Highlights from PHENIX at RHIC

Abstract

Abstract. Hadrons conveying strange quarks or heavy quarks are essential probes of the hot and dense medium created in relativistic heavy-ion collisions. With hidden strangeness, φ meson production and its transport in the nuclear medium have attracted high interest since its discovery. Heavy quark-antiquark pairs, like charmonium and bottomonium mesons, are mainly produced in initial hard scattering processes of partons. While some of the produced pairs form bound quarkonia, the vast majority hadronize into particles carrying open heavy flavor. In this context, the PHENIX collaboration carries out a comprehensive physics program which studies the φ meson production, and heavy flavor production in relativistic heavy-ion collisions at RHIC. In recent years, the PHENIX experiment upgraded the detector in installing silicon vertex tracker (VTX) at mid-rapidity region and forward silicon vertex tracker (FVTX) at the forward rapidity region. With these new upgrades, the experiment has collected large data samples, and enhanced the capability of heavy flavor measurements via precision tracking. This paper summarizes the latest PHENIX results concerning φ meson, open and closed charm and beauty heavy quark production in relativistic heavy-ion collisions. These results are presented as a function of rapidity, energy and system size, and their interpretation with respect to the current theoretical understanding. Physics MotivationUntil now, Quantum Chromodynamics (QCD) is considered the fundamental theory of the strong interaction between quarks and gluons. Conforming to QCD, at ordinary temperatures or densities this force confines the quarks into composite hadrons. However, when the temperature reaches the QCD energy scale or its density rises to the point where the average inter-quark separation is less than 1 fm, hadronic matter under extremely dense and hot conditions undergoes a phase transition to form a Quark-Gluon Plasma (QGP or QCD matter) in which quarks and gluons no longer are confined to the size of a hadron [1,2]. Since the discovery of the QCD matter at the Relativistic Heavy Ion Colllider (RHIC) [3][4][5][6][7] at Brookhaven National Laboratory (BNL), the perception of the properties of strongly interacting matter at high temperatures has been a central goal of our research. This task is carried out by making measurements of multiple observables over a large range of energies and collision systems.