1. Measurement of charm and bottom production in RHIC-PHENIX
Yuhei Morino for the PHENIX collaboration
CNS, University of Tokyo
JSPS DC fellow

2. 1.Introduction RHIC is for the study of extreme hot and dense matter.
Freeze-out
Pre-equilibrium
QGP
Hadron gas
Hadronization
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 A GeV .
Heavy quarks (charm and bottom) are produced at only initial stage
good probe for studying property of the medium.
p+p collisions  base line study, pQCD test.
d+Au collisions  initial effect study.
Au+Au collisions  energy loss, hot and dense matter

3. Heavy quark measurement at PHENIX
lepton from semileptonic decay
large branching ratio
c and b mixture K+ p-
(single&di) lepton measurement has
been used for the study of heavy quark
p+p ~ Au+Au collisions
IN ADDITION
At p+p (d+Au) collisions,
direct measurement, e-h, e-m correlation
can be used.
important base line study.
direct measurement
direct ID (invariant mass)
large combinatorial background

4. 2 Measurement of non-photonic electron
Inclusive electron
( g conversion, p daliz,etc
　　and heavy quark )
Cocktail method
Ne Electron yield
Material amounts: 0
0.4%
1.7%
Dalitz : 0.8% X0 equivalent radiation length
With converter
W/O converter
0.8%
Non-photonic
Photonic
converter
Converter method
Background subtraction
Non-photonic electron
(charm,bottom and minor
background)
S/N>1
@pt>2GeV/c

5. 3 electron from heavy flavor (p+p@200GeV)
Phys. Rev. Lett 97, (2006)
Single electrons from heavy flavor (charm/bottom) decay are measured and compared with pQCD theory
FONLL pQCD calculation agree to the data within
uncertainty.
(Fixed Order plus Next to
Leading Log pQCD)
scc= 567 ± 57(stat) ±
224(sys) mb

6. bottom fraction in non-photonic electron
be/ce　is obtained
via D e K (no PID)
reconstruction
The result is consistent with FONLL
bottom component is dominant
at pt>3GeV/c
c2 /ndf 28.5/22 @b/(b+c)=0.42(obtained value)
(0.5~5.0GeV)

7. electron spectra from charm and bottom
be = (non-photonic) X (be/(ce+be))
PRL, 97, (2006)
charm
bottom
From bottom ratio in previous slide, electron spectra from charm and bottom are obtained by straight forward
calculation.
Black points are non-photonic electrons
red points are electron from charm and blue points are electrons from bottom including cascade decay.
From this b to e spectra, total cross section of bottom was obtained as this value.
Lines are FONLL predictions.
This figure is ratios of data over FONLL as a function pt.
The ratio is about 2, which is reasonable value comparing with other experiments CDF, HERA.

8. Heavy quark measurement via di-electron
e+e- pair
arXiv:
heavy quark is dominant
>1.1GeV ne K- e- e+

9. Di-electron from heavy quark
cocktail calculations are subtracted from data
bottom, DY,subtraction
 charm signal !!
mass extrapolation (pQCD)
rapidity extrapolation (pQCD)
c dominant
b dominant
After Drell-Yan subtracted,
fit (a*charm+b*bottom)
to the data.
charm and bottom cross sections from e+e- and c,be agree!

10. 4 electron from heavy flavor (d+Au@200GeV)
strong modification has not
been observed below 3GeV/c
The yield at d+Au collisions looks
like slightly enhanced
nuclear anti-showing of bottom?
However, there are large statistical
uncertainty for d+Au data.
The high statistics and low material
d+Au data is already collected.
initial effect for heavy flavor
will be revealed.

11. ５electron from heavy flavor(Au+Au@200GeV)
PHENIX PRL (2007)
Heavy flavor electron
compared to binary scaled p+p data (FONLL*1.71)
Clear high pT suppression
in central collisions MB
p+p
0%~
~92%

12. Nuclear Modification Factor: RAA
PHENIX PRL (2007)
large suppression at
high pt
large V2 is also
observed

13. Comparison with models
pt>~3GeV/c
bottom may also lose large
　energy in (s)QGP
pQCD radiative E-loss
langevin + D resonances
langevin +pQCD elastic
langevin + Tmatrix
Adil & Vitev, PLB 649(2007)139
alternative approaches
collisional dissociation
heavy baryon enhancement

14. shear viscosity of the matter
Rapp and Hees et al reproduce RAAand V2
simultaneously with langevin simulation
 DHQx2pT ~ 4-6
Moore and Teaney calculate the relation
of viscosity between diffusion constant.
 DHQ/ (h/(e+P)) ~ 6
The shear viscosity of the matter
is estimated by the above two theory.
h/s ~(1.3-2)/4p
near the quantum limit

15. 6 Summary non-photonic electron spectra was obtained in p+p@200GeV
be/(ce + be) has been studied in p+p collisions at √s =200GeV via e-h correlation. Cross section of bottom was obtained from electron spectra and be ratio
Cross sections of charm and bottom were obtained from di-electron in p+p collisions at √s =200GeV
High statistics data is already collected.
non-photonic electron spectra was obtained in
large suppression pt and large v2 was observed.
Model comparison suggests smallτ and/or DHQ are required
η/s is very small, near quantum bound.

16. back up

17. 4Measurement of di-electron(Au+Au@200GeV)
arXiv:
Yield(1.2<mee<2.8GeV)/Ncoll
No significant centrality dependence
consistent with PYTHIA & random cc scenarios
c ce e dominant

18. 3 Measurement of di-electron(p+p@200GeV)
p+p at √s = 200GeV
p+p at √s = 200GeV
Material conversion pairs removed by analysis cut
Combinatorial background removed by mixed events
additional correlated background:
cross pairs from decays with four electrons in the final state
particles in same jet (low mass)
or back-to-back jet (high mass)
well understood from MC
arXiv:
arXiv:

19. 4Measurement of di-electron(Au+Au@200GeV)
arXiv:
c ce e dominant
Cocktail agrees with data

20. total cross section of charm and bottom
total cross section of bottom
√s dependence of cross section with NLO pQCD
agrees with data

21. Direct measurement of D meson
direct ID(peak)
large combinatorial background p-
direct measurement:
DKp, DKpp K+
Meson
D±,D0
Mass
1869(1865) GeV
BR D0 --> K+p-
3.85 ± 0.10 %
BR D0 --> K+p-p0
14.1 ± 0.10 %
BR --> e+ +X
17.2(6.7) %

22. D0K-p+p0 reconstruction
S.Butsyk[poster]
large branching ratio(14.1%)
D0K- p+ p0 decay channel

23. electron tag reduce combinatorial background
D0K-p+ with electron tag
tag
reconstruct
observe D0 peak
cross section of D is coming up

24. Singnal and Background
Photonic Electron
Photon Conversion
Main photon source: p0 → gg
In material: g → e+e- (Major contribution of photonic electron)
Dalitz decay of light neutral mesons
p0 → g 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± → p0 e± e (< 3% of non-photonic in pT > 1.0 GeV/c)
Vector Meson Decays
w, , fJ → e+e- (< 2-3% of non-photonic in all pT.)
Non-photonic Electron

25. 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

26. 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 26

27. PHENIX experiment PHENIX central arm: |h| < 0.35 Df = 2 x p/2
p > 0.2 GeV/c
Charged particle tracking analysis using DC and PC → p
Electron identification
Ring Imaging Cherenkov detector (RICH)
Electro- Magnetic Calorimeter (EMC) → energy E
RNXP detector was installed at RUN7
improve determination of reaction plane

28. b contribution to non-photonic electron
FONLL:
FONLL c/(b+c)
FONLL b/(b+c)
Phys.Rev.Lett
FONLL: Fixed Order plus Next to Leading Log pQCD calculation
Large uncertainty on c/b crossing 3 to 9 GeV/c
Measurement of be/ce is key issue.

29. { e c,b separation in non-photonic electron
D0e+ K-(NO PID) reconstruction
Ntag = Nunlike - N like
background subtraction(unlike-like)
photonic component
jet component
tagging efficiency when trigger electron is detected,
conditional probability of associate hadron detectionin PHENIX acc 　
From data
From simulation (PYTHIA and EvtGen) {
decay component (~85%)kinematics e
jet component (~15%)
Main uncertainty of ec and eb 
production ratios (D+/D0, Ds/D0 etc)

30. ec edata eb reconstruction signal and simulation
c2 /ndf value)
(0.5~5.0GeV)
c2 /ndf 28.5/22 @b/(b+c)=0.42(obtained value)
(0.5~5.0GeV)
c2 /ndf value)
(0.5~5.0GeV)
count
tagging efficiency (ec,eb,edata)
tag efficiency of
charm increases as
electron pt
data gets near bottom ec eb
edata