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RHIC Strategy Meeting Wayne State University, August 24, 2013 Uncertainties in jet event generators due to hadronizaton scheme, Other issues with energy loss on E-by-E hydro, and the extraction of transport coefficients Rainer Fries Texas A&M University RHIC Strategy Meeting Wayne State University, August 24, 2013 Hadronization, Chemistry and Other Issues Rainer Fries Texas A&M University Hadronization Hadronization: Challenge or Opportunity? HQ sector Quark number scaling Extraction of Jet/High-PT Physics: JET Hadronization Module Flavor conversions revisited Rainer Fries RHIC Strategy 2013 3 Hadrons in Heavy Ion Collisions Proton/pion ratio RAA “Universal” hadronization in thermalized (low PT) and pure fragmentation (high PT) region. Intermediate momentum region in heavy ion collisions (2-8 GeV): No kinetic equilibrium; Multi-particle dynamics; No microscopic description of parton dynamics. Rainer Fries RHIC Strategy 2013 4 Can Hadronization Tell Us About QGP? Example: Quark Number dependent phenomena Usual interpretation: quark degrees of freedom were active in the collision. Rainer Fries RHIC Strategy 2013 5 Heavy Quark Sector I Recombination forces heavy quarks to feel the collective flow. Charm to D-meson coalescence in a recombination model with correct equilibrium limit. Recombination rate ~ c+light quark elastic scattering rate near Tc. Rainer Fries RHIC Strategy 2013 6 Heavy Quark Sector II Flavor effects in the heavy quark sector: Ds vs D Changes in chemistry are often hadronization effects. Rainer Fries RHIC Strategy 2013 7 C. Suarez (STAR), poster, QM2008 inclusive Au+Au: M. Lamont (STAR) SQM06 Cu+Cu: C. Nattrass (STAR), QM2008 Au+Au: J.B. (STAR), WWND07 Chemistry in Jet and Ridge pTtrig > 4.0 GeV/c 2.0 < pTassoc < pTtrig Au+Au: 2<pTtrig<3 GeV/c,Cu+Cu:3<pTtrig<6 GeV/c PHENIX, arXiv:0712.3033 Rainer Fries Jana Bielcikova Baryon/meson ratios: •“jet”: smaller than inclusive and similar to p+p • ridge: similar to inclusive RHIC Strategy 2013 Jana Bielcikova, Hard Probes 82008 Recombination in Jet Showers JET goal: jet shower Monte Carlo including medium-modified hadronization Well-established hadronization models for vacuum shower Monte-Carlo’s Lund string fragmentation Cluster hadronization How to generalize to jets in a medium? Recombination Challenge: get vacuum fragmentation right. Advantage: medium effects are straight forward to implement; does well with heavy ion single particle spectra. Need event-by-event formalism; momentum and energy conservation in each shower are important. Need to include space-time information. Rainer Fries RHIC Strategy 2013 9 String Fragmentation Here: PYTHIA parton showers, will eventually work with MM showers Standard PYTHIA Lund string fragmentation: Lund String String Decay Rainer Fries RHIC Strategy 2013 10 Recombination + Remnant Strings Here: PYTHIA parton showers, will eventually work with MM showers Standard PYTHIA Lund string fragmentation: Lund String Our approach: Force gluon decay String Decay Recombine Remnant strings String Decay Rainer Fries RHIC Strategy 2013 11 Recombine Quarks In absence of space-time information integrate out spatial coordinates in the Wigner functions. Monte-Carlo implementation of recombination probabilities Direct recombination produces hard spectra. Allow recombination into resonances with subsequent decay Mesons: π, ρ, a1, K, K*, and K1 Baryons N, N’, Δ, and Δ’ Reconnect remnant quarks by short strings that fragment. Rainer Fries RHIC Strategy 2013 12 Event-By-Event Vacuum Fragmentation Reproduction of vacuum fragmentation compares favorably to PYTHIA string fragmentation. + 100 GeV light quark jets in e +e [K. Han, C.M. Ko, R.J.F., arxiv:1209.1141] Lessons learnt: Resonances important. Event-by-event calculation important. Rainer Fries RHIC Strategy 2013 13 Adding Medium Partons Sampling thermal partons from a blastwave model (T=170 MeV, <v> = 0.6 (0.65)). Allow recombination of thermal partons Recombine Remnant strings Rainer Fries RHIC Strategy 2013 14 Shower-Thermal Recombination Pions and protons at RHIC. Thermal-thermal added. Baryon production clearly enhanced by shower-thermal recombination. Rainer Fries RHIC Strategy 2013 15 Recover Baryon Enhancement Proton/pion ratio is enhanced by shower-thermal recombination. Rainer Fries RHIC Strategy 2013 16 Lessons So Far? Hadronization effects in jets: too early to tell the full story Extrapolating from heavy quarks: jet-thermal recombination adds a layer of diffusion and makes “hard” hadrons feel collective flow. Broadening? Larger v2? Rainer Fries RHIC Strategy 2013 17 Conversions Example 1: excess production of particles which are rare in the medium and rare in the probe sample jet photon dN rare 1 jet N dt Example: photons Need enough yield to outshine other sources of Nrare. Example 2: chemical equilibration of a rare probe particle g s e.g. g s s g N rare, excess L N jet [RJF, Müller, Srivastava] [Srivastava, Gale, RJF] [Zakharov], ….. [Zhang, Vitev] [Renk] s w jet 5% u d jet @ 10 GeV for RHIC s wce 50% u d medium Example: strangeness at RHIC Coupling of jets (not equilibrated) to the equilibrated medium should drive jets towards chemical equilibrium. Quark-gluon conversion proton/pion ratio Rainer Fries RHIC Strategy 2013 [W. Liu, RJF, PRC 77 (2008)] [W. Liu, RJF, PRC 78 (2008)] 18 Conclusions Chemistry: Need identified hadrons up to 8-10 GeV with good statistics. Diffusion: out-of-cone energy/momentum in jet measurements near-side correlations of hadrons Rainer Fries RHIC Strategy 2013 19