Download - Heavy Quarkonium in Quark-Gluon Plasma
Heavy Quarkonium in Quark-Gluon Plasma
Cheuk-Yin Wong (黄卓然 ) Oak Ridge National Laboratory & University of Tennessee
IHEP
October 15,2004
• Introduction • Heavy quarkonium in spectral function analysis• Heavy quarkonium in potential model• Heavy quarkonium bound states in QGP• Cross section for g + J/ψ C + C• Cross section for C + C g + J/ψ• Conclusions C.Y.Wong, hep-ph/0408020
J/ψ suppression as a signature of QGP
• J/ψ suppression as a signature of QGP Matsui & Satz, PLB178, 416 (`86)• J/ψ is bound at T slightly greater than Tc Hansson, Lee, & Zahed, PRD37, 2672
(`88)• J/ψ suppresion by collisions with nucleons Gerschel and Huefner, PLB207, 253 (`88)• J/ψ suppresion by collisions with produced particles Vogt, Gavin, Capella, Wong, Barnes,
Swanson,Ko,Lin, Lee,Haglin, Blaschke,……• J/ψ enhancement by recombination Thews & Rafelski, NPA689, 575 (`02)
J/ψ suppression as a signature of QGP
• Lattice gauge results for Fav
Digal, Petreczky, Karsch, PRD64 094015 (`01)• Lattice gauge spectral function analysis Asakawa,Hatsuda, PRL92, 012001 (`03), Datta,Karsch,Petreczky, J. Phys. G,S431 (`04)• Lattice gauge calculations of color-singlet Q-Qbar potential Kaczmarek, Karsch, Petreczky, & Zantow, hep-
lat/030912 Petreczky & Petrov, hep-lat/0405009• Heavy quarkonium bound state calculations
Wong, PRC65,034902(`02) & J. Phys.G28, 2349 (`02)• J/ψ suppression and recombination
Grandchamp, Rapp, and Brown, J. Phys. G30, S1355 (`04)
• QGP at T slightly above Tc supports weakly bound meson states Zahed & Shrylak, hep-ph/0307267,
hep-ph/0403127
Spectral function analysis
Lattice gauge spectral analyses in the quenched approximation show that the width of J/ψ remains narrow up to T ≤ 1.6 TC
M. Asakawa, T. Hatsuda, and Y. Nakahara, Nucl. Phys. A715, 863 (03)
P. Petreczky, S. Datta, F. Karsch, and I. Wetzorke, hep-ph/0309012.
Questions:
1. Are there other independent ways to assess the stability of J/ψ in the quark-gluon plasma?
2 What does the potential model say about the stability of J/ψ?
3. What is the binding energy of J/ ψ?4. How easy is it to dissociate J/ ψ by gluon
collisions?5. How easy is it to recombine C and C to
form J/ ψ in QGP?
T
T)(r,1FTT)(r,1FT)(r,1V
T)/T(r,1Fe(0)TrL(r)L
Kaczmarek, Karsch, Petreczky, Zantow calculated the color-singlet C-C potential in the quenched approximation [hep-lat/0309121]
V1
V1(r,T) was calculated in the Coulomb gauge
We parameterize the color-singlet Q-Q potential as a screened color-Coulomb potential
re
3(T)4α
- C(T) t)(r,V-μ(T)r
eff1
re
3(T)4α
- C(T) t)(r,V-μ(T)r
eff1
Probable reasons for strong coupling αeff(T) just above Tc
• Density of gluons increases substantially above Tc
• Gluons have a spin (in color space)• Spin response is paramagnetic ---- a spin (in color space)
tends to align with the imposed color magnetic field, in such a way to enhance the imposed field
• This enhancement leads to anti-screening• There is a competition between anti-screening and dis-
alignment due to thermal motion• Magnetic anti-screening wins at T slightly greater than Tc• Magnetic anti-screening wins at large T Therefore, there is a strong coupling αs(T) just above Tc.
and αs(T) decreases as T increases.
Solve for Q-Q bound states
T)ε(T)ψ(r,T)ψ(r,T)],(r1VT)(r,1[Vred2μ
2
Solve for Q-Q bound states
T)ε(T)ψ(r,T)ψ(r,T)],(r1VT)(r,1[Vred2μ
2
Dissociation temperatures in quenched QCD
Heavy Quarkonium Potential Model Spectral Analysis
J/ψ ~ 2.0 TC ~ 1.6 TC
χ, ψ ' ~ 1.2 TC ~ 1.1 TC
Υ ~ 4.5 TC
χb,Υ' ~ 2.0 TC
Why different dissociation temperatures?
• Potential model gives the spontaneous dissociation temperature
• Heavy quarkonium can dissociate even before reaching spontaneous dissociation temperature by collision with gluons
• Spectral analysis includes the interaction of gluons with heavy quarkonium
Quarkonium dissociation process in the potential model
octetcolorforC
singletcolorforC
r
eTCTCTrV
c
drrruruI
Ek
B
EBE
IkkE
f
f
rTeff
f
eff
c
effgQ
s
gluon
gQgluondis
6
1
,3
4
)()(),(
6
1|1|
2|8|
)()(
2
2
)(3
4)(
)(
2
1
0
2
2
2122
J/ψ dissociation cross section g + J/ψ → c + c
Average dissociation cross section and dissociation width Γdis
disgdis
disgJ
Tp
gg
Tpdisg
dis
n
ndt
dne
dppgn
e
dppp
ggn
/
/
2
02
/
2
02
12
1)(
2
Cross section for production of J/ψ by collision of C and C
)/(||
||
)/(
_
2/
2
_
_
ccJgp
p
Jgcc
Jg
cc
Rate of J/ψ production
Conclusion
• Just above TC, J/ψ and Υ are strongly bound, probably as a result of anti-screening due to free gluons
• In the potential model, J/ψ dissociates spontaneously at about 2TC
• Below T=2TC, J/ψ dissociates by collision with gluons.. Its collision dissociation width is equal to its binding energy at T=1.2TC
• The potential model and the spectral analysis are qualitatively consistent with each other