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Theoretical predictions of jet suppression: a systematic comparison with RHIC and LHC data

Theoretical predictions of jet suppression: a systematic comparison with RHIC and LHC data Magdalena Djordjevic Institute of Physics Belgrade, University of Belgrade. Jet suppression. Light and heavy flavour suppressions are excellent probes of QCD matter.

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Theoretical predictions of jet suppression: a systematic comparison with RHIC and LHC data

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  1. Theoretical predictions of jet suppression: a systematic comparison with RHIC and LHC data Magdalena Djordjevic Institute of Physics Belgrade, University of Belgrade

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

  3. e-, J/psi 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/psi.

  4. Dynamical energy loss Computed radiative and collisional 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 (PLB, in press)

  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 A. Dainese, EPJ C33:495,2004. • Multi-gluon fluctuations • M. Gyulassy, P. Levai, I. Vitev, PLB 538:282 (2002). • DSS fragmenation for light flavor • D. de Florian, R. Sassot, M. Stratmann, PRD 75:114010 (2007) • BCFY and KLP fragmenation for heavy flavor • M. Cacciari, P. Nason, JHEP 0309: 006 (2003) • Decays of heavy mesons to single electron and J/psiaccording to • M. Cacciari et al., JHEP 1210, 137 (2012) • Temperature T=304 MeV for LHC and T=221 MeV for RHIC. • M. Wilde, Nucl. Phys. A 904-905, 573c (2013) (ALICE Collab.) • A. Adareet al., Phys. Rev. Lett. 104, 132301 (2010) (PHENIX Collab.)

  6. Generating predictions • Provide joint predictions across diverse probes • charged hadrons, pions, kaons, D mesons, • non-photonic single electorns, non-prompt J/psi • M. D. and M. Djordjevic, arXiv:1307.4098 (PLB, in press) • Puzzles (apparently surprising data) • Measured charged hadron vs. D meson supression • M.D., PRL 112, 042302 (2014) • Concentrate on all centrality regions • M. D., M. Djordjevic and B. Blagojevic, arXiv:1405.4250 All predictions generated • By the same formalism • With the same numerical procedure • No free parameters in model testing

  7. Comparison with LHC data (central collision) M. D. and M. Djordjevic, arXiv:1307.4098 (PLB, in press) 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., PRL 112, 042302 (2014)

  10. Hadron RAAvs.parton RAA D meson is a genuine probe of bare charm quark suppression Distortion by fragmentation Charged hadron RAA = (bare) light quark RAA M.D., PRL 112, 042302 (2014)

  11. Puzzle explanation RAA (h±) = RAA (light quarks) RAA (light quarks) = RAA (charm) RAA (D) = RAA (charm) RAA (h±) = RAA (D) Puzzle explained! M.D., PRL 112, 042302 (2014)

  12. Comparison with RHIC data (central collisions) RHIC Very good agreement!

  13. Non central collisions @ LHC (fixed centrality and charged hadrons) An excellent agreement for different centrality regions! M. D., M. Djordjevic and B. Blagojevic, arXiv:1405.4250

  14. Non central collisions @ LHC (fixed centrality and D mesons) Excellent agreement! Predictions for upcoming measurements. M. D., M. Djordjevic and B. Blagojevic, arXiv:1405.4250

  15. Non central collisions @ RHIC (fixed centrality and neutral pions) Also a good agreement for RHIC! M. D., M. Djordjevic and B. Blagojevic, arXiv:1405.4250

  16. RAAvs.Npart for RHIC and LHC Very good agreement for both RHIC and LHC and for whole set of probes! M. D., M. Djordjevic and B. Blagojevic, arXiv:1405.4250

  17. Assessing medium model A robust agreement with suppression data, for different probes, experiments and centrality regions. Predictions are generated with the same model, parameter set and with no free parameters. NOTE: We use a sophisticated energy loss model, but do not explicitly include the medium evolution (i.e. we take average/effective medium parameters).

  18. PROPOSAL: Medium evolution may not be a major effect in hard probe (>10 GeV) suppression. HYPOTHESIS: High energy jets sense only the average (effective) medium conditions. CONSEQUENCE: May significantly simplify both generating predictions and analyzing phenomena behind experimental data.

  19. 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 and B. Blagojevic 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.

  20. Main results The dynamical energy loss can simultaneously explain central-collision measurements for a diverse set of probes at LHC and RHIC. The formalism can explain puzzling data (“the heavy flavor puzzle at LHC”). We obtain a very good agreement with the non-central collision data as well. Results suggest that the medium evolution is not a major effect for suppression of hard probes.

  21. The end

  22. Finite magnetic mass The dynamical energy loss formalism is based on HTL perturbative QCD, which requires zero magnetic mass. However, different non-perturbative approaches show a non-zero magnetic mass at RHIC and LHC. Can magnetic mass be consistently included in the dynamical energy loss calculations?

  23. Generalization of radiative jet energy loss to finite magnetic mass zero magnetic mass From our analysis, only this part gets modified. Finite magnetic mass: , where . M.D. and M. Djordjevic, Phys.Lett.B709:229,2012

  24. A simple constraint on the magnetic mass If magnetic mass is larger than electric mass, the quark jet would, overall, start to gain (instead of lose) energy in this type of plasma. An apparent violation of the second law of thermodynamics. It is impossible to observe a plasma with magnetic mass larger than electric M.D. and M. Djordjevic, Phys.Lett.B709:229,2012 Various non-perturbative approaches suggest that, at RHIC and LHC, 0.4 < μM/μE < 0.6.

  25. Running coupling Collisional energy loss Radiative energy loss M. D. and M. Djordjevic, arXiv:1307.4098 q k,c p q,a p

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