum chromodynamics (gluon saturation physics or the color glass condensate (CGC) formalism), analyzed and numerically calculated the azimuthal angular correlation between a heavy quarkonium(J/Psi) and a charged light hadron in proton-nucleus collisions, successfully explaining the newly discovered elliptic flow of the heavy flavor meson produced in the proton-lead nucleus collision at the Large Hadron Collider. The results of the study, entitled "Elliptic Flow of Heavy Quarkonia in pA Collisions", were published on May 3, 2019, in the international journal Physical Review Letters.
Elliptic flow is an important physical quantity describing the collectivity of many particles produced in heavy ion collisions. Recently, ALICE and CMS collaborations at the LHC discovered that the heavy meson, which is ten times heavier than light hadrons, has sizable elliptic flows as large as light hadrons. Due to relatively large mass, it is difficult for hydrodynamics approach, which is the most popular theory in this field, to describe this new results. In this study, the team used the theory of color glass condensation in quantum chromodynamics to carry out theoretical analysis and numerical calculation and found that this theory could naturally explain the elliptical flow of light hadron and heavy meson at the same time. This study had important physical significance for revealing the mechanism of elliptical flow in high-energy nuclear collisions and the experimental evidence to explore the phenomenon of gluon saturation.
The first author of this article is Cheng Zhang, who is a PhD student at the College of Physical Science and Technology in CCNU, the corresponding author is Professor Bowen Xiao, and the coauthors are Professor Guangyou Qin of the College of Physical Science and Technology in CCNU, Research Scientist Cyrille Marquet and Dr. Wei Shuyi of École Polytechnique in France. The study was supported by the Natural Science Foundation of China (NSFC) and Agence Nationale de la Recherche.
Earlier last month, in collaboration with Dr. Spencer Klein and Dr. Feng Yuan of Lawrence Berkeley National Laboratory as well asProf. Alfred Mueller of Columbia University, Prof. Bowen Xiao published another paper entitled “Acoplanarity of a Leopton Pair to Probe the Electromagnetic Property of Quark Matter” in Physical Review Letters. This paper paves the way for using leptons to study the electromagnetic property of quark gluon plasma created in heavy ion collisions. This study is partially supported by NSFC.