Quarkonia at High-Luminosity LHC: Can we determine the in-medium QCD force?

1. Quarkonia at High-Luminosity LHC:Can we determine the in-medium QCD force? Ralf Rapp Cyclotron Institute + Dept. of Physics & Astronomy Texas A&M University College Station, TX USA General WG-5 Heavy-Ion Meeting CERN (Geneva, Switzerland), Mar 06, 2018 [remote presentation from CS]

2. 1.) Introduction: A “Calibrated” QCD Force 1.5 1 0.5 0 -0.5 -1 [GeV] V1 [GeV] T=0 r [fm] 0.25 0.5 0.75 1 1.25 1.5 [Bazavov et al ‘13] • Vacuum quarkonium spectroscopy well described • Confinement ↔ linear part of potential Opportunity: Utilize quarkonia to probe in-medium QCD force ↔ infer consequences for transport coeffs. + spectral functs. ↔ probe QGP properties at varying resolution

3. - 1.2 Heavy Quark/onia on the Lattice QQFree Energy Onium Correlators Quark Suscept./Diffusion hc hb t [fm] hc Heavy-quark potential Energy + 3-mom. dep. of Y + ϒspectral fcts. Individual heavy quarks in QGP Ample source of information  Compelling Case for Experiment!

4. 1.3 Quarkonia in Medium • Lattice-QCD suggests gradual progression • of color screening • Remnant confining force above Tpc • (1S): color-Coulomb (EB=1.1GeV) • J/y, (2S,3S): confining force (0.6-0.2) • y(2S): barely bound(<0.1) • Do not use as a thermometer … • Screening lowers binding energies EB(T) •  opens phase space for dissociation • Dissociation rate Gy(p;T) is key transport • parameter for phenomenology

5. 1.4 Systematic Approach to Heavy Flavor in Matter TheoryTransportExperiment latQCD HQ free energy Heavy-quark potential HQ interactions in QGP (Ds) Open HF observables Quarkonium observables Quarkonium binding EB Quarkonium reaction rate GY

6. Outline 1.) Introduction 2.) Current Status 3.) In-Medium Binding and Dissociation • Melting vs. Regeneration 4.) Cold-Nuclear-Matter Effects • Baseline vs. in-Medium Probe 5.) Conclusions

7. 2.1 Excitation Functions in AuAu / PbPb Charmonium Bottomonium • Gradual increase of total J/yRAA • Regeneration and suppression increase • Regeneration concentrated at low pT! [data: NA50, PHENIX, STAR, ALICE, CMS] • Gradual suppression • Regeneration (Nϒeq) small • Qualitative difference from J/y

8. 2.2 Current Quarkonium Phenomenology Use temperature estimates from hydro/photons/dileptonsto infer: Tmelt(y’) < TSPS(~240) <Tmelt(J/y,)≤TRHIC (~350) < Tmelt() ≤ TLHC (~550) • Remnants of confining force survive at SPS[melt y’, J/y intact] • Confining force screened atRHIC+LHC [melt J/y+’] • Color-Coulomb screening at LHC[(1S) suppression] • Thermalizing charm quarks recombine at LHC[large J/y yield] 1.5 1 0.5 0 -0.5 -1 r [fm] 0.25 0.5 0.75 1 1.25 1.5 350 240 550 (2S) J/, (2S) (1S)

9. Outline 1.) Introduction 2.) Current Status 3.) In-Medium Binding and Reaction Rate • Melting vs. Regeneration 4.) Cold-Nuclear-Matter Effects • Baseline vs. in-Medium Probe 5.) Conclusions

10. 3.1 Binding Energies + Reaction Rates: Y States 1S 1P 2S 1S 2S 1P 1S 1P 2S • Reduced binding “accelerates” dissociation ( GY(EB=0) = 2Gb ) • Localizes dissociation temperatures (centrality dependence!) • Same rate for regeneration – experimental signatures of production time?

11. 3.2 Sensitivity of RAA to Binding Energies 1S 2S 1P • ϒ(1S) suppression can discriminate (gradual) melting scenarios, need good control over auxiliary model components (bulk, CNM,...) • ϒ(2S,3S): need lower energies (RHIC), smaller systems (pPb!), or…

12. 3.3  Elliptic Flow • Directly reflects production/suppression time! (1S):early, (2S):late(r)

13. 3.4 Charmonia: Production Time + “Flow Bump” J/y y’ • Need low-pTRAAdata to discriminate • Sequential regeneration?! • Recall double ratio of CMS…

14. Outline 1.) Introduction 2.) Current Status 3.) In-Medium Binding and Dissociation • Melting vs. Regeneration 4.) Cold-Nuclear-Matter Effects • Baseline vs. in-Medium Probe 5.) Conclusions

15. 4.1 Divide out Cold-Nuclear-Matter Effects RAAhotRAAtot / SCNM • J/y suppression at SPS mostly from feeddown (N ~7.5mb), melts in the RHIC→ LHC regime (not unlike (2S))

16. 4.2 (1S): Rapidity Puzzle • problem of large(r) suppression in 2.76 TeV ALICE data • beware of cold nuclear matter effects • Regeneration: Nbb ~ 1 for central PbPb canonical limit NY~ (Nbb)1 y

17. 3.5 y(2S) in p/dA: A Sensitive Medium Probe d-Au (0.2TeV) p-Pb (5.02TeV) [ALICE] [PHENIX] - -EPS09 • noticeable y but little J/ysuppression, consistent with “comovers” • supports fireball formation with: tFBG(y) ~ 1  Gavg(y) ~ 50-100 MeV similar to thermal tFBG(J/y) << 1  Gavg(J/y) < 20 MeV widths at T 200MeV [Ferreiro ‘15] [Du et al ‘15]

18. 5.) Summary • Heavy quarkonia: hard production but soft medium probe • Unique opportunity to unravel in-medium QCD force via thorough rooting in lattice QCD • Both regeneration (Y) and dissociation () provide tell-tale signatures of in-medium screening • Heavy-quark reaction rates rooted in open-HF phenomenology • Key roles also in pA: CNM effects (J/y, (1S)) + sensitive probes of putative medium (y(2S), (3S))

19. 2.2 Quarkonium Width Comparisons Charmonium Bottomonium J/y (1S) melted • Fair agreement for J/y • Larger spread for  states • Binding energies differ (2S) melted

20. q q 2.) Theoretical Tools • Statistical Hadronization model: • chem. equil. of charm hadrons • Transport Approaches • Boltzmann equat. • →Rate equation • Reaction Rate Gy “Weak” binding EB< mD “Strong” binding EB≥ T • gluo-dissosciation (“singlet-to-octet”) [Bhanot+Peskin’85, Brambilla et al’08, Liu et al‘13…] • “quasi-free”/ Landau damping [Grandchamp+RR‘02, Songetal’07, Laineetal‘07,…]

21. 3.3 Properties of Charmonium Excess • excess concentrated at low pT • low-pT excess carries sizable v2 • systematic softening of J/y pT-spectra with increasing √s → nature of source changes [Tsinghua]

22. 4.1 Charm Thermalization + J/y Regeneration → Softening of charm-quark spectra facilitates regeneration J/yEquilibrium Fraction Charm-Quark Diffusion Coeff. (Nyeq)off-c / (Nyeq)thermal-c 1-exp[-t /tceq] t /tceq T /Tc [Ko et al ‘12] [Prino+RR ‘16] • Charmonium phenomenology • favors tceq≤ 5 fm/c • (“strong”coupling) Ds = tceq T/mQ≤ (4-8) /(2pT)

23. 4.2 Heavy-Quark Potential and (1S) Suppression Input “Potential” UQQ [TAMU] [Kent St] FQQ • (1S)suppression prefers “strong” (U) over “weak” (F) in-med. potential • role of regeneration for (1S), (2S) ?

24. 1.3 Quarkonium Transport in URHICs 0 0.5 5 10 | | | | t [fm/c] fireball time c - c production + evolution of cc wave pack. c-quark diffusion in QGP ~ Tmelt: y can form QGP kinetics c+c↔y ~ Tpc: c and c hadronize - hadronic kinetics - - tform~1fm/c tceq ~5fm/ctyeq~ 1/Gy [Satz et al, Capella et al, Spieles et al, PBM et al, Thews et al, Grandchamp et al, Ko et al, Zhuang et al, Zhao et al, Chaudhuri, Gossiaux et al, Young et al, Ferreiro et al, Strickland et al, Brambilla et al, …]

25. 4.2 (1S) and (2S) Transport cont’d … as implemented in current transport approaches (1S) [Tsinghua] [Ko et al] • (2S) more sensitive sensitive to in-medium potential

26. 4.5  pt Spectra in Pb-Pb(5.02TeV)

27. 4.5 In-Medium Quarkonium Binding Energies

28. 2.1 Potential Extraction from Lattice Data • Free Energy - • QQSpectral Function Bayesian Approach T-Matrix Approach U V F lattice data 1.2 Tc r [fm] • Account for large imaginary parts • Remnant of confining force! • Potential close to free energy [Burnier et al ’14] [S.Liu+RR ’15]

29. 3.3 Heavy-Flavor Transport at RHIC + LHC • flow bump in RAA +large v2↔ strong coupling near Tpc(recombination) • high-precision v2: transition from elastic to radiative regime?