High pT direct photon spectra and azimuthal anisotropy measurements in 200GeV Au Au collisions at RHIC-PHENIX

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High pT direct photon spectra and azimuthal
anisotropy measurements in 200GeV AuAu
collisions at RHIC-PHENIX

• Quark-Matter 2008
• 20th International Conference on
• Nucleus Nucleus Collisions

Kentaro MIKI (Univ. of Tsukuba) for the PHENIX
collaboration mail to kentaro_at_rcf2.rhic.bnl.gov
02/08/2008
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1-1. Introduction Photons
Photons are emitted from several stage of heavy
ion collisions!
sQGP Thermal
Hadron decay
Jet fragmentation
Hard scattered
Jet Brems.
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1-1. Introduction Photons
Photons are emitted from several stage of heavy
ion collisions!
sQGP Thermal
Hadron decay
Jet fragmentation
Hard scattered
Jet Brems.
Direct photons are not suppressed in AuAu
collisions.
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1-2. Introduction direct photon
Direct photon is penetrating probe for initial
hot and dense matter. There are many photon
sources in heavy ion collisions.
All
NLO-pQCD
QGP-Thermal
Jet-photon
Phys. Rev., C69014903(2004)
QM 2006
thermal window -gt 13 GeV/c (?) prompt
photon -gt 6 GeV/c (?)
High pT direct photons are produced in the
initial stage. Thermal radiation are emitted in
the low pT region.
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1-3. Introduction v2
The collision participation part in the early
stage has spatial anisotropy. Pressure gradient
is the largest in the shortest direction of the
ellipsoid. Emitted particles reflect initial
spatial anisotropy.
-Elliptic flow (v2) is defined by the 2nd
coefficient of Fourier expansion
gt S. Huang, (Parallel talk XII)
? azimuthal angle of particles ? azimuthal
angle of reaction plane
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2-1. PHENIX experiment
lead scintillator (PbSc) energy resolution
2.1 ? 8.1 / E1/2 GeV
? lt 0.375 ??90??2
lead glass (PbGl) energy resolution 0.76 ?
5.95 / E1/2 GeV
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3-1. Analysis method
ex. ?0 invariant mass distribution
3.0 lt pT lt 4.0
?0
?
?
?
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3-1. Analysis method
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3-2. Direct photon analysis spectra
200 GeV
Run4 direct photon pT spectra (900M
events) Reached up to 18GeV/c Direct photon
spectra well described by NLO pQCD calculations.
QM2006 proceeding T. Isobe
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3-2. Direct photon analysis spectra
200 GeV
AuAu Direct ? RAA is equal to 1 below 14GeV/c.
(no suppress/enhance)
Direct ? RAA is less than 1 above 14GeV/c.
( Isospin effect? EMC effect?
Suppression of fragmentation photons? )
K. Reygers (parallel session I)
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3-2. Direct photon analysis spectra
200 GeV
CuCu Direct ? RAA equal to 1 up
to pT 17 GeV/c. Direct photon RAA in CuCu
supports simple TAB scaling of hard scattering
up to highest pT
CuCu
K. Reygers (parallel session I)
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3-3. Direct photon analysis spectra
62.4 GeV
Run4 AuAu 62.4 GeV direct photon spectra Direct
photon at 62.4 GeV is also well described by NLO
pQCD calculation above 5 GeV/c.
?sNN 62.4 GeV, Au Au
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4-1. Direct photon analysis v2
The v2 is sensitive to the initial geometric
overlap zone and pressure gradient. Therefore,
direct photon v2 is considered to depend on the
production processes of photons.
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4-1. Direct photon analysis v2
photons from jet
annihilation compton scattering
v2 gt 0
Bremsstrahlung (energy loss)
v2 lt 0
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4-2. Run4 Result
Direct photon v2 at 200GeV AuAu (Run4) Above to
4GeV/c, equal to 0 ? In 3 to 4 GeV/c region is
Non-zero v2 ?? Centrality dependence ???
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4-3. Compared with predictions
Rupa et al calculation
Hydrodynamics with a thermalization at early
times followed by hadronization and decoupling.
PRL 96, 202302 (2006)
gt R. Chatterjee (poster 80)
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4-3. Compared with predictions
Rupa et al calculation
Tuibide et al calculation
Hydrodynamic with a thermalization at early
times followed by hadronization and decoupling.
2D1 hydrodynamical model. Several different
sources are considered.
arXiv0712.0732v2
PRL 96, 202302 (2006)
gt R. Chatterjee (poster 80)
consistent to theoretical calculation ?
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5-1. How to update?
gt Direct photon v2 in Run4 has large error bar
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5-1. How to update?
gt Direct photon v2 in Run4 has large error bar
gt Low pT region -- thermal photon from
virtual gamma analysis
gt T. Dahms, (parallel talk XV)
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5-1. How to update?
gt Direct photon v2 in Run4 has large error bar
gt Low pT region -- thermal photon from
virtual gamma analysis
gt T. Dahms, (parallel talk XV)
gt High pT region -- more statistics!
-- Run 7 analysis -- improvement of
event plane resolution! -- New detector
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5-2. Reaction plane detector (RXNP)
Run7 has new detector for reaction plane
definition.
RXNP has twice better resolution than BBC.
gt Y. Ikeda, (poster 123)
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5-3. ?0 v2 Run7 with RXNP
1.8 B events collected. Good agreement with Run4
Preliminary. Good accuracy up to 10 GeV/c. More
data to analyze gt up to 13 or 16 GeV/c
gt R. Wei, (poster 128) gt Y. Aramaki, (poster 143)
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5-4. compared with
with inclusive photon v2 (Run 4)
We can see the same (or less) statistical
uncertainty even inclusive photon. Run7 allows
us more detail comparison between hadron decay
photon and inclusive photon.
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5-4. compared with
with inclusive photon v2 (Run 4)
with charged hadron v2 (Run 7)
We can see the same (or less) statistical
uncertainty even inclusive photon. Run7 allows
us more detail comparison between hadron decay
photon and inclusive photon.
Good agreement to charged pion v2.
gt S. Huang, (parallel talk XII)
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6. Summary
1. Direct photon is one of the interesting
measurement as penetrating probe for initial
hot and dense matter. 2. The photon excess ratio
is measured in 200 GeV and 62.4 GeV. 3. The
invariant yield is well described by NLO
pQCD. 4. Direct photon v2 is measured in Run4,
with large error bar. gt consistent with
theoretical prediction in high pT. 5.
Run7 ?0 v2 is measured as a function of pT.
gt Run7 allows us more detail direct
photon study at high pT in a near future. 6.
Thank you for all collaborators!
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Ex
Back up
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Ex.
In the 24 GeV/c region, 1. Enhancement of
direct photon in AuAu 2. Direct photon v2
might be non-zero gt There is other
components ??
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Ex. Decay photon and inc. photon (run 4)
?0 v2 as EXODUS input
?0 v2 from latest Daves analysis. In order to
define the EXODUS input, fitting 1 function below
4GeV/c and fitting point to point above 4GeV/c.
decay photon and inc. photon v2
Generated decay photon v2 by Monte Carlo. Error
bar is propagated from ?0 sta. and sys. error to
decay photon as sys. error. In this plot, assumed
the KET scaling for ?, ?, ? and ?.
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Ex. pi0 v2 in Run4