# Presentation: 862909

## Summary and Outlook

**Supplement**

- Energy dependence of jet quenching
- Azimuthal angle dependence of jet quenching
- Hadrons correlations in jets
- Dihadron fragmentation function
- Jet cone structure
- Heavy quark energy loss
- Future of jet quenching

- Xin-Nian Wang (LBNL)

- RBRC workshop on jet correlations

- March 11, 2005

## From Theoretical Prediction

**Notes:**
For anyone who is observing the RHIC physics, jet physics has never failed to bring excitement to the field. Though, we have come a long way

## To the first hints of jet quenching

## To explicit jet quenching 

## And medium modification

- F. Wang

- W. Holtzman

## Theoretical development

- Bjorken (82): elastic energy loss
- Gyulassy & XNW (94) radiative energy loss
- Zakharov (96), Baier et al (97)
- Gyulassy-Levai-Vitev (00);Wiedemann (01); Guo-Wang (01)

**The field has matured.**** **
**But do we understand what is really going on ?**

## Suppression of spectra at 63 GeV

- Less suppression but
- Similar to 200 GeV as
- predicted given no new
- physics happening:

- XNW
- Vitev
- Adil & Gyulassy

## Energy Dependence of quenching

- D. d’Enterria, Hard Probes 2004

**63 GeV**

## Effect of non-Abelian energy loss

***E**g**=****E**q*

***E**g**=2****E**q*

- Qun Wang & XNW nucl-th/0410079

## Effect of non-Abelian energy loss

## Reaction plane dependence of away-side

## Reaction plane dependence of R_AA

- B. Cole, Hard Probes 2004

## Hadron Correlations in jets

- Away-side correlation:
- 	Modification of single hadron distribution inside a jet

## Effect of radiated gluons

- Fragmentation of
- Gluon with a few
- GeV energy?

- Other medium
- Effects?

## Abnormal angular distribution

## Sonic Boom

- M

- Trigger

- Casalderrey-Solana, Shuryak and Teaney

- Linearize disturbance

- Can hydro equation be applied to a few particles?
- (2) Transverse expansion?

- Dumitru

## Background, background, ...

- Pedestal

## The Devil is in the details

- Background subtraction

- Small number of particles!

- Ying Guo

- Voloshin

## Angular distribution of radiative gluons

- Vitev

- Radiation in vacuum

- Further interaction of the radiated gluons with the medium?

## What about DIS e+A?

- Jet quenching observed

- pT broadening of leading hadron or suppression of low pt hadrons:

- Dominance of leading hadrons from the jet with reduced energy

- Usefulness of dihadron distribution (fragmentation)

## Di-hadron fragmentation function

**Di-hadron fragmentation function**

- Majumder

## Modification of the dihadron distribution

## Parton recombination

- Hwa; Fries

- Particle or parton correlations are not trivial

## Parton recombination revisited

## Modification due to recombination

## Future of Jet quenching 

- +jet correlation in Au+Au in run4?

- More accurate determination of initial Et

## Modification for Heavy Quarks

- (1) Slow clock for formation time

- Djordjevic & Gyulassy
- Zhang & XNW
- Armesto,Dainese, Salgado & Wiedemann

- (2) Color factor

- (3) Dead cone effect

- EQ<Eg, Eq

- Zhang & XNW

## Charm quark

- Large charm quark
- Suppression?

- Hadronic scattering?

## Light-heavy quark correlation

- Charm quark as a trigger:
- Distribution of radiative gluons
- Sonic boom associated with a large pt charm quark
- Jet physics at LHC: abundant

## Summary

- Beginning of jet tomography study
- Details of modified fragmentation
- Heavy quark fragmentation
- Dihadron fragmentation
- Jet-gamma events