Search For Quark-gluon Plasma Research Articles

SURPRISES FROM THE SEARCH FOR QUARK-GLUON PLASMA? WHEN WAS QUARK-GLUON PLASMA SEEN?

The historical context of the recent results from high energy heavy ion reactions devoted to the search of quark-gluon plasma (QGP) is reviewed, with emphasis on the surprises encountered. The evidence for QGP from heavy ion reactions is compared with that available from particle reactions.

Phase diagram of QCD at finite temperature and chemical potential from lattice simulations with dynamical Wilson quarks

We present the first results for lattice QCD at finite temperature $T$ and chemical potential $\mu$ with four flavors of Wilson quarks. The calculations are performed using the imaginary chemical potential method at $\kappa=0$, 0.001, 0.15, 0.165, 0.17 and 0.25, where $\kappa$ is the hopping parameter, related to the bare quark mass $m$ and lattice spacing $a$ by $\kappa=1/(2ma+8)$. Such a method allows us to do large scale Monte Carlo simulations at imaginary chemical potential $\mu=i \mu_I$. By analytic continuation of the data with $\mu_I < \pi T/3$ to real values of the chemical potential, we expect at each $\kappa\in [0,\kappa_{chiral}]$, a transition line on the $(\mu, T)$ plane, in a region relevant to the search for quark gluon plasma in heavy-ion collision experiments. The transition is first order at small or large quark mass, and becomes a crossover at intermediate quark mass.

The Little Bang: searching for quark–gluon matter in relativistic heavy-ion collisions

I review the status of the search for quark-gluon plasma in relativistic heavy-ion collisions. The available data provide strong evidence for the "three pillars of the Little Bang model": strong radial expansion of the collision fireball with Hubble-like scaling, thermal hadron emission and primordial hadrosynthesis. It is argued that the initial state of the reaction zone exhibits features which cannot be understood with conventional hadronic dynamics, but are consistent with the formation of deconfined quark-gluon matter.

Search for quark-gluon plasma and jets production in ultra-relativistic ion collisions

We analyze the sensitivity of the collisional and radiative energy losses of hard partonic jets to the main parameters and space-time evolution of the dense matter, which is expected to be created in ultra-relativistic heavy ion collisions. The problem of “true” QCD-jets recognition against the “false” jets background (statistical fluctuations of the transverse energy flux arising from a huge multiplicity of “thermal” secondary particles in an event) is also considered.

Nucleus-nucleus collisions: what we have learned from the heavy ion program at CERN

In the first part, I give a brief description of the quark-gluon plasma search at CERN and of some experimental results. In the second part, I review a dynamical model of nucleus-nucleus interactions and propose a physical interpretation of those results.

The lead ion accelerating facility and the relative experimental program at CERN SPS fixed target

The status of the lead beam construction and commissioning is reviewed. A very wide experimental program with heavy nuclei was approved at the CERN SPS for a dedicated study of ultrarelativistic nucleus-nucleus collisions. An arbitrary and very short summary of the advantages and motivations for the use of heavier nuclei in the quark-gluon plasma search will be presented.

A multiplicity trigger processor for a quark-gluon plasma search at the Tevatron collider

A fast trigger processor was developed for the study of high multiplicity charged particle events in collisions at the Tevatron Collider accelerator. The processor allowed the scaling of triggers for specified multiplicity ranges and was incorporated in the fast trigger logic.

Multidimensional intermittency analysis

We propose a method to perform the intermittency analysis of multi hadron production in up to three momentum space dimensions. The analysis of realistic (approximately) selfsimilar cascade models shows that the strongest rise of multiplicity moments with decreasing phase space intervals and the closest approach to a power law occurs in three dimensions. Moments of higher orderF(q) are related to the second momentF(2) by a power law in good approximation. These powers are found independent of the dimensions in the models and in available data; furthermore, they are only weakly dependent on the reaction type. The relevance to the quark gluon plasma search is discussed.

Review of high energy hadron-nucleus data

In this review we will summarize new data on hardron-nucleus interactions. The possibility that quark-gluon plasma may be created in heavy ion collisions has led to renewed interest in hadron-nucleus collisions. In particular one hopes that understanding the energy loss of hadrons in h-A collissions will allow us to estimate the optimum energy in AA collisions in order to achieve maximum baryon and/or maximum energy density. This will allow us to choose the optimal experimental environment in the search for quark-gluon plasma. This review will thus omit many interesting results from hadron-nucleus collisions, such as the A dependence of lepton pair production, EMC effect and others. We will focus our attention on the following: (i) Estimating the rate of energy loss of the incident hadron as it propagates through the target. (ii) Determining where the enmergy is deposited in central hadron-nucleus collisions. It is clear that there is no direct or unique method of extrapolating our knowledge of h-A collisions to predict what will happen in AA-collisions. The knowledge and understanding of pp and pA collisions is, however, a useful and necessary guide to what one can expect in AA collisions. In this review we will concentrate on three experimental approaches to the study of h-A collisions. In Section 1 we will discuss the present status of pA → p + X inclusive measurements. In Section 2 measurements from visual detectors, in this case results from the 30″ hybrid spectrometer, which allows investigations of global event properties will be presented. In Section 3 data using 2π calorimeters, where one can trigger and measure transverse energy and energy flow over a given rapidity region, will be discussed. The conclusions will be given in Section 4.