Infobox Particle bgcolour name Gluon image caption num types 8 composition Elementary particle statistics ... and H. J. Meyer year 2011 title Y 9.46 GeV and the gluon discovery a critical recollection of PLUTO ... ref name SOE cite journal author P. S ding year 2010 title On the discovery of the gluon journal ... of the gluon journal Physics Letters B volume 345 issue 4 page 524 bibcode 1995PhLB..345..524Y ... thumb 200px right Diagram 1 e sup sup e sup &minus sup Y 9.46 3g File Feynmann Diagram Gluon Radiation.svg ... s photons are represented by sinusoids and gluons by spirals The gluon is a vector boson like the photon ... states, massless gauge bosons like the gluon have only two polarization states because gauge invariance ... requires that gauge bosons have zero mass experiment limits the gluon s mass to less than a few MeV c sup 2 sup . The gluon has negative intrinsic parity physics parity . Numerology of gluons Unlike the single ... types of gluon in QCD. This may be difficult to understand intuitively. Quark s carry three types ... be a gluon with a color state described by math r bar b b bar r sqrt 2 math This is read as red antiblue ... able to make a direct measurement of the color of a gluon in this state, there would be a 50 chance ... states because long range gluon interactions do not exist, this illustrates that gluons in the singlet ... be equal probabilities of it being red antired, blue antiblue, or green antigreen. Eight gluon colors ... gluons themselves carry color charge, they participate in strong interactions. These gluongluon interactions ... phase of QCD at extreme temperatures and pressures , quark gluon plasma forms. In such a plasma there are no hadrons ... and also the spin 1 nature of the gluon ref cite journal author Ch. Berger et al. PLUTO Collaboration ... interpreted as q overline q gluon bremsstrahlung , now clearly visible, by TASSO , ref cite journal ... author Ch. Berger et al. PLUTO Collaboration year 1979 title Evidence for Gluon Bremsstrahlung in e ... three jet events in e sup sup e sup &minus sup annihilation and evidence for gluon bremsstrahlung journal ... more details
In Quantum chromodynamics QCD , the gluon condensate is a non perturbative property of the QCD vacuum which could be partly responsible for giving masses to certain hadrons. If the gluon field tensor is represented as G sub sub , then the gluon condensate is the vacuum expectation value math langle G mu nu G mu nu rangle math . It is not clear yet whether this condensate is related to any of the known phase changes in quark matter . There have been scattered studies of other types of gluon condensates, involving a different number of gluon fields. For more on the context in which this quantity occurs, see the article on the QCD vacuum . See also Quantum chromodynamics QCD vacuum and chiral condensate s Vacuum Quantum mechanical definition Vacuum in quantum field theory Quark gluon plasma QCD matter References Savvidy, G. K., Infrared instability of the vacuum state of gauge theories and asymptotic freedom http dx.doi.org 10.1016 0370 2693 2877 2990759 6 Category Quantum chromodynamics Category Quark matter physics stub ... more details
gluon plasma QGP or quark soup ref cite journal bibcode 1977NuPhB.128..275B author1 Bohr, Henrik author2 ... quark s and gluon s, which are several of the basic building blocks of matter. Experiments at CERN s Super ... have tentatively claimed to have created a quark gluon plasma with an approximate temperature of 4 ... appears to have created multiple quark gluon plasmas with temperatures in the tens of trillions of degrees. General introduction Quark gluon plasma is a state of matter in which the elementary particles ... s and gluon s that compose baryonic matter. ref http theory.tifr.res.in sgupta ilgti infocenter ... predicted as producing a quark gluon plasma have been realized in the laboratory, the resulting matter ... dense fluid. ref name Zajc Cite journal title The fluid nature of quark gluon plasma author WA Zajc ... arxiv 0802.3552 postscript . bibcode 2008NuPhA.805..283Z ref Actually, the fact that the quark gluon ... gluon plasma first M. last Pl mer first2 S. last2 Raha lastauthoramp yes first3 R. M. last3 Weiner ... on the sound velocity in a quark gluon plasma journal Phys. Lett. B volume 139 issue 3 pages ... charge of the quark s and gluon s is screened. The QGP has other analogies with a normal plasma ... Gluon Plasma have been reviewed in http arxiv.org PS cache hep lat pdf 9503 9503010v1.pdf and in http ..., there is a discussion about a hypothetical precursor state of the Quark gluon plasma, the so called ... groups was that they had created a quark gluon liquid of very low viscosity . However, contrary to what ... QCD calculation, where the entropy density of quark gluon plasma approaches the weakly interacting ... PhysRevLett.104.122003 journal Physical Review Letters volume 104 title Gluon Thermodynamics at Intermediate ... temperature quark gluon plasma class hep ph year 2003 ref See also Hadron s that is meson s and baryon ... arxiv.org pdf nucl ex 0405007 2004 experiment Quark Gluon Plasma reviews http arxiv.org abs 1101.3937 ... http www.aip.org pnu 2005 split 728 1.html Physics News Update article on the quark gluon liquid ... more details
Unreferenced stub auto yes date December 2009 Orphan date December 2009 Image Feynmann Diagram Gluon Radiation.svg 300px thumb right In this Feynman diagram , electron s annihilate and become a quark antiquark pair. Then one radiates a gluon . Time goes left to right. In particle physics , a radiative process refers to one elementary particle emitting another and continuing to exist. This typically happens when a fermion emits a boson such as a gluon or photon . See also bremsstrahlung DEFAULTSORT Radiative Process Category Radiation Category Particle physics Particle stub ... more details
The TASSO collaboration refers to the group of people working on the TASSO detector, at PETRA , at DESY . They are famous for having discovered the gluon , the mediator of the strong interaction and carrier of the color charge . ref name 25YoG cite web title Twenty Five Years of Gluons url http cerncourier.com cws article cern 29201 publisher Cern Courrier year 2004 author Flegel, I S ding, P location DESY ref Four of them, Paul S ding , Bj rn Wiik Bj rn Wiik , G nter Wolf , and Sau Lan Wu , were award the Prize for High Energy and Particle Physics from CERN in 1995. A special prize was also awarded to the TASSO collaboration, as well as the PETRA , JADE , MARK J , and PLUTO experiment PLUTO collaborations, in recognition of their combined work on the gluon as the definite existence of the gluon emerged gradually from the results of the TASSO collaboration and the other experiments working at PETRA, JADE, MARK J and PLUTO . ref name 25YoG See also Gluon Particle physics References reflist Further reading cite journal author P. S ding year 2010 title On the discovery of the gluon journal European Physical Journal H volume 35 issue 1 pages 3 28 doi 10.1140 epjh e2010 00002 5 bibcode 2010EPJH...35....3S DEFAULTSORT Tasso Category Particle experiments Category Gluons ... more details
In physics , deconfinement in contrast to confinement is the property of a Phase of matter phase in which certain particles are allowed to exist as free Excited state excitations , rather than only within bound state s. Various examples exist in particle physics and Condensed matter physics condensed matter , where certain Gauge theory gauge theories exhibit Phase transition transitions between confining and deconfining phases. A prominent example, and the first case considered as such in theoretical physics , occurs at high energy in quantum chromodynamics when quark s and gluon s are free to move over distances larger than a femtometer the size of a hadron . This phase is also called the quark gluon plasma . Spin charge separation is an example of deconfinement in condensed matter physics the electron can be viewed as a bound state of a spinon and chargon , which under certain conditions can become free to move separately. See also Quantum chromodynamics Colour confinement Quark gluon plasma Quark nova Fractionalization Category Quark matter Physics stub it Deconfinamento ... more details
saved book title Matter subtitle cover image Phase change en.svg cover color Matter Main article Matter Phases of ordinary matter Phase matter Phase Phase diagram State of matter Solid Liquid Gas Plasma physics Plasma Astrophysical plasma Bose Einstein condensate Fermionic condensate Superconductivity BCS theory Neutron star Pulsar Magnetar Quark gluon plasma QCD matter Gluon Hadron Structure of ordinary matter Quark Baryon Degenerate matter Lepton Other types of matter Antimatter Dark matter Lambda CDM model Weakly interacting massive particles WIMPs Galaxy formation and evolution Dark matter halo Dark energy Exotic matter Category Wikipedia books on physics Matter ... more details
name SMY cite journal author B.R. Stella and H. J. Meyer year 2011 2012 title Y 9.46 GeV and the gluon ... in the Y hadronic decays, the gluons have the spin 1, the gluon bremsstrahlung exists found together with three more experiments at PETRA , all of these leading to the discovery of the gluon and of the gluon ... review of the discovery of the quark and gluon jets and its impact on QCD journal European Physical ......36..245A ref concerning the first gluon evidence by PLUTO at DORIS , see page 247 and pages 264 268 ch. 4 Gluon Jets in Y decays . A Special High Energy and Particle Physics Prize of the European Physical ... and JADE collaborations for establishing the existence of the gluon in independent and simultaneous ... Prize 1995.JPG was implicitly meant for the discovery of the gluon bremsstrahlung process at PETRA in 1979 ... more details
Strangeness production is a signature and a diagnostic tool of quark gluon plasma or QGP formation and properties ... mechanism of production involves gluon s only present when matter has changed into the QGP phase ... in quark antiquark pairs meson s . Quark gluon plasma in the early universe and in the laboratory ..., J. Rafelski year 2002 title Hadrons and Quark Gluon Plasma pages publisher Cambridge University Press isbn 0 521 38536 9 ref in a very hot gas of free quarks, antiquarks and gluon s. This gas is called a quark gluon plasma QGP , since the quark interaction charge color charge is mobile and quarks ... gluon plasma in laboratory. In a small space domain we thus create for a very short time conditions ... is being assembled. The process of the formation of quark gluon plasma lasts little longer than the time ... s collision illustrated above makes the study of free quarks in quark gluon plasma an experimental challenge. Strangeness in quark gluon plasma The diagnosis and the study of the properties of quark gluon plasma can be undertaken using quarks not present in matter seen around us. The experimental ... of quark gluon plasma proposed in 1980 by Johann Rafelski Rafelski and Rolf Hagedorn Hagedorn . ref ... flavor, strange quarks, will reach its high quark gluon plasma thermal abundance only on the most .... What is at the end? The peak in strange quark production? date August 2009 Gluon fusion into strangeness ... possible due to a new process, the gluon fusion, as shown by Rafelski and Berndt M ller M ller ... in the Quark Gluon Plasma journal Physical Review Letters volume 48 pages 1066 doi 10.1103 PhysRevLett.48.1066 bibcode 1982PhRvL..48.1066R issue 16 ref The top section of the figure shows gluon fusion ... quark pair arises from the lighter pair of quarks shown as dashed lines. The gluon fusion process occurs ... bang . ref cite journal author J. Rafelski year 1984 title Strangeness production in the quark gluon .....215R ref The gluon collisions here are occurring within the thermal matter phase and are thus ... more details
Orphan date February 2009 A Particle in cell particle in cell simulation for Non abelian gauge theory non Abelian colored particles and fields. Can be used to simulate an equilibrium or non equilibrium Quark gluon plasma quark gluon plasma . References G. Moore, C. Hu, and B. Muller, Chern Simons number diffusion with hard thermal loops , Phys. Rev. D58, 045001 1998 http arxiv.org abs hep ph 9710436 A. Dumitru, Y. Nara, and M. Strickland, Ultraviolet avalanche in anisotropic non Abelian plasmas , Phys. Rev. D75, 025016 2007 http arxiv.org abs hep ph 0604149 Y. Nara, 3D Wong Yang Mills simulations of instabilities , http www.int.washington.edu talks WorkShops int 06 3 People Nara Y Nara.pdf Category Quantum chromodynamics Category Plasma physics Category Particle physics physics stub ... more details
indicates that this particle is a particularly energetic gluon, radiative process radiated by one ... stray hadron s between the jets and in the same plane . Since the quark gluon interaction is stronger ... in that jet being a gluon. The line of reasoning is illustrated below. Please note that the drawings ... Three jet gluon string.png Two quark s solid lines and a gluon curly line fly apart, with the Lund string model strings red bars primarily between the gluon and each quark. Image Three jet gluon jets.png ... of the discovery of the quark and gluon jets and its impact on QCD journal European Physical Journal ... P. S ding year 2010 title On the discovery of the gluon journal European Physical Journal H volume ... jet events in e sup sup e sup sup annihilation and evidence for gluon bremsstrahlung journal Physics ... Evidence for gluon bremsstrahlung in e sup sup e sup sup annihilations at high energies journal Physics ... Collaboration year 1980 title Evidence for a spin 1 gluon in three jet events journal Physics Letters ... more details
Deleted image removed File Quark spin yellow.jpg thumb right Nucleon spin structure Nucleon spin structure describes the partonic structure of nucleon proton and neutron intrinsic angular momentum Spin physics spin . The key question is how the nucleon s spin, whose magnitude is 1 2 , is carried by its constituent parton particle physics parton s quark s and gluon s . It was originally expected before the 1980s that quarks carry all of the nucleon spin, but later experiments contradict this expectation. In the late 1980s, the European Muon Collaboration EMC conducted experiments that suggested the spin carried by quarks is not sufficient to account for the total spin of the nucleons. This finding astonished particle physicists at that time, and the problem of where the missing spin lies is sometimes referred to as the proton spin crisis . Experimental research on these topics has been continued by the Spin Muon Collaboration SMC and the COMPASS experiment at CERN , experiments E154 and E155 at SLAC National Accelerator Laboratory SLAC , DESY HERMES HERMES at DESY , experiments at Thomas Jefferson National Accelerator Facility JLab and RHIC , and others. Global analysis of data from all major experiments confirmed the original EMC discovery and showed that the quark spin did contribute about 30 to the total spin of the nucleon. A major topic of modern particle physics is to find the missing angular momentum, which is believed to be carried either by gluon spin, or by gluon and quark orbital angular momentum. This fact is expressed by the sum rule, math frac 1 2 frac 1 2 Sigma q Sigma g L q L g. math The gluon spin components math Sigma g math are being measured by many experiments. Quark and gluon angular momenta will be studied by measuring so called generalized parton distributions GPD through deeply virtual compton scattering DVCS experiments, conducted mainly at JLab. External links http www.cerncourier.com main article 42 1 16 Polarized colliders may prove to be ... more details
GlueX will be a particle physics experiment located at the Thomas Jefferson National Accelerator Facility JLab particle accelerator accelerator . Its primary purpose is to understand the nature of color confinement confinement in quantum chromodynamics by mapping the spectrum of exotic meson s generated by the excitation of the gluon ic field binding the quark s. If successful, GlueX would be the first experiment to discover such exotic mesons, which have never before been observed. The experiment will be able to probe new areas by using photoproduction that is, the scattering of a real photon on a nucleon to produce exotic states. The GlueX detector is being installed in a new Hall D the fourth such hall at JLab being constructed during the accelerator s upgrade to 12 GeV energy. ref http www.jlab.org div dept physics division GeV index.html 12 GeV Upgrade Future Science at Jefferson Lab Project Information Bot generated title ref GlueX will probably begin taking data around 2014. See also Exotic meson Glueball Gluon References references External links http gluex.org GlueX.org official website DEFAULTSORT Gluex Category Particle physics Category Physics experiments Quantum stub ... more details
The Chromo Weibel instability is a plasma instability present in homogeneous or nearly homogeneous Non abelian gauge theory non abelian Plasma physics plasmas which possess an anisotropy in momentum space. In the linear limit it is similar to the Weibel instability in electromagnetic plasmas but due to non linear interactions present in non abelian plasmas the late development of this instability is characterized by a turbulent cascade of modes. This instability is relevant in the understanding of the early time dynamics of the Quark gluon plasma quark gluon plasma as produced in Relativistic Heavy Ion Collider heavy ion collisions . See also Weibel instability References S. Mrowczynski, Color collective effects at the early stage of ultrarelativistic heavy ion collisions , Phys. Rev. C49, 2191 1994 http prola.aps.org abstract PRC v49 i4 p2191 1 M Strickland, The Chromo Weibel instability , Braz. J. Phys. 37, 762 2007 http arxiv.org abs hep ph 0611349 P. Arnold and G. Moore, The Turbulent spectrum created by non Abelian plasma instabilities , Phys. Rev. D73, 025013 2006 http arxiv.org abs hep ph 0509226 Category Quantum chromodynamics Category Plasma physics Category Particle physics ... more details
saved book title Natural History subtitle An Elucidation of why we have Today cover image Geologic Clock with events and periods remake.png cover color Black Natural History An Elucidation of why we have Today In the beginning Big Bang Timeline of the Big Bang Planck units Planck epoch Quantum gravity Grand unification epoch Grand Unified Theory Inflationary epoch Inflation cosmology Inflation Electroweak epoch Electroweak interaction Quark epoch Strong interaction Quark Gluon Quark gluon plasma Hadron epoch Hadron Baryogenesis Lepton epoch Lepton Electron Positron Photon Annihilation Standard Model Big Bang nucleosynthesis Atomic nucleus Photon epoch Reionization Cosmic microwave background radiation Structure in the Universe Lambda CDM model Dark energy Dark matter Introduction to general relativity General relativity Galaxy formation and evolution Galaxy Observable universe Solar systems Nebular hypothesis Star formation Star Solar System Stellar evolution Humanity Holocene Timeline of human evolution Evidence of common descent Human Evolution of ageing Animal communication Great ape language Animal cognition Primate cognition Evolution of human intelligence Emotion in animals Evolution of emotion Evolution of morality Category Wikipedia books on science Category Wikipedia books on astronomy Natural History Category Wikipedia books on natural sciences Category Wikipedia books on nature ... more details
The NA35 experiment was a particle physics experiment that took place in the North Area of the Super Proton Synchrotron SPS at European Organization for Nuclear Research CERN . It used a streamer chamber with comprehensive hadronic and electromagnetic calorimetry . This experiment was used to observe the properties of nucleus nucleus collisions at 60 and 200 GeV nucleon, to understand the degree of stopping and thermalization , determine the energy densities achievable in those conditions, and to measure other related properties and quantities. ref name Quark Gluon http www.actaphys.uj.edu.pl vol19 pdf v19p0307.pdf Search for the quark gluon plasma The NA35 experiment at the CERN SPS ref The NA35 experiment was approved on 18 September 1991 and completed on 19 October 2002. It was succeeded by the NA49 experiment . The spokesperson for the experiment was Peter Seyboth . ref name CERN SPS http www.slac.stanford.edu spires find experiments www2?ee CERN NA 035 Study of Relativistic Nucleus Nucleus Collisions at the CERN SPS ref ref name NA35 IONS http greybook.cern.ch programmes experiments NA35.html NA35 Ions Streamer Ch. ref See also NA34 3 experiment NA36 experiment NA49 experiment NA61 experiment List of SPS experiments References reflist External links http www.sciencedirect.com science article pii 037594749500236T Results from NA35 SPS experiments Category Particle experiments Category CERN ... more details
Orphan date July 2011 merge to Three jet event discuss Talk Three jet event Ellis Karliner angle date March 2011 Confusing date December 2006 In physics , the Ellis Karliner angle is kinematical angle between the highest energy Jet particle physics jets in a three jet event . ref cite journal author J. Ellis, I. Karliner year 1979 title Measuring the spin of the gluon in e sup sup e sup sup annihilation journal Nuclear Physics B volume 148 pages 141 doi 10.1016 0550 3213 79 90019 1 bibcode 1979NuPhB.148..141E ref The angle is not measured in the lab frame , but in a frame Lorentz transform boosted along the energy of the highest energy jet so that the second and third jets are back to back. By measuring the distribution of the Ellis Karliner angle at the PETRA electron positron storage ring at DESY , physicists determined that the gluon has spin physics spin one rather than spin zero or spin two. ref cite journal author R. Brandelik et al. TASSO TASSO Collaboration year 1980 title Evidence for a spin 1 gluon in three jet events journal Physics Letters B volume 97 pages 453 doi 10.1016 0370 2693 80 90639 5 bibcode 1980PhLB...97..453B issue 3 4 ref ref cite journal author C. Berger et al. PLUTO experiment PLUTO Collaboration year 1980 title A study of multi jet events in e sup sup e sup sup annihilation journal Physics Letters B volume 97 pages 459 doi 10.1016 0370 2693 80 90640 1 bibcode 1980PhLB...97..459B issue 3 4 ref Subsequent experiments ref cite journal author G. Alexander et al. OPAL OPAL Collaboration year 1991 title Measurement of Three Jet Distributions Sensitive to the Gluon Spin in e sup sup e sup sup Annihilations at s 91 GeV journal Zeitschrift f r Physik C volume 52 pages 543 doi 10.1007 BF01562326 bibcode 1991ZPhyC..52..543A issue 4 ref at the LEP storage ring at CERN confirmed this result. References reflist Category Standard Model particle stub ... more details
saved book title Particles of the Standard Model subtitle cover image Elementary particle interactions.svg cover color DarkSeaGreen Particles of the Standard Model Introduction Standard Model List of particles Quarks Quark Up quark Down quark Charm quark Strange quark Top quark Bottom quark Leptons Lepton Neutrino Electron Electron neutrino Muon Muon neutrino Tau particle Tau Tau neutrino Tau neutrino Gauge bosons Gauge boson W and Z bosons Gluon Photon Higgs boson Higgs boson Composite particles Hadron Meson List of mesons Baryon List of baryons Category Wikipedia books on physics Particles of the Standard Model ... more details
orphan date July 2010 Infobox VG title image caption developer A1 Games publisher Success Corporation Success distributor designer version released February 28, 2001 genre Shoot em up modes Single player ratings platforms PlayStation console PlayStation media requirements input cabinet arcade system cpu sound display Sanvein is top down, multidirectional shooter released by A1 Games . Players can select different floors of various complexes to do battle with various enemies and bosses. Although the story is very vague, the game involves the attempt to escape from, and ultimately destroy, a giant space station called St. Schutz, a suggestively corrupted utopia the player controls the titular Sanvein on such an attempt by battling with the station s defense mechanisms. Gameplay The game is laid out in an arcade type format. The player can select one of three different elements for their ship s movement, normal and special attacks. The choices include Gluon , Photon and Graviton . The Gluon parts fire attack patterns in spread shots while its special fired missiles, the Photon fired concentrated shots while its special unleashed a short range laser blade and the Graviton fired explosive bullets and its special laid land mines. The player can select which floor they want to go to per stage, starting with either the Stratum, the Inner or Outer wards then leading into the Mine area and eventually the station s Core. Every floor is timed, meaning the player has to destroy every enemy on screen before the time runs out. Whenever the player s ship is damaged, they lose time. Seconds are earned per floor depending on how quickly enemies are destroyed. When time runs out, the player has the option to start back at the mission select page at the current mission. The missions are laid out in hexagons, and each form a different shape. After all bosses are defeated, a stage boss appears. After you defeat it, you are taken to a new room. Category 2001 video games Category PlayStati ... more details
JADE was a particle detector at the particle accelerator PETRA at DESY , Hamburg . It was operated from 1979 to 1986. JADE s most important scientific achievement was the discovery of the gluon in three jet events . It also helped greatly in establishing quantum chromodynamics . JADE is an acronym for Ja pan, D eutschland, and E ngland, the three countries from which the participating universities originated. The JADE jet chamber is now exhibited in the physics lecture hall at the University of Heidelberg . Although the last data taken with JADE are 20 years old, analysis continues with the most recent paper published in 2005. External links http www.icepp.s.u tokyo.ac.jp history jade e.html A brief history of JADE at the ICEPP, Japan http de.arxiv.org abs hep ex 0505026 New QCD tests with old JADE data http wwwjade.mppmu.mpg.de Old homepage of the JADE Revival Project Category Particle experiments ... more details
higher densities when it comes to quark matter , gluon matter , or neutrino matter . In the immediate ... s. See also Nuclear equation of state Nuclear matter Quark gluon plasma Nuclear compressibility ... more details
The color glass condensate is an extreme type of matter theorized to exist in atomic nuclei travelling near the speed of light . According to Einstein s theory of relativity , a high energy nucleus appears length contraction length contracted , or compressed, along its direction of Motion physics motion . As a result, the gluon s inside the nucleus appear to a stationary frame of reference observer as a gluonic wall traveling near the speed of light. At very high energies, the density of the gluons in this wall is seen to increase greatly. Unlike the quark gluon plasma produced in the collision of such walls, the color glass condensate describes the walls themselves, and is an intrinsic property of the particles that can only be observed under high energy conditions such as those at RHIC . Color in the name color glass condensate refers to a type of charge that quark s and gluons carry as a result of the strong nuclear force . The word glass is borrowed from the term for silica and other materials that are disordered and act like solid s on short time scales but liquid s on long time scale s. In the gluon walls, the gluons themselves are disordered and do not change their positions rapidly because of time dilation . Condensate means that the gluons have a very high density. The color glass condensate is important because it is proposed as a universal form of matter that describes the properties of all high energy, strongly interacting particles. It has simple properties that follow from first principles in the theory of strong interactions, quantum chromodynamics . It has the potential to explain many unsolved problems such as how particles are produced in high energy collisions, and the distribution of matter itself inside of these particles. References http www.bnl.gov bnlweb pubaf pr 2003 colorglasscondensate background.htm Article on CGC at Brookhaven National Laboratory http arxiv.org abs hep ph 0104285 The Color Glass Condensate and Small x Physics 4 Lectures ... more details
In high energy physics , jet quenching is a phenomenon that can occur in the collision of ultra high energy particles. In general, the collision of high energy particles can produce jet particle physics jet s of elementary particle s that emerge from these collisions. Collisions of ultra relativistic heavy ion particle beams create a hot and dense medium comparable to the conditions in the early universe , and then these jets interact strongly with the medium, leading to a marked reduction of their energy. This energy reduction is called jet quenching . Physics background In the context of high energy hadron collisions, quark s and gluon s are collectively called parton particle physics parton s. The jets emerging from the collisions originally consist of partons, which quickly combine to form hadrons, a process called hadronization . Only the resulting hadrons can be directly observed. The hot, dense medium produced in the collisions is also composed of partons it is known as a quark gluon plasma QGP . In this realm, the laws of physics that apply are those of quantum chromodynamics QCD . High energy nucleus nucleus collisions make it possible to study the properties of the QGP medium through the observed changes in the jet fragmentation functions as compared to the unquenched case. According to QCD, high momentum partons produced in the initial stage of a nucleus nucleus collision will undergo multiple interactions inside the collision region prior to hadronization. In these interactions, the energy of the partons is reduced through collisional energy loss ref D. H. Perkins 2000 . Introduction to High Energy Physics , Cambridge University Press. ref and medium induced gluon radiation, ref D. Gross and F. Wilczek 1973 . Phys. Rev. Lett. 30, 1343. ref the latter being the dominant mechanism in a QGP. The effect of jet quenching in QGP is the main motivation for studying jets as well as high momentum particle spectra and particle correlations in heavy ion collisions. ... more details
NNPDF is used to denote the parton distribution functions from the NNPDF Collaboration. The NNPDF approach can be divided into four main steps The generation of a large math N rep O 1000 math sample of Monte Carlo replicas of the original experimental data, in a way that central values, errors and correlations are reproduced with enough accuracy. The training minimization of the math chi 2 math of a set of PDFs parametrized by artificial neural network neural network s on each of the above MC replicas of the data. PDFs are parametrized at the initial evolution scale math Q 2 0 math and then evolved to the experimental data scale math Q 2 math by means of the DGLAP equations. Since the PDF parametrization is redundant, the minimization strategy is based in genetic algorithm s The neural net training is stopped dynamically before entering into the overlearning regime, that is, so that the PDFs learn the physical laws which underlie experimental data without fitting simultaneously statistical noise Once the training of the MC replicas has been completed, a set of statistical estimators can be applied to the set of PDFs, in order to assess the statistical consistency of our results. For example, the stability with respect PDF parametrization can be explicitly verified. The set of math N rep math PDF sets trained neural networks provides a representation of the underlying PDF probability density, from which any statistical estimator can be computed The NNPDF Collaboration strategy is summarized in this diagram Image General strategy evol.jpg 300px The NNPDF approach The image below shows the gluon at small x from the http arxiv.org abs 0808.1231 the NNPDF1.0 analysis , available through http projects.hepforge.org lhapdf the LHAPDF interface Image Gluon log ref.jpg The NNPDF1.0 gluon NNPDF Parton Distributions ul li NNPDF1.0 http arxiv.org abs 0808.1231 arxiv 0808.1231 li li NNPDF1.1 li li NNPDF1.2 li li NNPDF2.0 A global analysis of all relevant hard scattering data DIS, ... more details
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