High pT direct photon spectra and azimuthal anisotropy measurements in 200GeV Au+Au co

llisions at RHIC-PHENIX

Quark-Matter 200820th International Conference on

Nucleus Nucleus Collisions

02/08/2008

Kentaro MIKI (Univ. of Tsukuba)Kentaro MIKI (Univ. of Tsukuba)for the PHENIX collaborationfor the PHENIX collaboration

mail to: kentaro@rcf2.rhic.bnl.govmail to: kentaro@rcf2.rhic.bnl.gov

02 / 08 / 2008 QM 2008 - Kentaro Miki -

1-1. Introduction ~Photons~Photons are emitted from several stage of heavy ion collisions!

Hard scattered

sQGP Thermal

Jet Brems.

Jet fragmentation

Hadron decay

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1-1. Introduction ~Photons~Photons are emitted from several stage of heavy ion collisions!

Direct photons are not suppressed in Au+Au collisions.

Hard scattered

sQGP Thermal

Jet Brems.

Jet fragmentation

Hadron decay

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1-2. Introduction ~direct photon~

QGP-Thermal Jet-photon

NLO-pQCD

All

Direct photon is penetrating probe for initial hot and dense matter.There are many photon sources in heavy ion collisions.

High pT direct photons are produced in the initial stage.Thermal radiation are emitted in the low pT region.

Phys. Rev., C69:014903(2004) QM 2006

thermal window -> 1~3 GeV/c (?)prompt photon -> 6~ GeV/c (?)

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1-3. Introduction ~v2~

: azimuthal angle of particles : azimuthal angle of reaction plane

-Elliptic flow (v2) is defined by the 2nd coefficient of Fourier expansion

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.

> S. Huang, (Parallel talk XII)

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2-1. PHENIX experiment

lead scintillator (PbSc)・ energy resolution 　 2.1 8.1 %/ E1/2 [GeV]

lead glass (PbGl)・ energy resolution 0.76 5.95 %/ E1/2 [GeV]

|| < 0.375 =902

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3-1. Analysis method

Direct hadron decay 　

Inclusive photon

0 ’

ex. 0 invariant mass distribution

3.0 < pT < 4.0

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3-1. Analysis method

Direct hadron decay 　

Inclusive photon

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3-2. Direct photon analysis ~spectra~

Run4 direct photon pT spectra (900M events)Reached up to 18GeV/cDirect photon spectra well described by NLO pQCD calculations.

200 GeV

QM2006 proceeding T. Isobe

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3-2. Direct photon analysis ~spectra~

200 GeV

RAA with pQCD

RAA with p+p data

K. Reygers (parallel session I)

Au+Au: 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? )

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3-2. Direct photon analysis ~spectra~

200 GeV

RAA with pQCD

RAA with p+p data

Cu+Cu

K. Reygers (parallel session I)

Cu+Cu: Direct RAA equal to 1 up to pT 17 GeV/c.

Direct photon RAA in Cu+Cu supports simple TAB scaling of hard scattering up to highest pT

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3-3. Direct photon analysis ~spectra~

62.4 GeV Run4 Au+Au 62.4 GeV direct photon spectra

Direct photon at 62.4 GeV is also welldescribed by NLO pQCD calculationabove 5 GeV/c.

sNN = 62.4 GeV, Au + Au

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4-1. Direct photon analysis ~v2~

Direct Hadron decay 　

Inclusive photon

hard scatter

Jet Brems.

Jet Fragment

sQGP

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~

Direct Hadron decay 　

Inclusive photon

hard scatter

Jet Brems.

Jet Fragment

sQQP

annihilationcompton scattering

Bremsstrahlung (energy loss)

v2 > 0

v2 < 0

hard scatter

Jet Brems.

Jet Fragment

sQGP

v2 = 0

v2 < 0

v2 > 0

v2 ≥ 0

photons from jet

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4-2. Run4 Result

1

* _2

.2.

2

R

vvRv

photonBGphotonincphotondir

photonBG

photoninc

N

NR

_

.

Direct photon v2 at 200GeV Au+Au (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

> R. Chatterjee (poster 80)

PRL 96, 202302 (2006)

Hydrodynamics with a thermalization at early times followed by hadronization and decoupling.

Rupa et al calculation

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4-3. Compared with predictions

arXiv:0712.0732v2

> R. Chatterjee (poster 80)

PRL 96, 202302 (2006)

Hydrodynamic with a thermalization at early times followed by hadronization and decoupling.

Rupa et al calculation Tuibide et al calculation2D+1 hydrodynamical model.Several different sources are considered.

consistent to theoretical calculation … ?

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5-1. How to update?

> Direct photon v2 in Run4 has large error bar

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5-1. How to update?

> Direct photon v2 in Run4 has large error bar

> Low pT region -- thermal photon from virtual gamma analysis

> T. Dahms, (parallel talk XV)

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5-1. How to update?

> Direct photon v2 in Run4 has large error bar

> Low pT region -- thermal photon from virtual gamma analysis

> T. Dahms, (parallel talk XV)

> 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)

> Y. Ikeda, (poster 123)

RXNP has twice better resolution than BBC.

Run7 has new detector for reaction plane definition.

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5-3. 0 v2 Run7 with RXNP

> R. Wei, (poster 128)> Y. Aramaki, (poster 143)

1.8 B events collected.Good agreement with Run4 Preliminary. Good accuracy up to 10 GeV/c.More data to analyze => up to 13 or 16 GeV/c

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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.

> 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. => consistent with theoretical prediction in high pT.

5. Run7 0 v2 is measured as a function of pT. => 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 2~4 GeV/c region, 1. Enhancement of direct photon in Au+Au 2. Direct photon v2 might be non-zero

=> There is other components ??

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Ex. Decay photon and inc. photon (run 4)0 v2 as EXODUS input

decay photon and inc. photon v2

0 v2 from latest Dave’s analysis. In order to define the EXODUS input,fitting 1 function below 4GeV/c and fitting point to point above 4GeV/c.

Generated decay photon v2

by Monte Carlo. Error bar is propagated from0 sta. and sys. error to decayphoton as sys. error.In this plot, assumed the KET

scaling for , , and ’.

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Ex. pi0 v2 in Run4