Alan Dion - Tata Institute of Fundamental Researchtheory.tifr.res.in/~qgpsat/dion.pdf · Heavy...

Heavy Flavor at

Alan DionIowa State University

2008-02-14

Measuring Charm/Bottom at PHENIX

Direct ReconstructionD0 → K + π−

D0 → K + π−π0

Difficult without accurate ver-tex measurement (cτ ∼ 123µm)

Indirect MeasurementMeasure contribution from semilep-tonic decays of heavy flavor toelectron spectra.

Both single and pair spectra

Heavy Flavor at PHENIX: 2008-02-14 Alan Dion 2

Electron Identification

DetectorsTracking in drift chamber. Track matching to RICH andEMC.Ring size/shape in RICHE/p distribution from the EMC and DC


Electron Identification

E/p [c]0.4 0.6 0.8 1 1.2 1.4 1.60

2000

4000

6000

8000

10000

12000

14000

16000

< 2.5 GeV/cT

E/p for 2.0 GeV/c < p

total

Kaon decays,some photonconversions

associatedhadrons

vertex electrons,beampipe

conversions

flip

slide

North South

Hadronic BackgroundSome hadronic tracks are randomlyassociated with a ring in the RICH.These are statistically subtracted byswapping the north and south sides ofthe RICH in software.

Energy/Momentum DistributionThe E/p distribution gives strong evidence that we understand our eID. Kaonswhich decay far from the collision have mis-reconstructed momentum. Mosttracks passing cuts form a Gaussian centered at 0.98.


Cocktail Method

MethodAll relevant background sources aremeasured.

Decay kinematics and photon conver-sion rate are simulated.

Background cocktail is subtractedfrom inclusive spectrum.

Performs well at high pT where sig-nal/background is large.

Not limited by statistics.

[GeV/c]T

p0 1 2 3 4 5 6 7 8 9 10

[GeV/c]T

p0 1 2 3 4 5 6 7 8 9 10

]3/c

-2p

[m

b G

eV3

/dσ3E

d-1210

-1110

-1010

-910

-810

-710

-610

-510

-410

-310

-210

-110

1

10

210 = 200 GeV (Run-5)sp+p @

)/2-+e+cocktail: (eeeγ → 0π

conversionγeeγ → ηeeγ →’ η

ee→ ρee0π → ω ee and → ω

eeη → φ ee and → φ contributionsγdirect

Ke3all electrons


Converter Method

MethodAdd material of known thicknessaround the beampipe and compare theelectron spectra with and without thematerial installed.

NHF =RγNinc −N converter

inc

Rγ − 1

Works best at low pT where photonicsources are significant

Limited by statistics of converter run

Converter method is used to normalizethe cocktail method

[GeV/c]T

p0 1 2 3 4 5 6 7 8 9

±b

ackg

rou

nd

e

±h

eavy

-fla

vor

e

0

0.5

1

1.5

2

2.5


Electrons from Heavy Flavor in p+p)3 c

-2 (

mb

GeV

3/d

pσ3

E d

-1010

-910

-810

-710

-610

-510

-410

-310

-210

-110

(a)=200 GeVs)/2 + X at - + e+

(e→ p+p

PHENIX dataFONLL(total)

e)→FONLL(c e)→FONLL(b

e)→ c →FONLL(b

(GeV/c)Tp0 1 2 3 4 5 6 7 8 9 10

0.51

1.52

2.53

DA

TA

/FO

NL

L (b)

For pT between 4-6 GeV/c, the electron signal/background in PHENIX is about 2. Evenif PHENIX subtracted no electron background, they would still be below the STAR result!


Muon Sources


Single Muon Methodology


Muons from Heavy Flavor in p+p


Suppression of Charm in Au+Au

[GeV/c]T

p0 1 2 3 4 5 6 7 8 9

)]-2

[(G

eV/c

)d

yT

dp

N2d

T

pπ21

-1410

-1310

-1210

-1110

-1010

-910

-810

-710

-610

-510

-410

-310

-210

-110

1

10

210

310

[GeV/c]T

p0 1 2 3 4 5 6 7 8 9

±b

ackg

rou

nd

e

±h

eavy

-fla

vor

e0

0.5

1

1.5

2

2.5

4 10×Min-Bias 2 10×0-10%

1 10×10-20% 0 10×20-40% -1 10×40-60% -2 10×60-92%

/42mb-2 10×p+p = 200 GeVNNsAu+Au @

partN0 50 100 150 200 250 300 350

AA

R0

0.2

0.4

0.6

0.8

1

1.2

1.4 = 200 GeVNNsAu+Au @

> 0.3 GeV/cT

: p±e

> 3.0 GeV/cT

: p±e

> 4.0 GeV/cT

: p0π


Models for Charm Suppression

[GeV/c]T

p0 1 2 3 4 5 6 7 8 9 10

AA

R

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

= 200 GeVNNsAu+Au @

0-10% centralPHENIX

STAR

DGLV

Col. Dis.

[GeV/c]T

p0 1 2 3 4 5 6 7 8 9 10

AA

R

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

= 200 GeVNNsAu+Au @

0-10% centralPHENIX

STAR

q̂ = 4GeV 2/fm

q̂ = 10GeV 2/fm

q̂ = 14GeV 2/fm

(GeV/c)T

p0 1 2 3 4 5 6 7 8 9

AA

R

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6 PHENIX data/D enhancement factor of 5cΛ/D enhancement factor of 12cΛ

Lots of models, not much constraint fromheavy flavor suppression alone.


Charm/Bottom Separation

The IdeaLook for D0 → eK with no PID on theKaon.

Reconstruct invariant mass for the electronhadron pair.

Subtract mass distribution from like-signcombination.

The Calculation

εdata ≡Ntag

NHeavy Flavor e±=Nc→tag +Nb→tag

Nc→e +Nb→e

εc ≡Nc→tag

Nc→e, εb ≡

Nb→tag

Nb→e

Nb→e

Nc→e +Nb→e=εc − εdata

εc − εb

Tagging efficiency determined fromsimulation. Production ratios of variousheavy flavor mesons gives the mainuncertainty.


Charm/Bottom Separation

Bottom/charm ratio is in good agreement with FONLL.


Electron Spectra from Charm and Bottom


Bottom Cross Section

σbb = 4.61± 1.31(stat)+2.57−2.22(sys)µb


D0 → K−π+π0 Reconstruction

Utilize the photon trigger to enhance statistics. Low pT is currently being worked onusing electron tagging.


Dielectrons in p + p

)2 (GeV/ceem0 1 2 3 4 5 6 7 8

/GeV

) IN

PH

EN

IX A

CC

EP

TA

NC

E2

(c

ee d

N/d

mev

t1/

N

-1110

-1010

-910

-810

-710

-610

-510

-410

-310 = 200 GeVsp+p at DATA

|y| < 0.35 > 0.2 GeV/c

Tp

)2 (GeV/ceem0 1 2 3 4 5 6 7 8

/GeV

) IN

PH

EN

IX A

CC

EP

TA

NC

E2

(c

ee d

N/d

mev

t1/

N

-1110

-1010

-910

-810

-710

-610

-510

-410

-310

)2 (GeV/ceem0 0.2 0.4 0.6 0.8 1

/GeV

) IN

PH

EN

IX A

CC

EP

TA

NC

E2

(c

ee d

N/d

mev

t1/

N

-710

-610

-510

-410

-310 eeγ → 0π

eeγ → η

eeγ →’ η

ee→ ρ

ee0π ee & → ω

eeη ee & → φ

ee→ ψJ/

ee→’ ψ

ee (PYTHIA)→ cc

ee (PYTHIA)→ bb

ee (PYTHIA)→DY

sum

)2 (GeV/ceem0 0.2 0.4 0.6 0.8 1

/GeV

) IN

PH

EN

IX A

CC

EP

TA

NC

E2

(c

ee d

N/d

mev

t1/

N

-710

-610

-510

-410

-310

)2 (GeV/ceem0 1 2 3 4 5 6 7 8

/GeV

) IN

PH

EN

IX A

CC

EP

TA

NC

E2

(c

ee d

N/d

mev

t1/

N

-1110

-1010

-910

-810

-710

-610

-510 = 200 GeVsp+p at DATA - COCKTAIL

ee (PYTHIA)→ cc

ee (PYTHIA)→ bb

ee (PYTHIA)→DY

sum

|y| < 0.35 > 0.2 GeV/c

Tp

)2 (GeV/ceem0 1 2 3 4 5 6 7 8

/GeV

) IN

PH

EN

IX A

CC

EP

TA

NC

E2

(c

ee d

N/d

mev

t1/

N

-1110

-1010

-910

-810

-710

-610

-510

Dielectrons above and below J/ψ mass compared to charm, bottom and Drell-Yanfrom PYTHIA.

σbb = 3.9± 2.5(stat)+3−2(sys)µb

σcc = 518± 47(stat)± 135(sys)± 190(model)µb


Dielectrons in Au + Au

)2 (GeV/ceem0 0.5 1 1.5 2 2.5 3 3.5 4 4.5

/GeV

) IN

PH

EN

IX A

CC

EP

TA

NC

E2

(c

ee d

N/d

mev

t1/

N -710

-610

-510

-410

-310

-210

-110 = 200 GeVNNsmin. bias Au+Au at eeγ → 0π

eeγ → ηeeγ →’ η

ee→ ρ

ee0π ee & → ωeeη ee & → φ

ee→ ψJ/ ee→’ ψ ee (PYTHIA)→ cc

sum ee (random correlation)→ cc

DATA|y| < 0.35

> 0.2 GeV/cT

p

Agreement with PYTHIA in charm region. But dielectrons in charm region should besuppressed since D mesons change direction in the medium. So maybe there is room forthermal component.


Single Electron v2

[GeV/c]T

p0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

2In

clu

sive

Ele

ctro

n v

0

0.05

0.1

0.15

0.2

0.25

minimum-bias

PH ENIXPRELIMINARY

Au+Au√

sNN = 200 GeV

[GeV/c]T

p0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

2v

0

0.05

0.1

0.15

0.2

0.25

0-10%

10-20%

20-40%

40-60%

min-bias

v2 of inclusive electrons measured usingthe event plane from the new RXPNdetector.

Cocktail for photonic electron v2 takesmeasured hadron v2 as input.


Single Electron v2

[GeV/c]T

p0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

2H

eavy

Fla

vor

Ele

ctro

n v

-0.1

-0.05

0

0.05

0.1

0.15

0.2

0.25

0-10%

PH ENIXPRELIMINARY

Au+Au√

sNN = 200 GeV

[GeV/c]T

p0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

2H

eavy

Fla

vor

Ele

ctro

n v

-0.1

-0.05

0

0.05

0.1

0.15

0.2

0.25

10-20%

PH ENIXPRELIMINARY

Au+Au√

sNN = 200 GeV

[GeV/c]T

p0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

2H

eavy

Fla

vor

Ele

ctro

n v

-0.1

-0.05

0

0.05

0.1

0.15

0.2

0.25

20-40%

PH ENIXPRELIMINARY

Au+Au√

sNN = 200 GeV

[GeV/c]T

p0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

2H

eavy

Fla

vor

Ele

ctro

n v

-0.1

-0.05

0

0.05

0.1

0.15

0.2

0.25

0.3

40-60%

PH ENIXPRELIMINARY

Au+Au√

sNN = 200 GeV


Single Electron v2

[GeV/c]T

p0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

2H

eavy

Fla

vor

Ele

ctro

n v

-0.1

-0.05

0

0.05

0.1

0.15

0.2

PHENIX Final Run4

PHENIX Preliminary Run7

minimum-bias

Run-7 was bad for electrons. The HBD didn’t work, we used a weaker magnetic field(for the HBD), and we had no helium bag (conversions in air). The systematic errors willimprove, but will stay larger than the Run4 result.

We have only analyzed half of the Run7 data so far.


Charm Quarks Flow

[GeV/c]T

p0 1 2 3 4 5 6 7 8 9

AA

R

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

= 200 GeVNNsAu+Au @

0-10% central

Moore &Teaney (III) T)π3/(2

T)π12/(2

van Hees et al. (II)

Armesto et al. (I)

[GeV/c]T

p0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

2H

eavy

Fla

vor

Ele

ctro

n v

-0.1

-0.05

0

0.05

0.1

0.15

0.2

PHENIX Final Run4

PHENIX Preliminary Run7van Hees et al.

minimum-bias

The transport model from van Hess et. al. fits the data pretty well, and its resonancesnear the D mass gain some support from lattice calculations. It would be nice to see whateffect adding gluon radiation would have.


Short-Term Outlook

D meson ReconstructionThis measurement should improve in the near future. Run 6 p+ pand Run 8 d + Au have not been looked at. But this is a verydifficult measurement.

e− µ correlationsSome electron-muon correlation analyses have begun. Azimuthalopening angle distributions look promising for another heavy flavormeasurement. e − µ can also be used as a trigger for the directreconstruction.

Cu + Cu DataWe still have Cu+Cu data to analyze. This is simply a manpowerissue.


Long-Term Outlook

5 cm

55 cme-

e+

Hadron Blind DetectorWe have one more shot at gettingthis thing to work, and we think weknow how. The dielectron measure-ment from Run-9 is something to lookforward to.

Silicon Vertex DetectorWith decay positions measured accu-rately, direct D and B measurementwill be a breeze.


Alan Dion - Tata Institute of Fundamental Researchtheory.tifr.res.in/~qgpsat/dion.pdf · Heavy...

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