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This lecture explores the mechanisms underlying J/ψ suppression in high-energy heavy ion collisions, emphasizing the role of charmonium bound states and plasma screening effects. We analyze experimental results from the NA50 collaboration at CERN and discuss the dependence of life on temperature for quarkonia states. The impact of screening on quarkonium dissociation is examined alongside the extraction of signals for deconfinement. Furthermore, we address the challenges faced by heavy ion physicists in interpreting complex data from experiments like PHENIX.
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Michel GONIN Lecture 2 on J/ suppression 1. Charmonium bound states 2. Screening effects in the plasma 3. Experimental results 4. Life (for physicist) is tough
quarkonia q q Lattice QCD ’ T > Tc = 0 Signals for the Deconfinement Successive (vs. temperature) melting for the quarkonia Satz et al.
Screening Temperature Energy density(GeV/fm3)ε Suppression Bounding Energy (MeV) ψ χ ’ ψ’ Quakonia Screening 1 2 3 4 5 ε Satz et al.
NA50 at CERN Electromagnetic desintegration c c
How does PHENIX see the J/ ? J/ e+e– identified in RICH and EMCal • || < 0.35 • p > 0.2 GeV J/μ+μ– identified in 2 fwd spectrometers • 1.2 < || < 2.4 • p > 2 GeV
Cathode-strip chambers = 24000 voies analogiques / bras • Pistes = 1cm s (barycentre) = 100mm Bruit/Signal ~ 1% • ADC 11 bits, 4 échantillons temporels à 100 ns
d-Au sample Di-electron analysis Di-muons analysis Mass Resolution ~ 100 MeV Mass Resolution ~ 150 MeV
peripheral central NA50 at CERN …
Ordinary absorption NA50 ANOMALOUS J/ SUPPRESSION
Beam EZDC (GeV)
With E T With EZCD
ψ χ ’ ψ’ ε 1 2 3 4 5 Suppression Satz et al.
NA50 Suppression ψ χ ’ ψ’ Satz et al. ε 1 2 3 4 5
NA50 Evidence for ψ χ ψ’ Screening Effects
ψ’ Suppression ψ χ ’ ψ’ Satz et al. ε 1 2 3 4 5
DECONFINEMENT !!! High Energy Physics Heavy Ion Physics
Heavy Ion Physicists Life is tough
WITH PLASMA t = 0 c c - Screening effects - hard gluon scattering Deconfinement c c t 2 fm/c mixed phase c d t 5 fm/c c d Hadronization D D Hadronic gas J/ψ J/ψ 10 fm/c t 20 fm/c Freeze-out
S-U Pb-Pb R.Rapp Regeneration : answer from RHIC
ψ’ Suppression ψ χ ’ ψ’ Satz et al. ε 1 2 3 4 5
Heavy Ion Physicists Life is tough
D- D+ CHARMONIA DISSOCIATION J/ p J/ +protons (neutrons) open charm
L = path length abs. Glauber absorption model Rarely produced (no multi-production) Uniforme (inside the nucleus) production probability • Short ( 1fm/c) formation time • straight line trajectories
data model Does it work ?? Yes
antiproton CERN :abs. = 21.4 2 mb BNL :abs. = 24.8 3 5 mb
Drell-Yan Glauber absorption model Drell-Yan no absorption abs. 0
