Hadronization from DIS at CLAS K Hicks CLAS

Hadronization from DIS at CLAS K. Hicks* (CLAS Collaboration) DIS 2009 Conference, Madrid April 27, 2009 *working with Aji Daniel and the eg 2 run-group. Ken Hicks, Ohio U. DIS 2009, April 27

Introduction § Goal: measure observables of quark propagation through cold QCD matter. § Pions: Ph. D work of H. Hakobyan (Yerevan) § Kaons: work of postdoc A. Daniel (Ohio) § Do kaons hadronize differently than pions? § Heavy s-quarks could affect the hadronization. § K+ and K- attenuation ratios differ (HERMES). § No difference between p+, p- or p 0. § New: K 0 attenuation ratios (not done by HERMES). Ken Hicks, Ohio U. DIS 2009, April 27 2

Relevance to RHIC Relativistic Heavy-Ion Collisions Deep Inelastic Scattering p p e These experiments try to recreate conditions of the early universe. Ken Hicks, Ohio U. e’ Initial quark energy is known Properties of medium are known DIS 2009, April 27 Graphics by Will Brooks 3

Observables Hadronic multiplicity ratio: Transverse momentum: Binning: Q 2 (range 1. 0 -2. 5 Ge. V 2) n (range 2. 6 -4. 3 Ge. V) z (range 0. 1 -1. 0) Ken Hicks, Ohio U. DIS 2009, April 27 4

Theoretical Models § No (dynamical) lattice calculations yet. § Accardi et al. (nucl-th/0211011): § gluon radiation and absorption included. § good agreement with HERMES data. § increased deconfinement in nuclei. § Many other phenomenological models. Ken Hicks, Ohio U. DIS 2009, April 27 5

Inside the Models HERMES: K+ and Kdifferent. Ken Hicks, Ohio U. DIS 2009, April 27 6

CLAS – the CEBAF Large Acceptance Spectrometer Ken Hicks, Ohio U. DIS 2009, April 27 7

eg 2: pion attenuation H. Hakobyan analysis: one of ~50 bins Ken Hicks, Ohio U. DIS 2009, April 27 8

Examples of multi-variable (preliminary) CLAS data Q 2 dependence n dependence p. T 2 dependence zh dependence Ken Hicks, Ohio U. DIS 2009, April 27 9

p. T Broadening and Quark Energy Loss § Quarks lose energy by gluon emission as they propagate within a medium n This energy loss is manifested by Dp. T 2 n Dp. T 2 gives the production time tp n DE ~ L dominates in QED n DE ~ L 2 dominates in QCD? gluons propagating quarks in nuclei L Ken Hicks, Ohio U. nucleus DIS 2009, April 27 Medium-stimulated loss calculation by BDMPS 10

eg 2: pion p. T broadening H. Hakobyan analysis Pb Dp. T 2 Fe C n (Ge. V) Ken Hicks, Ohio U. DIS 2009, April 27 11

A-dependence of Dp. T 2 Only statistical errors shown Only Ken Hicks, Ohio U. f o e n o m ta a d AS L C f ns o i b y an DIS 2009, April 27 12

0 K from + M(p p ) at z=0. 55 LD 2 target Ken Hicks, Ohio U. +p-) April DIS 2009, 27 M(p [Ge. V] Fe target 13

z-dependence of 0 K peak (CLAS PRELIMINARY) Ken Hicks, Ohio U. DIS 2009, April 27 14

0 K Multiplicity Ratio (CLAS PRELIMINARY) z = Eh/n Ken Hicks, Ohio U. DIS 2009, April 27 15

K 0 broadening of <pt 2> (CLAS PRELIMINARY) Ken Hicks, Ohio U. DIS 2009, April 27 16

K 0 Cronin Effect (CLAS PRELIMINARY) Ken Hicks, Ohio U. DIS 2009, April 27 17

12 Ge. V Anticipated Data p+ Ken Hicks, Ohio U. DIS 2009, April 27 Bins in yellow accessible at 5 Ge. V at CLAS 18

Summary § There is good statistical precision of the pion data at 5 Ge. V. § Hadronization ratios, Dp. T 2, and Cronin effect. § Results are still preliminary but nearly final. § There is modest statistical precision for the K 0 data at 5 Ge. V. § From these data, we hope to learn about the quark mass dependence of hadronization. § The JLab 12 Ge. V upgrade creates new possibilities to study quark-matter propagation. Ken Hicks, Ohio U. DIS 2009, April 27 19

Backup Slides Ken Hicks, Ohio U. DIS 2009, April 27 20

CLAS EG 2 Targets • Two targets in the beam simultaneously • 2 cm LD 2, upstream • Solid target downstream • Six solid targets: -Carbon -Aluminum (2 thicknesses) -Iron -Tin -Lead Ken Hicks, Ohio U. DIS 2009, April 27 Al + empty target 21

Cronin Effect Theoretical prediction: Carbon Probes reaction mechanism Iron Lead Ken Hicks, Ohiodata U. CLAS preliminary z=0. 5 and 0. 7 DIS 2009, April 27 22