Bottomonium suppression in the quark-gluon plasma Michael Strickland Kent State University Kent, OH USA Sharif University of Technology July 14, 2020
Quarks are normally “confined” inside hadrons HADRONS Baryons … Mesons Gluons hold the quarks together … M. Strickland 2
Quarks and anti-quarks Name Mass Electric Charge [GeV/c 2 ] Up u 0.0024 +2/3 Blue Anti-Red Green Down d 0.0048 -1/3 “Colorless” Strange s 0.104 -1/3 Anti-Blue Anti-Green Charm c 1.27 2/3 Red Bottom b 4.2 -1/3 Top t 171.2 2/3 Quarks are fermions (spin ½); • Diagram Symbol have electric charge and “color charge” q There are also anti-quarks that have the opposite • quark electric charge and “anti-color charge” q antiquark The proton is (primarily) composed of uud • Compare the masses above to the mass of the • flow of time proton which is ~ 1 GeV M. Strickland 3
Melting hadrons Color ionized plasma M. Strickland 4
Quantum chromodynamics (QCD) phase diagram 1000 T [MeV] 200 MeV à 2 x 10 12 K 300 Quark Gluon Plasma Quark-Gluon Plasma 200 Second Order Crossover T c ~ 154 MeV First Order 100 Hadron Gas Quark Color Nuclear Matter Matter Superconductor Vacuum 0 μ [MeV] 0 300 600 900 1200 1500 B M. Strickland 5
Pressure vs temperature – µ B = 0 MeV Andersen, Leganger, Su, and MS 1009.4644, 1103.2528 N. Haque, J.O. Andersen, M.G. Mustafa, MS, N. Su, 1309.3968 1.0 1 loop α s ; 176 MeV μ B 0 MeV MS 0.8 Quark Gluon Plasma 0.6 ideal LHC 5.023 TeV LHC 2.76 TeV 0.4 RHIC 200 GeV No fit parameters! NNLO HTLpt 0.2 Hadron Resummed perturbation theory (Strickland et al) Lattice QCD (Wuppertal-Budapest group) Resonance Wuppertal Budapest Gas 0.0 200 400 600 800 1000 T MeV M. Strickland 6
QCD phase diagram 1000 T [MeV] 200 MeV à 2 x 10 12 K LHC 5.023 TeV à T 0 ~ 700 MeV LHC 2.76 TeV à T 0 ~ 600 MeV RHIC 200 GeV à T 0 ~ 400 MeV 300 Quark Gluon Plasma 200 Second Order Crossover T c ~ 154 MeV First Order 100 Hadron Gas supernovae Quark Color Nuclear neutron stars Matter Matter Superconductor Vacuum 0 μ [MeV] 0 300 600 900 1200 1500 B M. Strickland 7
98% of the mass in the universe is made during the QGP transition The Higgs boson only provides a small • fraction of the mass of observed hadronic matter. Most of the mass around us emerges • from the strong force. Figure courtesy B. Muller Bashir et al, Commun. Theor. Phys. 58 (2012) 79-134. Logarithmic scale M. Strickland 8
Experiments and Phenomenology M. Strickland 9
Ultrarelativistic heavy-ion collisions RHIC , BNL – Au-Au @ 200 GeV/nucleon (highest energy) à T 0 ∼ 400 MeV • LHC , CERN – Pb-Pb @ 2.76 TeV à T 0 ∼ 600 MeV • • LHC , CERN – Pb-Pb @ 5.03 TeV à T 0 ∼ 700 MeV RHIC , BNL BES – Au-Au @ 7.7 - 39 GeV à T 0 ∼ 30-100 MeV [+finite density] • FAiR (GSI), NICA (Dubna) – U-U @ 35 GeV -> T 0 ∼ 100 MeV [+finite density] • T = 200 MeV à 2 x 10 12 K 200 MeV à 2 x 10 12 K ~ 10 -14 m ~ 10 -14 m Entire event lasts Entire event lasts ~ 10 fm/c which is ~ 10 fm/c which is ~ 3 x 10 -23 s !!! ~ 3 x 10 -23 s !!! M. Strickland 10
Ultrarelativistic heavy-ion collisions RHIC , BNL – Au-Au @ 200 GeV/nucleon (highest energy) à T 0 ∼ 400 MeV • LHC , CERN – Pb-Pb @ 2.76 TeV à T 0 ∼ 600 MeV • • LHC , CERN – Pb-Pb @ 5.03 TeV à T 0 ∼ 700 MeV RHIC , BNL BES – Au-Au @ 7.7 - 39 GeV à T 0 ∼ 30-100 MeV [+finite density] • FAiR (GSI), NICA (Dubna) – U-U @ 35 GeV -> T 0 ∼ 100 MeV [+finite density] • T = 200 MeV à 2 x 10 12 K 200 MeV à 2 x 10 12 K ~ 10 -14 m ~ 10 -14 m Entire event lasts Entire event lasts ~ 10 fm/c which is ~ 10 fm/c which is ~ 3 x 10 -23 s !!! ~ 3 x 10 -23 s !!! M. Strickland 11
Some Key Experimental Observables Collective Flow – flow of the matter provides evidence of collectivity in the QGP • and allows us to extract transport coefficients like the shear viscosity Jet Quenching – effects of plasma interactions on high-energy particle • propagation; provides information about momentum diffusion and energy loss of partons in the QGP Suppression of heavy quarkonia – provides information about screening and • bound state survival in the QGP Electromagnetic Radiation – high energy photons and dileptons provide • information about initial conditions Particle spectra across species – provides information about the degree to which • final particle distributions are thermalized Multiparticle correlations such as Hanbury-Brown-Twiss (HBT) interferometry – • provides information about the size of the QGP and collective flow profiles M. Strickland 12
Some Key Experimental Observables Collective Flow – flow of the matter provides evidence of collectivity in the QGP • and allows us to extract transport coefficients like the shear viscosity Jet Quenching – effects of plasma interactions on high-energy particle • propagation; provides information about momentum diffusion and energy loss of partons in the QGP Suppression of heavy quarkonia – provides information about screening and • bound state survival in the QGP Electromagnetic Radiation – high energy photons and dileptons provide • information about initial conditions Particle spectra across species – provides information about the degree to which • final particle distributions are thermalized Multiparticle correlations such as Hanbury-Brown-Twiss (HBT) interferometry – • provides information about the size of the QGP and collective flow profiles M. Strickland 13
Why heavy quarkonia? M. Strickland 14
What is bottomonia? E288 exp @ Fermilab, 1977 M. Strickland 15
Why bottomonia? Vacuum decay lifetime = 3654 fm/c ~ 10 -20 s Vacuum bindng energy of Y(1s) is ~ 1 GeV M. Strickland 16
Melting hadrons – conceptual correction Color ionized plasma M. Strickland 17
Why bottomonia in AA? • Can reliably use heavy quark effective theory • Cold nuclear matter (CNM) effects in AA decrease with increasing quark mass • The masses of bottomonia (~ 10 GeV) are much higher than the temperature (T < 1 GeV) generated in HICs à bottomonia production A. Mocsy, P. Petreczky, and MS, 1302.2180 dominated by initial hard scatterings • Since bottom quarks and anti-quarks are relatively rare in LHC HICs, the probability for regeneration of bottomonia through statistical recombination is much smaller than for charm quarks [see e.g. E. Emerick, X. Zhao, and R. Rapp, arXiv:1111.6537] M. Strickland 18
Heavy quark effective theory Name Mass Electric Charge Normally, for QCD bound • [GeV/c 2 ] states one needs a fully relativistic treatment Up u 0.0024 +2/3 If the quark mass is • Down d 0.0048 -1/3 sufficiently high then one can Strange s 0.104 -1/3 take the “heavy quark limit” This reduces the problem to • Charm c 1.27 2/3 having to deal with a non- Bottom b 4.2 -1/3 relativistic terms plus Top t 171.2 2/3 relativistic corrections M. Strickland 19
How well does this work? As the table to the right • shows, it works quite well Maximum error in the • masses of the bottomonium sates is 0.22% J. Alford and MS, 1309.3003 M. Strickland 20
Debye-screening in a plasma Screening of electric interaction with screening length A test charge polarizes the particles of the plasma and r D = 1/m D they “screen” its charge V Coloumb ( r ) = − α V Debye ( r ) = − α r e − m D r − → r Peter Debye The same phenomena that occurs in an • 1884 - 1966 electric plasma occurs in the QGP A screening mass m D ~ gT is generated by • strong interactions of quarks and gluons M. Strickland 21
Debye-screening in a plasma 0 - 1 - 2 V Coloumb ( r ) = − α V Debye ( r ) = − α r e − m D r V − → r - 3 Coloumb - 4 Debye - screened - 5 1 2 3 4 5 r M. Strickland 22
Debye-screening in a plasma 0 - 1 - 2 V Coloumb ( r ) = − α V Debye ( r ) = − α r e − m D r V − → r - 3 Coloumb - 4 Debye - screened - 5 1 2 3 4 5 r M. Strickland 23
Debye-screening in a plasma 0 - 1 - 2 V Coloumb ( r ) = − α V Debye ( r ) = − α r e − m D r V − → r - 3 Coloumb - 4 Debye - screened - 5 1 2 3 4 5 r M. Strickland 24
In-medium breakup (decay) rates • In addition to Debye screening, which reduces the effective coupling between quarks and antiquarks, the states also acquire a temperature dependent breakup rate (width) which increases as the temperature increases. • Primarily, heavy quark bound states breakup via strong processes which result in the quark/antiquark becoming unbound inside of the QGP, e.g. Landau damping , collisional disassociation , etc. M. Strickland 25
In-medium heavy quark potential Using the real-time formalism one can express the potential in terms of the static advanced, retarded, and Feynman propagators d 3 p (2 π ) 3 ( e i p · r − 1)1 Z ⇣ ⌘ D ∗ L R + D ∗ L A + D ∗ L V ( r , ξ ) = − g 2 C F F 2 Real part can be written as p 2 + m 2 α + m 2 d 3 p Z γ (2 π ) 3 e i p · r Re[ V ( r , ξ )] = − g 2 C F ( p 2 + m 2 γ )( p 2 + m 2 β ) − m 4 α + m 2 δ With direction-dependent masses, e.g. Anisotropic potential calculation: Dumitru, Guo, and MS, 0711.4722 and 0903.4703 Gluon propagator in an anisotropic plasma: Romatschke and MS, hep-ph/0304092 M. Strickland 26
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