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Measurement of charm and bottom production in RHIC-PHENIX

Yuhei Morino for the PHENIX collaboration

CNS, University of Tokyo

JSPS DC fellow

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1.Introduction

•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, flow? @ hot and dense matter

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 .

Freeze-out

Pre-equilibrium

QGP

Hadron gas

Hadronization

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Heavy quark measurement at PHENIX

•direct ID (invariant mass)•large combinatorial background

lepton from semileptonic decay•large branching ratio•c and b mixture

cc

0D0D-

K

direct measurement

(single&di) lepton measurement has been used for the study of heavy quarkp+p ~ Au+Au collisions

IN ADDITIONAt p+p (d+Au) collisions,direct measurement, e-h, e-correlationcan be used.important base line study.

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Inclusive electron( conversion, daliz,etc 　　 and heavy quark )

Background subtraction

Non-photonic electron(charm,bottom and minorbackground)

2 Measurement of non-photonic electron

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

Converter method

S/N>1@pt>2GeV/c

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Phys. Rev. Lett 97,252002 (2006)

3 electron from heavy flavor (p+p@200GeV)

• 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)

• cc= 567 57(stat) ± 224(sys) b

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bottom fraction in non-photonic electron

•The result is consistent with FONLL•bottom component is dominant at pt>3GeV/c

2 /ndf 28.5/22 @b/(b+c)=0.42(obtained value)(0.5~5.0GeV)

be/ce 　 is obtainedvia D e K (no PID)reconstruction

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electron spectra from charm and bottom

charm

bottom

PRL, 97, 252002 (2006)

be = (non-photonic) X (be/(ce+be))

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Heavy quark measurement via di-electron

cc

0D

0D

e

K

e-

e+

heavy quark is dominantsource @mee >1.1GeV

arXiv:0802.0050e+e- pair

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Di-electron from heavy quark

c dominant

b dominant

cocktail calculations are subtracted from data

After Drell-Yan subtracted,fit (a*charm+b*bottom)to the data.

charm and bottom cross sections from e+e- and c,be agree!

bottom, DY,subtraction charm signal !!mass extrapolation (pQCD)rapidity extrapolation (pQCD)

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4 electron from heavy flavor (d+Au@200GeV)

strong modification has notbeen observed below 3GeV/c

The yield at d+Au collisions lookslike slightly enhancednuclear anti-showing of bottom?However, there are large statisticaluncertainty for d+Au data.

The high statistics and low materiald+Au data is already collected. initial effect for heavy flavor will be revealed.

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MB

p+p

0%~

~92%

５ electron from heavy flavor(Au+Au@200GeV)

Heavy flavor electroncompared to binary scaled p+p data (FONLL*1.71)

Clear high pT suppression in central collisions

PHENIX PRL98 173301 (2007)

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Nuclear Modification Factor: RAA

tpp

tAA

colltAA dpdN

dpdN

NpR

/

/1)(

large suppression athigh pt

PHENIX PRL98 173301 (2007)

large V2 is also observed

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Comparison with models

• pQCD radiative E-loss

• langevin + D resonances

• langevin +pQCD elastic

• langevin + Tmatrix

be/ce>~1 @ pt>~3GeV/cbottom may also lose large 　 energy in (s)QGP

alternative approaches•collisional dissociation •heavy baryon enhancement

Adil & Vitev, PLB 649(2007)139

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shear viscosity of the matter

The shear viscosity of the matter is estimated by the above two theory./s ~(1.3-2)/4near the quantum limit

Rapp and Hees et al reproduce RAAand V2 simultaneously with langevin simulation

DHQx2pT ~ 4-6

Moore and Teaney calculate the relationof viscosity between diffusion constant.

DHQ/ (/(e+P)) ~ 6

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6 Summary

• non-photonic electron spectra was obtained in p+p@200GeV• be/(ce + be) has been studied in p+p collisions at √s =200GeV via

e-h correlation. Cross section of bottom was obtained from electron spectra and be ratio

• Cross sections of charm and bottom were obtained from di-electron in p+p collisions at √s =200GeV

• High statistics d+Au@200GeV data is already collected.

• non-photonic electron spectra was obtained in Au+Au@200GeV

• large suppression pattern@high pt and large v2 was observed.

• Model comparison suggests smallτ and/or DHQ are required

• η/s is very small, near quantum bound.

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back up

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4Measurement of di-electron(Au+Au@200GeV)

c ce e dominant

Yield(1.2<mee<2.8GeV)/Ncoll

•No significant centrality dependence•consistent with PYTHIA & random cc scenarios

arXiv:0706.3034

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• 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

p+p at √s = 200GeVp+p at √s = 200GeV

arXiv:0802.0050

3 Measurement of di-electron(p+p@200GeV)

arXiv:0802.0050

p+p at √s = 200GeVp+p at √s = 200GeV

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4Measurement of di-electron(Au+Au@200GeV)

c ce e dominant

arXiv:0706.3034

Cocktail agrees with data points@1.2<Mee<2.8.

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total cross section of charm and bottom

√s dependence of cross section with NLO pQCDagrees with data

total cross section of bottom

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Direct measurement of D meson

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) %

•direct ID(peak)•large combinatorial background

cc

0D

0D

-

Kdirect measurement:DK, DK

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D0K-+0 reconstruction

large branching ratio(14.1%) S.Butsyk[poster]

D0K- + 0 decay channel

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electron tag reduce combinatorial background

•observe D0 peak•cross section of D is coming up

D0K-+ with electron tagtag

reconstruct

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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

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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

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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

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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

RNXP detector was installed at RUN7improve determination of reaction plane

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FONLL:

FONLL c/(b+c)FONLL c/(b+c)FONLL b/(b+c)

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

Measurement of be/ce is key issue.

Phys.Rev.Lett 95 122001

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decay component (~85%)kinematics

Ntag = Nunlike - N likeD0e+ K-(NO PID) reconstruction

From data

From simulation (PYTHIA and EvtGen)

Main uncertainty of c and b •production ratios (D+/D0, Ds/D0 etc)

c,b separation in non-photonic electron

background subtraction(unlike-like)•photonic component•jet component

tagging efficiency when trigger electron is detected,conditional probability of associate hadron detectionin PHENIX acc 　

{jet component (~15%)

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count

tagging efficiency (c,b,data)

reconstruction signal and simulation

2 /ndf 21.2/22 @b/(b+c)=0.26(obtained value)(0.5~5.0GeV)2 /ndf 28.5/22 @b/(b+c)=0.42(obtained value)(0.5~5.0GeV)2 /ndf 18.7/22 @b/(b+c)=0.56(obtained value)(0.5~5.0GeV)

•tag efficiency of charm increases as electron pt•tag efficiency of data gets near bottom

c

b

data