Recent results on high-pT particles and jets from PHENIX experiment
2019 January 24
2019 October 09
Extensive study of heavy ion collisions at RHIC has resulted in discovery of a new state of matter - strongly coupled Quark Gluon Plasma (sQGP). Measurements of high-$p_T$ particles and jets contributes to systematic study of the properties of sQGP. Reconstructed jets are directly associated with partons in the medium, their spectra and nuclear modification factors can be measured up to the high transverse momenta (40 GeV/c at RHIC energies). Yields of leading particles such as $\pi^0$ and $\eta$ mesons can be measured with high precision at high transverse momenta, which also presents a good opportunity for hard probe measurements. Study of high-$p_T$ observables in different collision systems allows the investigation of the path length dependence of energy loss in the medium. Cu+Au is a first asymmetric heavy ion collision system, available for the analysis. U+U presents an opportunity to research non-spherical heavy ion collision system with highest energy density in central collisions. Non-zero elliptic flow and a hint of suppression of high-$p_T$ hadrons suggests that mini-QGP can be formed in collisions of light and heavy nuclei characterized by high charged particle multiplicities. To address the question of collective behaviour in small systems RHIC provided series of geometry controlled experiments with highly asymmetric systems (p+Au, d+Au, $^3He$+Au). This paper will present the most recent PHENIX results on $\pi^0$, $\eta$ and reconstructed jets production in various collision systems such as p+Au, d+Au, $^3He$+Au, Cu+Au and U+U. Results will be presented as functions of $p_T$ and centrality.