Long Range Correlations and The Soft Ridge

1
Long Range Correlations and The Soft Ridge
Based on work with Sean Gavin Larry
McLerran arXiv0806.4718 nucl-th

• Outline
• Correlation Measurements
• PHOBOS
• STAR
• CGC Correlations
• Flux Tubes
• Glasma
• Qs Dependence
• Blast Wave Correlations
• Transverse Flow
• Glasma Flow
• Comparison to STAR

• George Moschelli

Wayne State University
25th Winter Workshop on Nuclear Dynamics
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PHOBOS High pt Triggered Ridge
from Edward Wenger, RHIC AGS Users Meeting, 08
3
PHOBOS High pt Triggered Ridge
from Edward Wenger, RHIC AGS Users Meeting, 08
4
PHOBOS High pt Triggered Ridge
from Edward Wenger, RHIC AGS Users Meeting, 08
5
PHOBOS Untriggered Ridge
from Edward Wenger, RHIC AGS Users Meeting, 08

• soft ridge with very long range in rapidity?
• caution v2 not yet removed

6
Long Range Correlations
from Raju Venugopalan, RHIC AGS Users Meeting,
08

• must originate at the earliest stages of the
  collision
• like super-horizon fluctuations in the Universe
• information on particle production mechanism

7
STAR Soft Ridge
from Lanny Ray, RHIC AGS Users Meeting, 08
Peak Amplitude
Peak ? Width
Peak f Width
peripheral
central
near side peak
Medium range correlationsimplications for long
range?

• v2 and experimental effects subtracted
• peak height and azimuthal width
• not the rapidity width -- structure too narrow
• Gavin Abdel-Aziz Gavin Pokharel Moschelli

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Hard vs. Soft Ridge
hard ridge explanations -- jet interactions with
matter

• N. Armesto, C.A. Salgado, U.A. Wiedemann, Phys.
  Rev. Lett. 93, 242301 (2004)
• P. Romatschke, Phys. Rev. C 75, 014901 (2007)
• A. Majumder, B. Muller, S. A. Bass, Phys. Rev.
  Lett. 99, 042301 (2007)
• C. B. Chiu, R. C. Hwa, Phys. Rev. C 72, 034903
  (2005)
• C. Y. Wong, arXiv0712.3282 hep-ph
• R. C. Hwa, C. B. Yang, arXiv0801.2183 nucl-th
• T. A. Trainor, arXiv0708.0792 hep-ph
• A. Dumitru, Y. Nara, B. Schenke, M. Strickland,
  arXiv0710.1223 hep-ph
• E. V. Shuryak, Phys. Rev. C 76, 047901 (2007)
• C. Pruneau, S. Gavin, S. Voloshin,
  Nucl.Phys.A802107-121,2008

soft ridge -- similar but no jet -- collective
behavior

• S. Gavin and M. Abdel-Aziz, Phys. Rev. Lett. 97,
  162302 (2006)
• S. A. Voloshin, Phys. Lett. B 632, 490 (2006)
• S. Gavin and G. Moschelli, arXiv0806.4366
  nucl-th
• A. Dumitru, F. Gelis, L. McLerran and R.
  Venugopalan, arXiv0804.3858 hep-ph
• S. Gavin, L. McLerran, G. Moschelli,
  arXiv0806.4718 nucl-th
• F. Gelis, T. Lappi, R. Venugopalan,
  arXiv0807.1306 hep-ph

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Flux Tubes and Glasma

• Flux Tubes longitudinal fields early on

• Tubes?quarksgluons

• Correlated Particles come from the same tube

Cross sectional slices are the same

• Causally disconnected

Large ??
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Flux Tubes and Glasma

• Single flux tube phase space density of gluons

• Flux tube transverse size

• Number of flux tubes

• Gluon rapidity density

Kharzeev Nardi
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Flux Tubes and the Correlation Function
pair density n2
single particle density n1

• Correlation function

Assume

• Partons from the same tube are correlated

• Correlations between tubes are negligible

flux tube transverse size Qs-1 ltlt RA
correlation strength
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Correlation Strength

• Correlation Strength

• Long range glasma fluctuations scale the phase
  space density

Dumitru, Gelis, McLerran Venugopalan Gavin,
McLerran Moschelli

• Energy and centrality dependence of correlation
  strength

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Flow and Azimuthal Correlations
STAR soft ridge
Fireball cross section at freeze out
from Lanny Ray, RHIC AGS Users Meeting, 08
Fluid cells
r

• Mean flow depends on position

• Opening angle for each fluid element depends on
  r

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Blast Wave and Correlation Function
Schnedermann, Sollfrank Heinz

• Single Particle Spectrum

• Boltzmann Distribution

• Cooper Frye Freeze Out Surface

• Pair Spectrum

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Blast Wave and Correlation Function

• Correlation Function

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Glasma Blast Wave
STAR measures
We calculate
Peak Amplitude 200 GeV

• v and T from Blast Wave

Akio Kiyomichi, PHENIX
Blast Wave (with correlations)

• Scaled to fit 200 GeV

STAR 200 GeV

• Glasma Qs dependence
• 200GeV?62GeV

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Glasma Energy Dependence

• v and T from Blast Wave

Akio Kiyomichi, PHENIX

• Scaled to fit 200 GeV

• Glasma Qs dependence
• 200GeV?62GeV

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Angular Correlations

• Fit using Gaussian offset

• Range

Peak ? Width

• Error band 20 shift in fit range

computed angular width is approximately
independent of energy
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Summary

• Long Range Correlation Measurements
• PHOBOS may extend to large rapidity
• STAR measurements in a smaller range

• Blast Wave Glasma
• Describes amplitude and azimuthal width
• Glasma energy and centrality dependence