Upload
yosefu
View
62
Download
0
Tags:
Embed Size (px)
DESCRIPTION
Measurement of Heavy Quark production at RHIC-PHENIX. Yuhei Morino CNS, University of Tokyo. flow & energy loss ? insight into the property of the medium. 1.Introduction. RHIC is for the study of extreme hot and dense matter. p+p, d+Au, Cu+Cu, Au+Au collision - PowerPoint PPT Presentation
Citation preview
1
Measurement of Heavy Quark production at RHIC-PHENIX
Yuhei Morino
CNS, University of Tokyo
2
flow & energy loss ? insight into the property of the medium
1.Introduction
•Heavy quarks (charm and bottom) is produced in initial collision good probe for studying property of the medium.small energy loss and large thermal equilibration time are expected due to their large mass.
RHIC is for the study of extreme hot and dense matter.
•p+p, d+Au, Cu+Cu, Au+Au collision •√s = 22.4, 62, 130, 200 GeV A.
3
2.PHENIX experiment
• PHENIX central arm:– || < 0.35 = 2 x /2– p > 0.2 GeV/c
• Charged particle tracking analysis using DC and PC → p
• Electron identification– Ring Imaging Cherenkov de
tector (RICH) – Electro- Magnetic Calorimet
er (EMC) → energy E
4
cc
0D
electron/muon from semileptonic decay
0D
K
+
K
direct measurement:DK, DK
Meson D±,D0
Mass 1869(1865) GeV
BR D0 --> K (3.85 ± 0.10) %
BR --> e +X D±: 17.2, D0: 6.7 %
3.Heavy quark measurement at PHENIX
5
Upper limit of FONLL
PRL, 97, 252002 (2006)
• cc= 567 57(stat) ± 224(sys) b
• FONLL: Fixed Order plus Next to Leading Log pQCD
• Central value for data/FONLL predictions ~1.7 ( reasonable value)
Inclusive electron( conversion, daliz,etc and heavy quark )
Background subtraction
Non-photonic electron(charm and bottom)
3.2 Result of p+p at 3.2 Result of p+p at ssNNNN = 200 GeV = 200 GeV
6
3.3 Result of Au+Au at 3.3 Result of Au+Au at ssNNNN = 200 GeV = 200 GeV
MB
p+p
0%~
~92%
Heavy flavor electroncompared to binary scaled p+p data (FONLL*1.71)
Clear high pT suppression in central collisions
PHENIX PRL98 173301 (2007)
7
3.4 Nuclear Modification Factor: RAA
tpp
tAA
colltAA dpdN
dpdN
NpR
/
/1)(
large suppression!
Radiative energy loss does not describe!.•dead cone effect
PHENIX PRL98 173301 (2007) Djordjevic, PLB632 81 (2006)
8
3.5 Non-photonic electron v2 Greco, Ko, Rapp: PLB 595 (2004) 202
data suggests non-zero charm v2
charm is strongly coupled to the matter.
pQCD fail [PRB637,362]
9
3.6 comparison with models.
• pQCD radiative E-loss with 10-fold upscaled transport coeff.
• elastic pQCD + D resonances + coalescence
• 2-6 upscaled pQCD elastic
various models exist.
These calculations suggest that DHQ (~(3~6)/2T..near quantum bound) are required to reproduce the data.
PLB649(2007)139
Collisional dissociation heavy quarks can fragment inside the medium and can be suppressed by dissociation
be RAA
ce RAAbehavior of bottom differ from charm c/b separation is necessaryfor further discussion.
10
4. B contribution to non-photonic electron
• FONLL: Fixed Order plus Next to Leading Log pQCD calculation
Large uncertainty on c/b crossing 3 to 9 GeV/c
Experimental determination of ce/be is one of most important next steps
FONLL:
11
cc
0D
electron/muon from semileptonic decay
0D
K
+
K
Heavy quark measurement at PHENIX
D e K partial reconstruction
12
5 ce/be via e-h correlation
Ntag = Nunlike - N like
unlike sign e-h pairs contain large background from photonic electrons.like sign pair subtraction (Ntag is from semi-leptonic decay)
From real data analysisNc(b)e is number of electronsfrom charm (bottom)Nc(b)tag is Ntag from charm (bottom)
From simulation (PYTHIA and EvtGen)
data can be written by only charm and bottom component
The tagging efficiency is determined only decay kinematics and the production ratio of D(B)hadrons to the first order(85%~).
Main uncertainty of c and b •production ratios (D+/D0, Ds/D0 etc)•contribution from NOT D(B) daughters
13
theoretical uncertaintyis NOT included.
comparison of data with simulation (0.5~5.0 GeV)
pt(e) 2~5GeV/c2 /ndf 58.4/45 @b/(b+c)=0.34
5.2 ce/be via e-h correlationYear5 p+p s=200GeV data set is used
14
(be)/(ce+be) as a function of electron pt
(b max) and (c min)
(b min) and (c min)
(b min) and (c max)
(b max) and (c max)
5.3 ce/be via e-h correlationYear5 p+p s=200GeV data set is used
15
cc
0D
0D
K
+
K direct measurement:
D0K+D0K+-
Heavy quark measurement at PHENIX
Meson D±,D0
Mass 1869(1865) GeV
BR D0 --> K+- 3.85 ± 0.10 %
BR D0 --> K+-0 14.1 ± 0.10 %
BR --> e+ +X 17.2(6.7) %
BR --> ++X 6.6 %
16
6. Direct measurement of D0
• Year5 p+p s=200GeV data set is used• Observe 3 significant signal in pT D range 5 ~ 15 GeV/c• No clear signal is seen for pT D < 5 GeV/c• The signal is undetectably small for pT D > 15 GeV/c• Signal is fitted with parabola(B) + gaussian(S)
D0K+-+ reconstruction
17
Momentum Dependence
• Observe clear peak in all pT bins from 5 GeV/c to 10 GeV/c
• Fits are parabola + gaussian• Background is uniform within fitting r
ange
6.2 Direct measurement of D0
D0K+-+ reconstruction
Analysis to determine invariant cross section is on going.
18
6.3 Direct measurement of D0
D0K+- reconstruction with electron tag
tag
reconstruct
real eventmixing event
back ground subtracted
•observe D0 peak•Analysis to determine invariant cross section is on going
Year5 p+p s=200GeV data set is used
19
Summary and outlook• A large suppression pattern and azimuthal anisotropy of single electron has been observed in Au+Au collisions
at √sNN=200GeV.• be/(ce + be) has been studied in p+p collisions at √s =200GeV via e-h correlation for further discussion. analysis for more statistics and high pt extension is on going • Clear peak of D0 meson observed in p+p collisions at √s =200GeV in D0K+ - 0 and D0K+ - channels. Analysis to determine invariant cross section is on going. The results of direct measurement will be compared with
the results of measurement via semi-leptonic decay
20
back up
21
Singnal and Background
Photon Conversion
Main photon source: → In material: → e+e- (Major contribution of photonic electron)
Dalitz decay of light neutral mesons→ e+e- (Large contribution of photonic)
The other Dalitz decays are small contributions Direct Photon (is estimated as very small contribution)
Heavy flavor electrons (the most of all non-photonic) Weak Kaon decays
Ke3: K± → e± e (< 3% of non-photonic in pT > 1.0 GeV/c) Vector Meson Decays
J → e+e-(< 2-3% of non-photonic in all pT.)
Photonic Electron
Non-photonic Electron
22
Most sources of backgroundhave been measured in PHENIX
Decay kinematics and photon conversions can be reconstructed by detector simulation
Then, subtract “cocktail” of all background electrons from the inclusive spectrum
Advantage is small statistical error.
Background Subtraction: Cocktail Method
23
Background Subtraction: Converter Method
We know precise radiation length (X0) of each detector material
The photonic electron yield can
be measured by increase of
additional material
(photon converter )
Advantage is small systematic
error in low pT region
Background in non-photonic
is subtracted by cocktail method
Ne Electron yield
Material amounts:
0
0.4% 1.7%
Dalitz : 0.8% X0 equivalent radiation length
0
With converter
W/O converter
0.8%
Non-photonic
Photonic
converter
CLp 9
7
24
Consistency Check of Two Methods
Both methods were checked each other
Left top figure shows Converter/Cocktail ratio of photonic electrons
Left bottom figure shows non-photon/photonic ratio
25
charm productionbottom productioncharm c = 0.0364 +- 0.0034(sys)bottomb = 0.0145 +- 0.0014(sys)
4. Analysis(2)
unlike pairlike pair
From real data
Electron pt 2~5GeV/cHadron pt 0.4~5.0GeV/c
countX 1/Nnon-phot e data
0.029 +- 0.003(stat) +- 0.002(sys)
From simulation (PYTHIA and EvtGen)
Electron pt 2~5GeV/cHadron pt 0.4~5.0GeV/c
unlike pairlike pair
(unlike-like)/# of ele
26
27
5. Result (electron Pt 2~3GeV/c)theoretical uncertaintyis NOT included.comparison of data with simulation
(0.5~5.0 GeV)
pt(e) 2~5GeV/c2 /ndf 58.4/45 @b/(b+c)=0.34
pt(e) 2~3GeV/c2 /ndf 34.3/22 @b/(b+c)=0.28
28
5. Result (electron Pt 3~4GeV/c)theoretical uncertaintyis NOT included.comparison of data with simulation
(0.5~5.0 GeV)
pt(e) 2~5GeV/c2 /ndf 58.4/45 @b/(b+c)=0.34
pt(e) 2~3GeV/c2 /ndf 34.3/22 @b/(b+c)=0.28
pt(e) 3~4GeV/c2 /ndf 13.4/22 @b/(b+c)=0.66
29
theoretical uncertaintyis NOT included.comparison of data with simulation
(0.5~5.0 GeV)
pt(e) 2~5GeV/c2 /ndf 58.4/45 @b/(b+c)=0.34
pt(e) 2~3GeV/c2 /ndf 34.3/22 @b/(b+c)=0.28
pt(e) 3~4GeV/c2 /ndf 13.4/22 @b/(b+c)=0.66
pt(e) 4~5GeV/c2 /ndf 21.9/22 @b/(b+c)=0.75
5. Result (electron Pt 4~5GeV/c)
30
6.DiscussionCollisional dissociation in hot and dense matter?
Input be/ce
heavy quarks can fragment inside the medium and can be suppressed by dissociation
suppression of non-photonic electron is not so strong asprediction by collisional dissociation model.
31
Open Charm in p+p STAR vs. PHENIX
• PHENIX & STAR electron spectra both agree in shape with FONLL theoretical prediction
• Absolute scale is different by
a factor of 2
31
32
p+p 200 GeV
• Fit e-h correlation with PYTHIA D and B
• Data shows non-zero
B contribution
STAR QM2006
Bottom !
33
Photon Converter
e+
e-
34
Non-photonic electron v2 measurement
Non photonic electron v2 is given as;
v2 γ.e ; Photonic electron v2
Cocktail method (simulation) stat. advantage Converter method (experimentally)
v2e ; Inclusive electron v2
=> Measure RNP = (Non-γ e) / (γ e)=> Measure
NP
eeNPenon
enonee
R
vvRv
d
dN
d
dN
d
dN
.22.
2
..
)1(
page4
(1)
(2)
35
Inclusive electron v2
inclusive electron v2 measured w.r.t reaction plane converter --- increase photonic electron photonic & non-photonic e v2 is different
page6
36
Photonic e v2 determination
decaye vRv 2.
2
good agreement converter method (experimentally determined)
photonic electron v2
=> cocktail of photonic e v2
page7
R = N X->e/ Nγe
photonic e v2 (Cocktail)
decay
v2 (π0)
pT<3 ; π (nucl-ex/0608033)pT>3 ; π0 (PHENIX run4 prelim.)