# Presentation: 933237

## Summary of Experimental Results 

- Jamie Nagle
- University of Colorado at Boulder

## Outline

- We have had an excellent workshop presenting a wealth of experimental results from RHIC and elsewhere.
- My purpose here is not to re-present all the results shown at the workshop.  Instead:
- I hope to learn something by highlighting certain results and asking certain questions.
- I hope you will learn something that you might have missed or not considered during the earlier presentations.

## Excellent Talks

- T. Gunji (PHENIX)
- W. Dong (STAR)
- F. Kajihara (PHENIX)
- H. Zhang (STAR)
- E. Scomparin (SPS)
- J.-C. Peng (pA)
- R. Seuster (BELLE/OPAL)
- A. Geiser (HERA)
- M. Bishai (FNAL)
- T. Frawley (PHENIX)*
- J. Dunlop (STAR)*
- P. Crochet (LHC)*

## Heavy Quarks

## CERN Charm Enhancement?

- Factor 3 Charm Enhancement
- in central Pb-Pb

- M.C. Abreu et al., NA50, Eur. Phys. J C14(2000)443

## NA60 Resolution

-  Open charm and Drell-Yan generated with PYTHIA*
-  Drell-Yan normalization fixed using the high mass region
-  Open charm normalization using the world-average cc cross section

-  **Clear excess in the IMR** (1.2<m<2.7 GeV/c2)
-  same order of magnitude as the NA50 result
-  excess is **not** due to open charm enhancement
-  the excess is due to a **prompt**  source - _which is still not known_!

**NA60 In+In 158 AGeV**

## Total Charm Scaling at RHIC

- Quiz:  What fraction of the charm cross section is
- represented by electrons above pT > 0.8 GeV?
- (a)  0.85, (b) 0.50, (c) 0.15

- From the STAR data we know charm scales between 0.6 and 1.6 (but only for minimum bias AuAu).  Thus, we should be cautious in our conclusions on scaling.

## What to Expect for Total Charm?

- Extrapolating from lower energy is dangerous.
- Factor of 2 differences at RHIC, but large systematics.

## Charm/Beauty and pQCD NLO

- Charm / Beauty in Photoproduction

- Tevatron

## STAR Baseline

- D and electron results complementary, but not
- possible to quote charm from electrons alone.

## Enormous pT Reach!

## PHENIX Baseline

## Suppression of High pT Charm

- Suppression of High pT Charm

## STAR Results - Moderate pT

## Experimental Comparison

- "Suppression same as for light hadrons"
- RAA the same is not the same as the same energy loss.

- RAA agrees, but the proton-proton references are different by ~ 50% and so must the gold-gold !
- 	       -- at least at the time of QM2005 --

## Beauty Limits Suppression Factor?

- M. Djordjevic et al., nucl-th/0507019

## Quiz

- Plot shown by Wicks/Horowitz

- What is the difference between these plots?
- 1.  alpha_s = 0.3 (left) and alpha_s = 0.4 (right)
- 2.  The STAR data shown at QM2005 and in their proceedings are different.

## New Direct Comparison

- "STAR TOF, BEMC
- and PHENIX agree
- reasonably well.
- Systematic
- uncertainties are
- under evaluation"
- STAR high pT data
- has decreased
- significantly, and the
- PHENIX results are
- somewhat higher.

## ***

## Possible Ds Measurement ?

- _name_    _b.f. D____eX_        _percentage contribution to electrons in PYTHIA_
- D+	   17.2%		21.6%
- D0	    7.7%		66.8%
- D+S	    8.0%		11.6%
- Note that most all excited charm mesons do not decay semi-leptonically, but only contribute via sequential decay
- D*+      D0 +    68.3%
- 	D+ 0    30.6%
- 	D+        1.1%
- D*0      D0 0     61.9%
- 	D0       38.1%
- D+/D0 = 0.32  (PYTHIA) gives an average b.f. DeX of **9.7%**
- PHENIX paper uses D+/D0 = 0.65  0.35 which gives b.f. DeX of **11.0%**
- Theory prediction of Lin, Vogt, Wang uses b.f. DeX of **12.0%**

## Heavy Quark Anisotropy

## Non-Photonic Electron Flow

## Kinematics Reminder

-  between D and electron
- pT electron between 0.25 GeV, 1.25 GeV, 2.25 GeV
- Using FOCUS experiment simulation of decays.

- Example D v2 and resulting electron v2...

## STAR QM2005 Result

## STAR Workshop Report

- "The detector material in STAR caused too much photonic background, which caused huge systematic and statistical uncertainties. Our result is not sensitive enough to make any conclusion about heavy quark v2 so far. More work ahead!"

## Detailed Theory

- In a calculation by Teaney and Moore (hep-ph/0412346), they calculate the expected elliptic flow (v2) and transverse momentum modifications for different charm quark diffusion coefficients.  The two effects go hand in hand.

- My comment:  Anything that increases the cross section for interactions will have this general effect.
- Does the specific resonance picture give something unique?  Miklos' question on Form Factor.

## Theory Comparison

- Theory curves from:Greco, Ko, Rapp: Phys. Lett. B595 (2004) 202

- Note that v2 does not necessarily mean "flow"

## Heavy Quarkonia

## "Future of the History"...

- What from the past is "solid" knowledge is often
- not so clear?
- Must establish clearly what the facts are before a true theory can be developed and tested.
- I think we are moving a long way in that direction!

## Heavy Quarkonia

- Lattice QCD results show that the confining potential between heavy quarks is screened at high temperature.

- This screening should suppress bound states such as J/.
- However, recent lattice results indicate that the J/ spectral functions only show modest modification near the critical temperature, and thus may not be suppressed until higher T.

## Theorists Tell Us...

-  free energy :  S.Digal et al. Phys.Rev.D64(2001)094015
-  linear comb. of both:  C.Y.Wong hep-ph/0509088
-  internal energy: W.M.Alberico et al. hep-ph/0507084

**“****Strong evidence for the formation    of a transient quark-gluon phase without color confinement is provided by the observed suppression of the charmonium states J/********, ********c****, and ********’.”**
- 	         Maurice Jacob and Ulrich Heinz

## NA50 Publication

- “A clear onset of the anomaly is observed.  It excludes models based on hadronic scenarios since only smooth behavior with _**monotonic derivatives**_ can be inferred from such calculations”
-                 Phys. Lett. B 450, 456 (1999).

- Baseline is color octet c-c is absorbed by nucleons with
-  = 6.2 mb

## Resolving "Discontinuity" Is Important

- D. Kharzeev, Nucl. Phys. A638, 279a (1998).

- Invoking a model of bubble nucleation, one is able to reproduce the suppression.   This implies a relatively strong 1st order phase transition.  Or what about 2nd order with finite volume effects?

## Monotonic Derivatives

## What do we learn?

- Earlier papers from Satz *et al.* stated that nuclear absorption of 6 mb for octet state and 2 mb for singlet state.
- Now the absorption cross section measured has changed from 6.2 mb to
- abs)=4.18 +/- 0.35 mb (hep-ex/0412036)
- Does that mean not all octet?
- Lack of reliability of calculation?
- Is this important for detailed balance calculations?

## NA60 Data

- Quiz:  What is the most central bin for which one can reliably quote Glauber parameters with "no systematic error"?
- (a) 20%, (b) 10%, (c) 5%, (d) 1%, (e) 0.1%

## Similar but no Discontinuity?

## New Heavy Quarkonia

- Note that most theories so far treat the topics of heavy quarks and heavy quarkonia quite separately, but they are intimately related.
- Given the talks at this workshop, this lesson is something most theorists have accepted.

## proton-nucleus data

## Production Mechanisms

## Tevatron Production

## J/ at HERA - NLO Singlet

## Polarization

## PHENIX Deuteron-Gold Data

## Normal Nuclear + Shadowing

- Forward rapidity

## Looks Like CERN Suppression

## Slide 48

## Quiz:  Given an infinite number of predictions, what percentage of the time will some subset agree with the data?

- (a) 5%, (b) 20%, (c), 80%, (d) 100%
- Thus, we must find further discriminants!

## More in the Near Future...

## Balancing Effects

## Rapidity Dependence

- nucl-th/0505055

- nucl-th/0507027

## Feed-Down - Key Measure!

## Critical STAR Contribution

## Excellent Upgrade Lessons

## Summary of the Summary

- Great progress in utilizing heavy flavor for understanding heavy ion created medium.
- Perhaps the start of also gaining more basic information such as production mechanics.

- Final Examination
- Who should we thank?
- (a) all speakers
- (b) the organizers
- (c) RIKEN-BNL
- (d) Pam Esposito and Jane Lynsik
- (e) All of the Above

## Backup Slides

## z

- _Light quarks (u,d)_
- blue = Fields-Feynman
- black dash = Lund fragmentation

- dN/dz * z

- _Heavy quarks (c,b)_
- red = Peterson function
- black dash = Lund fragmentation
- Bowler correction not shown
- (1-z) is obvious

- For charm quarks, the Peterson and Lund fragmentation roughly agree and give an average
- <z> ~ 0.8.

**First paper on the J/****ψ**** suppression**

- photo: Prof. Osamu Miyamura

- Digression:

- to return to the subject...

** ****Suppression(?) ****in d going direction**
** ****Enhancement(?) ****in Au going direction**

***d***

**Au**

**South**

**North**

**Beam direction**

## Upsilon Result

- Measurements on beauty will help significantly.

## PHENIX Recently Submitted

**PRL accepted recently (****nucl-ex/0510047****).**

## Future of the History

- STAR shown at QM2005

- RAA to 10 GeV/c in non-photonic electrons
- Suppression is approximately the same as for hadrons

## Clearing up a few things