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 didn’t predict ~ constant RAA then it’s hard to argue that it uniquely describes the observed suppression.

• Especially given Sarcevic et al analysis showing similar feature from Bethe-Heitler energy loss.

Test #1

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

“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

Test #2

• 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.

“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

Test #3JET TOMOGRAPHY OF AU+AU REACTIONS INCLUDING MULTIGLUON

FLUCTUATIONS, Gyulassy, Levai, Vitev, Phys.Lett.B538:282-288,2002

• Evaluates effect of fluctuations in # of emitted gluons

• RAA looks less flat with pt for both cases ??

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 !

Comparison: Wang

• Prediction before there was ANY data.

• Already uses RAA !

• Clearly has the wrong trend with pT.

Last Call for RHIC Predictions, X. Wang Nucl.Phys.A661:205-260,1999, nucl-th/9907090

Comparison: Sarcevic

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

• Bethe-Heitler “best”.

LARGE P(T) INCLUSIVE PI0 PRODUCTION IN HEAVY ION COLLISIONS AT RHIC AND LHC, Jeon Jalilian-Marian Sarcevic Jul 2002. Nucl.Phys.A723:467-482,2003, hep-ph/0207120

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.

What about Hadronic Reinteraction?

• (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.

Cassing, Gallmeister Greiner Nucl.Phys.A735:277-299,2004, hep-ph/0311358