Thinking about the correlation landscape in terms of

1. Agnes Mocsy 9:05 PM What’s this talk about?? Paul Sorensen 9:06 PM Thinking about the correlation landscape in terms of bulk phenomenon

2. Outline • Do 2-particle correlations at intermediate or low pT represent modified jets or mini-jets? • Laundry list: • Chemical composition of the correlations • Baryon-to-Meson ratios are like the bulk • Peak amplitude • Correlations don’t scale with Nbin or Npart but with M(M-1) instead • Near-side and Away-side have same centrality dependence • Longitudinal and Azimuthal Width • They’re both different from fragmentation • pT spectra of the ridge and the jet cone • The ridge is soft and the real jet-cone is hard • These make me think of correlations as a bulk phenomenon •  the jet’s are both diluted and quenched to ~nothing 

3. The question Are the correlation structures a modification of structures known in p+p? Or a new feature of the medium? Peak Amplitude Peak η Width Peak φ Width STAR Preliminary STAR Preliminary STAR Preliminary 200 GeV 62 GeV M. Daugherity: QM08 peripheral central

4. above transition ridge yield scales with background STAR Preliminary Navneet Kumar Pruthi Ridge scales with the background! Ridge ratio is independent of minimum pT cut Jet signal diluted by combinatorics as expected. Jet ratio grows with minimum pT cut leading and subleading dihadrons (different quantity than usual associate particle yields)

5. Flow + Initial-State-Correlations = Near-side Gaussian How might we explain the observed correlations? Boosted emission function with discrete, correlated source points • Similar To Treatments by: • Longacre, Lindenbaum: Phys.Rev.C78:054904,2008 • Dumitru, Gelis, Venugopalan, McLerran: Nucl.Phys.A810:91,2008 • Pruneau, Voloshin, Gavin: Nucl.Phys.A802:107-121,2008 • Gavin, McLerran, Moschelli

6. Flow + Initial-State-Correlations = Near-side Gaussian σ ≈ 1.32 – 1.10*<β>

7. lumpy initial conditions and a QGP expansion collision evolution particle detectors expansion and cooling kinetic freeze-out distributions and correlations of produced particles lumpy initial energy density hadronization QGP phase quark and gluon degrees of freedom collision overlap zone quantum fluctuations  ~ 1015 fm/c  ~ 10 fm/c  ~ 0 fm/c 0~1 fm/c

8. The Landscape The Ridge, The Valley, and the Away-side: What does a radial flow induced near-side Gaussian have to do with all these complicated structures? The answer may be related to incomplete equilibration and the finite lifetime of the system “valley” “jet” “ridge” STAR Preliminary pT correlations (STAR)

9. What happens with this near-side Gaussian Flow+Initial State correlations yields a near-side Gaussian with a width σ = 1.32 – 1.10*<β> The Fourier transform of a Gaussian is a Gaussian This gives the harmonics vn2(n,<β>) for the flow induced Gaussian. *odd values do not have to be zero (fluctuations) Can azimuth correlations be described by a few harmonics (see next slide)

10. Few parameter fit of azimuthal correlations I can name that tune in 5 notes 4-5 harmonics give a good description of the data

11. The difference between data and the ideal Gaussian The difference between the Gaussian and Data is the suppression of long wavelength modes! See Also Discussions of Superhorizon fluctutions in HIC, Ananta P. Mishra, Ranjita K. Mohapatra, et al.

12. The difference between data and the ideal Gaussian The difference between the Gaussian and Data is the suppression of long wavelength modes! See Also Discussions of Superhorizon fluctutions in HIC, Ananta P. Mishra, Ranjita K. Mohapatra, et al.

13. Multipole moments and the valley See Also Discussions of Superhorizon fluctuations in HIC, Ananta P. Mishra, Ranjita K. Mohapatra, et al. Short lifetime leads to incomplete equilibration Similar to conclusion from v4/v22 (Ollitrault) Valley is indicative of suppression of lower harmonics

14. Credit: NASA kinetic freeze-out distributions and correlations of produced particles lumpy initial energy density hadronization QGP phase quark and gluon degrees of freedom collision overlap zone quantum fluctuations  ~ 0 fm/c 0~1 fm/c  ~ 10 fm/c Analogies with the early universe Heavy-ion Collisions: Rapid Expansion collision evolution particle detectors The Universe: Slow Expansion expansion and cooling WMAP STAR

15. How Can We Test These Models QGP boundary mapped in an energy scan at RHIC? RHIC beam energy scan will test the models (Qs?) An 8-9 week run in run 10 will allow STAR to gather sufficient statistics for 2-D low pT ridge studies down to √snn≈10 GeV (1.5 weeks at 10GeV)

16. Conclusions Are we sure correlations at intermediate and low pT require the concept of a jet? Chemistry, Centrality dependence, Spectra and Widths all change from fragmentation expectations. An ideal/instantaneous radial flow model will give you a nearly perfect near-side Gaussian Suppression of long wavelength modes due to finite lifetime effects and acoustic horizons may account for the remaining structure

17. Life is short hadronization lumpy initial energy density Correct scale shows: regions remain outside the event horizon QGP phase quark and gluon degrees of freedom collision overlap zone quantum fluctuations  ~ 10 fm/c  ~ 0 fm/c 0~1 fm/c

18. A Post-summary Question The Baryon/Meson ratio is enhanced in the ridge similar to inclusives The Baryon/Meson ratio is also enhanced at UA1 Does anyones model say something about p+p collisions? Multi-parton effects in p+p? QGP?