at Pupin Lab
of Columbia University (see Map)
ALICE/LHC ATLAS/LHC CMS/LHC STAR/RHIC PHENIX/RHIC
The Columbia University Nuclear Theory group works on the theory of such extremely hot and ultra-dense states of (Quantum Chromodynamic QCD) strongly interacting matter. We predict a wide range of observables to help diagnose the properties of that new form of matter via relativistic nuclear reactions. Our research is supported by the US Office of Science, DOE Nuclear Physics :
Currently Teaching Physics G6040 Fall 2014, Physics G6094 Spring 2015 ; see CU Courseworks link
Quark Matter 2014 5/20/12 "Perfect Fluidity in light of pDA & BES vn data"
BNL Colloquium 3/20/12 "Jet Tomography versus Jet Holography at RHIC and LHC"
FIAS talks 1/18/07 "So, s'What's a s'QGP?" presented at the 2007 Helmholtz School, Frankurt DE
QM04 talk 1/16/04 "The Discovery of the QGP @ RHIC" presented at workshop
RBRC talk 12/04/03 "The High pT View of the QGP @ RHIC"
CU Theory Seminar 9/15/03 : "The QGP has been found at RHIC"
The Deuterium+Au data on the absence of jet quenching in this reaction in the pT~3-10 GeV range proved that the previous observation of strong jet quenching in Au+Au (1) and the striking unquenching of back-to-back correlations in D+Au reported from the four experiments, STAR , PHENIX , PHOBOS , and BRAHMS , confirmed our predictions (Ivan Vitev, M.G, PRL89(02)) and the predictions of other colleagues. These data established that strong jet quenching effect and the mono-jet topology observed in central Au+Au reactions > must be due to quark and gluon jet energy loss in the dense QCD matter that is produced in central Au+Au reactions at 200 AGeV. An alternate hypothesis based on strong initial state gluon shadowing was ruled out in the mid rapidity kinematic range (x> 0.01).
PHENIX and STAR in 2005 confirmed our jet quenching predictions out to pT~ 20 GeV/c. The absence of suppression of direct photons provides a further control showing that only colored quark and gluon jets are quenched as we predicted via the Standard Model QCD.
Our jet tomographic analysis of the Au+Au quenching pattern indicates that the initial energy density of the QCD matter in Au+Au central reactions was about 100 times higher than in ordinary nuclei. The predictions and analysis were based on our GLV opacity expansion formalism of nonabelian energy loss. Jet quenching in high energy nuclear collisions was proposed in collaboration with Michael Pluemer and Xin-Nian Wang as a novel probe of ultra-dense QCD matter produced at RHIC and higher energies. For a (pdf format) review of our theory of jet quenching and tomography click [GVWZ_03.pdf]
The quenching pattern in Au+Au, together with the striking bulk hydrodynamic collective elliptic flow pattern prove not only that the highest density matter ever formed in the laboratory was produced at RHIC, but that it is the sought after new form of primordial Quark-Gluon-Plasma (QGP) phase of matter since 1975.
The bulk collectivity observed predicted by hydrodynamics agrees with the observed elliptic flow moments, v2(pT<2 GeV,h), when the lattice QCD equation of state is used as input. Significantly, the initial density inferred from our jet tomographic analysis is close to that infered from hydrodynamic analysis . In contrast, at lower (SPS, AGS) energies the bulk collective flow was found to be much weaker than predicted via perfect fluid hydrodynamics. The accumulated evidence on the remarkable collective flow characteristics led to the April 18, 2005 BNL announcement of the "Perfect Fluid" property of the QGP observed at RHIC.
For these and other reasons I concluded  that a QGP was discovered at RHIC . In collaboration with T. Hirano, we have further concluded that the "perfect fluidity" discovered at RHIC is a unique experimental signature of the deconfinement of quark and gluon degrees of freedom above a temperature T>170 MeV as predicted by lattice QCD. While many details of the QGP dynamics are not yet understood, the existence of this ultra-dense form of QCD matter is now established via its high opacity to penetrating jets, its remarkable bulk elliptic flow patterns, and the null results of D+aU control experiments.
The next task at RHIC is to map out with higher precision and detail the other properties of this new phase of matter. Essential probes such as the lepton spectra from heavy (charm, bottom) quarks, direct photons radiated from energetic quarks, photon tagged jets, and multipacticle correlations will require extensive new measurements. Our group is now evaluating the possible new physics implications of first LHC heavy ion data at CERN and carefully comparing that physics emerging from the upgraded high intensity RHIC/BNL detectors.
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