Quarkonia (J/psi, psi', chi_C, Upsilon) production provides a sensitive probe of gluon distributions and their modification in nuclei; and is a leading probe of the hot-dense (deconfined) matter created in high-energy collisions of heavy ions. We will discuss the physics of quarkonia production in the context of recent p+p measurements at PHENIX. We next discuss Cold-Nuclear Matter (CNM) effects as seen in our measurements in $d+Au$ collisions - both for intrinsic physics such as gluon saturation and final-state dissociation, and as a baseline for studies in nucleus-nucleus collisions. Then we review the latest nucleus-nucleus results in the light of the expected CNM effects, and discuss two leading scenarios for the observed suppression patterns. Finally we show the latest data from PHENIX, including new d+Au data from the 2007-2008 run; and then look into the future.
Quarkonia suppression in nucleus-nucleus collisions is a powerful tool to probe the density and temperature of the medium created in heavy ion collisions. Forward rapidity measurements in $p(d)$+Au collisions are essential to understand how quarkonia states are affected by initial state effects, formation time, and local particle multiplicity. Earlier measurements in Au+Au collisions showed a stronger suppression of forward $J/ψ$ compared to mid-rapidity results, indicating the possibility of a smaller contribution of regenerated quarkonia states at forward rapidity. These proceedings report o…
The PHENIX collaboration efforts towards constraining and understanding quarkonia production mechanisms are outlined. J/psi measurements and feed-down sources studies in p-p collisions at 200 GeV, together with their possible indications on the hadro-production mechanisms, are discussed. J/psi photo-production in ultra-peripheral collisions at 200 GeV is also examined. Finally, a glimpse of the first bottomonia results in minimum bias Au-Au collisions at 200 GeV and their implications are presented.
This contribution presents the latest results on heavy quarkonia (j/psi and upsilon) production in d+A and A+A collisions at RHIC at a center of mass energy per nucleon-nucleon collision sqrt(s_NN) = 200 GeV, measured by the PHENIX experiment, as well as their implications in terms of understanding cold nuclear matter effects and the possible formation of a quark gluon plasma in central $\auau$ collisions.}
Quarkonia provide a sensitive probe of the properties of the hot dense medium created in high energy heavy ion collisions. Hard scattering processes result in the production of heavy quark pairs that interact with the collision medium during hadronization. These in-medium interactions convey information about the fundamental properties of the medium itself and can be used to examine the modification of the QCD confining potential in the collision environment. Baseline measurements from p+p and d+Au collision systems are used to distinguish cold nuclear matter effects while measurements from he…
Heavy quarks (charm and bottom) are good probes of the hot and dense medium created in relativistic heavy ion collisions since they are mainly generated at the beginning of collisions and interact with the media in all collision stages. In addition, heavy flavor quarkonia production is thought to be uniquely sensitive to the deconfined medium of the Quark Gluon Plasma (QGP) through color screening. Heavy quark production has been studied by the PHENIX experiment at RHIC via measurements of single leptons from semi-leptonic decays in both the electron channel at mid-rapidity and in the muon cha…
The measurement of quarkonia production in relativistic heavy ion collisions provides a powerful tool for studying the properties of the hot and dense matter created in these collisions. To be really useful, however, such measurements must cover a wide range of quarkonia states and colliding species. The PHENIX experiment at RHIC has successfully measured J/psi, psi-prime, chi_c and Upsilon production in different colliding systems at various energies. In this talk I will present recent results from the PHENIX collaboration on charmonium production in d+Au, Cu+Au and U+U collisions at 200 GeV/…
We report new quarkonia measurements necessary to understand production mechanisms and cold nuclear matter effects in the yields observed at RHIC energy. Results obtained in p+p collisions collected during the 2006 RHIC Run include J/psi, Psi' and Upsilon differential cross sections as well as J/psi polarization. Revisited interpretations of the published J/psi nuclear modification factors and statistically improved observations in d+Au collisions taken in the 2008 Run are also discussed in the view of the recent understanding of the initial state effects and breakup cross section.
We present here a brief summary of new results on heavy quarks and heavy quarkonia from the PHENIX experiment as presented at the "Quark Gluon Plasma Thermalization" Workshop in Vienna, Austria in August 2005, directly following the International Quark Matter Conference in Hungary.
Heavy quarks are good probes of the hot and dense medium created in relativistic heavy ion collisions since they are mainly generated early in the collision and interact with the medium in all collision stages. In addition, heavy flavor quarkonia production is thought to be uniquely sensitive to the deconfined medium of the Quark Gluon Plasma (QGP) through color screening. Heavy quark production has been studied by the PHENIX experiment at RHIC via measurements of single leptons from semi-leptonic decays, in both the electron channel at mid-rapidity and in the muon channel at forward rapidity.…
The dissociation of quarkonia in the medium created in heavy ion collisions is still one of the most debated topics in the heavy ion community. Progress in understanding the effect relies on a broad range of measurements in collisions with different nuclear sizes, covering a broad rapidity range. This presentation will report the $J/ψ$ measurements performed by the PHENIX collaboration at forward and backward rapidities of 1.2 $< |y| <$ 2.2 in $p$+Al, $p$+Au, and $^3$He+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV, and the corresponding nuclear modification factors.
We will review the latest physics developments from PHENIX concentrating on cold nuclear matter effects, the initial state for heavy-ion collisions, and probes of the earliest stages of the hot-dense medium created in those collisions. Recent physics results from p + p and d + Au collisions; and from direct photons, quarkonia and low-mass vector mesons in A+A collisions will be highlighted. Insights from these measurements into the characteristics of the initial state and about the earliest times in heavy-ion collisions will be discussed.
Heavy quarkonia production is expected to be sensitive to the formation of a quark gluon plasma (QGP). The PHENIX experiment has measured $J/ψ$ production at $\sqrt{s_{NN}}=$~200 GeV in Au+Au and Cu+Cu collisions, as well as in reference p+p and d+Au runs. $J/ψ$'s were measured both at mid ($|y|<0.35$) and forward ($1.2<|y|<2.2$) rapidity. In this letter, we present the A+A preliminary results and compare them to normal cold nuclear matter expectations derived from PHENIX d+Au and p+p measurements as well as to theoretical models including various effects (color screening, recombination, seque…
High energy heavy ion collisions at the Relativistic Heavy Ion Collider (RHIC) produce a novel medium characterized by an initial energy density over an order of magnitude above the expected phase transformation value and that then evolves as a nearly inviscid liquid. Probing the medium with auto-generated particles is a key methodology to quantitatively determine the medium properties. Pairs of heavy quarks are an excellent probe since their spatial separation to form various quarkonia states spans the relevant range of color screening lengths in the medium. In this proceedings, we describe r…
In recent years, PHENIX has studied many important observables related to heavy-flavor physics through their leptonic decay measurements including the invariant yield of electrons from nonphotonic sources, and prompt single muons, both of which are dominated by D and B mesons. Charm and beauty cross-sections were measured and compared through single lepton, and lepton-hadron correlations in p+p collisions at $\sqrt{s}$ = 200 GeV. Observables for quarkonia production such as invariant yield and polarization were also measured in p+p collisions. In Au+Au collisions, preliminary results for the $…
Quarkonia provide a sensitive probe of the properties of the hot dense medium created in high energy heavy ion collisions. Hard scattering processes result in the production of heavy quark pairs that interact with the collision medium during hadronization. These in medium interactions convey information about the fundamental properties of the medium itself and can be used to examine the modification of the QCD confining potential in the collision environment. Baseline measurements from the d+Au and p+p collision systems can be used to distinguish cold nuclear matter effects while measurements …
Heavy quarkonia production is predicted to be sensitive to the formation of the quark gluon plasma in relativistic heavy ion collisions via competing mechanisms such as color screening and/or quark recombination. During 2004 and 2005 RHIC data taking periods, the PHENIX collaboration has measured jpsi decay into lepton pairs both at mid and forward rapidity in Au+Au and Cu+Cu collisions at $\sqrt{s_{NN}}$=200 GeV. We present the jpsi nuclear modification factor and the $\jpsi$ mean square transverse momentum as a function of the collision centrality for both systems, as well as the rapidity de…
The production of different quarkonium states provides unique insight to the hot and cold nuclear matter effects in the strongly interacting medium that is formed in high energy heavy ion collisions. While LHC explores the energy frontier, RHIC has a broad physics program to explore the nuclear modification at different energies in a wide range of systems. Some of the most interesting recent results on $J/ψ$ and $Υ$ production in p+p, d+Au and A+A collisions from PHENIX and STAR are summarized in this work.
Three measurements that broaden the scope of the experimental investigation of quarkonia modifications in heavy ion collisions are presented. Although the current statistical precision on the first two measurements does not allow one to draw significant conclusions, J/$ψ$ elliptic flow and high pT suppression results are important proofs of principle measurements, and make the case for higher luminosities at RHIC. Finally, the first measurement of an upper limit on the nuclear modification R_AA of dielectrons in the $Υ$ mass region in Au+Au collisions is presented. The results show a significa…
An overview of the latest results on the hard probes from the PHENIX experiment at RHIC is given. The results on the measurements of high $p_{T}$ hadrons, hadron-hadron correlations, open heavy flavor and quarkonia, and direct photons from large (Au+Au) to small collision systems ($p$+Al and $p/d/^3$He+Au) provided a deeper insight on the medium created in the large systems and the possible onset of QGP-nization in transition from small to large systems.
Hadrons carrying heavy quarks, i.e. charm or bottom, are important probes of the hot and dense medium created in relativistic heavy ion collisions. Heavy quark-antiquark pairs 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. Heavy quark production has been studied by the PHENIX experiment at RHIC via measurements of single leptons from semi-leptonic decays in both the electron channel at mid-rapidity and in the muon channel at forward rapidity. A lar…
Recent results indicate that the J/psi suppression pattern differs with rapidity showing a larger suppression at forward rapidity. J/psi suppression mechanisms based on energy density (such as color screening, interaction with co-movers, etc.) predict the opposite trend. On the other hand, it is expected that more c\bar{c} pairs should be available to form quarkonia at mid-rapidity via recombination. Some models provide a way to differentiate J/psi production from initially produced c\bar{c} pairs and final state recombination of uncorrelated pairs, via the rapidity and transverse momentum dep…
Massachusetts Institute of Technology（麻省理工学院）；Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）；Brookhaven National Laboratory（布鲁克海文国家实验室）；Los Alamos National Laboratory（洛斯阿拉莫斯国家实验室）
Heavy quarkonia production is expected to be sensitive to the formation of a quark gluon plasma (QGP). It was (and still is with ongoing data analyses) extensively studied at the CERN SPS, at collision energy $\sqrt{s_{NN}}$ of the order of 20 GeV. An anomalous suppression was clearly observed. The PHENIX experiment at RHIC has presented preliminary results that exhibit a similar amount of $J/ψ$ suppression, at ten times higher collision energy. I review the results obtained at both facilities. While interpreting and comparing them, the importance of understanding normal nuclear effects is emp…
First results on charm quarkonia production in heavy ion collisions at the Relativistic Heavy Ion Collider (RHIC) are presented. The yield of J/Psi's measured in the PHENIX experiment via electron-positron decay pairs at mid-rapidity for Au-Au reactions at sqrt(s_NN) = 200 GeV are analyzed as a function of collision centrality. For this analysis we have studied 49.3 million minimum bias Au-Au reactions. We present the J/Psi invariant yield dN/dy for peripheral and mid-central reactions. For the most central collisions where we observe no signal above background, we quote 90% confidence level u…
In case of an UA(1) symmetry restoration in a hot and dense hadronic matter, the mass of the produced hadrons and mesons can significantly change, and their production cross-section can also be modified. In this M.Sc. Thesis I search for the signature of an eta' enhancement in the PHENIX dilepton spectrum in 200 GeV Au+Au collisions, which has a significant enhancement in the low-mass region, e.g. in the (0.1-1.0) GeV invariant electron-positron mass range. This is also the region of the eta' meson's Dalitz-decay (eta'->ee gamma), so the eta' enhancement might be responsible for at least a par…
Understanding the detailed production and hadronization mechanisms for heavy quarkonia and their modification in a nuclear environment presents one of the major challenges in QCD. Calculations including nuclear-modified parton distribution functions (nPDFs) and fitting of break-up cross sections (sigma_breakup) as parameters have been successful at describing many features of J/psi modification in proton(deuteron)-nucleus collisions. In this paper, we extend these calculations to explore different geometric dependencies of the modification and confront them with new experimental results from t…
In these proceedings, an overview of recent quarkonium measurements in nuclear collisions carried out at both RHIC and LHC is presented. In p+p collisions, despite theoretical progresses made in understanding the production mechanisms for quarkonia, a complete picture is still yet to be achieved. In p+A collisions where measurements are done to quantify the cold nuclear matter effects, significant suppression of quarkonium production is observed for low transverse momentum region at both forward- and mid-rapidities. Furthermore, results from A+A collisions show the interplay of dissociation an…
Measurements of quarkonia (heavy quark and antiquark bound states) and open-heavy flavour hadrons in hadronic collisions provide a unique testing ground for understanding quantum chromodynamics (QCD). Although recently there was significant progress, our understanding of hadronic collisions has been challenged by the observation of intriguing effects in high-multiplicity proton-proton (pp) and p-Pb collisions, such as collective phenomena. The excellent particle identification, track and decay-vertex reconstruction capabilities of the ALICE experiment are exploited to measure quarkonia as well…
An overview is given of the theoretical developments on heavy quarks and quarkonia in heavy-ion collisions as reported at the "Hard and EM Probes 2018" conference. Specifically, we address progress in the understanding of heavy-flavor diffusion and its hadronization, quarkonium transport and the extraction of quarkonium melting temperatures, energy loss of heavy quarks at high momentum, and their rescattering in small colliding systems.
Heavy quarkonia are observed to be suppressed in relativistic heavy ion collisions relative to their production in p+p collisions scaled by the number of binary collisions. In order to determine if this suppression is related to color screening of these states in the produced medium, one needs to account for other nuclear modifications including those in cold nuclear matter. In this paper, we present new measurements from the PHENIX 2007 data set of J/psi yields at forward rapidity (1.2<|y|<2.2) in Au+Au collisions at sqrt(s_NN)=200 GeV. The data confirm the earlier finding that the suppressio…
