Hadronization from Hadronization from DIS at CLASDIS at CLASK. HicksK. Hicks** (CLAS Collaboration) (CLAS Collaboration)

DIS 2009 Conference, MadridDIS 2009 Conference, Madrid

April 27, 2009April 27, 2009*working with Aji Daniel and the eg2 run-group.

Ken Hicks, Ohio U.Ken Hicks, Ohio U. DIS 2009, April 27DIS 2009, April 27 22

IntroductionIntroduction

Goal: measure observables of quark Goal: measure observables of quark propagation through cold QCD matter.propagation through cold QCD matter.

Pions: PhD work of H. Hakobyan (Yerevan)Pions: PhD work of H. Hakobyan (Yerevan) Kaons: work of postdoc A. Daniel (Ohio)Kaons: work of postdoc A. Daniel (Ohio)

Do kaons hadronize differently than pions?Do kaons hadronize differently than pions? Heavy s-quarks could affect the hadronization.Heavy s-quarks could affect the hadronization.

KK++ and K and K-- attenuation ratios differ (HERMES). attenuation ratios differ (HERMES). No difference between No difference between ++, , -- or or 00.. New: KNew: K00 attenuation ratios (not done by HERMES). attenuation ratios (not done by HERMES).

Ken Hicks, Ohio U.Ken Hicks, Ohio U. DIS 2009, April 27DIS 2009, April 27 33

Deep Inelastic ScatteringRelativistic Heavy-Ion Collisions

e e’

Initial quark energy is knownProperties of medium are known

Relevance to RHICRelevance to RHIC

These experiments try to recreate conditions of the early universe.

Graphics by Will Brooks

Ken Hicks, Ohio U.Ken Hicks, Ohio U. DIS 2009, April 27DIS 2009, April 27 44

ObservablesObservables

Hadronic multiplicity ratio: Transverse momentum:

DIS

DT

DIS

ATT ppp 222

Binning:

Q2 (range 1.0-2.5 GeV2) (range 2.6-4.3 GeV) z (range 0.1-1.0)

Ken Hicks, Ohio U.Ken Hicks, Ohio U. DIS 2009, April 27DIS 2009, April 27 55

Theoretical ModelsTheoretical Models

No (dynamical) lattice calculations yet.No (dynamical) lattice calculations yet. Accardi et al. (nucl-th/0211011):Accardi et al. (nucl-th/0211011):

gluon radiation and absorption included.gluon radiation and absorption included. good agreement with HERMES data.good agreement with HERMES data. increased increased deconfinementdeconfinement in nuclei. in nuclei.

Many other phenomenological models.Many other phenomenological models.

Ken Hicks, Ohio U.Ken Hicks, Ohio U. DIS 2009, April 27DIS 2009, April 27 66

Inside the ModelsInside the Models

HERMES: K+ and K- different.

Ken Hicks, Ohio U.Ken Hicks, Ohio U. DIS 2009, April 27DIS 2009, April 27 77

CLAS – the CEBAF Large Acceptance Spectrometer

Ken Hicks, Ohio U.Ken Hicks, Ohio U. DIS 2009, April 27DIS 2009, April 27 88

eg2: pion attenuationeg2: pion attenuation

H. Hakobyan analysis: one of ~50 bins

Ken Hicks, Ohio U.Ken Hicks, Ohio U. DIS 2009, April 27DIS 2009, April 27 99

Examples of multi-variable Examples of multi-variable (preliminary) CLAS data(preliminary) CLAS data

zh dependence

Q2 dependence

pT2 dependence

dependence

Ken Hicks, Ohio U.Ken Hicks, Ohio U. DIS 2009, April 27DIS 2009, April 27 1010

ppTT Broadening and Quark Broadening and Quark Energy LossEnergy Loss

nucleus

propagating quark

quarks in nuclei

gluons

L

Quarks lose energy by Quarks lose energy by gluon emissiongluon emission as they propagate within a mediumas they propagate within a medium

Medium-stimulated losscalculation by BDMPS

ThisThisenergy loss is manifested by energy loss is manifested by pT2

pT2 gives the production time p

E ~ L dominates in QEDE ~ L dominates in QED

E ~ LE ~ L22 dominates in QCD? dominates in QCD?

Ken Hicks, Ohio U.Ken Hicks, Ohio U. DIS 2009, April 27DIS 2009, April 27 1111

eg2: pion peg2: pion pTT broadening broadening

H. Hakobyan analysis

Pb

Fe

C

pT

2

(GeV)

Ken Hicks, Ohio U.Ken Hicks, Ohio U. DIS 2009, April 27DIS 2009, April 27 1212

A-dependence of A-dependence of ppTT22

Only statistical errors shown

Only one of many bins of CLAS data

Ken Hicks, Ohio U.Ken Hicks, Ohio U. DIS 2009, April 27DIS 2009, April 27 1313

KK00 from M( from M(++--) at ) at z=0.55z=0.55

M(+-) [GeV]

LD2 target Fe target

Ken Hicks, Ohio U.Ken Hicks, Ohio U. DIS 2009, April 27DIS 2009, April 27 1414

z-dependence of Kz-dependence of K00 peakpeak

(CLAS PRELIMINARY)

Ken Hicks, Ohio U.Ken Hicks, Ohio U. DIS 2009, April 27DIS 2009, April 27 1515

KK00 Multiplicity Ratio Multiplicity Ratio

z = Eh/

(CLAS PRELIMINARY)

Ken Hicks, Ohio U.Ken Hicks, Ohio U. DIS 2009, April 27DIS 2009, April 27 1616

KK00 broadening of <p broadening of <ptt22>>

(CLAS PRELIMINARY)

Ken Hicks, Ohio U.Ken Hicks, Ohio U. DIS 2009, April 27DIS 2009, April 27 1717

KK00 Cronin Effect Cronin Effect

(CLAS PRELIMINARY)

Ken Hicks, Ohio U.Ken Hicks, Ohio U. DIS 2009, April 27DIS 2009, April 27 181812

GeV

Anti

cipate

d D

ata

12

GeV

Anti

cipate

d D

ata

Bins in yellow accessible at 5 GeV at CLAS

+

Ken Hicks, Ohio U.Ken Hicks, Ohio U. DIS 2009, April 27DIS 2009, April 27 1919

SummarySummary There is good statistical precision of the pion There is good statistical precision of the pion

data at 5 GeV.data at 5 GeV. Hadronization ratios, Hadronization ratios, ppTT

22, and Cronin effect. , and Cronin effect. Results are still preliminary but nearly final.Results are still preliminary but nearly final.

There is modest statistical precision for the KThere is modest statistical precision for the K00 data at 5 GeV.data at 5 GeV. From these data, we hope to learn about the quark From these data, we hope to learn about the quark

mass dependence of hadronization.mass dependence of hadronization. The JLab 12 GeV upgrade creates new The JLab 12 GeV upgrade creates new

possibilities to study quark-matter propagation.possibilities to study quark-matter propagation.

Ken Hicks, Ohio U.Ken Hicks, Ohio U. DIS 2009, April 27DIS 2009, April 27 2020

Backup SlidesBackup Slides

Ken Hicks, Ohio U.Ken Hicks, Ohio U. DIS 2009, April 27DIS 2009, April 27 2121

CLAS EG2CLAS EG2TargetsTargets

• Two targets in the beam simultaneously

• 2 cm LD2, upstream

• Solid target downstream

• Six solid targets:

-Carbon

-Aluminum (2 thicknesses)

-Iron

-Tin

-Lead

Al +emptytarget

Ken Hicks, Ohio U.Ken Hicks, Ohio U. DIS 2009, April 27DIS 2009, April 27 2222

Cronin Cronin EffectEffect

Carbon

Iron

Lead

Theoretical prediction:

CLAS preliminary dataz=0.5 and 0.7

Probes reaction mechanism