1

Jet quenching, Nov. 2003

hep-ph/0310079; CERN-TH-2003-244

2

During last VRVS meeting I suggested to look at http://www-cdf.fnal.gov/physics/talks_transp/2003/cipanp_qcd_mesropian.pdf

3

http://www-cdf.fnal.gov/physics/talks_transp/2003/cipanp_qcd_mesropian.pdf

4

http://www-cdf.fnal.gov/physics/talks_transp/2003/cipanp_qcd_mesropian.pdf

Higher pT jets are “more focused”

5

http://www-cdf.fnal.gov/physics/talks_transp/2003/cipanp_qcd_mesropian.pdf

6

Medium Modification of Jet Shapes and Jet Multiplicities Salgado, C A; Wiedemann, U A hep-ph/0310079; CERN-TH-2003-244

Distribution of gluons radiated

from initial hard parton

2=k2/ (mean pT

2 transferred

from the medium

to the projectile on the length L

Soft gluons dominate and they populate small pT

7

Medium Modification of Jet Shapes and Jet Multiplicities Salgado, C A; Wiedemann, U A hep-ph/0310079; CERN-TH-2003-244

Observable

Vacuum shapes fromFixed cone jet definitions in D0 and R(sep) Abbott, B- D0 Collaboration.FERMILAB-Pub-97-242-E

8

Medium Modification of Jet Shapes and Jet Multiplicities Salgado, C A; Wiedemann, U A hep-ph/0310079; CERN-TH-2003-244

Calo granularity

i.e. L=32 !?!

Jet (not subjet) E resolution50%/E+2% for 50 GeV = 9%for 100 GeV = 7%

9

Medium Modification of Jet Shapes and Jet Multiplicities Salgado, C A; Wiedemann, U A hep-ph/0310079; CERN-TH-2003-244

I have a “challenged” child and I know what it means

10

Medium Modification of Jet Shapes and Jet Multiplicities Salgado, C A; Wiedemann, U A hep-ph/0310079; CERN-TH-2003-244

Some optimism

Partonic jet multiplicity is a new perspective …

11

Medium Modification of Jet Shapes and Jet Multiplicities Salgado, C A; Wiedemann, U A hep-ph/0310079; CERN-TH-2003-244

Upper limit of radiated gluons energy

A visible broadening!

12

Medium Modification of Jet Shapes and Jet Multiplicities Salgado, C A; Wiedemann, U A hep-ph/0310079; CERN-TH-2003-244

Pesimism?Optimism?A challenge …

13

But we will always have some averaging …

TA(b).TB(b) driving the probability of a jet creation

Pb Pb

-8

-6

-4

-2

0

2

4

6

8

TA(b)+TB(b) driving the density of the medium (no expansion here)

14

Some references

A Dynamical Scaling Law for Jet Tomography /Salgado, C A; Wiedemann, U Ahep-ph/0204221; CERN-TH-2002-086.- Geneva : CERN, 18 Apr 2002 . - 4 p   Published in: Phys. Rev. Lett. 89 (2002) 092303/1-4

On the Angular Dependence of the Radiative Gluon Spectrum /Baier, R; Dokshitzer, Yu L; Müller, A H; Schiff, D hep-ph/0105062;   Published in: Phys. Rev., C 64 (2001) 057902

Energy Loss of Hard Partons in Nuclear Matter /Wiedemann, Urs Ahep-ph/0103332; 30 Mar 2001 . Published in: Nucl. Phys., A 698 (2002) 615-618

Jet Quenching versus Jet Enhancement : a Quantitative Study of the BDMPS-Z Gluon Radiation Spectrum /Wiedemann, Urs Ahep-ph/0008241; Published in: Nucl. Phys., A 690 (2001) 731-51

Gluon Radiation off Hard Quarks in a Nuclear Environment : Opacity Expansion /Wiedemann, Urs A hep-ph/0005129;   Published in: Nucl. Phys., B 588 (2000) 303-344….

Hard Probes in Heavy Ion Collisions at the LHC: Jet Physics /Accardi, A et al.hep-ph/0310274; 23 Oct 2003 . - 123 p