Goal

1
Goal

• Answer question
• Was the approximate constancy of RAA in GLV
  calculations a pre-diction or post-diction.
• Why is this important ?
• Jamie made a good argument
• There are only two clear features in
  single-particle RAA
• Suppression magnitude
• Constancy with pT
• If GLV didnt predict constant RAA then its
  hard to argue that it uniquely describes the
  observed suppression.
• Especially given Sarcevic et al analysis showing
  similar feature from Bethe-Heitler energy loss.

2
Test 1
DISCOVERY OF JET QUENCHING AT RHIC AND THE
OPACITY OF THE PRODUCED GLUON PLASMA, P. Levai
et al, Nucl. Phys. A698 631-634,2002 --
nucl-th/0104035

• Use fixed opacity clearly too simple but
  opacity 2-4 all constant in unmeasured region.

3
Test 2
THE ROLE OF JET QUENCHING IN THE ANTI-P GREATER
THAN OR EQUAL TO PI- ANOMALY AT RHIC,
Proceedings of International Europhysics
Conference on High-Energy Physics, July 2001,
hep-ph/0109198

• Both charged pion constant with pt
• Pion shows some slope vs pt
• h/- less suppressed at 7-8 GeV/c for same gluon
  dn/dy.

4
Test 3
JET TOMOGRAPHY OF AUAU REACTIONS INCLUDING
MULTIGLUON FLUCTUATIONS, Gyulassy, Levai, Vitev,
Phys.Lett.B538282-288,2002

• Evaluates effect of fluctuations in of emitted
  gluons
• RAA looks less flat with pt for both cases ??

5
Test 3 Compared to others/data

• Put test 3 RAA on same scales as other plots
  data.
• Calculations are consistent.
• As is data out to 10 GeV !

6
Comparison Wang
Last Call for RHIC Predictions, X. Wang
Nucl.Phys.A661205-260,1999, nucl-th/9907090

• Prediction before there was ANY data.
• Already uses RAA !
• Clearly has the wrong trend with pT.

7
Comparison Sarcevic
LARGE P(T) INCLUSIVE PI0 PRODUCTION IN HEAVY ION
COLLISIONS AT RHIC AND LHC, Jeon Jalilian-Marian
Sarcevic Jul 2002. Nucl.Phys.A723467-482,2003,
hep-ph/0207120

• Compares constant dE/dx, LPM (BDMS), and
  Bethe-Heitles (incoherent) vs pt.
• Bethe-Heitler best.

8
Conclusion

• The approximately flat suppression vs pt in GLV
  was predicted before the data existed.
• It results from full calculation
• Log(E) is only an approximation
• Presumably same approximation in BDMS.

9
What about Hadronic Reinteraction?
Cassing, Gallmeister Greiner Nucl.Phys.A735277-29
9,2004, hep-ph/0311358

• (Only) 1/3 of true hadrons suffer final-state
  interactions.
• How reliable is this estimate ?
• What about pre-hadrons interactions ?
• My opinion ad-hoc cartoon (not even a
  calculation) of energy loss.