Jet%20Correlations%20from%20PHENIX:%20From%20Low-pT%20to%20High-pT - PowerPoint PPT Presentation

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Title: Jet%20Correlations%20from%20PHENIX:%20From%20Low-pT%20to%20High-pT

Jet Correlations from PHENIX From Low-pT to
Nathan Grau, Columbia University, Nevis Labs For
the PHENIX Collaboration
  • Focus entirely on AA collisions
  • Low-trigger pT correlations
  • Away-side shape modification
  • RP dependence
  • High-trigger pT correlations
  • Can we do jet tomography?
  • What does theory tell us?
  • Many thanks to Paul Constantin, Wolf Holzmann,
    Jiangyong Jia, Jiamin Jin, and Hua Pei for work
    Im showing.
  • Also thanks to Brian Cole, Barbara Jacak, Craig
    Ogilvie, Paul Stankus, and Mike Tannenbaum for
    useful discussions.

Jet Quenching
  • Single particle suppression pattern persists to
    20 GeV

Constructing Jet Correlations
Mixed events corrects pair acceptance
Sum over all events ? jets measured on a
statistical basis
High-pT Jet Correlations
Away-Side Jet in AuAu!
  • C(Df) strength S/B of jets
  • Red and blue lines are the uncertainty in v2
  • Jets seen above the background for trigger gt5
    GeV/c and associated gt2 GeV/c

Clear Away-Side in CuCu!
  • Larger jet S/B in central CuCu than central
  • v2 modulation is smaller as well

Away-Side Yield Suppression
  • h-h correlations in AuAu
  • Near-side unmodified
  • Away-side yield is suppressed!

J. Jia Hard Probes 2006
Expected Broadening of Away-Side
I. Vitev hep-ph/0501255
  • Consequence of energy loss is broadening of the
    away-side correlations
  • multiple scattering of the parton
  • gluon radiation

Lack of Away-Side Broadening!
D. Magestro QM2005
Trigger 5-10 GeV/c
Widths do not change between pp and AuAu?!?
Punch-through Events (I)
T. Renk hep-ph/0602045
  • Monte Carlo includes radial expansion reducing
    the effect of DE L2
  • Non-zero probability to lose no energy
  • Away-side only sensitive to none-zero energy loss?

Production vertices of events with trigger gt 8
GeV Red circles indicate an associated hadron (gt
4 GeV) suffering no E-loss
Punch-through Events (II)
Comparison of MC to STAR away-side yields.
  • Yield suppression sensitive to the probability of

Non-zero Probability for E-loss
  • Important quantitative question not answered by
  • ASW
  • qhat 15 GeV/fm2 and L2
  • P(0) 30-40!
  • GLV
  • P(0) 0!
  • Can these data help constrain this result?

Weidemann, Vitev Hard Probes 2006
Lower pT Correlations
  • h-h Correlations in AuAu (upper plots)
  • C(Df) strength jet S/B
  • Few S/B at lowest pT Correlations.
  • h-h Correlations with background subtracted
    (lower plots)

Different Colliding Systems and Energies
AuAu _at_ 200 GeV
Parameterize the Away-Side Shape
Could be a bent jet or a mach/ Cherenkov cone
Parameterize the away-side shape as a double
Gaussian that are offset symmetrically around Df
p by fit parameter D.
Physical Mechanism of the Away-Side Structure
  • Deflection due to flowing medium
  • Sensitive to jet bulk interaction
  • hep-ph/0411341, Armesto, Salgado, Wiedemann
  • Shoulder position dependent on the RP
  • Cones
  • Mach cones
  • measure speed of sound
  • nucl-th/0406018 Stoecker, hep-ph/0503158 Muller,
    Ruppert, hep-ph/0411315 (2004) Casalderrey-Solana,
    Shuryak, Teaney
  • Cerenkov Cones
  • measure index of refraction
  • nucl-th/0507063 Koch, Majumder, Wang
  • Both would conclude shoulder position independent
    of RP orientation.
  • Distinguish by pT dependence to the shape.
  • Do we understand the root-s and system size

AuAu Reaction Plane Dependence (I)
Look at 4th bin since it has the smallest v2. Dip
exists at most central before substraction!
AuAu Reaction Plane Dependence (II)
Know v2 depending on triggers RP orientation.
J. Bielcikova et al, Phys. Rev. C69021901, 2004
Mach Cones in From Theory
  • Mach shocks do not produce the two-particle
    correlation structure?
  • Hydro calculation of energy lost by jets

U. Heinz HP2006
For the future 3-Particle Correlations (I)
  • 3-particle correlations 3 jet 2 jetx1 thermal
    1 jetx2 thermal 3 thermal.
  • Determining background is difficult
  • 3 jet correlation signal-to-background worse than
    2 jet correlation signal-to-background
  • Looking for few effect.

For the future 3-Particle Correlations (II)
  • Study the 3-particle correlations in the high-pT
    reference frame
  • Project associated particles to perpendicular

For the future 3-Particle Correlations (III)
PHENIX Preliminary
For the future Direct g-h
PRL 94 232301 (2005)
  • Direct photons not suppressed in the medium.
  • Much less trigger bias i.e. less biased toward
    skin emission
  • Photon measures jet energy ? measured away-side
    D(z) modification

Inclusive g-h Correlations in AuAu
g 5-10 GeV/c h 1-2 GeV/c
g 5-10 GeV/c h 3-5 GeV/c
Comparison with p0 triggered data necessary to
extract direct photon correlations. NB a dip at
p exists in the left CF after subtraction
Summary of pT Evolution
  • The jet functions in AuAu collisions evolve with
    both partner and trigger pT

Away-side peak visible
Away-side shoulders visible
Neither visible
Based on PHENIX preliminary and nucl-ex/0507004
P. Stankus CIPANP06
Summary and Conclusions
  • High-pT triggered correlations show
  • AuAu away-side not broadened
  • A suppressed away-side yield consistent with
    punch-through jets.
  • What is learned about the medium from this data?
  • Low-pT triggered correlations show a strongly
    modified away-side shape
  • independent of system size and collision energy
  • Independent of trigger orientation to the RP
  • What is learned about the medium from this data?
  • Still left to do with current data
  • Three particle correlations Sorting out
    deflected, vs. mach/cerenkov
  • Further RP studies Can we show DE L2,L,Ln?
  • Direct g-h D(z) modification

Comparison of g- and p0- Triggered Widths
Near-side widths are consistent between
g-triggered and p0-triggered. Dominant inclusive
photon correlation is decay from jet fragments
g-h Near Side Yields
50 direct photons above 5 GeV/c in the most
central. Also seen in g-triggered near side yield
ratio to p0 -triggered yield.
For the future RP-Dependence At Higher pT
  • Qualitatively No hint of a volcano shape in any
    RP bin