1. Long range rapidity correlations in high energy nucleus collisions at RHIC and LHC
Heavy Ion Ohsaka University
Takahito Todoroki
University of Tsukuba & Riken Nishina Center
2011 Feb 18th
T. Todoroki, University of Tsukuba

2. T. Todoroki, University of Tsukuba
Outline
Overview of basic ridge property
Ridge study via Df correlations with respect to Reaction Plane
Triangular flow
Dh correlations with respect to trigger h
Ridge in high multiplicity p+p events at LHC-CMS
Summary
2011 Feb 18th
T. Todoroki, University of Tsukuba

3. Long range rapidity correlations
Phys. Rev. C 80, (2009)
2< pTasso < pTtrig
2< pTasso < pTtrig
Jet
Jet
Ridge
Long range rapidity correlations up to large rapidity = “Ridge”
Seen in Au+Au, absent in d+Au collisions
Superposition of jet and ridge at Df~0 & Dh~0 in Au+Au collisions
2011 Feb 18th
T. Todoroki, University of Tsukuba

4. pT spectra of Jet and Ridge yield
Phys. Rev. C 80, (2009)
Jet spectrum is increasing with pTtrig as jet fragmentation
Ridge spectrum is softer and approximately independent of pTtrig
Ridge is “bulk-like”
2011 Feb 18th
T. Todoroki, University of Tsukuba

5. Ridge shape gets clearer with pT
2011 Feb 18th
T. Todoroki, University of Tsukuba

6. Centrality evolution of Ridge
Au+Au 200GeV data - fit (except same-side peak)
pT > 0.15 GeV
M.Daughersity, QM08, J.Phys.G35:104090,2008
83-94%
55-65%
46-55%
0-5%
STAR Preliminary
STAR Preliminary
STAR Preliminary
STAR Preliminary
ηΔ width
Rapid transition from 55-65% to 46-55%
Small change to most central after transition
Ridge may be phenomena of underlying event
2011 Feb 18th
T. Todoroki, University of Tsukuba

7. Ridge and Jet Df correlations with respect to Reaction Plane
Jet = (|Dh|<0.7) -Accep*(|Dh|>0.7)
|Dh|>0.7 = near-side ridge + away-side
Flow subtraction by ZYAM
2011 Feb 18th
T. Todoroki, University of Tsukuba

8. Ridge correlations have reaction plane dependence1 2 3 4 5 6
2011 Feb 18th
T. Todoroki, University of Tsukuba

9. Correlated Emission Model
Chiu,Hwa, arXiv:
Correlated Emission Model (CEM)
in-plane
jet flow aligned
more ridge
out-of-plane
jet flow misaligned
less ridge
Asymmetric ridge peak predicted
2011 Feb 18th
T. Todoroki, University of Tsukuba

10. Ridge and Jet Df correlations with respect to Reaction Plane
Jet = (|Dh|<0.7) -Accep*(|Dh|>0.7)
|Dh|>0.7 = near-side ridge + away-side
Flow subtraction by ZYAM
2 Gaussian fit to away side and subtracted
Ridge obtained 1 2 3 4 5 6 Df
2011 Feb 18th
T. Todoroki, University of Tsukuba

11. Near side peak asymmetry
Jet shape is symmetric
Ridge is asymmetric!
shift to Df>0 side
Ridge may come from jet-flow alignment 4 3 5 2 6 1
2011 Feb 18th
T. Todoroki, University of Tsukuba

12. T. Todoroki, University of Tsukuba
Back to Back Ridge
Jet = (|Dh|<0.7) -Accep*(|Dh|>0.7)
|Dh|>0.7 = near-side ridge + away-side
Flow subtraction by ZYAM
Fit : Back-to-Back Ridge + away conical emissions
2011 Feb 18th
T. Todoroki, University of Tsukuba

13. T. Todoroki, University of Tsukuba
Triangular Flow
Pictures : Alver RHIC-AGS Meeting 2010
arXiv: v1
Triangular flow is possible source of ridge!
2011 Feb 18th
T. Todoroki, University of Tsukuba

14. Comparison of AMPT and STAR
VnD = <cos n(fasso - ftrig)>~ Vn2
v2 & v3 are depending on initial geometry in AMPT
AMPT simulations have good consistency with data at pT >0.8GeV
arXiv: v3
2011 Feb 18th
T. Todoroki, University of Tsukuba

15. T. Todoroki, University of Tsukuba
S. Esumi WWND2011
2011 Feb 18th
T. Todoroki, University of Tsukuba

16. Dh correlations with respect to trigger h
Jet and Ridge property as function of trigger h
Back/Forward asymmetry of correlation shapes
Gradient of correlation functions
2011 Feb 18th
T. Todoroki, University of Tsukuba

17. T. Todoroki, University of Tsukuba
PYTHIA8
2011 Feb 18th
T. Todoroki, University of Tsukuba

18. T. Todoroki, University of Tsukuba
AMPT
Near side : |Df| < p/4
Flow Not Subtracted
0 ~ 20%
C2 : arbitrary unit
20 ~ 50%
50 ~ 93%
Dh = hasso- htrig :[-4,+4]
htrig = -2.0
htrig = 2.0
htrig = 0
2011 Feb 18th
T. Todoroki, University of Tsukuba

19. T. Todoroki, University of Tsukuba
PHENIX Data Analysis
Trigger “sign” selection : “h<0” and “h>0”
Precise trigger selection : [-0.35,0.35] 14bins step.
Dh correlations : projected from Df - Dh correlations
Near side : |Df| < p/4
Away side : |Df - p| < p/4
Superposition of jet and ridge due to central arm accep. |h|<0.35
2011 Feb 18th
T. Todoroki, University of Tsukuba

20. Trigger h sign selected correlations
2011 Feb 18th
T. Todoroki, University of Tsukuba

21. Projected Dh correlations : Trigger h sign selected
Near : |Df|<p/4
Away: |Df - p|<p/4
2011 Feb 18th
T. Todoroki, University of Tsukuba

22. Near side Dh correlations : precise trigger selection
Near : |Df|<p/4
2011 Feb 18th
T. Todoroki, University of Tsukuba

23. Away side Dh correlations : precise trigger selection
Away: |Df - p|<p/4
2011 Feb 18th
T. Todoroki, University of Tsukuba

24. Backward / Forward asymmetry
“Forward” : Dh>0
“Backward” : Dh<0
Centrality : 0~20
trigger (hadron): Pt 2~4GeV
ηtrig [0, 0.05]
associate (hadron) : Pt 1~2GeV
Yield Ratio = (AvgForward - AvgBackward)/(AvgForward + AvgBackward)
Forward : 0 < Dh <0.25
Backward : < Dh <0
YR=0 : symmetric shape
YR>0 or <0 : shift for Forward or Backward direction
2011 Feb 18th
T. Todoroki, University of Tsukuba

25. Backward / Forward asymmetry : trigger sign selection
Degree of asymmetry
at most 2s in peripheral at near side
at most 1s in peripheral at away side
2011 Feb 18th
T. Todoroki, University of Tsukuba

26. Backward / Forward asymmetry : trigger precise selection
Large statistical & systematic error on both near and away side
2011 Feb 18th
T. Todoroki, University of Tsukuba

27. Gradient of correlations as function of trig h
if htrig >0
if htrig <0
Centrality : 0~20
trigger (hadron): Pt 2~4GeV
ηtrig [0, 0.05]
associate (hadron) : Pt 1~2GeV
Fitting function : [0] + [1]*x
Fitting range
Dh : [ 0,0.35] if htrig <0
Dh : [-0.35,0] if htrig <0
2011 Feb 18th
T. Todoroki, University of Tsukuba

28. Gradient of correlations seems to be flat
Gradient of correlations seems to be flat at near side
Away side also seems to be flat though still large statistical error
2011 Feb 18th
T. Todoroki, University of Tsukuba

29. Correlations in high multiplicity p+p events at LHC-CMS
Minimum Bias
no cut on multiplicity
High multiplicity data set
and N > 110
The peak is truncated
in both distributions
Back-to-back jet correlations enhanced in high multiplicity sample.
2011 Feb 18th
T. Todoroki, University of Tsukuba

30. T. Todoroki, University of Tsukuba
Minimum Bias
no cut on multiplicity
High multiplicity data set
and N>110
New “ridge-like” structure extending to large  at  ~ 0
2011 Feb 18th
T. Todoroki, University of Tsukuba

31. T. Todoroki, University of Tsukuba
Data and PYTHIA8
2011 Feb 18th
T. Todoroki, University of Tsukuba

32. Other simulation models
2011 Feb 18th
T. Todoroki, University of Tsukuba

33. Data and PYTHIAD6T at 0.9, 2.36 and 7 TeV
PT inclusive
2011 Feb 18th
T. Todoroki, University of Tsukuba

34. Comparison 7 TeV p+p and 200 GeV Cu+Cu correlations
High multiplicity data set N>110
Hard Probe 2010, Putschke
Correlations in Cu+Cu at similar multiplicity dominated by flow.
How correlation shape changed if v2 exists in high mult. p+p event?
Need to survey azimuthal dynamics in high mult. p+p events
2011 Feb 18th
T. Todoroki, University of Tsukuba

35. Accumulative azimuthal correlations
Trigger
arxiv:nucl-ex/ v3
STAR AuAu 200GeV
<Si cos2(ftrig - fiasso)> = Mult.*v2 (pTtrig) v2asso+{non-flow}
0.15 < pTasso <2.0GeV/c at |h|<1.0
Consistent with p+p minimum bias at peripheral
Enhance of Au+Au correlations at mid central & central by flow-like component
Method to search the possible modification in high multiplicity p+p events from minimum bias because no event plane needed
2011 Feb 18th
T. Todoroki, University of Tsukuba

36. Accumulative correlations in high multiplicity p+p events at 200 GeV
Midori Kajigaya Univ. of Tsukuba
<Si cos2(fPt - fi)> = Mult.*v2 (pT) v2asso + {non-flow}
Enhance in mid-rapidity high multiplicity event
Azimuthal dynamics in p+p events depends on multiplicity if track number count and calculation done in same rapidity range.
2011 Feb 18th
T. Todoroki, University of Tsukuba

37. Possible ridge in p+p collisions at RHIC energy?
CERN-ISR
Nucl. Phys. B145 (1978)
p+p √s = 52.6 GeV
0.5< Passo
data to analyze : 500GeV, 200GeV and 62.4 GeV
2011 Feb 18th
T. Todoroki, University of Tsukuba

38. T. Todoroki, University of Tsukuba
Summary
Overview of basic ridge property
Ridge study via Df correlations with respect to Reaction Plane
Ridge depends on Reaction Plane
Triangular flow
Possible source of ridge
AMPT well describes STAR experimental data at pT >0.8GeV
Dh correlations with respect to trigger h
No trigger h dependence seen in PHENIX acceptance…
Ridge in high multiplicity p+p events at LHC-CMS
2011 Feb 18th
T. Todoroki, University of Tsukuba

39. T. Todoroki, University of Tsukuba
Back Up Slides
2011 Feb 18th
T. Todoroki, University of Tsukuba

40. T. Todoroki, University of Tsukuba
2011 Feb 18th
T. Todoroki, University of Tsukuba

41. T. Todoroki, University of Tsukuba
2011 Feb 18th
T. Todoroki, University of Tsukuba

42. None trigger selected Df-Dh correlations
2011 Feb 18th
T. Todoroki, University of Tsukuba

43. T. Todoroki, University of Tsukuba
2011 Feb 18th
T. Todoroki, University of Tsukuba