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Theory Center Seminar<br>
Monday, April 1, 2013<br>
1:00 p.m. (coffee at 12:45 p.m.)<br>
CEBAF Center, Room L102<br>
<br>
<br>
Raju Venugopalan <br>
Brookhaven National Laboratory <b><br>
<br>
Evidence for BFKL and Saturation Dynamics in High Multiplicity<br>
Collisions at the LHC </b> <br>
<br>
A novel QCD phenomenon, discovered in high multiplicity
proton-proton and proton-nucleus<br>
collisions at the LHC, is the azimuthal collimation of pairs of
charged hadrons that are widely<br>
separated in rapidity. We argue that these long range in rapidity
"ridge" correlations provide <br>
distinctive images of the structure of chromo-electromagnetic fields
at very early times in these<br>
collisions. In particular, the systematics of the phenomenon
provides evidence both for <br>
Balitsky-Fadin-Kuraev-Lipatov (BFKL) renormalization group dynamics
as well as gluon <br>
saturation in high energy QCD. Alternative scenarios, which
interpret the ridge phenomenon<br>
in terms of collective flow are also discussed.
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