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Jet suppression at LHC: theory vs. experiment Magdalena Djordjevic

Jet suppression at LHC: theory vs. experiment Magdalena Djordjevic Institute of Physics Belgrade, University of Belgrade. Jet suppression at LHC. Light and heavy flavour suppressions are excellent probes of QCD matter.

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Jet suppression at LHC: theory vs. experiment Magdalena Djordjevic

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  1. Jet suppression at LHC: theory vs. experiment Magdalena Djordjevic Institute of Physics Belgrade, University of Belgrade

  2. Jet suppression at LHC Light and heavy flavour suppressions are excellent probes of QCD matter. Suppression for a number of observables at LHC has been measured. Comparison of theory with the experiments allow testing our understanding of QCD matter.

  3. e-, J/ hadrons partons 1) production 2) medium energy loss 3) fragmentation 4) decay Jet suppression Initial momentum distributions for partons Parton energy loss Fragmentation functions of partons into hadrons Decay of heavy mesons to single e-and J/.

  4. Dynamical energy loss Computed both collisional and radiative energy loss in finite size dynamical QCD mediumof thermally distributed massless quarks and gluons. Abolishes approximation of static scatterers. M. D. PRC 80:064909 (2009), M. D. and U. Heinz, PRL 101:022302 (2008). Finite magnetic mass effects. M. D. and M. Djordjevic, PLB 709:229 (2012) Includes running coupling M. D. and M. Djordjevic, arXiv:1307.4098

  5. Numerical procedure • Light flavor productionZ.B. Kang, I. Vitev, H. Xing, PLB 718:482 (2012) • Heavy flavor production M. Cacciari et al., JHEP 1210:137 (2012) • Path-length fluctuations • WHDG, NPA 784:426 (2007), A. Dainese, EPJ C33:495 (2004) • Multi-gluon fluctuations • M. Gyulassy, P. Levai, I. Vitev, PLB 538:282 (2002). • DSS and KKP fragmenation for light flavor • D. de Florian, R. Sassot, M. Stratmann, PRD 75:114010 (2007) • B. A. Kniehl, G. Kramer, B. Potter, NPB 582:514 (2000) • BCFY and KLP fragmenation for heavy flavor • M. Cacciari, P. Nason, JHEP 0309: 006 (2003) • Decays of heavy mesons to single electron and J/according to • M. Cacciari et al., JHEP 1210:137 (2012) • Temperature T=304 MeV • M. Wilde, Nucl. Phys. A 904-905:573c (2013) (ALICE Collab.)

  6. Generating predictions • Provide joint predictions across diverse probes • charged hadrons, pions, kaons, D mesons, • non-photonic single electorns, non-prompt J/ • M. D. and M. Djordjevic, arXiv:1307.4098 • Puzzles (apparently surprising data) • Measured charged hadron vs. D meson supression • M. D., arXiv:arXiv:1307.4702 • Fine resolution hierarchy • Measured pionvs.kaon suppression • M. D. and M. Djordjevic, arXiv:1307.4714 • All predictions generated • By the same formalism • With the same numerical procedure • No free parameters in model testing

  7. Comparison with LHC data M. D. and M. Djordjevic, arXiv:1307.4098 ALICE and CMS data ALICE data ALICE data ALICE data ALICE data CMSdata Very good agreement with diverse probes!

  8. Heavy flavor puzzle at LHC Significant gluon contribution in charged hadrons Much larger gluon suppression RAA (h±) < RAA (D)

  9. Charged hadrons vs D meson RAA ALICE data RAA (h±) = RAA (D) Excellent agreement with the data! Disagreement with the qualitative expectations! M. D., arXiv:arXiv:1307.4702

  10. Hadron RAAvs.parton RAA D meson is a genuine probe of bare charm quark suppression Distortion by fragmentation Charged hadron RAA = light quark RAA M. D., arXiv:arXiv:1307.4702

  11. Puzzle summary RAA (h±) = RAA (light quarks) RAA (light quarks) = RAA (charm) RAA (D) = RAA (charm) RAA (h±) = RAA (D) Puzzle explained! M. D., arXiv:arXiv:1307.4702

  12. Fine resolution hierarchy ALICE and CMS data ALICE data ALICE data ALICE data ALICE data CMS data

  13. Pionvs.kaon RAA ALICE data Clear (fine resolution) hierarchy between pion and kaon RAAs. Disagreement Agreement M. D. and M. Djordjevic, arXiv:1307.4714

  14. KKP vs. DSS A reversed hierarchy in gluon to light quark contributions! M. D. and M. Djordjevic, arXiv:1307.4714

  15. Summary The dynamical energy loss can simultanuously explain measurements for a diverse set of probes at LHC. The formalism can explain puzzling data (“the heavy flavor puzzle at LHC”). Charged hadron suppression is a genuine probe of light quark suppression, which can considerably simplify interpretation of the relevant data. Can explain fine resolution hierarchy.

  16. Acknowledgement FP7 Marie Curie International Reintegration grant L’Oreal UNESCO For Women in Science Serbia Ministry of Science and Education in Serbia • Many thanks to: • M. Djordjevic for collaboration on this project. • I. Vitev and Z. Kang for providing the initial light flavor distributions and useful discussions. • M. Cacciari for useful discussions on heavy flavor production and decay processes. • ALICE Collaboration for providing the preliminary data • M. Stratmann and Z. Kang for help with DSS fragmentation functions.

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