1 jozsó zimányi (1931 – 2006). 2 jozsó zimányi i met prof. zimányi in india in 1984. member,...
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Jozsó Zimányi (1931 – 2006)
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Jozsó ZimányiJozsó Zimányi I met Prof. Zimányi in India in 1984.I met Prof. Zimányi in India in 1984.
• Member, NA49 and PHENIX Collaborations• Nuclear Equation of State with derivative scalar
coupling.• ALCOR : A Dynamic model for hadronization.• Particle ratios in heavy ion collisions.• Charmed and strange hadron productions in heavy ion
collisions.• Exotic particles in heavy ion collisions.• Quark and hadro-chemistry.
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Photon and dilepton production Photon and dilepton production in heavy-ion collisionsin heavy-ion collisions
Bikash SinhaBikash Sinha
Saha Institute of Nuclear PhysicsSaha Institute of Nuclear Physicsandand
Variable Energy Cyclotron CentreVariable Energy Cyclotron Centre
BudapestJuly 2007
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Contemporary
Wisdom (Again?)
Lattice Calculation F.Karsch’95
No Quarks: Pure SU(N) gauge theories Phase transition Second order for N=2 1st order for N=3
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QCD nf light quarks
Phase transition 1st order nf 3
seems to be continuous for nf =2
Tc number of partonic degree of freedom in units of the string tension Tc /
Tc (nf =2) 150 MeV
Tc( nf =0) 160 MeV Glue balls
O(1GeV)
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QCD Phase Diagram
Quark Matter
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HOT DENSE HADRON MATTER
EQ of StateRadiative Properties of the
Sizzling HadronsChiral Properties
m*x
MELTING PROPERTIES ?
( Decay widths )Chiral Hadrodynamics
Mesons, Vector mesons, BaryonsNo Universal law of m*
x
Brown – RHO Scaling law does not seem to holdIe,
p
p
N
N
m
m
m
m
m
m***
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Medium effects : (Finite Temp Field th.)P. Roy, S. Sarkar, J. Alam, B.S., Nucl Physics A 653 (1999)S. Sarkar, P. Roy, J. Alam, B. S.Phys. Rev. C (1999) & Annals of Phys 2000
2/1
2
2***
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co
o
v
v
v
v
T
T
f
f
m
m
fv Coupling between electromagnetic current & vector meson Field , ω0 Continuim ThresholdShould not
N
N
v
v
m
m
m
m **
J. AlamS. SarkarT. HatsudaT. NayakB. S. (2000)
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VARIATION OF VECTOR MESON MASS WITH TEMPERATURE
Sarkar et al. NPA 1998
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Photons
Hadronic matter Quark matter
qg->qqq->g
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B.S.PLB 1983
R / + - = const( , sq
q
Light from QGP
qq + -~ T4
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Dileptons
Hadronic matter Quark matter
e+e- qq->e+e-
e+e- qg -> q *
e+e- qq -> g *
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Space time evolution
• Relativistic hydrodynamics
∂T
Transverse expansion with boost invariance in the longitudinal direction
Equation of state : Bag model for QGP and resonance gas model for hadrons
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Isentropic expansion :
dy
dN
aRT
Aii
4)3(45
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ARri
e
r
1
),( 0
0; ),(v ri
Hydrodynamics takes care of the evolutionof the transverse motion.
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•Alam et al. PRC (2003) 054901•Data from: Aggarwal et al. (WA98 Collaboration) PRL (2000) 3595
Direct Photons at SPS
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J. Alam, S. Sarkar, T. Hatsuda, J. Phys. G (2004)
CERES
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Radiation at RHIC
J. Alam, J. Nayak, P.Roy, A. Dutt-Mazumder, B.S.: nucl-th/0508043 Jour. Phys. G (2007)
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Sometime ago it was noted that: “The ratio of the production rates (/+-) and ( o, /+-) from quark gluon plasma is independent of the space time evolution of the fireball”. Universal Signal :
Only a function of universal constants.
)( 424
TOxd
d
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)( T1nOxd
dss
(1)
(2)
ss nR 1 2
(3)
B.S.PLB 1983
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Invariant yield of thermal photons can be written as
Q QGP
M Mixed (coexisting phase of QGP and hadrons)
H Hadronic Phase
is the static rate of photon production convoluted
over the space time expansion.
xddypd
Rd
dypd
Nd
iHMQi i TT
4
,,2
2
2
2
iT dypd
Rd
2
2
0
2
2
022 *
yTyTem dypd
NddypdNdR
Thermal Photons
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Thermal photons from QGP :Thermal photons from QGP :
using hard thermal loop approximation. Again,
Resumming ladder diagrams in the effective theory
Thermal photons from hadrons :
(i) (ii) (with , , , and a1, in the intermediate state) (iii) (iv) , and &
Similarly from strange meson sector
gqq
gqgqqqqqqqqqgqgq & , ,
~s onAnnihilati &Compton
qqgqq
Collinear equation:
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Rather similar to photons, dileptons can be efficient probe for QGP – again not suffering from final state interactions.
One has to subtract out contributions from:
(a) Drell–Yan process,
(b) Decays of vector mesons within the life time of the fireball
(c) Hadronic decays occurring after the freeze out.
Invariant transverse momentum distribution of thermal dileptons (e+e- or virtual photons, *):
integrated over the invariant mass region:
xddMdydMpd
Rd
dypd
Nd
iHMQi i TT
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,,22
2
2
2 *
*
sqq 2*
GeVMm 05.12
Dileptons
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Dileptons from light vector mesons (, ) & (Hadronic Sector) :
])()(
[ 2
*
2222
2
3
2
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VV
VVBE
T MmM
Mff
dypddM
Rd
)] (1 x )/)exp((1
1
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1 s
Mwo
Consistent with e+e- V() data
fV(V) : coupling between electromagnetic current and vector meson fields
mV and V are the mass and width of the vector V and w0 are the continuum threshold above which the asymptotic freedom is restored.
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The number density as a function of temperature. Effect of mass modification and width modification is shown.
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Photons at SPS
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Photons at RHIC
J. Alam, J. Nayak, P.Roy, A. Dutt-Mazumder, B.S.: J. Phys. G 2007
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Di-electrons at RHIC
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RESULTS from the ratio:RESULTS from the ratio:
dypd
Rd
dypd
RdR
TTem 2
*2
2
2
• The variation of Rem (the ratio of the transverse momentum spectra of
photons and dileptons) has been studied for SPS, RHIC and LHC.
• Simultaneous measurements of this quantity will be very useful to
determine the value of the initial temperature of the system.
• Rem reaches a plateau beyond PT=1 GeV. The value of Rem in the
plateau region depends on Ti but largely independent of Tc, vo, Tf and the
EOS.
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2*
22
2
dypdRd
dypdRd
R TT
em
Ratio (Rem) at SPS
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2*
22
2
dypdRd
dypdRd
R TT
em
Ratio (Rem) at RHIC
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2*
22
2
dypdRd
dypdRd
R TT
em
Ratio (Rem) at LHC
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Ratio (Rem) for pQCD processes
FILTERING OUT pQCD PHOTONS
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2*
22
2
dypdRd
dypdRd
R TT
em
arXiv:0705.1591 [nucl.th]
Ratio (Rem) vs. Initial Temperature
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OBSERVATIONS:1. The medium effect on Rem is negligibly small
2. Hydrodynamic effects such as viscosity, flow get sort of erased
out by observing the ratio, Rem3. Equivalently, model dependent uncertainties also get cancelled out
through Rem4. Contributions from Quark Matter increase with the increase of the
initial temperature –
a) thermal photons mostly for hadronic phase at SPS
b) thermal photons from RHIC and more so from LHC originate
from QGP
5. Rem flattens out beyond pT ~ 0.5GeV
6. Rem increases with initial temperature and flattens out beyond T i ~
800MeV
7. In the plateau region: RemLHC > Rem
RHIC>RemLHC
8. EOS including quasi particle in the quark matter is being tackled.
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• The ratio, Rem seems to be insensitive to EOS, medium effects on hadrons, final state effects, Tc, flow. However, it is sensitive to Ti Rem can be used to estimate Ti.
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OBSERVATIONS, contd.WHY & HOW
Rem (in Born approx.) => )M(
T 4
2
2s2
S
At the end Rem still remains by far and large model independent:SPS => RHIC => LHC
Thus Rem is a universal signal of QGP,model independent and unique.
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We see that is a function of the universal constants and the temperature. Because of the slow (logarithmic) variation as with temperature, one can assume
T 2s
In an expanding system, however, Rem involves the superposition of results for all temperatures from Ti to Tf, so the effective (average) temperature, Teff will lie between Ti and Tf and T 2
effemR
This explains: SPSem
RHICem
LHCem RRR
It is also interesting to note that for s = 0.3, T=0.4GeV,(M)2 ~ 1 (Mmax=1.05, Mmin=0.28), we get: Rs~ 260.This is comparable to Rem obtained in the present calculation.
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2*
22
2
dypdRd
dypdRd
R TT
em
WHAT DO WE EXPECT at LHC
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Photons and di-electrons in the ALICE experiment
Photons
Electron-pairs
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Muon chambersPMD
Modules
PMDphotons
PMDphotons
MUON arm -pairs
MUON arm -pairs
ALICE Experiment at LHC
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/e+e- as well as
at the Large Hadron Collider
LOOKING FORWARD TO THE VERIFICATION OFTHE UNIVERSAL SIGNATURE:
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