Long range correlations and the soft ridge
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Long Range Correlations and The Soft Ridge. Based on work with: Sean Gavin & Larry McLerran arXiv:0806.4718 [nucl-th]. Outline: Correlation Measurements PHOBOS STAR CGC + Correlations Flux Tubes Glasma Q s Dependence Blast Wave + Correlations Transverse Flow

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Long Range Correlations and The Soft Ridge

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Long range correlations and the soft ridge

Long Range Correlations and The Soft Ridge

Based on work with:

Sean Gavin

&

Larry McLerran

arXiv:0806.4718 [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


Phobos high p t triggered ridge

PHOBOS: High pt Triggered Ridge

from Edward Wenger, RHIC & AGS User’s Meeting, ‘08


Phobos high p t triggered ridge1

PHOBOS: High pt Triggered Ridge

from Edward Wenger, RHIC & AGS User’s Meeting, ‘08


Phobos high p t triggered ridge2

PHOBOS: High pt Triggered Ridge

long range correlations

from Edward Wenger, RHIC & AGS User’s Meeting, ‘08


Phobos untriggered ridge

PHOBOS: Untriggered Ridge

from Edward Wenger, RHIC & AGS User’s Meeting, ‘08

  • soft ridge with very long range in rapidity?

  • caution: v2 not yet removed


Long range correlations

Long Range Correlations

from Raju Venugopalan, RHIC & AGS User’s Meeting, ‘08

  • must originate at the earliest stages of the collision

  • like super-horizon fluctuations in the Universe

  • information on particle production mechanism


Star soft ridge

STAR: Soft Ridge

from Lanny Ray, RHIC & AGS User’s Meeting, ‘08

Peak Amplitude

Peak η Width

Peak φ Width

peripheral

central

near side peak

Medium range correlations…implications 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


Hard vs soft ridge

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, arXiv:0712.3282 [hep-ph]

  • R. C. Hwa, C. B. Yang, arXiv:0801.2183 [nucl-th]

  • T. A. Trainor, arXiv:0708.0792 [hep-ph]

  • A. Dumitru, Y. Nara, B. Schenke, M. Strickland, arXiv:0710.1223 [hep-ph]

  • E. V. Shuryak, Phys. Rev. C 76, 047901 (2007)

  • C. Pruneau, S. Gavin, S. Voloshin, Nucl.Phys.A802:107-121,2008

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, arXiv:0806.4366 [nucl-th]

  • A. Dumitru, F. Gelis, L. McLerran and R. Venugopalan, arXiv:0804.3858 [hep-ph]

  • S. Gavin, L. McLerran, G. Moschelli, arXiv:0806.4718 [nucl-th]

  • F. Gelis, T. Lappi, R. Venugopalan, arXiv:0807.1306 [hep-ph]


Flux tubes and glasma

Flux Tubes and Glasma

  • Flux Tubes: longitudinal fields early on

  • Tubesquarks+gluons

  • Correlated Particles come from the same tube

Cross sectional slices are the same

  • Causally disconnected

Large 


Flux tubes and glasma1

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:


Flux tubes and the correlation function

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

correlation strength

flux tube transverse size ~ Qs-1 << RA


Correlation strength

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


Flow and azimuthal correlations

Flow and Azimuthal Correlations

STAR soft ridge

Fireball cross section at freeze out

from Lanny Ray, RHIC & AGS User’s Meeting, ‘08

Fluid cells

r

  • Mean flow depends on position

  • Opening angle for each fluid element depends on r


Blast wave and correlation function

Blast Wave and Correlation Function

Schnedermann, Sollfrank & Heinz

  • Single Particle Spectrum

  • Boltzmann Distribution

  • Cooper Frye Freeze Out Surface

  • Pair Spectrum


Blast wave and correlation function1

Blast Wave and Correlation Function

  • Correlation Function


Glasma blast wave

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


Glasma energy dependence

Glasma Energy Dependence

  • v and T from Blast Wave

Akio Kiyomichi, PHENIX

  • Scaled to fit 200 GeV

  • Glasma Qs dependence

    200GeV62GeV


Angular correlations

Angular Correlations

  • Fit using Gaussian + offset

  • Range:

Peak  Width

  • Error band: 20% shift in fit range

computed angular width is approximately independent of energy


Summary

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


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