Post on 19-Jan-2016
July 2007 Workshop of European Research Group on Ultra-Relativistic Heavy Ion Physics, Nantes, France S.Kiselev
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Direct photons for FASTMC
Sergey Kiselev, ITEP, Moscow Introduction Prompt photons for FASTMC Thermal photons from hot hadron gas for
FASTMC Conclusions and next steps
July 2007 Workshop of European Research Group on Ultra-Relativistic Heavy Ion Physics, Nantes, France S.Kiselev
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Introduction - UHKM package Universal Hydro Kinetic Model (UHKM) (
http://uhkm.jinr.ru). Now includes: FASTMC – FAST Monte-Carlo hadron freeze-out generator. Particles are generated on the chemical or thermal freeze-out hyper-surface represented by a parameterization or a numerical solution of relativistic hydrodynamics. UKM – Universal Kinetic Model. Treats further evolution (scattering and decays) solving relativistic Boltzmann equations numerically.SPHES – Smoothed Particle Hydrodynamics Equations Solver. Solves (1+3D) – relativistic perfect hydrodynamics equations at given initial condition and equation of state and provides hadron freeze-out hyper-surface.
July 2007 Workshop of European Research Group on Ultra-Relativistic Heavy Ion Physics, Nantes, France S.Kiselev
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Introduction - photons for UHKM decay photons: trivial (π0, , … decays) prompt photons (high pT):
p+p – data fit & A+B – binary scaling thermal photons (low pT):
thermal rates from QGP/Hot HadronGas (HHG) have to be convoluted over the space-time history of the A+B reaction given by hydrodynamics
hard-thermal photons (intermediate pT): ??? Should think how jet-γ conversion, jet-bremsstrahlung could be implemented in UHKM.
ITEP group has prepared for FASTMC: prompt photons thermal photons from HHG in Bjorken -(1+1)-hydrodynamics Have been implemented into FASTMC by Ludmila Malinina
July 2007 Workshop of European Research Group on Ultra-Relativistic Heavy Ion Physics, Nantes, France S.Kiselev
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Prompt photons: RHIC and D0 pp data
Srivastava’s fit does not describe D0 data at xT>0.1
July 2007 Workshop of European Research Group on Ultra-Relativistic Heavy Ion Physics, Nantes, France S.Kiselev
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Prompt photons: pp data fit + binary scaling
PHENIX hep-ph/0609037
(√s)5 Ed3σ/d3p = F(xT,y) One can use a data tabulation of
the F(xT,y) to generate prompt photons.
A+B:
Ed3N/d3p(b)=
Ed3σpp/d3p AB TAB(b)=
Ed3σpp/d3p Ncoll(b)/σppin
Nuclear effects (Cronin, quenching, …) are not taken into account.
Realization: GePP.C macros for ROOT
July 2007 Workshop of European Research Group on Ultra-Relativistic Heavy Ion Physics, Nantes, France S.Kiselev
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Generator of Prompt Photons (GePP): results
Comparison with RHIC data Prediction for LHC
July 2007 Workshop of European Research Group on Ultra-Relativistic Heavy Ion Physics, Nantes, France S.Kiselev
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Thermal photons Thermal rates from QGP:
Perturbative QCD, the lowest order in s
qq gγ, qg qγ
dN/d4xd3p s ln(0.23E/sT) exp(-E/T) T2/E, ZP C53, 433bremsstrahlung
dN/d4xd3p s exp(-E/T) T2/E, PL B510, 98 Thermal rates from hot hadron gas:
effective theory for hadron interactionsπρ πγ, ππ ργ, ρ ππγ, ω πγdN/d4xd3p ~ T2.15 exp(-E/T) / exp((1.35 ET)0.77), PL B510, 98
The thermal rates can be convoluted over the space-time history of the A+B reaction given by SPHES
July 2007 Workshop of European Research Group on Ultra-Relativistic Heavy Ion Physics, Nantes, France S.Kiselev
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Thermal production rates from HHG
C.Song and G.Fai, Phys.Rev., C58 (1998) 1689.
parameterizations for the processes ππ →ργ , πρ → πγ, and ρ →ππγ , in which the a1 meson is taken into account properly
F.D.Steffen and M.H.Thoma, Phys.Lett., B510 (2001) 98.For hard photons, E >1 GeV, a rough estimate of this sum plus ω πγ by the parameterization
July 2007 Workshop of European Research Group on Ultra-Relativistic Heavy Ion Physics, Nantes, France S.Kiselev
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Bjorken -(1+1)-hydrodynamics
Proper time and rapidity y Phys.Rev., D27 (1983) 140
There is no dependence onLorenz boost variable y:
Landau hydrodynamical model, viscosity and conductivity are neglected
July 2007 Workshop of European Research Group on Ultra-Relativistic Heavy Ion Physics, Nantes, France S.Kiselev
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Photon spectrumPhoton spectra follow from convoluting the photon production rates with the space–time evolution of the collision
For a longitudinally expanding cylinder
For proper time and rapidity y`
For an ideal hadron gas
Main parameters: initial 0 , T0 and Tf (at freeze-out)
Connection with the local rest frame
Realization: GeTP.C macros for ROOT
July 2007 Workshop of European Research Group on Ultra-Relativistic Heavy Ion Physics, Nantes, France S.Kiselev
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Generator of Thermal Photons (GeTP): results
Choosing T0 and 0 one can fit data in the hadron scenario
comparison with data, Tf = 100 MeV
July 2007 Workshop of European Research Group on Ultra-Relativistic Heavy Ion Physics, Nantes, France S.Kiselev
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GeTP: prediction for LHC
July 2007 Workshop of European Research Group on Ultra-Relativistic Heavy Ion Physics, Nantes, France S.Kiselev
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GeTP: sensitivity to the parameters
sensitivity to T0 sensitivity to Tf
July 2007 Workshop of European Research Group on Ultra-Relativistic Heavy Ion Physics, Nantes, France S.Kiselev
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Conclusions and next steps
In FASTMC one can generate:
prompt photons
thermal photons from HHG in Bjorken -(1+1)- hydrodynamics
Direct photon data at SPS and RHIC can be reproduced by choosing the T0 and 0 parameters in the hadron scenario
The thermal photons rates can be easy implemented into more realistic hydrodynamics (SPHES, …)
Next step: thermal photons from HHG in (2+1) – hydrodynamics of FASTMC.
July 2007 Workshop of European Research Group on Ultra-Relativistic Heavy Ion Physics, Nantes, France S.Kiselev
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Back up
July 2007 Workshop of European Research Group on Ultra-Relativistic Heavy Ion Physics, Nantes, France S.Kiselev
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Compton Annihilation
In p+p Hard photons:direct component
q + g + q q + q + g
Photons in A+A
Direct Photons Decay Photons
hard thermal hard+thermal
QGP Hadron gasdirect fragmentation
Preequilibriumphotons
jet--conv.
Medium induced bremsstr.
In A+A picture is much more complicated:
V2=0V2<0V2<0
V2>0V2>0V2>0