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The CGC and Glasma: Summary Comments. The CGC, Shadowing and Scattering from the CGC Inclusive single particle production J/Psi Two Particle Correlations. The Glasma and Nuclear Collisions Evolution to the QGP The Earliest Times and Two Particle Correlations.
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The CGC and Glasma: Summary Comments The CGC, Shadowing and Scattering from the CGC Inclusive single particle production J/Psi Two Particle Correlations The Glasma and Nuclear Collisions Evolution to the QGP The Earliest Times and Two Particle Correlations Note: Not a comprehensive summary of the field but a highlighting of recent results and their importance
Gluons and quarks at high x are replaced by sources of coherent classical fields at small x (the x of interest) As x of interest decreases, more and more sources, and phase space fills up to some saturation momentum scale
Individual gluons arise from coherent sum of nucleon sources Evolution to small x involve coherent sum of fields from several sources This coherent sum of fields is the CGC Corresponds to Fock space states of gluons that have very high phase space density and with sources that are incoherent, like a spin glass, as a consequence opf Lorentz time dilation
Particle Production on the CGC Example gluon from a projectile deuteron scatters from a CGC of a gold nucleus Eikonal scattering from a strong color field of CGC Correction of order alpha for longitudinal energy loss Do not confuse: Method of scattering from CGC with the CGC The frame in which computation is done with the existence of the highly coherent fields of the CGC
1 1 1 100 Single Particle Distributions in dA Collisions: Two effects: Multiple scattering: more particles at high pT CGC modification of evolution equations => less particles It also includes DGLAP and BFKL evolution Simplest CGC computation includes effects of evolution of gluons density (leading and non-leading twist shadowing) through eikonalized scattering and generalized BFKL evolution. Is longitudinal energy loss in scattering from the CGC important? Leading twist does not explain effect.
J/Psi Production: Because CGC fields are strong the leading order mechanism is different from that assumed for pp When saturation momentum is large compared to charm quark mass, charm quark behaves like a light mass quark (except for probability to be found in projectile wavefunction) In this limit, there is extended Feynman scaling and cross sections scale as
Complicated because saturation momentum at RHIC energy is of the order of the charm mass. Are there corrections to the assumed scattering from the CGC associated with longitudinal energy loss?
Two Particle Correlations in dAu Collisions: PHENIX data should be described by the saturation based prediction of Qiu and Vitev. Computation done in nuclear rest frame to leading order in twist expansion. Extracts saturation momentum. Computation to all orders including full non-linearity of CGC is not yet done!
200 GeV p+p and d + Au Collisions Run8, STAR Preliminary ppd+Au (peripheral) d+Au (central) “Jet Quenching” in dA Collisions: Forward backward angular correlation between forward produced, and forward-central produced particles. Reasonable agreement with computations of Marquet
The Glasma and Evolution to the QGP Longitudinal electric and magnetic fields are set up in a very short time
Time Scales in the Evolution of the Glasma: Sheets of CGC pass through one another, are dusted with color electric and magnetic charge, longitudinal flux lines form Little evolution of longitudinal fields Longitudinal fields evolve into transverse fields and radiated gluons. Glasma dissolves Onset of turbulence, density fluctuations at all scales Terra Incognita and Paradox: If QGP is sQGP, natural time scale for evolution to sQGP is inverse saturation scale. Unknown how this conversion happens. Indicates a rapid conversion. Some adSCFT insight from Peschanski and friends.
Almost Conserved Quantities: Particle multiplicities and Long Range Rapidity Correlations Assumes little processing of transverse distribution of multiplicity in Glasma evolution phase (multiplicity conservation?) Little gneration of flow in Glasma phase
Forward Backward Correlations and STAR Long range correlation involve large energy difference so correlation must be set up early. Cannot be erased by late time processes that are local in rapidity
The Ridge: Imaging Flux Tubes Glasma flux tube, Pomeron interactions, Beam fragmentation jets: The physics and descriptions overlap but one is trying to describe the same basic phenomenon
On theoretical side: How do the initial flux tubes evolve through the QGP? Some early studies by Brazilians (and Nu Xu) show that tubes survive evolution. Produce backwards going ridge and its reflection. Mach cone like structure? If we are really imaging structures on the Fermi scale, this is a BIG DEAL. Imaging of jets was revolutionary in its impact upon particle physics.
Summary: A number of unexpected scientific discoveries at RHIC make a compelling case for the existence of two distinct forms of high energy density matter. The first is the Color Glass Condensate that is highly coherent gluonic matter, with a density that is saturated. The second is the Glasma produced in collisions of high energy nuclei that evolves from initially strong longitudinal color electric and color magnetic fields into an almost perfect fluid.