Scielo RSS <![CDATA[Brazilian Journal of Physics]]> http://www.scielo.br/rss.php?pid=0103-973320070005&lang=en vol. 37 num. 2C lang. en <![CDATA[SciELO Logo]]> http://www.scielo.br/img/en/fbpelogp.gif http://www.scielo.br <![CDATA[<B>Foreword</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500001&lng=en&nrm=iso&tlng=en <![CDATA[<B>Parametrization of Bose-Einstein correlations and reconstruction of the source function in hadronic Z-boson decays using the L3 detector</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500002&lng=en&nrm=iso&tlng=en Bose-Einstein correlations of pairs of identical charged pions produced in hadronic Z decays are analyzed in terms of various parametrizations. A good description is achieved using a Lévy stable distribution in conjunction with a hadronization model having highly correlated configuration and momentum space, the tau-model. Using these results, the source function is reconstructed. <![CDATA[<B>Fluctuations and fermi-dirac correlations in <I>e<SUP>+</SUP>e<SUP>-</I></SUP>-annihilation</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500003&lng=en&nrm=iso&tlng=en In this talk I first present a short review of fluctuations in e+e--annihilations. I then describe some new results on FD correlations. Experimental analyses of pp and <FONT FACE=Symbol>L L</FONT> correlations indicate a very small production radius. This result relies very strongly on comparisons with MC simulations. A study of the approximations and uncertainties in these simulations implies that it is premature to draw such a conclusion from the data. <![CDATA[<B>Fragmentation and correlation of hadrons in <I>ep</I> collisions</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500004&lng=en&nrm=iso&tlng=en Electron-proton (ep) collisions at HERA can be regarded as an interaction between a virtual photon and the proton. The interaction gives a unique opportunity for studying particle production in the hadronic final state of the ep collisions. This contribution reviews the momentum distribution of fragmented hadrons and strange meson and baryon production. Also the Bose-Einstein correlation length and azimuthal asymmetry were measured. <![CDATA[<B>Evidence for non-gaussian tail in 3-dimensional pion emission source at SPS</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500005&lng=en&nrm=iso&tlng=en The NA49 experiment at CERN SPS has acquired a huge data set of Pb+Pb events over a broad range of energy and centrality during the last several years. This high statistics data set, coupled with a state-of-the-art analysis technique, allows for the first model-independent extraction and energy scan of 3D emission sources for pion pairs at SPS energies. These 3D pion emission sources provide new insights into the nature of a long-range source previously reported by PHENIX at RHIC. Preliminary results indicate that the pion source function is essentially Gaussian from 20 AGeV to 80 AGeV but it displays significant non-Gaussian tails at 158 AGeV. <![CDATA[<B>Source chaoticity in relativistic heavy ion collisions at SPS and RHIC</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500006&lng=en&nrm=iso&tlng=en We investigate degree of coherence of pion sources produced in relativistic heavy ion collisions using multi-particle interferometry. In order to obtain ''true'' chaoticity, lambdatrue from two-pion correlation functions measured in experiments, we make a correction for long-lived resonance decay contributions. Using this lambdatrue and the weight factor which are obtained from parameter fitted to two- and three-pion correlation function, we calculate a chaotic fraction e and the number of coherent sources alpha for different colliding energies. The result gives constraints on the source and shows an increase of the minimum number of alpha with multiplicity, although multiplicity independent chaoticity is not excluded. <![CDATA[<B>Numerical symmetrization of state of identical particles</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500007&lng=en&nrm=iso&tlng=en The method of numerical symmetrization of state of identical particles proposed by us before is clarified and discussed. <![CDATA[<B>Event-by-event fluctuations of transverse momentum and multiparticle clusters in relativistic heavy-ion collisions</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500008&lng=en&nrm=iso&tlng=en We analyze the event-by-event fluctuations of mean transverse momentum measured recently by the PHENIX and STAR Collaborations at RHIC. We argue that the observed scaling of strength of dynamical fluctuations with the inverse number of particles can be naturally explained by formation of multiparticle clusters. <![CDATA[<B>Fluctuations, correlations and non-extensivity</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500009&lng=en&nrm=iso&tlng=en The present status of investigations on fluctuations and correlations seen in high energy multiparticle production processes made using the notion of nonextensivity is reviewed. <![CDATA[<B>Effect of event-by-event fluctuations on hydrodynamical evaluation of elliptical flow</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500010&lng=en&nrm=iso&tlng=en Elliptic flow at RHIC is computed event-by-event with NeXSPheRIO. We show that when symmetry of the particle distribution in relation to the reaction plane is assumed, there is a disagreement between the true and reconstructed elliptic flows. We suggest a possible way to take into account the asymmetry and get good agreement between these elliptic flows. <![CDATA[<B>Inhomogeneities in the freeze-out of relativistic heavy-ion collisions</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500011&lng=en&nrm=iso&tlng=en An inhomogeneous decoupling surface of hadrons produced in relativistic heavy-ion collisions may occur, if the expanding hot and dense matter passes through a first order phase transition. We show that due to the non-linear dependence of the particle densities on the temperature and baryon-chemical potential such inhomogeneities should be visible even in the integrated, inclusive abundances. We analyze experimental data from Pb+Pb collisions at CERN-SPS and Au+Au collisions at BNL-RHIC to determine the amplitude of inhomogeneities and the role of local and global strangeness neutrality. <![CDATA[<B>Accelerating solutions of perfect fluid hydrodynamics for initial energy density and life-time measurements in heavy ion collisions</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500012&lng=en&nrm=iso&tlng=en A new class of accelerating, exact, explicit and simple solutions of relativistic hydrodynamics is presented. Since these new solutions yield a finite rapidity distribution, they lead to an advanced estimate of the initial energy density and life-time of high energy heavy ion collisions. Accelerating solutions are also given for spherical expansions in arbitrary number of spatial dimensions. <![CDATA[<B>Obtaining femtoscopy results in models with resonances</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500013&lng=en&nrm=iso&tlng=en We present femtoscopic results from models in which the resonance contribution is taken into account. The Therminator program, which implements a single freeze-out model and takes into account propagation and decay of all known resonances, was used. We test methods of determining the femtoscopic size of the system, or the ''HBT radii''. We show that the best one is the two-particle method combined with the exact calculation of the two-pion wave function including the wave-function symmetrization and Coulomb effects. We compare it to other methods and comment on their validity and applicability. <![CDATA[<B>Heavy flavor measurements at RHIC</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500014&lng=en&nrm=iso&tlng=en The study of heavy flavor production in relativistic heavy ion collisions is an extreme experimental challenge but provides important information on the properties of the Quark-Gluon Plasma (QGP) created in Au+Au collisions at RHIC. Heavy quarks are believed to be produced in the initial stages of the collision, and are essential on the understanding of parton energy loss in the dense medium created in such environment. Moreover, heavy-flavor quarkonia production is an important tool to understand deconfinement. In this work we review recent results on open heavy flavor and quarkonia production and their interaction with the hot and dense medium at RHIC. <![CDATA[<B>Open charm tomography of cold and hot nuclear matter</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500015&lng=en&nrm=iso&tlng=en We identify the nuclear effects that modify the cross sections for open heavy flavor production in proton-nucleus and nucleus-nucleus collisions. In p+A reactions, we calculate and resum the coherent nuclear-enhanced power corrections from the final-state parton scattering in the medium. We find that single and double inclusive open charm production can be suppressed as much as the yield of neutral pions from dynamical high-twist shadowing. Effects of energy loss in p+A collisions are also investigated. These lead to significantly weaker transverse momentum dependence of the nuclear attenuation and give a sizable contribution to the forward rapidity hadron suppression. In A+A reactions we revisit the question of the measured large heavy flavor quenching at RHIC. We derive the collisional broadening of the heavy meson's transverse momentum and the distortion of its intrinsic light cone wave function. The medium-induced dissociation probability of heavy mesons is shown to be sensitive to the opacity of the quark-gluon plasma and the time dependence of its formation and evolution. In contrast to previous results on heavy quark modification, our approach predicts suppression of B-mesons comparable to that of D-mesons at transverse momenta as low as pT ~ 10 GeV. It allows for an improved description of the large attenuation of non-photonic electrons in central Au+Au reactions at RHIC. Preliminary results in the implementation of collisional and radiative energy loss in a Langevin simulation approach to heavy quark diffusion and attenuation are also presented. <![CDATA[<B>Heavy flavour production in ep collisions at HERA</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500016&lng=en&nrm=iso&tlng=en Heavy flavour quarks in ep collisions are produced mostly from pair-production through a fusion of a virtual photon and a gluon from the proton. Therefore, the production cross sections provide information on the gluon distribution in the proton. The presence of a hard scale from the heavy quark mass, in principle, ensures that the cross sections are calculable through pQCD. Measurements in ep collisions, however, show that the calculations reasonably agree with the data in general, but underestimate the cross sections in some regions of phase space. <![CDATA[<B>QCD sum rule approach to the new mesons and the <I>gD<SUB>sJ</SUB>DK</I> coupling constant</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500017&lng=en&nrm=iso&tlng=en We use diquark-antidiquark currents to investigate the masses and partial decay widths of the recently observed mesons D+sJ(2317), D*0(0)(2308) and X(3872), considered as four-quark states, in a QCD sum rule approach. In particular we investigate the coupling constant gDsJ DK. We found that the gDsJ DK obtained in this four-quark scenario is smaller than the coupling constant obtained when D+sJ(2317) is considered as a conventional cs state. <![CDATA[<B>Charmless hadronic penguin <I>B</I> decays with BaBar</B>: <B><I>B</I><SUP>0</SUP>$B^0(\overline{B}^0)\rigtarrow \overline{K}^0}K^0$<I>K</I><SUP>0</SUP> or <FONT FACE=Symbol>h¢ h¢</FONT></B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500018&lng=en&nrm=iso&tlng=en Recent results from the BaBar experiment on searches for New Physics using the charmless channels B0 -> $\overline{K}^0}K^0$K0 and B0 ® <FONT FACE=Symbol>h¢ h¢</FONT> are discussed. <![CDATA[<B>Production of light particles by very strong and slowly varying magnetic fields</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500019&lng=en&nrm=iso&tlng=en The possibility that around some astrophysical objects there are non-static magnetic fields of enormous intensity suggests that in these situations real particles may be produced. The slowness of the variation is compensated by the huge intensity. The main issue is the production of e+-e- pairs annihilating into photons and the direct production of photons, as one of the concurrent process in the GRB (gamma ray bursts). Then some simple effects due to the presence of the intense gravity are studied and finally a look is given to the production of other kinds of particles. <![CDATA[<B>Particle production from soft processes</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500020&lng=en&nrm=iso&tlng=en Relativistic heavy-ion collisions provide a unique environment to study matter under extreme conditions of high temperature andenergy density. In the soft pT region (< 2 GeV/c) particle production is governed by the bulk properties (e.g. hydrodynamic pressure, freeze-out temperature) of the collisions.Total particle yields as well as their distributions in phase space are strongly dependent on these properties. These bulk properties will be discussed and we will compare our heavy-ion results to measurements in the p+p reference system, where multiparticle processes such as recombination and rescattering are generally thought to be negligible. However, we will show evidence for pi+ pi- rescattering interactions even in p+p collisions. <![CDATA[<B>The chromo-weibel instability</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500021&lng=en&nrm=iso&tlng=en I discuss the physics of non-Abelian plasmas which are locally anisotropic in momentum space. Such momentum-space anisotropies are generated by the rapid longitudinal expansion of the matter created in the first 1 fm/c of an ultrarelativistic heavy ion collision. In contrast to locally isotropic plasmas anisotropic plasmas have a spectrum of soft unstable modes which are characterized by exponential growth of transverse chromo-magnetic/-electric fields at short times. This instability is the QCD analogue of the Weibel instability of QED. Parametrically the chromo-Weibel instability provides the fastest method for generation of soft background fields and dominates the short-time dynamics of the system. The existence of the chromo-Weibel instability has been proven using diagrammatic methods, transport theory, and numerical solution of classical Yang-Mills fields. I review the results obtained from each of these methods and discuss the numerical techniques which are being used to determine the late-time behavior of plasmas subject to a chromo-Weibel instability. <![CDATA[<B>Distribution of hyperons in 200<I>A</I> GeV Au-Au in smoothed particle hydrodynamics</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500022&lng=en&nrm=iso&tlng=en The transverse momentum distributions of hadrons in 200GeV Au-Au collisions at RHIC are calculated using the smoothed particle hydrodynamics code SPheRIO. They are compared with data from STAR and PHOBOS Collaborations. By employing an equation of state which explicitly incorporates the strangeness conservation and introducing strangeness chemical potential into the code, the transverse spectra give a reasonable description of experimental data, except the multiplicities of hyperons. <![CDATA[<B>Partonic equation of state in relativistic heavy ion collisions</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500024&lng=en&nrm=iso&tlng=en Recent results on chemical freeze-out, elliptic flow v2 and multi-strange hadron transverse momentum distributions are discussed and compared with model predictions. The idea of heavy flavor collectivity and light flavor thermalization is presented in the light of recent heavy flavor measurement at RHIC. <![CDATA[<B>Causality, memory effect and relativistic dissipative hydrodynamics</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500025&lng=en&nrm=iso&tlng=en We discuss the minimal structure of relativistic dissipative hydrodynamics which satisfies the covariance and causality by introducing the memory effect in irreversible currents. <![CDATA[<B>Melting <FONT FACE=Symbol>r</FONT> meson and thermal dileptons</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500026&lng=en&nrm=iso&tlng=en We first give a brief survey of theoretical evaluations of light vector mesons in hadronic matter, focusing on results from hadronic many-body theory. We emphasize the importance of imposing model constraints in obtaining reliable results for the in-medium spectral densities. The latter are subsequently applied to the calculation of dilepton spectra in high-energy heavy-ion collisions, with comparisons to recent NA60 data at the CERN-SPS. We discuss aspects of space-time evolution models and the decomposition of the excess spectra into different emission sources. <![CDATA[<B>From RHIC to LHC</B>: <B>a relativistic diffusion approach</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500027&lng=en&nrm=iso&tlng=en We investigate stopping and particle production in heavy-ion collisions in a Relativistic Diffusion Model (RDM). Using three sources for particle production, the energy- and centrality dependence of rapidity distributions of net protons, and pseudorapidity distributions of charged hadrons in heavy systems at RHIC energies are precisely reproduced in the analytical model. The transport coefficients are then extrapolated from Au + Au at RHIC energies (<FONT FACE=Symbol>Ö</FONT>sNN=19.6 - 200 GeV) to Pb + Pb at LHC energies of <FONT FACE=Symbol>Ö</FONT>sNN= 5.52 TeV. Rapidity distributions for net protons, and pseudorapidity spectra for produced charged particles are obtained and discussed in a three-sources model at LHC energies. <![CDATA[<B>Gluon dominance model and cluster production</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500028&lng=en&nrm=iso&tlng=en Multiparticle production in lepton and hadron processes is studied by means of the Gluon Dominance Model (GDM) which is based on the Quantum Chromodynamics (QCD) and phenomenological scheme of hadronization. The model describes the multiplicity distributions and their moments very well. It has revealed an active role of gluons in multiparticle production and confirmed the fragmentation mechanism of hadronization in e+e- annihilation and its change to a recombination mechanism in hadron and nucleus interactions. The GDM explains the shoulder structure of multiplicity distributions. The hadron-pion ratio obtained by GDM has turned out to be in agreement with the experimental RHIC data of Au+Au peripheral collisions. Besides, development of GDM allows one to study the multiplicity behavior of p$p\bar{p}$ annihilation at tens of GeV. The mechanism of soft-photon production and estimates of their emission region have been offered in the framework of this model. The experimental data (project "Thermalization", U-70, IHEP) indicated the cluster nature of multiparticle production revealed by using GDM. <![CDATA[<B>A remark on the low mass dilepton yield</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500029&lng=en&nrm=iso&tlng=en The recent data on the enhancement of the low mass dilepton yield in heavy ion collisions are interpreted as an effect of the "prolonged life" of resonances in the hadron gas phase. The value of the enhancement factor gives an upper limit for the duration time of this phase. <![CDATA[<B>Measurement of DIS cross section at HERA</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500030&lng=en&nrm=iso&tlng=en This paper presents recent measurements of the inclusive DIS cross section performed by the H1 and ZEUS collaborations at the HERA collider. We discuss relations of the HERA results with the upcoming experiments at the LHC. Importance of the planed measurement of the longitudinal proton structure function F L is commented. <![CDATA[<B>An extraction of the skewing factor from DESY-HERA data</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500031&lng=en&nrm=iso&tlng=en In this contribution we present recent investigation on the extraction of the skewing factor, defined as the ratio of the imaginary parts of the amplitudes Im ${\cal A}$(gamma* p <FONT FACE=Symbol>® g</FONT>* p)/ Im ${\cal A}$(gamma* p <FONT FACE=Symbol>® g</FONT> p). This factor is extracted from the data using the recent DVCS and the inclusive inelastic cross section measurements at DESY-HERA. We compare the results to the theoretical predictions for NLO QCD and the color dipole approach. <![CDATA[<B>Saturation and the Ratio <FONT FACE=Symbol>s</FONT><I><SUP>diff</I></SUP>/<FONT FACE=Symbol>s</FONT><I><SUP>tot</I></SUP> in an electron-ion collider</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500032&lng=en&nrm=iso&tlng=en In this paper we investigate the saturation physics in diffractive deep inelastic electron-ion scattering. We estimate the energy and nuclear dependence of the ratio sigmadiff/sigmatot. We show that saturation physics predicts that up to 37 % of the events observed at eRHIC should be diffractive. We have also studied how our results depend on the prescription to extend the saturation scale to the nuclear case. <![CDATA[<B>New CDF results on diffraction</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500033&lng=en&nrm=iso&tlng=en We report new diffraction results obtained by the CDF collaboration in proton-antiproton collisions at the Fermilab Tevatron collider at <FONT FACE=Symbol>Ö</FONT>s = 1.96 TeV. The first experimental evidence of exclusive dijet and diphoton production is presented. The exclusive results are discussed in context of the exclusive Higgs production at LHC. We also present the measurement of the Q² and t dependence of the diffractive structure function. <![CDATA[<B>Neutrino structure functions in the QCD dipole picture</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500034&lng=en&nrm=iso&tlng=en In this contribution we present an exploratory QCD analysis of the neutrino structure functions in charged current DIS using the color dipole formalism. The corresponding dipole cross sections are taken from recent phenomenological and theoretical studies in deep inelastic inclusive production, including nuclear shadowing corrections. The theoretical predictions are compared to the available experimental results in the small-x region. <![CDATA[<B>Inclusive measurements on diffractive processes in <I>ep</I> collisions</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500035&lng=en&nrm=iso&tlng=en Measurements from the H1 and ZEUS collaborations of the diffractive deep-inelastic scattering process, ep -> eXY, where Y is a proton or a low mass proton excitation, are presented for photon virtualities in the range 2.2 < Q² < 1600 GeV² and squared four-momentum transfer at the proton vertex satisfying | t | < 1 GeV². Diffractive parton distribution functions and their uncertainties are determined from a next-to-leading order DGLAP QCD analysis. Combining measurements of the inclusive diffractive deep-inelastic scattering process with an analysis of diffractive dijet production allows a very sensitive determination of both quark and gluon distributions. <![CDATA[<B>Exclusive processes in diffraction at HERA</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500036&lng=en&nrm=iso&tlng=en Recent results from the H1 and ZEUS experiments on exclusive processes in diffractive ep collisions at HERA are reviewed. The measurements discussed here include dijets and charm in photoproduction as well as in deep inelastic scattering. Such processes are sensitive to the partonic structure of the diffractive exchange, particularly to the gluon content, and represent complementary tests for the validity of QCD factorization in diffraction. The measurements are compared to theoretical models, including NLO predictions, using the most recent diffractive parton densities as extracted from inclusive measurements. Recent results on exclusive vector meson production and deeply virtual compton scattering are also presented. <![CDATA[<B>Energy conservation and pomeron loops in high energy evolution</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500037&lng=en&nrm=iso&tlng=en We present a formalism which modifies the Mueller Dipole Model such that it incorporates energy-momentum conservation as well as important colour suppressed effects in the cascade evolution. The formalism is implemented in a Monte Carlo simulation program, and the results are compared to inclusive data from HERA and the Tevatron. We here find a generally very good agreement between our model and the experimental data. <![CDATA[<B>Distribution amplitudes of light mesons and the photon in the instanton model</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500038&lng=en&nrm=iso&tlng=en The leading- and higher-twist distribution amplitudes of the pion, the rho-meson and real and virtual photons are analyzed in the instanton liquid model. <![CDATA[<B>Jets and parton energy loss at RHIC</B>: <B>experimental status</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500039&lng=en&nrm=iso&tlng=en Experimental evidence from RHIC indicates that matter having an energy density far in excess of the value required for the creation of a deconfined phase is produced in ultrarelativistic Au+Au collisions at <FONT FACE=Symbol>Ö</FONT>sNN=200 GeV. This matter thermalizes rapidly, is strongly interacting, and displays hydrodynamic properties akin to a fluid with very low viscosity. Studies of the interaction of hard scattered partons with this matter provide an important probe of its properties. In fact, studies of the suppression of high-pT hadrons have been one of the key arguments used by the RHIC experiments that the matter created is something fundamentally new and exciting. I review the current experimental picture that has emerged from the data collected at RHIC, with an emphasis on the effort to extract quantitative measurements from the suppression of high-pT hadrons. <![CDATA[<B>New results on jet fragmentation at CDF</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500040&lng=en&nrm=iso&tlng=en Presented are the latest results of jet fragmentation studies at the Tevatron using the CDF Run II detector. Studies include the distribution of transverse momenta (Kt) of particles jets, two-particle momentum correlations, and indirectly global event shapes in p$\bar{p}$ collisions. Results are discussed within the context of recent Next-to-Leading Log calculations as well as earlier experimental results from the Tevatron and e+e- colliders. <![CDATA[<B>Generalized <I>z</I>-scaling and <I>pp</I> collisions at RHIC</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500041&lng=en&nrm=iso&tlng=en New generalization of the z-scaling in inclusive particle production is proposed. The scaling variable z is expressed in terms of the momentum fractions x1 and x2 of the incoming protons. Explicit dependence of z on the momentum fractions y a and y b of the scattered and recoil constituents carried by the inclusive particle and recoil object is included. The scaling function psi (z) for charged and identified hadrons produced in proton-proton collisions is constructed. The scheme allows unique description of data on inclusive cross sections of charged hadrons, pions, kaons, antiprotons and lambdas produced at RHIC energies. The obtained results suggest that the z-scaling may be used as a tool for searching for new physics phenomena of particle production in high transverse momentum and high multiplicity region at proton-proton colliders RHIC and LHC. <![CDATA[<B>An introduction to mini black holes at LHC</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500042&lng=en&nrm=iso&tlng=en Relying on the existing estimates for the production cross sections of mini black holes in models with large extra dimensions, we review strategies for identifying those objects at collider experiments. We further consider a possible stable final state of such black holes and discuss their characteristic signatures. <![CDATA[<B>Measurement of the W + jet cross section at CDF</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500043&lng=en&nrm=iso&tlng=en A measurement of W -> enu + n-jet cross sections in p$\bar{p}$ collisions at <FONT FACE=Symbol>Ö</FONT>s = 1.96 TeV using the Collider Detector at Fermilab in Run II is presented. The measurement is based on an integrated luminosity of 320 pb-1, and includes events with jet multiplicity from > 1 to > 4. In each jet multiplicity sample the differential and cumulative cross sections with respect to the transverse energy of the n th-leading jet are measured. For W+ > 2 jets the differential cross section with respect to the 2-leading jets invariant mass m j1j2 and angular separation deltaRj1j2 is also reported. The data are compared to predictions from Monte Carlo simulations. <![CDATA[<B>Inclusive jet production at CDF </B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500044&lng=en&nrm=iso&tlng=en We present results on inclusive jet production in proton-antiproton collisions at <FONT FACE=Symbol>Ö</FONT>s = 1.96 TeV. The measurements are based on 1.0 fb-1 of CDF Run II data and were carried out for jets in five different jet rapidity regions up to |Y| = 2.1. Both the midpoint cone based algorithm and kT algorithm were investigated to reconstruct the jets. The results are compared to next-to-leading order perturbative QCD predictions. <![CDATA[<B>Jet physics in <I>ep</I> collisions</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500045&lng=en&nrm=iso&tlng=en The most recent results of jet cross section measurements at HERA collider in photoproduction and deep inelastic scattering are presented. The forward jet and multiple jet productions are discussed from point of view of QCD dynamics. Results of precise extractions of the strong coupling alphas are presented. <![CDATA[<B>Jet quenching measurements at RHIC</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500046&lng=en&nrm=iso&tlng=en Experimental observation of jet quenching in ultra-relativistic heavy-ion collisions is one of the most remarkable discoveries at RHIC. High-pT hadron suppression, disappearance of back-to-back jets, and strong away-side modification at intermediate to low pT have provided us many insights into the matter created at RHIC. Particularly, angular correlations have become a powerful tool to study the QCD matter through its interactions with jets. Di-hadron correlations reveal significant broadening and softening of associated hadrons on the away side of a triggered high-pT particle. Many mechanisms have been proposed to accommodate the data, including the intriguing Mach cone shock waves in a thermalized hydrodynamic matter, which can be discriminated by 3-particle correlations. Here a brief overview of these remarkable experimental measurements on jet quenching is presented and implications of these measurements are discussed. <![CDATA[<B>Jet conversions in a quark-gluon plasma</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500047&lng=en&nrm=iso&tlng=en We report our recent work on conversions between gluon and quark jets as they traverse through a quark-gluon plasma (QGP) and their effects on the nuclear modification factors for quark and gluon jets as well as the ratios of p/pi+ and $\bar{p}$/pi- at high transverse momentum in ultra-relativistic heavy ion collisions. <![CDATA[<B>Summary talk for ISMD 06</B>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332007000500048&lng=en&nrm=iso&tlng=en I give an overview of the presentations at the International Symposium on Multiparticle Dynamics. 2006