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

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

4. Dynamical energy loss Computed radiative and collisional energy loss in finite size dynamical QCD medium of 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. M. Djordjevic 5 Numerical procedure Light flavor production Z.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/psi according 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. Adare et al., Phys. Rev. Lett. 104, 132301 (2010) (PHENIX Collab.)

6. M. Djordjevic 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. M. Djordjevic 7 Comparison with LHC data (central collision) Very good agreement with diverse probes! M. D. and M. Djordjevic, arXiv:1307.4098 (PLB, in press)

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

9. M. Djordjevic 9 Charged hadrons vs D meson R AA R AA (h ± ) = R AA (D) Excellent agreement with the data! Disagreement with the qualitative expectations! M.D., PRL 112, 042302 (2014) ALICE data

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

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

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

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

16. M. Djordjevic 16 R AA vs. N part 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. M. Djordjevic 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. M. Djordjevic 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 Ministry of Science and Education in Serbia FP7 Marie Curie International Reintegration grant L’Oreal UNESCO For Women in Science 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. M. Djordjevic 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. M. Djordjevic 21 The end

22. M. Djordjevic 22 The dynamical energy loss formalism is based on HTL perturbative QCD, which requires zero magnetic mass. Finite 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. M. Djordjevic 23 Generalization of radiative jet energy loss to finite magnetic mass M.D. and M. Djordjevic, Phys.Lett.B709:229,2012 zero magnetic mass From our analysis, only this part gets modified. Finite magnetic mass:, where.

24. 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 Various non-perturbative approaches suggest that, at RHIC and LHC, 0.4 < μ M /μ E < 0.6. M.D. and M. Djordjevic, Phys.Lett.B709:229,2012

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