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Measurement of phi and omega @RHIC-PHENIX
Misaki Ouchida
f or the PHENIX Collaboration
Hiroshima University
What is expected? Hadron suppression C.S.R. signal
( Flow → Talk by D.W.)
( Continuum → Talk by S.C.)
What we have ?
outline
2010 WWND
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Misaki Ouchida2010 WWND
What is expectedHigh pT physicsHigh pT physics
Hadron SuppressionHadron SuppressionThe inclusive pi0 production in Au+Au
PRL 91. 072301 (2003)
QGP
Hadron Production will be suppressed due to the jet quenching occurred in the heavy-ion collisions as an effect of the matter
ssuudd
How phi & omega How phi & omega behave?behave?
Temperature
Density
RHICRHIC
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Misaki Ouchida2010 WWND
What is expectedHigh pT physicsHigh pT physics
Hadron SuppressionHadron Suppression
PRC 77. 064907 (2008)
QGP
Hadron Production will be suppressed due to the jet quenching occurred in the heavy-ion collisions as an effect of the matter
ssuudd
How phi & omega How phi & omega behave?behave?
Temperature
Density
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Misaki Ouchida2010 WWND
Low pT physicsLow pT physics
TemperatureDensity
Chiral Symmetry RestorationChiral Symmetry Restoration
Hot/dense matter Hot/dense matter ↓↓Quark condensate decreaseQuark condensate decrease↓↓changes hadron mass changes hadron mass properties in mediumproperties in medium
What is expected
<qq>quark condensate
-
Measurements of vector mesonsMeasurements of vector mesons Access quark condensate with theoretical calculationsAccess quark condensate with theoretical calculations
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Misaki Ouchida2010 WWND
PredictionModel PredictionModel Prediction
Unfortunately, quark condensates Unfortunately, quark condensates is not an observableis not an observable Link condesates and vector mLink condesates and vector meson spectrumeson spectrum
- Lowering of in-medium mass?- Lowering of in-medium mass?- Broadening of resonance?- Broadening of resonance?
R. Rapp, Phys. Rev. C63(2001) 054907
T.Hatsuda and S.Lee Phys.Rev.C46-1 1992
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Misaki Ouchida2010 WWND
PHENIX spectrometer<Global detector>• BBC & ZDC : Event trigger, Collision vertex, Centrality <Central arm>•DC & PC : tracking, momentum• RICH & EMC : electron ID• TOF, EMC : hadron ID<Muon arm>• MuID : muon ID
How do we measure?
PHENIX acceptancepseud-rapidity range : |η| < 0.35azimuthal angle : 2x90 degree
φ mesons (= 46fm/c)
φ→e+e- BR ~ 10-4
φ→K+K- BR ~ 50 %
ω mesons (= 23 fm/c)
ω→e+e- BR ~ 10-5
ω→π0γ BR ~ 9 % ω→π0π+π- BR ~ 90 %
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Misaki Ouchida2010 WWND
Systematic Measurement-different decay mode (lepton, hadron)
Rec
on
stru
cted
Rec
on
stru
cted
Eff
icie
ncy
Eff
icie
ncy
e+e- (BR:7x10-3%)
(BR:9%)
ωpTωpT
Can Approach to high pT
Advantage of Systematic Measurement- Leptonic Decay mode: no final distortion
- Hadronic Decay mode: high BR,
no ρ-contribution (e+e- case)
- Wide kinematic coverage
- Reference study (comparing collision system)
- Line Shape Analysis (BR check)
-different collision mode (p+p, d+Au, A+A)
e+
e-
K+
K-
φ mesons
φ→e+e- BR ~ 10-4
φ→K+K- BR ~ 50 %
ω mesons
ω→e+e- BR ~ 10-5
ω→π0γ BR ~ 9 % ω→π0π+π- BR ~ 90 %
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Misaki Ouchida2010 WWND
So far, what we have ?So far, what we have ?
Collected Data (√s = 200 GeV)
- p+p (run5) - d+Au (run3, run8) - Cu+Cu (run5) - Au+Au (run4)
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Misaki Ouchida2010 WWND
p+p
φ e+e-
+-
p+p
Both leptonic andhadronic decay channel are measured
Base Line – p+p
φ K+K-
φ K+K-
No PID methNo PID method was introdod was introduced to exteuced to extend the accepnd the acceptance to hightance to higher pT er pT
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Misaki Ouchida2010 WWND
d+ Au
d+ Au
φ e+e-
Base Line – d+Au
Both leptonic andhadronic decay channel are measured
φ K+K-
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Misaki Ouchida2010 WWND
• Spectra (p+p & d+Au)
Base Line
dAudAu
pppp
Results are consistent Fitting of Levy fun
c.
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Misaki Ouchida2010 WWND
• Spectra (p+p & d+Au)
Base Line
Results are consistent
dAudAu
pppp
Fitting of Levy func.
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Misaki Ouchida2010 WWND
Subtracting Backgrounds ( 2 body: φ e+e-φ K+K- )
φBG
BGcombinatorial backgroundsextract
by Event Mixing
→eeBGSignalSignal
Trails – A+A
→K+K-
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Misaki Ouchida2010 WWND
Black: FG
[GeV/c^2]
Peripheral (cent 60~92 %)3.5<pT<4.5[GeV/c]
Magenta: Uncorrelated BG + Correlated BG2 + Ks contribution
BG3
BG2
BG1
Gaussian (Mean and With are Fixed by Embedding simulation)
after subtraction of
BG1+BG2+BG3
coun
t
Reconstructed invariant mass
Subtracting Backgrounds ( 3 body: ( 2)
Trails – A+A
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Misaki Ouchida2010 WWND
• Spectra (Au+Au)
Results & Discussionφ , φ e+e- @ Au+Au
MBMB
Suppression of phi in central collisionNo significant modification observed?
0 - 20%0 - 20%
20 - 40%20 - 40%
40 - 92%40 - 92%
PHENIX Preliminary
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Misaki Ouchida2010 WWND
• Spectra (Au+Au) , e+e- @ Au+Au
Results & Discussion
MBMB
20 - 60%20 - 60%
0 - 20%0 - 20%
60 - 92%60 - 92%
Suppression of omega in central collision
Scaled fromp+p spectra
PHENIX Preliminary
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Misaki Ouchida2010 WWND
Results & Discussion
The results are consistentBetween CuCu and AuAu
- Baryon/meson difference is apparentBaryon/meson difference is apparent- Suppression pattern of pi0 and eta is sameSuppression pattern of pi0 and eta is same- phi at intermediate pT do not follow pi0 and etaphi at intermediate pT do not follow pi0 and eta- omega in high pT needs more dataomega in high pT needs more data- All suppression patterns are similar at high pTAll suppression patterns are similar at high pT
R_AA (CuCu and AuAu)
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Misaki Ouchida2010 WWND
Issues and Outlook
signal electron
partner positronneeded for rejection
- The discussion in low pT physics is hard due to low statistics and S/N The discussion in low pT physics is hard due to low statistics and S/N - Run10 is now taking AuAu dataRun10 is now taking AuAu datawith activated HBDwith activated HBD e+ e -
e+ e -
“combinatorial pairs”
all signal
Able to reduce the BGfrom Dalitz and γconversion
Dalitz rejectorHadron Blind Detector
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Misaki Ouchida2010 WWND
Summary• PHENIX measured Low Mass Vector Meson, omeg
a and phi production in both leptonic and hadronic channels in different collision system.
– Spectra show good agreement in p+p and d+Au
– Mass modification discussion is hard to discuss – Yield measurement provide intriguing systematic
results of hadron suppression.
Base line
A+A