The study of quarkonium production in relativistic heavy ion collisions provides insight into the properties of the produced medium. The lattice studies show a sequential suppression of quarkonia states when compared to normal nuclear matter; which further affirms that a full spectroscopy including bottomonium can provide us a better thermometer for the matter produced under extreme conditions in relativistic heavy ion collisions. With the completion of the STAR Electromagnetic Calorimeter and with the increased luminosity provided by RHIC in Run 6 and 7, the study of $Υ$ production via the di-electron channel becomes possible. We present the results on $Υ$ measurements in p+p collisions (from Run 6) along with the first results from Au+Au collisions (in Run 7) at $\sqrt{s_{\rm{NN}}} = 200$ GeV from the STAR experiment.
We review hadron production in heavy ion collisions with emphasis on pion and kaon production at energies below 2 AGeV and on partonic collectivity at RHIC energies.
In these proceedings, an overview of recent hypernuclei measurements in heavy ion collisions is presented. These results include the lifetime, $Λ$ binding energy, production yield, and directed flow in heavy ion collisions. These results provide constraints on the hyperon-nucleon interaction, enhance our understanding in hypernuclear structure, and provide insight on the production mechanisms of hypernuclei in heavy ion collisions.
psi' production is studied in Pb-Pb collisions at 158 GeV/c per nucleon incident momentum. Absolute cross-sections are measured and production rates are investigated as a function of the centrality of the collision. The results are compared with those obtained for lighter colliding systems and also for the J/psi meson produced under identical conditions.
We present results from Experiment 864 for antiproton production and antideuteron limits in Au + Pb collisions at 11.5 GeV/c per nucleon. We have measured invariant multiplicities for antiprotons for rapidities 1.4<y<2.4 at low transverse momentum as a function of collision geometry. When compared with the results from Experiment 878 our measurements suggest a significant contribution to the measured antiproton yield from the decay of strange antibaryons. We have also searched for antideuterons and see no statistically significant signal. Thus, we set upper limits on the production at approxim…
Dielectrons probe a wide range of phenomena in heavy-ion collisions. These include light- and heavy-flavour meson production, thermal radiation and coherent photo-production. The latter process is distinguished by dielectron production at low transverse-pair momentum ($ \it{p}_{\textrm{T,ee}}$). Transverse momentum spectra of dielectrons in central and peripheral Pb-Pb collisions are extracted and compared to the corresponding expectations. In central collisions the data fit the expected spectrum, which is dominated by semi-leptonic decays of correlated heavy-flavour hadrons. In peripheral col…
We update briefly our understanding of hadron production in relativistic nucleus-nucleus collisions in terms of statistical models with emphasis on the relation of the data to the QCD phase boundary and on a puzzle in the beam energy dependence.
The STAR collaboration at RHIC presents measurements of \Jpsi$\to{e^+e^-}$ at mid-rapidity and high transverse momentum ($p_T>5$ GeV/$c$) in \pp and central \cucu collisions at \sNN = 200 GeV. The inclusive \Jpsi production cross section for \cucu collisions is found to be consistent at high $p_T$ with the binary collision-scaled cross section for \pp collisions, in contrast to previous measurements at lower $p_T$, where a suppression of \Jpsi production is observed relative to the expectation from binary scaling. Azimuthal correlations of $J/ψ$ with charged hadrons in \pp collisions provide a…
We present recent result on strange and non-strange D-meson production measured with ALICE in Pb--Pb collisions at the LHC. In addition, the measurements of the $Λ_{\rm c}^+$-baryon production and of the $Λ_{\rm c}^+/{\rm D^0}$ ratio in pp, p--Pb, and, for the first time ever, Pb--Pb collisions are reported.
Published measurements of semi-inclusive Lambda production in p-Au collisions at the AGS are used to estimate the yields of singly strange hadrons in nucleus-nucleus A-A collisions. Results of a described extrapolation technique are shown and compared to measurements of K+ production in Si-Al, Si-Au, and Au-Au collisions at the AGS and net Lambda production in Su-Su, S-Ag, Pb-Pb, and inclusive p-A collisions at the SPS. The extrapolations can account for more than 75% of the measured strange particle yields in all of the studied systems except for very central Au-Au collisions at the AGS where…
We study charm production through dimuon and single muon measurements at forward and backward rapidities in p+p and d+Au collisions with the PHENIX muon detectors. We also compare open charm to $J/ψ$ yields in the forward and backward rapidities in d+Au collisions and study the origin of the large forward and backward asymmetry in open charm production observed by the PHENIX experiment.
The first measurements of light antinucleus production in Au+Au collisions at RHIC are reported. The observed production rates for antideuterons and antihelions are much larger than in lower energy nucleus-nucleus collisions. A coalescence model analysis of the yields indicates that there is little or no increase in the antinucleon freeze-out volume compared to collisions at SPS energy. These analyses also indicate that the antihelion freeze-out volume is smaller than the antideuteron freeze-out volume.
This paper presents the CMS measurements of quarkonia and open heavy flavor production in \pp, \pPb, and \PbPb collisions at \sqrtsnn = 2.76 and 5.02 TeV. A brief outlook of the near-future CMS heavy flavor physics analyses is provided at the end.
Recent measurements of the electroweak-boson production performed by the ALICE Collaboration are reported. The W-boson production was measured at midrapidity in pp collisions at $\sqrt{s} = 13$ TeV, via the electronic decay of the boson. It was also measured in association with a hadron emitted back-to-back with respect to the electron. In heavy-ion collisions, the W- and Z-boson production was measured at forward rapidity in p--Pb collisions at $\sqrt{s_{\mathrm{NN}}} = 8.16$ TeV and Pb--Pb collisions at $\sqrt{s_{\mathrm{NN}}} = 5.02$ TeV, in their muonic decay channel. Measurements in pp co…
We report the STAR measurement of Phi meson production in Au+Au and p+p collisions at sqrt (s)=200 GeV. Using the event mixing technique, the Phi spectra and yields are obtained at mid-rapidity for five centrality bins in Au+Au collisions and for non-singly-diffractive p+p collisions. It is found that the Phi transverse momentum distributions from Au+Au collisions are better fitted with a single-exponential while the p+p spectrum is better described by a double-exponential distribution. The measured nuclear modification factors indicate that Phi production in central Au+Au collisions is suppre…
Measurements of heavy quark production and suppression in ultra-relativistic nuclear collisions probe the interactions of heavy quarks with the hot, dense medium created in the collisions. ATLAS has measured heavy quark production in $\sqrtsnn = 2.76$ \TeV \PbPb collisions via semi-leptonic decays of open heavy flavour hadrons to muons. Results are presented for the per-event muon yield as a function of muon transverse momentum, \pT, over the range of $4 < \pT < 14$ \GeV. The centrality dependence of the muon yields is characterized by the "central to peripheral" ratio, \Rcp. Muon production i…
We present the results for the measurement of $ϕ$ meson production in $\sqrt{s_{NN}}$ = 200 GeV Au+Au and pp collisions at the Relativistic Heavy Ion Collider (RHIC). Using the event mixing technique, spectra and yields are obtained from the $ϕ\to K^{+}K^{-}$ decay channel for five centrality bins in Au+Au collisions and in pp collisions. We observe that the spectrum shape in Au+Au collisions depends weakly on the centrality and the shape of the spectrum in pp collisions is significantly different from that in Au+Au collisions.
Open heavy-flavour and quarkonia measurements are important tools to study the hot and dense partonic medium formed in ultra-relativistic heavy-ion collisions. The modification of their production in those collisions, with respect to the pp and p-Pb ones, can help in the characterization of this medium. Quarkonia and open heavy-flavour production is measured in ALICE in the three different collision systems, at mid- and forward rapidity. A selection of those results recently obtained in Pb-Pb and p-Pb collisions by the ALICE Collaboration is presented.
Ultra-peripheral heavy ion collisions involve long range electromagnetic interactions at impact parameters larger than twice the nuclear radius, where no nucleon-nucleon collisions occur. We report on the first observation of rho meson production in dAu->d Au rho^0 and dAu-> n p Au rho^0.
We investigate modification of the bottom quark production due to cold nuclear matter effects (CNM) at mid-rapidity in d+Au collisions at $\sqrt{s_{NN}} = 200$ GeV at RHIC. Our results indicate that bottom production is not suppressed due to CNM effects in those collisions. We also found that shadowing and initial $k_T$ breadboarding for charm quarks explains at low $p_T$ ($p_T < 3$ GeV/c) the enhancement of heavy flavor decay electron yield in d+Au collisions at $\sqrt{s_{NN}} = 200$ GeV compared to p+p.
Measurements of direct photon production in p+Pb and p+C collisions at $\sqrt{s_\mathrm{NN}} = 17.4\mathrm{GeV}$ are presented. Upper limits on the direct photon yield as a function of $p_\mathrm{T}$ are derived and compared to the results for Pb+Pb collisions at $\sqrt{s_\mathrm{NN}} = 17.3$ GeV. The production of the $η$ meson, which is an important input to the direct photon signal extraction, has been determined in the $η\rightarrow 2γ$ channel for p+C collisions at $\sqrt{s_\mathrm{NN}} = 17.4\mathrm{GeV}$.
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 the measurement of the D+s production in pp collisions at sqrt{s} = 7 TeV and in Pb Pb collisions at sqrt{s_NN} =2.76 TeV performed with the ALICE detector at central rapidity through the reconstruction of the hadronic decay channel D+s-> K+K-pi+. The preliminary results of the D+s nuclear modification factor will be presented.
PHENIX has measured $J/ψ$ production at backward, central and forward rapidities both in p+p and d+Au collisions at $\sqrt{s_{NN}}=200$ GeV during the third run of the RHIC collider. From the p+p collisions, we measure the total J/$ψ$ cross section. From the d+Au collisions, we compute the nuclear modification factor versus transverse momentum, rapidity and centrality. All results presented here are preliminary.
The Compact Muon Solenoid (CMS) is fully equipped to measure leptonic decays of electroweak probes in the high multiplicity environment of nucleus-nucleus collisions. Electroweak boson production is an important benchmark process at hadron colliders. Precise measurements of W and Z production in heavy-ion collisions can help to constrain nuclear PDFs as well as serve as a standard candle of the initial state in PbPb collisions at the LHC energies. The inclusive and differential measurements of the Z boson yield in the muon and electron decay channel will be presented, establishing that no modi…
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.}
We present the centrality dependence of particle production in p-A collisions at sqrt(s_NN) = 5.02 TeV measured by the ALICE experiment, including the pseudo-rapidity and transverse momentum spectra, with a special emphasis on the event classification in centrality classes and its implications for the interpretation of the nuclear effects.
We present spectra of $π^0$, $η$ and $ω$ mesons in pp collisions and $π^{0}$ mesons in Pb-Pb collisions measured with ALICE at LHC energies. The $π^0$ and $η$ mesons are reconstructed via their two-photon decays by two complementary methods, using the electromagnetic calorimeters and photon conversion technique; both measurements show perfect agreement. We measure the nuclear modification factor ($R_{AA}$) of $π^0$ production in Pb-Pb collisions at different collision centralities and compare with lower energy results and theoretical predictions.
The ALICE detector at the LHC studies $π^0$ and $η$ meson production by two complementary methods, using electromagnetic calorimeters and the central tracking system for converted photons. Production spectra of $π^0$ and $η$ mesons were measured with ALICE in pp collisions at LHC energies at mid-rapidity in a wide transverse momentum range. The spectrum and the nuclear modification factor $R_{AA}$ of $π^0$ measured in Pb-Pb collisions at different centralities, show a clear pattern of strong suppression in a hot QCD medium with respect to pp collisions.
The fisrt measurement of the nuclear modification factor for single muons produced in CuCu collisions is presented which is the first measurement of the nuclear modification factor for open heavy flavor production made at forward angles in heavy ion collisions
This article presents recent results of the Z boson production in the proton-lead collisions and the charmonium production in the ultra-peripheral lead-lead collisions at the LHC collected during 2013 to 2018 by the LHCb detector. The potential heavy ion programs in these topics are also discussed.
Measurements of quarkonia production in ultra-peripheral heavy-ion collisions are of important value to study photon-photon and photon-nucleus interactions, the partonic structure of nuclei, and mechanisms of vector-meson production. LHCb has studied both coherent $J/ψ$ and $ψ(2S)$ mesons in ultra-peripheral collisions using PbPb data at forward rapidity with the highest precision currently accessible. In addition, measurements of $Z$ production in $p$Pb collisions provide new constraints on the partonic structure of nucleons bound inside nuclei. Here will present these measurements of quarkon…
Measurements of coherent charmonium production cross sections together with their ratio in ultra-peripheral PbPb collisions are studied at a nucleon-nucleon centre-of-mass energy of $5.02\,\mathrm{TeV}$, the differential cross-sections are measured as a function of rapidity and transverse momentum, separately. The photo-production of \jpsi mesons at low transverse momentum is studied in peripheral PbPb collisions, which confirms coherent \jpsi production in hadronic collisions. These latest results significantly improve previous measurements and are compared with some theoretical predictions.
The measurement of D-meson production in heavy-ion collisions at LHC energy provides insights into the mechanisms of interaction of charm quarks in the hot and dense medium formed in these collisions. ALICE results on the D-meson nuclear modification factor and azimuthal anisotropy in Pb-Pb collisions at $\sqrt{s_{\rm NN}}=2.76$ TeV are presented.
Measurements of jet production and jet properties in pp collisions provide a test of perturbative quantum chromodynamics (pQCD) and form a baseline for similar measurements in heavy ion (A--A) collisions. In this contribution, we report recent ALICE measurements of charged-particle jet production and intra-jet properties, including mean charged-constituent multiplicity and fragmentation distribution for leading jets, in minimum bias pp collisions at $\sqrt{s} = 13\,$TeV. In addition, the event multiplicity dependence of jet production and jet properties in pp collisions at $\sqrt{s} = 13\,$TeV…
We report the recent measurements of the inclusive J/ψ production in pp collisions at \sqrt{s} = 2.76 TeV, in pp collisions at \sqrt{s} = 7 TeV and in Pb-Pb collisions at \sqrt{s_{NN}} = 2.76 TeV with the ALICE detector at the LHC. The J/ψ mesons are detected down to pT = 0 GeV/c via their di-muon decay channel at forward rapidity (2.5 < y < 4) and via their di-electron decay channel at mid-rapidity (|y| < 0.9). A special emphasis is put on the nuclear modification factor which is compared to the predictions of current J/ψ production models.
This work presents the latest results on open heavy-flavour production in proton-proton, proton-lead, lead-lead and xenon-xenon collisions from the ALICE, ATLAS, CMS and LHCb Collaborations at the LHC.
Results on open heavy-flavour production in Pb-Pb collisions at sqrt{s_NN} = 2.76 TeV measured with ALICE at the LHC are presented. The nuclear modification factors, extracted in three different channels, show a strong suppression in central collisions. The measured D-meson azimuthal anisotropy indicates a non-zero v2, which is similar to the one of charged hadrons.
We present the recent results for D-meson production measured by the ALICE collaboration in pp collisions at $\sqrt{s}=7$ TeV, Pb-Pb collisions at $\sqrt{s_\mathrm{NN}}=2.76$ TeV and p-Pb collisions at $\sqrt{s_\mathrm{NN}}=5.02$ TeV.
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.
The energy densities reached in high-energy hadronic collisions at the LHC allow significant production of light (anti)nuclei. Their production yields have been measured as a function of $p_{\rm T}$ and charged-particle multiplicity in different collision systems and at different center-of-mass energies by ALICE. One of the most interesting results obtained from such a large variety of experimental data is that the dominant production mechanism of light (anti)nuclei seems to depend solely on the event charged-particle multiplicity. Evidence for this comes from the continuous evolution of the d…
In this contribution, recent ALICE measurements of the production cross section of single electrons, single muons and open charmed mesons in proton-proton collisions at sqrt(s) = 7 TeV are reported. The data are compared to next-to-leading-order perturbative QCD calculations. First open charm signals in Pb-Pb collisions at sqrt(sNN) = 2.76 TeV are shown.
This is a review of the Quantum Chromodynamics Cosmological Phase Transitions, the Quark-Gluon Plasma, the production of heavy quark states via p-p collisions and RHIC (Relativistic Heavy Ion Collisions) using the mixed hybrid theory for the $Ψ(2S)$ and $Υ(3S)$ states; and the possible detection of the Quark-Gluon Plasma via heavy quark production using RHIC. Recent research on fragmentation for the production of D mesons is reviewed, as is future theoretical and experimental research on the Collins and Sivers fragmentation functions for pions produced in polarized p-p collisions.
The measurement of heavy-flavour production and nuclear modification factor in heavy-ion collisions provides insights into the mechanisms of parton energy loss in the hot and dense medium formed in these collisions. ALICE results on heavy-flavour decay electrons and muons and on D mesons are presented.
Recent measurements performed in high-multiplicity proton-proton (pp) and proton-lead (p-Pb) collisions have shown features that are reminiscent of those observed in lead-lead (Pb-Pb) collisions. These observations warrant a comprehensive measurement of the production of identified particles. We report on the production of \allparts at mid-rapidity measured as a function of multiplicity in pp collisions at $\sqrt{s}$ = 7 TeV with the ALICE experiment. Spectral shapes studied both for individual particles and via particle ratios such as ($Λ/K^{0}_{S}$) as a function of $p_{T}$ exhibit an evolut…
We calculate the inclusive J/Psi production in heavy ion collisions including the effects of gluon saturation in the wave functions of the colliding nuclei. We argue that the dominant production mechanism in proton--nucleus and nucleus--nucleus collisions for heavy nuclei is different from the one in hadron-hadron interactions. We find that the rapidity distribution of primary J/Psi production is more peaked around midrapidity than the analogous distribution in elementary pp collisions. We discuss the consequences of this fact on the experimentally observed J/Psi suppression in Au-Au collision…
We study the nuclear enhancement of the transverse momentum imbalance for back-to-back particle production in both p+A and e+A collisions. Specifically, we present results for photon+jet and photon+hadron production in p+A collisions, di-jet and di-hadron production in e+A collisions, and heavy-quark and heavy-meson pair production in both p+A and e+A collisions. We evaluate the effect of both initial-state and final-state multiple scattering, which determine the strength of the nuclear-induced transverse momentum imbalance in these processes. We give theoretical predictions for the experiment…
We consider hadron production in deuteron gold collisions at RHIC in the forward rapidity region. Treating the target nucleus as a Color Glass Condensate and the projectile deuteron as a dilute system of valence quarks, we obtain good agreement with the BRAHMS minimum bias data on charged hadron production in the forward rapidity ($y=3.2$) and low $p_t$ region. We provide predictions for neutral pion production in minimum bias deuteron gold collisions in the forward rapidity region, $y=3.8$, measured by the STAR collaboration at RHIC.
We calculate the inclusive heavy quark production cross section for proton-nucleus collisions at high energies. We perform calculation in a quasi-classical approximation (McLerran-Venugopalan model) neglecting all low-x evolution effects. The derived expression for the differential cross section can be applied for studying the heavy quark production in the central rapidity region at RHIC.
We derive the formulae for the cross section of J/Psi production in high energy pA and AA collisions taking into account the gluon saturation/color glass condensate effects. We then perform the numerical calculations of the corresponding nuclear modification factors and find a good agreement between our calculations and the experimental data on J/Psi production in dA collisions. We also observe that cold nuclear modification effects alone cannot describe the data on J/Psi production in AA collisions. Additional final state suppression (at RHIC) and enhancement (at LHC) mechanisms are required …
Quarkonium production as a function of the charged-particle multiplicity could provide an insight into particle production processes at the partonic level in hadronic collisions. It is believed that multiple partonic interactions play an important role in particle production and affect both soft and hard processes. The study of correlations between quarkonia and charged-particle multiplicity may provide information about this. In this contribution, ALICE measurements of J$/ψ$ and $Υ$ production as a function of charged-particle multiplicity are presented for pp collisions at center-of-mass ene…
We apply the Color Glass Condensate formalism to photon $+$ hadron production cross section in high energy deuteron (proton)-gold collisions at RHIC. We investigate the dependence of the production cross section on the angle between the produced hadron and photon for various rapidities and transverse momenta. It is shown that the angular correlation between the produced hadron and photon is a sensitive probe of the saturation dynamics.
An experimental overview of the energy dependence of strangeness production is presented. The strange hadrons are considered a good probe to study the QCD matter created in relativistic nucleus-nucleus collisions. The heavy-ion experiments at SPS, RHIC, and LHC have recorded a wealth of data in proton-proton, proton-nucleus and nucleus-nucleus collisions at several beam energies. In this proceeding, I discuss the invariant yield and azimuthal anisotropy measurement of strange hadrons in nucleus-nucleus collisions at SPS, RHIC, and LHC.
