1 / 57

Hot Topic in Identified light/heavy Hadrons at high p T

This overview delves into the intriguing realm of identified heavy hadrons at high transverse momentum. Topics include thermalization of charm, resonances switching, coalescence in meson and baryon spectra, and jet quenching effects. The narrative navigates through key concepts such as baryon/meson quenching, parton spectrum, and fragmentation, shedding light on the evolving landscape of heavy-ion collisions. Noteworthy discussions touch upon various theories and observations surrounding phase-space coalescence, particle spectra enhancements, and v2 scaling. The interplay between hydrodynamics, jet fragmentation, and coalescence phenomena unveils fascinating intricacies, influencing the study of charm quark interactions and resonances. The text articulates trends in experimental data and theoretical models, exploring the complexities of particle interactions in high-energy nuclear collisions.

tmaddox
Download Presentation

Hot Topic in Identified light/heavy Hadrons at high p T

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Hot Topic in Identified light/heavy Hadrons at high pT ? V. Greco Universita di Catania INFN-LNS Future of ALICE - CERN, 12-13 July 2011

  2. Charm-Bottom Thermalization? Shadowing not included. Spectra same parameter of PPR-ALICE initial initial Don’t look at B • LHC spectra considerably harder ! • At Tc charm nearly thermalized • Resonances switched-off at 2 Tc, both B and D

  3. Outline • Modified hadronization by coalescence (?!): • - coalescence a little beyond pT/2+pT/2 -> pT • - relevance at LHC • - when pure fragmentation and jet quenching sets in? • Is there a tool to follow theorethically PID physics at 2 < pt < 20 GeV? - first result from a transport approach • Do we have a QGP or a Quark plasma? - open issue in identified hadrons up and beyond 10 GeV

  4. Surprises… Baryon/Mesons Quenching Au+Au p+p p0 suppression: evidence of jet quenching before fragmentation PHENIX, PRL89(2003) In vacuum pp collisions: p/p ~ 0.3 Protons appear not suppressed! • Jet quenching should affect both Hadronization has been modified pT < 5-6GeV !? (> 10 Tmax)

  5. Hadronization in Heavy-Ion Collisions H Parton spectrum • Initial state: no partons in the vacuum but a thermal ensemble of partons • No direct QCD factorization scale for the bulk: dynamics much less violent (t ~ 4 fm/c) • dense parton systems no need for creation and splitting Fragmentation: • energy needed to create quarks from vacuum • hadrons from higher pT Baryon Coal. Coalescence: Meson • partons are already there $ to be close in phase space $ • ph= n pT ,, n = 2,3 baryons from lower momenta (denser) Fragmentation ReCo pushes out soft physics by factors x2 and x3 ! V. Greco et al./ R.J. Fries et al., PRL 90(2003)

  6. Phase-Space Coalescence (GKL) 3D-geometry with radial flow space-momentum correlation gH statistical factor color-spin-isospin • fqinvariant parton distribution function • thermalwith radial flow(b=0.5r/R) • quenched minijets (GLV- L/l = 3.5) gg -> qq , suppressed by mass (g->qq no dire effects) npQCD also encoded in quark masses (gluon dressing), mq=0.3 GeV, ms=0.475 GeV. fHhadron Wigner function Dx = 1/Dp (real free parameter different) If <r2> is fixed results are nearly indipendent on the w.f. shape

  7. Parton bulk matter parameters T=170 MeV quenched ET ~ 740 GeV T ~ 170 MeV b(r)~ 0.5 r/R soft hard L/l=3.5 P. Levai et al., NPA698(02) e ~ 0.8 GeVfm-3 dS/dy ~ 4800 Parton distributions Experiments lQCD Tc like Hydro Bulk matter consistent with hydro, experiments, lQCD REALITY: one spectrum with correlation kept also at pT < 2 GeV Coalescence at QCD phase transition

  8. FMNB Meson & Baryon Spectra Au+Au @200AGeV (central) sh GKL V. Greco et al., PRL90 (03)202302 PRC68(03) 034904 R. Fries et al., PRL90(03)202303 PRC68(03)44902 R. C. Hwa et al., PRC66(02)025205 • Proton suppression hidden by coalescence! ReCo dominates up to 4 (meson)-6(baryon) GeV/c; Fragmentation + energy loss takes over above.

  9. Well there is another special features …

  10. Elliptic flow from Hydro • Mass-dependence of v2(pT) suggests common transverse velocity field large • Larger v2(pT) suggests almost perfect fluid • At higher pT v2 for Baryon=Mesons in both - hydrodynamics - jet fragmentation • Again surprise Baryon ≠Mesons : v2 larger for Baryons

  11. Coalescence carries another features … Coalescence scaling Enhancement of v2 v2q fitted from v2p GKL Considering only momentum space x - p correlation neglected narrow wave function Molnar and Voloshin, PRL91 (2003) • v2 for baryon is larger and saturates at higher pT (more baryons in plane) baryons • Quark number scaling! Again agreement with unexpected observation mesons No free parameter !

  12. RAA–RCP and v2 Correlation Coalescence reverts the correlation Between RAA & v2: both are enhanced Rcp~1 with large v2 P.Sorensen This effect is essential also for the study of charm quark interaction

  13. Going beyond the most naive picture …

  14. w.f. + resonance decay p from K & p * Resonances & v2 scaling K, L, p …v2 not affected by resonances! p coal. moved towards data Greco-Ko, PRC 70 (03)

  15. Wave function & v2 scaling Baryon-to-Meson breaking of the scaling Dp momentum width of w.f. Breaking : • increasing with Dp • decreasing with pT Wavefunction+ Resonance decays

  16. Role of finite mass - 3D 2 schematic case • Importance of 3D phase-space lowering pT • At low pT scaling can be largely broken • but dumped by the shape of v2(pT) • Lower mass lead to larger breaking • of the scaling due to coalescence • between quark with large q=p1-p2 realistic shape The observed scaling tells that the coalescing quarks have small relative momentum!

  17. Has it been observed at LHC? The interesting part is at large pT ! Quark number scaling does not work for proton?! That kind of breaking may be due to many things but is not Anyway the region where coalescence manifest is unique features

  18. Λ/K ratio This exactly what you would expect moving from RHIC to LHC • 3 effects: • more flow (limited effect) • more jet quenching increase the • peak • modified spectra (more density • at intermediate pt)

  19. Consistency between B/M ratio, v2(pt), RAA(B/M) Nearly flat v2(pt) Typical of path-length Mechanism-> jet quenching Important to have PID up to 10 GeV More stringent test to coalescence Hadronization mechanism

  20. Do we have a theorethical approach that can follow the QGP dynamics up to pt ~10-15 GeV? Hydrodynamics does not apply for pt > 2 GeV

  21. Transport Theory Wigner Tranforms + semiclassical approx. Field Interaction -> e≠3P Collisions -> h≠0 Free streaming • valid also at intermediate pT out of equilibrium: region of modified hadronization at RHIC • valid also at high h/s -> LHC and/or hadronic phase • Relevant at LHC due to large amount of minijet production • Appropriate for heavy quark dynamics • can follow exotic non-equilibrium phase CGC: A unified framework against a separate modelling with a wider range of validity in h, z, pT + microscopic level.

  22. Viscous Hydrodynamics Relativistic Navier-Stokes but it violates causality, II0 order expansion needed -> Israel-Stewart tensor based on entropy increase ∂m sm >0 th,tz two parameters appears + df ~ feq reduce the pT validity range • Two effects: • Dissipative correction to um, T, n • Dissipative correction to f -> feq+dfneq There is no one to one correspondence! An Asantz (Grad) Grad

  23. Realistic Calculations No f.o. Hydrodynamics Transport -> Cascade Only collsions for massless particles means cs2=1/3 To Simulate a constant shear viscosity Relativistic Kinetic theory Cascade code =cell index in r-space Viscosity fixed varying s Au+Au 200 GeV

  24. Predicted shift in the lifetime of QGP from the point of view of collective flow build-up 50% more lifetime Agreement with first Estimate from HBT - QM11 50% more lifetime

  25. At low pt like in viscous-hydro good agreement with a fluid at 4ph/s ~ 1 • Very different impact of the cross-over and hadronic region • Intermedate pt tend to be over estimated

  26. Going to the wide pT range Transport – parton level Highly nopQCD Low h/s Disappearing of nonpQCD path-length v2 There is no parameter fine tuning it is just the natural shape coming from Transport theory, allow to have a basic tool to study PID physics from the perfect fluid to perturbative behavior

  27. Prediction of a coalescence + fragmentation model with the shape observed at LHC (consistent with transport theory) coalescence predicts a significant shift in the peak and wide region with v2(p) > v2(p) • For pT> 2-3 GeV • out or hydroflow • out of jet quenching • + fragm. with such a shape • Up to what pt? Coal. only + fragm. At pT=6 GeV nearly a factor of 5 in v2 between p & p w/o fragm. component Universal Flow at high pT ? This has never been observed and indeed it is strictly related to the understanding of RAA(p)/RAA(p) , jet quenching + hadronization mechanism

  28. Scaled plot, only coalescence contribution

  29. Open questions at pt > 8-10 GeV RAA Au+Au central 0-12% • Flavor puzzle But protons should be more suppressed High PT protons less suppressed than pions because they come more from gluons… QM09 protons …and gluons are more suppressed than quarks ΔEg=9/4* ΔEq pions with AKK RAA(q)/RAA(g) ~ 2 RAA(q)/RAA(g)≤1 You should see the opposite in a standard scenario. But indeed with KPP Fragm. Function protons are not gluon dominated. Need for a PID identification of the the jet cone above 10 GeV, indeed already in pp for baryons we need an understanding of frag. Func.

  30. A solution to flavor puzzle: Jet q<->g conversion Inelastic collisions cause a change of the flavor q<->g conversion rate is given by the collisional width Ko, Liu, Zhang Phys. Rev C 75 Liu, Fries Phys. Rev C 77 Scardina, Ditoro, Greco PRC83 Jet flavor conversion makes RAA (p) ~ RAA(p)

  31. The problem is even wider because again it is difficult to reproduce both RAA and v2: If one modifies the temperature (time) dependence of the energy loss

  32. One solution to azimuthal puzzle: Eloss near Tc Predominant energy loss at low T [Liao, Shuryak Phys. Rev. Lett. 102 (2009)] Solution of azimuthal puzzle? We analyze relation between T dependence of quenching and v2, with RAA fixed on data They are strongly correlated Elliptic Flow q/g RAA 20-30% p0

  33. Correlation RAA (quark)/RAA (gluon) - V2 RAA (pT) fixed on experimental data for pions Eloss athigh T GLVc GLV α(T) Eloss at low T Eloss at low T EoS lattice QCD without conversion with conversion Exp Scardina, Di Toro, Greco, PRC83(2010) flavor conversion becomes more necessary if you want to reproduce also the v2

  34. Do we have more gluons than expected from Standard jet quenching mechanism? The question of q/g is more shouldn’t we go toward chemical equlibration?

  35. Glasma o Quark Plasma? For m=0,2-flavor quarks & gluons the equilibrium ration is Nq+q/Ng=1.5=dq+q/dg approx. pQCD gg->qq cross-section Estimate for massive case final initial In a massive quasiparticle description that describe the lQCD e and P(Plumari,1103.5611 [hep-ph] ) Nq+q/Ng~ 3 because mq>mg Cascade calculation This can significantly modify the Nq/Ng up to 10 GeV and even more! Good we have a plasma at chemical equuilibrium like the early universe one!

  36. Using a simple QuasiParticle-model U.Heinz and P. Levai, PRC (1998) WB=0 guarantees Thermodynamicaly consistency Plumari, Alberico, Greco, Ratti, arxiV:1103.35611  M(T) from a fit to e from lQCD -> good reproduction of P, e-3P, cs NJL QP mg>mq lQCD-Fodor

  37. Glasma o Quasma? For massless quarks and gluons the equilibrium ration is Nq/Ng=1.5=dq+q/dg Approx. pQCD calculations as=0.3 Estimate for massive case final Jet quenching without Conversion moves this in the same direction initial • This modifies the background for the various energy loss scenarios • Affect the PID RAA of p,p,K,L at intermediate at high pT

  38. The region above 10 GeV • Indications of a different RAA at large pT also at ALICE? • Needed excellent resolution in p-p separation • At what pT we don’t see an anomalous behavior (if anamoalus) or we have remants of a quark plasma? • in pp: resolve fragmentation function ambiguities • (AKK, KKP, DSS) ALICE (QM 2011, preliminary) STAR (QM 2009, preliminary)

  39. General Message to prove experimentally the ideas envisaged theorethically - To have a quality of knoweledge need a measurement of both RAA and V2 - To understand heavy flavor interaction and hadronization need both baryon and meson up to 15-20 GeV. • Heavy Quarks : • pt< 6-8 GeV understanding if there is a resonant scattering, this • can provide a link to lQCD and may provide and answer to: • Is the QGP the one of lQCD? • pt>8 GeV understand pQCD in medium interaction • understanding heavy quark hadronization • Lc/D and even Lb/B can provide key informations

  40. Summary • The region or modified hadronization inside simple coalescence probably extends at pt~8 GeV ? - meausure PID v2 at to 10 GeV: v2(p)>v2(p) - an effect larger and wider than at RHIC out of hydrodynamical regime How it works with different mass? • Do we have a Gluon or Quark Plasma? - is there a net quark conversion? - how we explain RAA(p)> RAA(p) if it is so - it would be consistent with quark coalescence. • Up to what pt we see a modified hadronization not clear - indications of non vacuum effect also at pt> 10 GeV

  41. K=cost • RHIC: Particles at pt > 3-4 GeV doesn not affect at all the v2 below 3 GeV • LHC: minijet affect the v2 even below 3 GeV, against a jet + bulk modeling

  42. At RHIC the pT range is shrinked And when we included massive quarks and gluon there is Less time to reach equilibrium RHIC Shrinked region. Shorter lifetime and pretty steep spectra

  43. Fries, Muller, Bass, Nonaka, PRC68(2003)

  44. Quark Number Scaling at low mT ?! At low pt there is always a small breaking of the scaling quantitatevely depending on many details: resonance decays, wave function, hadronic rescatterings, … The maximum in v2(pt) and its behavior at larger pt much more interesting and indipendent the above details

  45. RAA and v2 generation with time RAA generated earlier than v2 V2 grows more continuosly

  46. Correlations Any residual interaction in f(p) 2-parton correlation from jet-bulk interaction lead correlation in the coalescing hadrons Similar to effect on v2 c0 and f0 fixed to fit data Baryon trigger Meson trigger Coalescence+Fragmentation reproduce the relative strength with baryon and meson trigger Fries et al., PRL94 (2005) to be seen the assumed Cab is dynamical reproduceble at RHIC -> coupling to transport approach

  47. Why same RAA with different v2? pT=10 GeV Calculation with GLV The formation time of RAA and v2 are different: one can quench the spectrum without generating v2 If you quench fast you can’t see the elliptic shape

More Related