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Heavy Quark: Theoretical Introduction

Heavy Quark: Theoretical Introduction. V. Greco Universita di Catania INFN-LNS. LHC. SPS. In collaboration with Van Hees, Mannarelli, Rapp. Specific of Heavy Quarks. produced by pQCD processes ( no thermal production)

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Heavy Quark: Theoretical Introduction

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  1. Heavy Quark: Theoretical Introduction V. Greco Universita di Catania INFN-LNS LHC SPS In collaboration with Van Hees, Mannarelli, Rapp

  2. Specific of Heavy Quarks • produced by pQCD processes (no thermal production) • teq > tQGP >> tq,g sensitive to interaction (even at soft scale) • Q anti-Q conserved separately • Concept of potential V(r) from lQCD (also nrEFT) : QGP <-> lQCDstudy the sQGP • Use Fokker-Planck in a hydro background • Abundance regulated in the wide energy (SPS –LHC) -> dissolution & regeneration of quarkonia

  3. QGP structure in the Heavy Quark sector RAA & v2 -> strong interaction (sQGP) • Jet Quenching (+ Elastic scatt.) insufficient • problematic RAA- v2 relation (pT<8 GeV) • presence of heavy-light Qq resonances (lQCD) • an EFT has shown a fairly good agreement at RHIC • improvement with a V(r) from lQCD • relevance of Hadronization mechanism for HQ • In –medium resonance -> coalescence + fragmentation • link J/Y Y <->D,B : one underlying c,b distribution Outline • From RHIC to LHC (new QGP phase?) • SimilarRAA & v2 proof of Qq resonances in the RHIC-QGP

  4. RAA , v2 of single e – Jet Quenching q q S. Wicks et al., nucl-th/07010631(QM06) N. Armesto et al., PLB637(2006)362 • Radiative energy loss not sufficient • sQGP: non perturbative effect Main Challenge is the in-medium quark interaction lQCD resonant (bound) states persist for QQ and qq -> Qq (D-like) resonant scattering

  5. “Light”-Quark Resonances 1.4Tc [Asakawa+ Hatsuda ’03] Spectral function in lQCD A(w)=w2r (w) Asakawa J/Y Studied in Potential model for J/Y - Mannarelli, Rapp - PRC72 (Bruckner-like) - Alberico, Beraudo, De Pace, Molinari - PRD 72 & 75 J/y (p = 0) disappears between 1.62Tc and 1.70Tc

  6. Equilibration time pQCD QGP- RHIC “D” Open-Charm Resonances in QGP • effective model with pseudo/scalar • + axial/vector “D-like” mesons • [chiral + HQ symmetry] • cross sectionISOTROPIC • more microscopic • from lQCD potential • [Hees et al., ArxiV 0709.2884] Ok, but can it describe RAA and v2? • t eqdown to 5 fm/c at RHIC !

  7. The model Hard production PYTHIA (PDF’s + pQCD ) HQ scattering in QGP Langevin simulation in Hydro bulk c,b quarks sQGP Hadronization Coalescence + Fragmentation c,b Semileptonic decay RAA & v2 of “non-photonic” e (with b contamination ) K D,B e ne

  8. Single-Electronv2andRAAat RHIC coalescence + fragment. fq from p, K Greco,Ko,Levai - PRL90 Hees, Greco, Rapp - PRC73 pQCD Reson. • Uncertainty: • better estimate of B/C contribution • Improvements: • include radiative E-loss • resonances from lQCD – potential model • no-sudden coalescence (full transport) • resonant scatteringmore effective forRAA – v2correlation • coalescenceincreases bothRAAandv2(anti-correlation)

  9. Impact of hadronization Fragmentation +Coalescence Fragmentation only Effect dumped by B Effect dumped by B

  10. Diffusion coefficient from lQCD

  11. VlQCD gives resonance states?! Scattering states included: Singlet + Octet – antitriplet -sextet (diquark) Kaczmrek et al., PPS 129,560(2004) Brueckner calculation • Solve in partial wave expansion • and V corrected by Breit interaction • Equation closed with the equivalent equation in the light sector,here simplified with a constant m and G

  12. Scattering from lQCD-V(r) • Assumptions • V(r) static potential (good in the vacuum) • V(r) extracted from lQCD Here calculation with V(r) Wong, PRC72(2005) Opposite T-dependence of g lQCD • With lQCD- V(r): • RAA is built in the early stage • V2 in the later stage • lQCD-> less RAA and more V2 Friction coefficient pQCD

  13. Results with T-matrix VlQCD Significant modification of RAA - V2 -> toward a better agreement with data -> opposite to pQCD elastic scattering -> naturally merging into a coalescence mechanism HQ are more sensitive to the QGP structure (teqtQGP)

  14. From RHIC to LHC? For min. bias. Hydro bulk dN/dy=2200 for central Tinit= 3 Tc Radial flow bmax=0.68 V2q light quark =7.5 % (hydro or numerology) v2q(pT) from a cascade [VG, Colonna, Ferini, Di Toro] dN/d2pT of b,c from PYTHIA (ALICE PPR-JPG32) Resonances off T>2Tc

  15. Charm Thermalization Shadowing not included yet! Spectra same parameter of PPR-ALICE • LHC spectra considerably harder ! • At Tc charm nearly thermalized • Resonances switched-off at 2 Tc

  16. From RHIC to LHC - RAA RHIC LHC bottom bottom charm charm • Suppression: RAA similar at RHIC and LHC! • Harder initial spectra at LHC • Resonance ineffective (“melted” T>2Tc) at early stage! • For 3-body scattering opposite behavior !

  17. From RHIC to LHC – v2 electrons RHIC LHC from D only ALICE • v2 similar at RHIC and LHC! • Resonance effective when anisotropy is reduced • Strong drag with the bulk flow at later stage! • v2 slightly higher at low pt • For 3-body scattering opposite behavior !

  18. RAA & v2 for D/B mesons at LHC • D and B via coalescence + fragmentation! • coalescence leads to increase both RAA and v2 • resonant scattering factor 3 in v2

  19. Open Heavy Flavor to see Hidden Flavor J/Y & Y <-> D,B common underlying HQ distribution

  20. No feed-down No direct contr. J/Y coal. Quarkonium <-> Heavy-Quark • Till now we have looked only at J/Y yield, but thanks to such a strong collective dynamics … • Regeneration is revealed in : • - pt spectra • elliptic flow v2Y from v2D : measure of Ncoal/NINI Greco, Ko, Rapp PLB595(2004) Coalecence only pT- Quarkonia from regeneration consistent with Open!? Suppression only

  21. Open markers : |y|<0.35 Solid markers : |y|~1.7 No recombination With recombination Recombination predictions for < pT²> vs Ncoll • Recombination ( Thews et al., nucl-th/0505055 ) predicts a narrower pT distribution with an increasing centrality, thus leading to a lower <pT²> • Within the large error bars : • <pT²> seems to be consistent with a flat dependence • data falls between the two hypothesis  partial recombination ? Au+Au Andry Rakotozafindrabe-SQM06

  22. Summary • RAA - v2e correlation for HQ entails: - presence of Q-q resonances (lQCD) - Relevance of coalescence • Similar RAA & v2 at RHIC- LHC: - if from RHIC to LHC a new QGP phase is created ! • Consistency of D and J/Y @ RHIC: - dN/dpT & v2 (pT) decisive contribution to J/Y issues Open Flavor Charm quark thermalization LHC ALICE Hidden • Link lQCD and QGP • - potential model from lQCD consistent with data Greco, Ko, Rapp-PLB595

  23. List of other observable for heavy quarks • Mass and color dependence of quenching (A. Dainese) • Mass dependence of Mach Cone effect (F. Antinori) • Production of multi-chamed hadron (F. Becattini) • DD angular correlation (V. Greco)

  24. Heavy-Flavor Baseline Spectra at RHIC Single-Electron Decays D-Mesons • bottom crossing at 5GeV !? • strategy: fix charm with D-mesons, • adjust bottom in e±-spectra

  25. DD angular correlation f Near-side Away-side Problem how to go from gluon wave to hadron? pTtrig=4-6 GeV/c pTassoc=0.15-4 GeV/c For HQ : • MH >>T no thermal production • back-to-back production (survive fragmentation) • Q & anti-Q conserved separetely Jet quenching Resonant scattering In AA f correlation can distinguish

  26. Thermalization w “D”-Mesons Cross section Equilibration time pQCD QGP- RHIC “D” Isotropicangular distribution sres essential for thermalization What is the RAA and v2 ? Transport approximated Fokker-Plank equation Background not affected by heavy quarks

  27. coal. coal.+ fragm. G = 0.75 GeV Baryon contamination due to coalescence … P. Soresen, nucl-ex/0701048 G. Martinez-Garcia et al., hep-ph/0702035 • Contamination of Lc in single e : • enhance v2e: v2Lc > v2D • enahencement modest + BRe 4.5% • but if one can verify those prediction … Apparent reduction if Lc/D ~1 consistent with RHIC data (pt~2-4 GeV) Heavy-Flavor and jet quenching- Workshop, Padova 29-9-2005

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