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Hadronization from DIS at CLAS

Hadronization from DIS at CLAS. K. Hicks * (CLAS Collaboration) DIS 2009 Conference, Madrid April 27, 2009. *working with Aji Daniel and the eg2 run-group. Introduction. Goal: measure observables of quark propagation through cold QCD matter. Pions: PhD work of H. Hakobyan (Yerevan)

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Hadronization from DIS at CLAS

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  1. Hadronization from DIS at CLAS K. Hicks* (CLAS Collaboration) DIS 2009 Conference, Madrid April 27, 2009 *working with Aji Daniel and the eg2 run-group.

  2. Introduction • Goal: measure observables of quark propagation through cold QCD matter. • Pions: PhD 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 p0. • New: K0 attenuation ratios (not done by HERMES). DIS 2009, April 27

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

  4. Observables Hadronic multiplicity ratio: Transverse momentum: Binning: Q2 (range 1.0-2.5 GeV2) n (range 2.6-4.3 GeV) z (range 0.1-1.0) DIS 2009, April 27

  5. 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. DIS 2009, April 27

  6. Inside the Models HERMES: K+ and K- different. DIS 2009, April 27

  7. CLAS– the CEBAF Large Acceptance Spectrometer DIS 2009, April 27

  8. eg2: pion attenuation H. Hakobyan analysis: one of ~50 bins DIS 2009, April 27

  9. Examples of multi-variable (preliminary) CLAS data Q2 dependence n dependence pT2 dependence zh dependence DIS 2009, April 27

  10. gluons propagating quark quarks in nuclei L nucleus pT Broadening and Quark Energy Loss • Quarks lose energy by gluon emission as they propagate within a medium • Thisenergy loss is manifested by DpT2 • DpT2 gives the production time tp • DE ~ L dominates in QED • DE ~ L2 dominates in QCD? Medium-stimulated loss calculation by BDMPS DIS 2009, April 27

  11. H. Hakobyan analysis Pb Fe C DpT2 n (GeV) eg2: pion pT broadening DIS 2009, April 27

  12. A-dependence of DpT2 Only statistical errors shown Only one of many bins of CLAS data DIS 2009, April 27

  13. K0 from M(p+p-) at z=0.55 LD2 target Fe target M(p+p-) [GeV] DIS 2009, April 27

  14. z-dependence of K0 peak (CLAS PRELIMINARY) DIS 2009, April 27

  15. K0 Multiplicity Ratio (CLAS PRELIMINARY) z = Eh/n DIS 2009, April 27

  16. K0 broadening of <pt2> (CLAS PRELIMINARY) DIS 2009, April 27

  17. K0 Cronin Effect (CLAS PRELIMINARY) DIS 2009, April 27

  18. p+ 12 GeV Anticipated Data 12 GeV Anticipated Data DIS 2009, April 27 Bins in yellow accessible at 5 GeV at CLAS

  19. Summary • There is good statistical precision of the pion data at 5 GeV. • Hadronization ratios, DpT2, and Cronin effect. • Results are still preliminary but nearly final. • There is modest statistical precision for the K0 data at 5 GeV. • From these data, we hope to learn about the quark mass dependence of hadronization. • The JLab 12 GeV upgrade creates new possibilities to study quark-matter propagation. DIS 2009, April 27

  20. Backup Slides DIS 2009, April 27

  21. CLAS EG2Targets • Two targets in the beam simultaneously • 2 cm LD2, upstream • Solid target downstream • Six solid targets: • -Carbon • -Aluminum (2 thicknesses) • -Iron • -Tin • -Lead Al + empty target DIS 2009, April 27

  22. Cronin Effect Theoretical prediction: Probes reaction mechanism Carbon Iron Lead CLAS preliminary data z=0.5 and 0.7 DIS 2009, April 27

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