The CGC and Glasma: Summary Comments The CGC, Shadowing and Scattering from the CGC Inclusive single...

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

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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


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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 CollisionsRun8, STAR Preliminary

pp d+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


are needed to see this picture. 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

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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.

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