Roy A. Lacey
This note rebuts an old, but recurring claim by Antoniou, Davis and Diakonos [1] that the critical point and associated critical exponents reported in Ref. [2], is based on an erroneous treatment of scaling relations near the critical point.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
继续探索
The experimental search for the location of the QCD critical point in the phase diagram is of primary importance. In a recent publication it is claimed that measurements at RHIC lead not only to the location of the critical point ($μ_{cep}=95$ MeV, $T_{cep}=165$ MeV) but also to the verification of its universality class ($3d$ Ising system) by extracting the values of the critical exponents ($γ=1.2$, $ν=0.66$). We argue that this claim is based on an erroneous treatment of scaling relations near the critical point. As a result, the correct interpretation of the measurements cannot be linked to…
The current experimental and theoretical status of hadron and jet production at large transverse momentum in high-energy nucleus-nucleus collisions is summarised. The most important RHIC results are compared to theoretical parton energy loss predictions providing direct information on the (thermo)dynamical properties of hot and dense QCD matter. Prospects for the LHC are also outlined.
We make up-to-date QCD predictions for open charm and bottom production at RHIC in nucleon-nucleon collisions at \sqrt{S} = 200 GeV. We also calculate the electron spectrum resulting from heavy flavor decays to allow direct comparison to the data. A rigorous benchmark, including the theoretical uncertainties, is established against which nuclear collision data can be compared to obtain evidence for nuclear effects.
Data on hadron production at high transverse momentum ($p_T>$ 2 GeV/$c$) in p+p, d+Au, and Au+Au collisions at $\sqrt{s_{NN}$ = 200 GeV from the PHENIX experiment at RHIC are reviewed. The single inclusive spectrum of light hadrons produced in central Au+Au reactions shows significant differences compared to p+p and d+Au collisions, and provides interesting information on the properties of the underlying QCD medium present in heavy-ion reactions at collider energies.
We derive a simple analytical scaling function which embodies the predictions of high density QCD on the energy, centrality, rapidity, and atomic number dependences of hadron multiplicities in nuclear collisions. Both centrality and rapidity dependences of hadron multiplicity in $Au-Au$ collisions as measured at RHIC at $\sqrt{s}= 130 {GeV}$ are well described in this approach. The centrality and rapidity dependences of hadron multiplicity at $\sqrt{s}= 200 \ {GeV}$ run at RHIC are predicted; the variation of these dependences with energy appear different from other approaches, and can be used…
We present a summary of the physics of gluon saturation and non-linear QCD evolution at small values of parton momentum fraction $x$ in the proton and nucleus in the context of recent experimental results at HERA and RHIC. The rich physics potential of low-x studies at the LHC, especially in the forward region, is discussed and some benchmark measurements in pp, pA and AA collisions are introduced.
We analyze the first results on charged particle multiplicity at RHIC in the conventional eikonal approach and in the framework of high density QCD. We extract the fraction $F$ of the hadron multiplicity originating from ``hard'' (i.e. proportional to the number of binary collisions) processes; we find a strong growth of this fraction with energy: $F(\sqrt{s}=56 {\rm GeV}) \simeq 22%$, while $F(\sqrt{s}=130 {\rm GeV}) \simeq 37 %$. This indicates a rapid increase in the density of the produced particles. We outline the predictions of high density QCD for the centrality, energy, and atomic numb…
The shear viscosity to entropy ratio ($η/s$) is estimated for the hot and dense QCD matter created in Au+Au collisions at RHIC ($\sqrt{s_{NN}}=200$ GeV). A very low value is found $η/s \sim 0.1$, which is close to the conjectured lower bound ($1/4π$). It is argued that such a low value is indicative of thermodynamic trajectories for the decaying matter which lie close to the QCD critical end point.
The RHIC Cold QCD program has produced a remarkable breadth of physics results and experimental techniques in the exploration of the fundamental structure of strongly interacting matter over the years. In this document, we present highlights of longitudinal and transverse spin physics to date and the 25 years of innovation in accelerator science from the RHIC Spin program. These measurements and techniques will be essential to fully realize the scientific missions of the Electron-Ion Collider (EIC) by providing a comprehensive set of measurements in hadronic collisions and laying the foundatio…
We perform a study of $W$-boson production in polarized proton-proton collisions through next-to-next-to-leading order (NNLO) in perturbative QCD. This calculation is required to extend the extraction of polarized parton distribution functions to NNLO accuracy. We present differential distributions at $\sqrt{s}=510$ GeV, relevant for comparison to measurements from the Relativistic Heavy Ion Collider (RHIC). The NNLO QCD corrections significantly reduce the scale dependence of the cross section. We compare the longitudinal single-spin asymmetries as a function of lepton pseudorapidity to RHIC …
Thermal photon production at mid-rapidity in Au+Au reactions at $\sqrt{s_{NN}}$ = 200 GeV is studied in the framework of a 2D+1 hydrodynamical model that describes efficiently the bulk identified hadron spectra at RHIC. The combined thermal plus NLO pQCD photon spectrum is in good agreement with the yields measured by the PHENIX experiment for all Au+Au centralities. Within our model, we demonstrate that the correlation of the thermal photon slopes with the charged hadron multiplicity in each centrality bin provides direct empirical information on the underlying degrees of freedom and on the e…
Higher moments of net-proton multiplicity distributions are applied to search for the QCD critical point. In this paper, we will present measurements for kurtosis ($κ$), skewness ($S$) and variance $σ^2$) of net-proton multiplicity distributions at the mid-rapidity ($|y|<0.5$) and transverse momentum range $0.4<p_{T}<0.8$ {\gevc} for Au+Au collisions at {\sNN} = 7.7, 11.5, 39, 62.4 and 200 GeV, Cu+Cu collisions at {\sNN} = 22.4, 62.4 and 200 GeV, $d$+Au collisions at {\sNN} = 200 GeV and p+p collisions at {\sNN} = 62.4 and 200 GeV. The moment products $κσ^2$ and $S σ$ of net-proton distributio…
Enhanced fluctuations and correlations have been observed in the phase transitions of many systems. Their appearance at the predicted QCD phase transition (especially near the expected critical point) may provide insight into the nature of the phase transition. Recent results from the QCD Critical Point Search at RHIC will be presented, with a focus on particle ratio ($K/π$, $p/π$, and $K/p$) fluctuations and their comparison to previous measurements and theoretical predictions.
Fluctuations of conserved quantities, such as baryon, electric charge and strangeness number, are sensitive observables in relativistic heavy-ion collisions to probe the QCD phase transition and search for the QCD critical point. In this paper, we review the experimental measurements of the cumulants (up to fourth order) of event-by-event net-proton (proxy for net-baryon), net-charge and net-kaon (proxy for net-strangeness) multiplicity distributions in Au+Au collisions at $\sqrt{s_{NN}}=7.7, 11.5, 14.5, 19.6, 27, 39, 62.4, 200$ GeV from the first phase of beam energy scan program at the Relat…
In the search of QCD phase boundary and critical point, higher-order cumulants of conserved quantities are proposed as promising observables and have been studied extensively both experimentally and theoretically. In this paper we present cumulant ratios up to $6^{th}$-order of net-proton number distributions in Au+Au collisions at $\sqrt{\mathrm{s_{NN}}}$ = 7.7 - 200 GeV from STAR Beam Energy Scan program phase I and $\sqrt{\mathrm{s}}$ = 200 GeV $p+p$ collisions. The results are compared with various models and Lattice QCD calculations.
In the initial years of operation, experiments at the Relativistic Heavy Ion Collider (RHIC) have identified a new form of matter formed in nuclei-nuclei collisions at energy densities more than 100 times that of a cold atomic nucleus. Measurements and comparison with relativistic hydrodynamic models indicate that the matter thermalizes in an unexpectedly short time, has an energy density at least 15 times larger than needed for color deconfinement, has a temperature about twice the critical temperature predicted by lattice QCD, and appears to exhibit collective motion with ideal hydrodynamic …
Recently, transport coefficients viz. shear viscosity, electrical conductivity etc. of strongly interacting matter produced in heavy-ion collisions have drawn considerable interest. We study the normalised electrical conductivity ($σ_{\rm el}$/T) of hot QCD matter as a function of temperature (T) using the Color String Percolation Model (CSPM). We also study the temperature dependence of shear viscosity and its ratio with electrical conductivity for the QCD matter. We compare CSPM estimations with various existing results and lattice Quantum Chromodynamics (lQCD) predictions with (2+1) dynamic…
Recent experimental results obtained at the Relativistic Heavy-Ion Collider (RHIC) will be discussed. Investigations of different nucleus-nucleus collisions in recent years focus on two main tasks, namely, the detailed study of sQGP properties and the exploration of the QCD phase diagram. Results at top RHIC energy provide important information about event shapes as well as transport and thermodynamic properties of the hot medium for various flavors. Heavy-ion collisions are a unique tool for the study of topological properties of theory. Experimental results obtained for discrete QCD symmetri…
We review some important results from the PHENIX experiment at RHIC. They were obtained in a unique environment for studying QCD bulk matter at temperatures and densities that sur- pass the limits where hadrons exist as individual entities, so raising to prominence the quark- gluon degrees of freedom. We present measurements of nuclear modification factors for neutral pions, light favors (strange hadrons), direct-photons and non-photonic electrons from decays of particles carrying charm or beauty quarks. We interpret the large suppression of hadron produc- tion at high transverse momenta as re…
Polarized proton-proton collisions at the Relativistic Heavy Ion Collider (RHIC) provide unique opportunities to study the spin structure of the nucleon. We will highlight recent results on the nucleon spin structure from the STAR and PHENIX experiments at RHIC: (1) A sizable gluon polarization in the proton is measured with longitudinal double spin asymmetries of jet and hadron production; (2) Longitudinal single spin asymmetries in W boson production improve constraints on the sea quark polarization. The new spin asymmetry results for W boson confirmed the SU(2) flavor asymmetry of the light…
Properties of the QCD Matter -- An Experimental Review of Selected Results from RHIC BES Program
本文讨论了21世纪初中国多气隙电阻板室TOF技术发展与STAR TOF探测器研制，综述了RHIC BES-I项目在集体性、手征性等多方面的最新实验结果。
Fluctuations and correlations of conserved quantities (baryon number, strangeness, and charge) can be used to probe phases of strongly interacting QCD matter and the possible existence of a critical point in the phase diagram. The cumulants of the multiplicity distributions related to these conserved quantities are expected to be sensitive to possible increased fluctuations near a critical point and ratios of the cumulants can be directly compared to the ratios of the susceptibilities from Lattice QCD calculations. In these proceedings, the measurements of the cumulants of net-proton multiplic…
A study of collective behavior in heavy ion collisions provides one of the most sensitive and promising probes for investigation of possible formation of new extreme state of strong interacting matter and elucidating its properties. Systematic of experimental results for final state azimuthal anisotropy is presented for heavy ion interactions at RHIC. Experimental data for azimuthal anisotropy indicate that the final state strongly interacting matter under extreme conditions behaves as near-ideal liquid rather, than ideal gas of quarks and gluons. The strong quenching of jets and the dramatic …
We will review recent results on quantitative description of global properties of bulk partonic matter at RHIC. These results include strangeness phase space factor of the partonic matter, azimuthal angular anisotropy $v_2$, and transverse momentum $p_T$ distributions of effective partons at the hadronization of bulk partonic matter. We present empirical constraints on parton energy loss in the high $p_T$ region ($>$ 5 GeV/c). A flat $R_{AA}$ as a function of $p_T$ at mid-rapidity implies a constant fraction of the parton energy loss ($Δp_T/p_T$) and the fraction reaches 25% for neutral $π$, c…
The Beam Energy Scan (BES) program is being pursued at RHIC to study the QCD phase diagram, and search for the possible QCD phase boundary and possible QCD critical point. The data for Phase-I of the BES program have been collected for Au+Au collisions at center-of-mass energies ($\sqrt{s_{NN}}$) of 7.7, 11.5, 19.6, 27, and 39 GeV. These collision energies allowed the STAR experiment to cover a wide range of baryon chemical potential $μ_{B}$ (100--400 MeV) in the QCD phase diagram. We report on several interesting results from the BES Phase-I covering the high net-baryon density region. These …
The past decade has seen huge advances in experimental measurements made in heavy ion collisions at the Relativistic Heavy Ion Collider (RHIC) and more recently at the Large Hadron Collider (LHC). These new data, in combination with theoretical advances from calculations made in a variety of frameworks, have led to a broad and deep knowledge of the properties of thermal QCD matter. Increasingly quantitative descriptions of the quark-gluon plasma (QGP) created in these collisions have established that the QGP is a strongly coupled liquid with the lowest value of specific viscosity ever measured…
Probing the nature of the QCD phase transition with higher-order net-proton number fluctuation and local parton density fluctuation measurements at RHIC-STAR
本研究利用STAR实验中质子与净质子多重数分布的高阶累积量及局部部分子密度涨落测量，探究了QCD相变性质，发现低能下数据趋势暗示强子相互作用主导，并观测到可能指示一阶相变的聚集信号。
Experiments using heavy ion collisions at ultrarelativistic energies aim to explore the QCD phase transition and map out the QCD phase diagram. A wealth of remarkable results in this field have been reported recently, for example the Upsilon suppression discovered recently. We discuss recent results from the STAR experiment focusing on strangeness, charm and beauty production.
We extract chemical freeze-out conditions via a thermal model approach from fluctuation observables measured at RHIC and compare with results from lattice QCD and statistical hadronization model fits. The possible influence of additional critical and non-critical fluctuation sources not accounted for in our analysis is discussed.
Quantum Chromodynamics (QCD) is a basic gauge field theory to describe strong interactions. Lattice QCD calculations predict a phase transition from hadronic matter to a deconfined, locally thermalized Quark-Gluon Plasma (QGP) state at high temperature and small baryon density. Plenty of exciting results from RHIC experiments in the first three years have demonstrated that a hot dense matter with strong collective motion which cannot be described with hadronic degrees of freedom was created at RHIC. Charm quarks are believed to be mostly created from initial gluon fusion in heavy ion collision…
I briefly describe the initial goals of relativistic nuclear collisions research, focusing on the LBL Bevatron/Bevalac facility in the 1970's. An early concept of high hadronic density fireball formation, and subsequent isentropic decay (preserving information as to the high density stage) led to an outline of physics observables that could determine the nuclear matter equation of state at several times nuclear ground state matter density. With the advent of QCD the goal of locating, and characterizing the hadron-parton deconfinement phase transformation suggested the need for higher $\sqrt{s}…
This work reports on investigations of the effects on the evolution of viscous hydrodynamics and on the flow coefficients of thermal dileptons, originating from a temperature-dependent specific shear viscosity $η/s (T)$ at temperatures beyond 180 MeV formed at the Relativistic Heavy-Ion Collider (RHIC). We show that the elliptic flow of thermal dileptons can resolve the magnitude of $η/s$ at the high temperatures, where partonic degrees of freedom become relevant, whereas discriminating between different specific functional forms will likely not be possible at RHIC using this observable.
One of the primary goals of high-energy heavy-ion collisions is to establish the QCD phase diagram and search for possible phase boundaries. The planned RHIC energy scan program will explore this exciting physics topic using heavy-ion collisions at various center of mass energies. The first test run with Au+Au collisions at $\sqrt{s_{NN}}$ = 9.2 GeV took place in early 2008. We present the results on identified particle ratios, azimuthal anisotropy parameters (v1 and v2) and HBT at midrapidity using data from this run. These results are compared to data for both lower and higher center of mass…
Beam Energy Scan (BES) program at RHIC is important to search for the existence of the critical point in the QCD phase diagram. Lattice QCD have shown that the predictions of the susceptibility of the medium formed in heavy-ion collisions can be sensitive to the various moments (mean ($μ$) =${<x>}$, variance ($σ^2$) = ${<(x-μ)^2>}$, skewness (S) = $\frac{<(x-μ)^3>}{σ^3}$ and kurtosis ($κ$) =$\frac{<(x-μ)^4>}{σ^4} -3$) of conserved quantities like net-baryon number ($Δ$B), net-electric charge ($Δ$Q) and net-strangeness ($Δ$S). Any non-monotonic behavior of the higher moments would confirm the e…
We update the study of the polarisation of J/psi produced in proton-proton collisions at RHIC at sqrt(s)=200 GeV using the QCD-based Colour-Singlet Model (CSM), including next-to-leading order partonic matrix elements from gluon and light quark fusion and leading-order contributions from charm-quark initiated processes. To do so, we also evaluate the corresponding cross section differential in P_T which agrees qualitatively with the measurements of PHENIX in the central and forward regions at low P_T -- for instance below 2 GeV --, while emphasising the need for Initial State Radiation (ISR) r…
The first decade of RHIC running has established the existence of a strongly coupled Quark Gluon Plasma (sQGP), a new state of nuclear matter with partonic degrees of freedom. Theory predicts how transitions to this sQGP depend on the baryon chemical potential, mu_B, and temperature, T. At low mu_B and high T a cross-over transition occurs. At high mu_B and low T the transition is of first order. Hence, at intermediate values, a critical point should occur. Experimentally we can vary these initial conditions by altering the beam energy. Thus a beam energy scan (BES) will allow us to explore th…
Two measurements related to the proton and anti-proton production near midrapidity in center of mass energies of 7.7, 11.5, 19.6, 27, 39, 62.4 and 200 GeV Au+Au collisions using the STAR detector at the Relativistic Heavy Ion Collider (RHIC) are discussed. At intermediate impact parameters the slope parameter of the directed flow versus rapidity (dv1/dy) for the net-protons shows a non-monotonic variation as a function of the beam energy. This non-monotonic variation is characterized by the presence of a minimum in dv1/dy between 11.5 and 19.6 GeV and a change in the sign of dv1/dy twice betwe…
There are compelling physics questions to be addressed by a new comprehensive detector at a future, high-luminosity RHIC II collider. These form the basis for this Expression of Interest. What precisely are the properties of the strongly-coupled Quark Gluon Plasma (sQGP)? Can a more weakly interacting QGP state be formed and investigated at RHIC? How do particles acquire mass and what is the effect of chiral symmetry restoration on hadronization in a dense medium? What is the chiral structure of the QCD vacuum and its influence on and contributions of different QCD vacuum states to the masses …
Recent experimental results obtained in STAR experiment at the Relativistic heavy-ion collider (RHIC) with ion beams will be discussed. Investigations of different nuclear collisions in some recent years focus on two main tasks, namely, detail study of quark-gluon matter properties and exploration of the quantum chromodynamics (QCD) phase diagram. Results at top RHIC energy show clearly the collective behavior of heavy quarks in nucleus-nucleus interactions. Jet and heavy hadron measurements lead to new constraints for energy loss models for various flavors. Heavy-ion collisions are unique too…
The PHENIX Experiment at RHIC has conducted a beam energy scan at several collision energies in order to search for signatures of the QCD critical point and the onset of deconfinement. PHENIX has conducted measurements of transverse energy production, muliplicity fluctuations, and the skewness and kurtosis of net charge distributions. The data analyzed to date show no significant indications of the presence of the critical point.
The exploration of the fundamental structure of strongly interacting matter has always thrived on the complementarity of lepton scattering and purely hadronic probes. As the community eagerly anticipates a future electron ion collider (EIC) in the U.S., an outstanding scientific opportunity remains to complete "must-do" measurements in p+p and p+A physics in the years preceding the EIC. As we describe in this document, these measurements will be essential to fully realize the scientific promise of the EIC by provid-ing a comprehensive set of measurements in hadronic collisions that, when combi…
We perform global fit to the quark Sivers function within the transverse momentum dependent (TMD) factorization formalism in QCD. We simultaneously fit Sivers asymmetry data from Semi-Inclusive Deep Inelastic Scattering (SIDIS) at COMPASS, HERMES, and JLab, from Drell-Yan lepton pair production at COMPASS, and from $W/Z$ boson at RHIC. This extraction is performed at next-to-leading order (NLO) and next-to-next-to leading logarithmic (NNLL) accuracy. We find excellent agreement between our extracted asymmetry and the experimental data for SIDIS and Drell-Yan lepton pair production, while tensi…
We present the measurements of invariant yields of $K^{*0}$ and $ϕ$ resonances at midrapidity in Au+Au collisions at $\sqrt{s_{NN}}$ = 7.7 - 200 GeV using the STAR detector. The transverse momentum ($p_{T}$) spectra and $p_{T}$-integrated yields of $K^{*0}$ and $ϕ$ have been studied. The ratios between resonance ($K^{*0}$ and $ϕ$) to non-resonance particles ($K$) are presented as a function of centrality. It is found that $K^{*0}/K^{-}$ ratios are suppressed in the most central collisions as compared to peripheral ones for all studied collision energies. On the other hand, $ϕ/K^{-}$ ratios are…
The PHENIX Experiment at RHIC has conducted a beam energy scan at several collision energies in order to search for signatures of the QCD critical point and the onset of deconfinement. PHENIX has conducted measurements of transverse energy production, muliplicity fluctuations, the skewness and kurtosis of net charge distributions, Hanbury-Brown Twiss correlations, charged hadron flow, and energy loss. The data analyzed to date show no significant indications of the presence of the critical point.
In this report we discuss the capabilities and limitations of the STAR detector to search for signatures of the QCD critical point in a low energy scan at RHIC. We find that a RHIC low energy scan will cover a broad region of interest in the nuclear matter phase diagram and that the STAR detector -- a detector designed to measure the quantities that will be of interest in this search -- will provide new observables and improve on previous measurements in this energy range.
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…
The main goals of relativistic heavy-ion experiments is to study the properties of QCD matter under extreme temperatures and densities. The focus of this talk is the studies that are underway at the Relativistic Heavy Ion Collider (RHIC), located at the Brookhaven National Laboratory (BNL) on Long Island, New York, U.S.A. I discuss selected highlights from the past couple of years that are key to elucidating the characteristics of the new state of matter created in these heavy-ion collisions, called a Quark Gluon Plasma.
High-energy nuclear collision provide a unique tool to study the strongly interacting medium. Recent results from the Relativistic Heavy Ion Collider (RHIC) on ϕ-meson production has revealed the formation of a dense partonic medium. The medium constituents are found to exhibit collective behaviour initiated due to partonic interactions in the medium. We present a brief review of the recent results on ϕproduction in heavy-ion collisions at RHIC. One crucial question is where, in the phase diagram, does the transition happen for the matter changing from hadronic to partonic degrees of freedom. …
Fluctuations of conserved quantities are sensitive observables to probe the signature of QCD phase transition and critical point in heavy-ion collisions. With the UrQMD model, we have studied the centrality and energy dependence of various order cumulants and cumulant ratios (up to fourth order) of net-proton,net-charge and net-kaon multiplicity distributions in Au+Au collisions at $\sqrt{s_{NN}}$= 7.7, 11.5, 19.6, 27, 39, 62.4, 200 GeV. The model results show that the production mechanism of the particles and anti-particles have significant impacts on the cumulants of net-particles multiplici…
Event-by-event fluctuations of global observables in relativistic heavy-ion collisions are studied as probes for the QCD phase transition and as tools to search for critical phenomena near the phase boundary. Dynamical fluctuations in mean transverse momentum, identified particle ratios and conserved quantities (such as net-charge, net-baryon) are expected to provide signatures of a de-confined state of matter. Non-monotonic behavior in the higher-moments of conserved quantities as a function of beam energy and collision centrality are proposed as signatures of the QCD critical point. To study…
QCD predicts a phase transition between hadronic matter and a Quark Gluon Plasma at high energy density. The Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory is a new facility dedicated to the experimental study of matter under extreme conditions. I will discuss the first round of experimental results from colliding heavy nuclei at RHIC and our current understanding of the state of matter generated in such collisions, concentrating on partonic energy loss and jet quenching as a probe of the medium.
The RHIC Beam Energy Scan focuses on the study of the QCD phase diagram --- temperature ($T$) vs. baryon chemical potential ($μ_B$). The aim is to verify some predictions from QCD: that a cross-over occurs at $μ_B$ = 0, that there exists a first-order phase transition at large $μ_B$ and a critical point at an intermediate $μ_B$. The spectra and ratios of produced particles can be used to extract $T$ and $μ_B$ in different energies and system sizes. The STAR experiment has collected data for Au+Au collisions at $\sqrt{s_{NN}}=$ 7.7 GeV, 11.5 GeV, and 39 GeV in the year 2010. We present midrapid…
With the measurement of several observables at SPS energies that demonstrate non-monotonic behavior as a function of centrality and $\sqrt{s_{NN}}$, there is growing interest in pursuing a scan of relativistic heavy ion collisions at low energies at the Relativistic Heavy Ion Collider. The capabilities of the PHENIX experiment to take quality measurements at low RHIC energies is described and directly demonstrated with analyses of Au+Au collisions at $\sqrt{s_{NN}}$ = 19.6 GeV and Cu+Cu collisions at $\sqrt{s_{NN}}$ = 22.5 GeV. The contribution of upgrades to the PHENIX detector in the upcomin…
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 exploration of the QCD phase diagram has been one of the main drivers of contemporary nuclear physics. The Relativistic Heavy Ion Collider (RHIC) at BNL is uniquely suited for this task through its Beam Energy Scan (BES) program which allowed for a large range in baryon chemical potential $μ_B$ as was successfully demonstrated after the completion of Phase 1 in 2014. Phase 2 of the BES at RHIC is scheduled to start in 2019 and will explore with precision measurements the intermediate-to-high $μ_B$ region of the QCD phase diagram, five energies $\sqrt{s_{NN}}$ from 7.7 to 19.6 GeV in collid…
A revolution in elementary particle physics occurred during the period from the ICHEP1968 to the ICHEP1982 with the advent of the parton model from discoveries in Deeply Inelastic electron-proton Scattering at SLAC, neutrino experiments, hard-scattering observed in p$+$p collisions at the CERN ISR, the development of QCD, the discovery of the J/$Ψ$ at BNL and SLAC and the clear observation of high transverse momentum jets at the CERN SPS $\bar{p}+p$ collider. These and other discoveries in this period led to the acceptance of QCD as the theory of the strong interactions. The desire to understa…
Search for the QCD Critical Point in High Energy Nuclear Collisions: A Status Report
本文综述了STAR实验最近关于净质子乘数波动的结果，旨在确定RHIC高能核碰撞中的QCD临界点，通过比较实验数据与非临界模型计算，探讨初始体积波动效应及未来研究方向。
A critical examination of RHIC paradigms is presented. Topics include: search for a critical point with a low energy scan; the lack of understanding of radiative processes in a medium in QCD compared in detail to examples from QED; the reason why some physicists started to measure particles at large pT in the 1960's; a review of the discovery of hard-scattering in p-p collisions in the 1970's via single-inclusive and two-particle correlations and application of these techniques at RHIC. Several paradigms in both soft and hard physics which are popular at RHIC are discussed and challenged.
Hadrons carrying open heavy flavor, i.e. single charm or bottom quarks, are among the key diagnostic tools available today for the hot and dense state of strongly interacting matter which is produced in collisions of heavy atomic nuclei at ultra-relativistic energies. First systematic heavy-flavor measurements in nucleus-nucleus collisions and the reference proton-proton system at Brookhaven National Laboratory's (BNL) Relativistic Heavy Ion Collider (RHIC) have led to tantalizing results. These studies are now continued and extended at RHIC and at CERN's Large Hadron Collider (LHC), where con…
扫码添加微信好友，提出您的宝贵建议 👇
💡 备注请填写：网站反馈
发表机构由 AI 从论文文本抽取，如发现错误，欢迎反馈修正建议。