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.
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 (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…
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 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.
New results from polarized p-p collisions at sqrt(s)=200 GeV of double longitudinal spin asymmetry in pi0 production using the PHENIX detector in the 2005 RHIC run are presented. Both positive and negative maximal gluon polarization scenarios are inconsistent with the data. The data is consistent with small |Δg|, including Δg=0.
The PHENIX experiment at RHIC has measured the ϕ-meson production at mid-rapidity in p+p, d+Au, Cu+Cu and Au+Au collisions at \sqrt{s_{NN}}=200 GeV via the K^+K^- decay mode. The transverse momentum spectra of the ϕ-meson and the nuclear modification factor as a function of centrality are reviewed here.
Measurement of jet fragmentation property in p + p collisions provides a crucial baseline for the study of a possible, modified fragmentation behavior at the presence of the quark-gluon plasma. We describe the first measurement of jet fragmentation functions in sqrt(s) = 200 GeV p + p collisions at RHIC. This is facilitated by extending the linear least square unfolding technique employed by high energy and nuclear experiments to multidimensional spectra, which allows us to correct the inefficiencies in the jet energy response encountered at detectors such as PHENIX.
PHENIX plans for low energy running are presented. Current detector setting makes it possible to measure dielectron spectra down to sqrt(s_NN)=39GeV, and photon/high pT hadron spectra down to below sub-injection energy (sqrt(s_NN)=5-10GeV). The upgrade of the trigger scheme after the installation of VTX detector will enable PHENIX to fully explore the sub-injection energy regime, starting 2011.
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.
Previous results indicated that high $p_T$ particle suppression in Au+Au interactions is a final state effect, since R$_{dA}$ ratios were compatible with unity, albeit within large experimental errors. It is important to test this conclusion to higher precision since the modification of structure functions may be involved. Recent d+Au data taken in 2008 improve the integrated luminosity by about a factor of thirty compared to the 2003 data. A more precise measurement of both $π^0$ and $γ$ at higher $p_T$ will shed new light on whether the initial state in the heavy nuclei is modified.
Measurement of quantumstatistical correlation functions in high energy nuclear physics is an important tool to investigate the QCD phase diagram. It may be used to search for the critical point, and also to understand underlying processes such as in-medium mass modifications or partially coherent particle production. Furthermore, the measurements of the femtoscopic correlation functions shed light on the space-time structure of particle production. Consequently, the precise measurements and description of the correlation functions are essential. The shape of two-pion Bose-Einstein correlation …
The study of formation of heavy quarkonia in relativistic heavy ion collisions provides important insight into the properties of the produced high density QCD medium. Lattice QCD studies show sequential suppression of quarkonia states with increasing temperature; which affirms that a full spectroscopy, can provide us a thermometer for the matter produced under extreme conditions in relativistic heavy ion collisions and one of the most direct probes of de-confinement. Muons from the decay of charmonium resonances are detected in ALICE Experiment in p+p and Pb+Pb collisions with a muon spectrome…
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.
We obtain the first measurement of $J/ψ$ elliptic flow at RHIC energies in forward rapidity using data from the PHENIX detector and applying an event plane method. The dataset used contains 19 billion events from the PHENIX experiment's Run 14 Au + Au dataset at $\sqrt{s_{NN}}=200$ GeV. PHENIX has measured a $J/ψ$ $v_2$ in a centrality range of $10-60\%$ that is consistent with zero. Taken together with results from LHC the measurement of $v_2$, which is consistent with zero may indicate that $J/ψ$ production by coalescence is not significant at forward rapidity at RHIC energy.
In the RHIC run of 2006, PHENIX recorded data from about 20/nb of transversely polarized p+p collisions at sqrt(s) = 62.4 GeV and polarization of about 50%. Also in this last run PHENIX successfully commissioned a new lead-tungstate based electromagnetic calorimeter, the Muon Piston Calorimeter (MPC), covering 2 pi in azimuth and 3.1<eta<3.7. The forward coverage allows PHENIX to measure high x_F pi^0 production. We present the current status of the analysis for the single inclusive pi^0 transverse asymmetry A_N at forward rapidities in PHENIX.
Results from the PHENIX Collaboration on the production of deuterons and anti-deuterons in collisions between gold nuclei at a nucleon-nucleon center-of-mass energy of sqrt(s) = 200 GeV are presented.
Measurement of electrons from heavy quarks by PHENIX has been done for various collision species and energy.PHENIX has measured single electron spectra from heavy flavor decays in Au+Au collisions at $sqrt{S_{NN}} = 200$ GeV.The measurement of heavy flavor production for p + p in PHENIX has also been measured which provided the baseline for studying hot and dense matter effects in heavy ion reactions. In Au + Au we observe a strong suppression of single electron compared with scaled p + p which challenges radiative energy loss models because heavy quarksare expected to radiate less than light …
The properties of the phi-meson have been measured via its e+e- and K+K- decay channels in Au+Au collisions at sqrt{s_NN} = 200 GeV by the PHENIX experiment. The preliminary yields and temperatures derived for the minimum bias and several centrality bins in both decay channels are presented.
The PHENIX experiment has established jet quenching at a center-of-mass energy of 200 GeV in Au+Au collisions. Recent measurements of Cu+Cu collisions at the same center-of-mass energy support a parton energy loss scenario. Furthermore, the onset of jet quenching was studied in Cu+Cu collisions for three center-of-mass energies 22.4, 62.4 and 200 GeV.
We present the latest results on event-by-event fluctuations of charged particle multiplicity in Au+Au and Cu+Cu collisions at $\sqrt{s_{NN}} = 200$ GeV and 62.4 GeV measured by PHENIX experiment at RHIC. The two particle correlation length to discuss order parameters, which can be extracted from scale dependence of the fluctuations, is supposed to be sensitive to the critical points of QCD phase transition. The obtained correlation length with respect to the pseudo rapidity gap indicates the power law behavior as a function of the number of participant nucleons for Au+Au collisions at $\sqrt{…
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…
This poster presents the PHENIX results on high-p_T gamma-hadron and pi0-hadron correlations and shows the modification of away side jet shape by the medium. By comparing their jet shapes and yields, we see some evidence of the direct gamma contribution to correlation functions.
Neutral pions ($π^0$) in $\sqrt{s_\mathrm{NN}}$ = 200 GeV and 62.4 GeV Au+Au collisions were measured at RHIC-PHENIX Year-4 Run. In $\sqrt{s_\mathrm{NN}}$ = 200 GeV, $π^0$ specta are measured up to p$_\mathrm{T}$ = 20 GeV/$c$. %PHENIX extended the p$_\mathrm{T}$ region of A strong suppression by a factor of $\sim$ 5 is observed and stays almost constant up to 20 GeV/$c$.
The paper presents recent PHENIX results for the nuclear modification factor R_AA in Au + Au Collisions at sqrt(s_NN) = 200 GeV for the electrons originating from semi-leptonic decays of open heavy flavor carrying particles. We also report the results of the azimuthal asymmetry (v_2) measurement for those electrons, which is directly related to the heavy quark elliptic flow.
The inclusive cross section for neutral pion production in the range 1<p_T<13GeV/c in |eta|<0.35 has been measured by the PHENIX experiment in proton-proton collisions at sqrt{s}=200GeV. An NLO pQCD calculation is, within the experimental and theoretical uncertainties, consistent with the measurement.
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…
One of the major objectives of the RHIC spin program at BNL is the measurement of the gluon helicity contribution, $ΔG$, to the proton spin via measuring the double longitudinal spin asymmetry ($A_{LL}$) in various channels. In PHENIX (Pioneering High Energy Nuclear Interaction eXperiment) the $A_{LL}$ in $π^{0}$, $η$, $J/ψ$ etc. are measured in wide rapidity range. In this talk, $A_{LL}$ in $π^{0}$ production in central rapidity and $J/ψ$ production in forward rapidity will be discussed. The $π^{0}$ is reconstructed through its diphoton decay channel within the rapidity range of $\left| η\rig…
The first measurement of the dielectron continuum at RHIC energies was performed by the PHENIX experiment for Au+Au collisions at sqrt(s_{NN}) = 200 GeV. Mass spectra for different centralities are presented and compared with the expectations from hadron decays.
In pp collisions at LHC energies, heavy quarks are produced in initial hard scatterings and then these quarks hadronize in either open heavy-flavor hadrons or quarkonia (e.g. J/$ψ$, $ψ(2S)$, $Υ$). The study of quarkonium production as a function of charged-particle multiplicity links soft and hard processes and allows one to study their interplay. While a linear increase of quarkonium production as a function of charged-particle multiplicity can be reasonably well understood in the context of multi-parton interactions, the observation of deviations with respect to a linear increase requires a …
Quarkonia have been studied in different collision system and energy in order to understand the effects of the hot and dense medium created in heavy-ion collisions. CMS is well suited to measure quarkonia decays to muons given the muon identification and charged particle tracking capability. We report here prompt, non-prompt J/ψ, and Υ production measured by the CMS experiment in pp collisions at \sqrt{s}=7 TeV. In addition, the J/ψ and Υ production in PbPb at \sqrt{s_{NN}}=2.76 TeV and pp collisions at the same per nucleon energy are measured and compared. Prompt and non-prompt J/ψ contributi…
We analyze the relative azimuthal ($Δϕ$) distribution of same-charge and opposite-charge particle pairs. We then remove elliptic flow background using the ZYAM method. Comparisons between near angle $Δϕ$ peak widths are presented for various centralities.
Different regions on the QCD phase diagram can be investigated by varying the collision energy and the centrality in heavy-ion collisions. In our latest measurements at the PHENIX experiment at RHIC, we utilize Lévy-type sources to describe the measured HBT correlation functions. In this paper we report the current status of the analysis of the centrality and beam energy dependence of the Lévy source parameters in Au+Au collisions from $\sqrt{s_{NN}}$ = 15 GeV to $\sqrt{s_{NN}}$ = 200 GeV.
The phase diagram of strongly interacting matter can be explored by analyzing data of heavy-ion collisions at different center of mass collision energies. For investigating the space-time structure of the hadron emission source, HBT correlation measurements are among the best tools. In this paper we present the latest results from the RHIC PHENIX experiment on such measurements in $\sqrt{s_{\rm NN}}=$ 39 GeV and 62 GeV Au+Au collisions.
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 $…
Dielectrons play an important role in heavy ion collisions since they are produced during all stages of the collision and interact only electromagnetically. The PHENIX experiment was upgraded with the Hadron Blind Detector which provides excellent background rejection by removing pairs from both partially reconstructed Dalitz decays and photon conversions. In these proceedings we will report on the results obtained from 2009 data in p+p collisions using the HBD as well as the Au+Au results obtained in 2010.
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 …
PHENIX has measured $Υ$ production in p+p, d+Au and Au+Au collisions at $\sqrt{s_{NN}}$=200 GeV. A baseline cross-section measurement has been made in p+p collisions. Preliminary studies of d+Au collisions found no suppression in the backward direction, but suppression was observed in the forward direction indicating the presence of cold nuclear matter effects. In Au+Au collisions preliminary studies of $Υ$ production at mid-rapidity found hints of suppression.
We present new results on the production of charged hadrons and neutral pions in Au+Au and d+Au collisions at sqrt{s_{NN} = 200 GeV, measured within the PHENIX experiment. We observe the opposite centrality dependence when comparing the two collision systems: an increase with centrality compared to the binary scaled yield from p+p collisions in d+Au and a decrease with centrality in Au+Au.
ALICE is the dedicated heavy-ion experiment at the Large Hadron Collider (LHC). It is designed to provide excellent capabilities to study the quark-gluon plasma (QGP) in the highest energy density regime opened up by the LHC. Quarkonia are crucial probes of the QGP. High-precision data from pp collisions are an essential baseline, and serve as a crucial test for competing models of quarkonium hadroproduction. ALICE measures quarkonia down to pt=0 via their decay channels into e+e- at central (|y|<0.9) and into mu+mu- at forward rapidity (-4.0<y<-2.5). We present first results on the transverse…
In 2001, PHENIX measured particle correlations of identical charged pions and kaons at mid-rapidity in Au-Au collisions at sqrt(s_NN)=200GeV. Bertsch-Pratt radius parameters of pion pairs are studied for 9 kT regions from 0.2 to 2.0 GeV/c and for 9 selections of collision centralities. The pion radius parameters are consistent with the result at sqrt(s_NN)=130GeV, and the ratio Rout/Rside is below 1 in all <kT> ranges up to 1.2 GeV/c. The radius parameters from charged kaon correlations are compared with those of pions.
The PHENIX experiment at RHIC has measured single electron spectra in proton-proton, deuteron-gold and gold-gold collisions at sqrt(s_NN)=200 GeV. The photonic contribution (photon conversions and Daltiz decays) is subtracted from the inclusive spectra resulting in non-photonic electron spectra. The principal source of non-photonic electrons is the semi-leptonic decay of charm and bottom mesons. The implications for heavy flavor production in hot and cold nuclear systems are discussed.
Bose-Einstein correlations of identical hadrons reveal information about hadron creation from the strongly interacting matter formed in ultrarelativistic heavy ion collisions. The measurement of three-particle correlations may in particular shed light on hadron creation mechanisms beyond thermal/chaotic emission. In this paper we show the status of PHENIX measurements of three pion correlations as a function of momentum differences within the triplets. We analyze the shape of the correlation functions through the assumption of Lévy sources and a proper treatment of the Coulomb interaction with…
PHENIX has measured direct photons in p+p and Au+Au collisions at sqrt{s_{NN}}=200 GeV. The p+p measurement is in good agreement with pQCD expectations. The nuclear modification factor in Au+Au is found to be consistent with unity for all centralities, and is compared to theoretical models. The data are found in agreement with models that take into account initial state modifications, as well as with those that account also for final state modifications.
We present results on identified particle production in p+p, d+Au and Au+Au collisions at $\sqrt{s_{NN}} = 200$ GeV at mid-rapidity measured by the PHENIX experiment. The centrality and flavor dependence of the Cronin effect in d+Au collisions is measured. The Cronin effect for the protons in d+Au is larger than that for the pions, but not large enough to account for the ``anomalous'' proton to pion ratio in central Au+Au collisions.
The PHENIX Run 4 Au+Au dataset provides a powerful opportunity for exploring the angular anisotropy of identified particle yields at high pT. Complementing traditional v2 measurements, we present pi0 yields as a function of angle with reaction plane, up to pT 10 GeV/c. The centrality dependence of the angular anisotropy allows us to probe the density and path-length dependence of the energy loss of hard-scattered partons. We will discuss various mechanisms for particle production in this high pT region.
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…
$J/ψ$ measurements in $p+p$ and $d+Au$ collisions serve as crucial references to understand the $J/ψ$ production in $Au+Au$ collisions at RHIC where quark gluon plasma (QGP) is expected to be formed. They also provide important clues to study various interesting phenomena such as the gluon shadowing and color glass condensate. We report the latest results from PHENIX experiment on $J/ψ$ production in $p+p$ and $d+Au$ collisions at forward, backward and midrapidity.
The transverse momentum dependence of the azimuthal anisotropy parameter v_{2}, the second harmonic of the azimuthal distribution, for electrons at mid-rapidity (|eta|<0.35) has been measured with the PHENIX detector in Au+Au collisions at sqrt(s_NN) = 200 GeV with respect to the reaction plane defined at high rapidities (|eta|=3-4). From the result we have calculated non-photonic electron v_{2}, which is expected to reflect the heavy-flavor azimuthal anisotropy, by subtracting v_{2} of electrons from other sources such as photon conversions, Dalitz decay etc.
We report the measurement of anisotropic flow at RHIC - PHENIX experiment. We present the v_4 results at sqrt(s_NN) = 200 GeV in Au+Au collision. The scaling ratio of v_4/(v_2)^2 is about 1.5 and it is found to be smaller than the prediction from simple coalescence model. The v_2 for high p_T identified particles ($\sim$ 5 GeV/c) measured with Aerogel Cherenkov Counter are presented. We discuss the constituent quark scaling of v_2 for identified particles. We also report the first observation of v_2 for inclusive charged hadrons as well as identified hadrons at sqrt(s_NN) = 200 GeV in Cu+Cu co…
Heavy flavor and quarkona production are important hard probes to test the Quantum Chromodynamics (QCD) and measure the properties of the Quark Gluon Plasma (QGP) created in high energy heavy ion collisions. The new PHENIX mid- and forward-rapidity silicon vertex detectors provide precise Distance of Closest Approach (DCA) determination, allowing charm and bottom yields identification, and improve di-muon mass resolution for charmonia studies. The relative $ψ(2S)$ over $J/ψ$(1S) yields measured in $p$+$p$, $p$+Al and $p$+Au data at $\sqrt{s}=$200 GeV help us to understand final state effects o…
The PHENIX experiment has shown that J/psis are suppressed in central Au+Au collisions at a center of mass energy per nucleon-nucleon collision sqrt s(NN) = 200 GeV, and that the suppression is larger at forward than at mid-rapidity. Part of this difference may be explained by cold nuclear matter effects but the most central collisions suggest that regeneration mechanisms could be at play. In 2007, PHENIX collected almost four times more Au+Au collisions at this energy than used for previous published results. Moreover, the addition of a new reaction plane detector allows a much better analysi…
