Heavy flavor production at RHICHeavy flavor production at RHIC

Yonsei Univ.Yonsei Univ.

Y. KwonY. Kwon

ContentsContents

• Introduction Introduction • Current measurementsCurrent measurements

– Total cross sections by PHENIX and STARTotal cross sections by PHENIX and STAR– Related differential cross sectionsRelated differential cross sections– RRAAAA, flow, and further results, flow, and further results– Charm/Bottom ratioCharm/Bottom ratio

• How do we obtain the result?How do we obtain the result?– Direct reconstructionDirect reconstruction– Non-photonic e & prompt Non-photonic e & prompt

• Results at higher energyResults at higher energy• A question?A question?

3

Introduction : heavy quarks as a probe

p+p :

pQCD test

baseline for A+A

A+A :

flow thermalization

high pT suppression

energy loss

parton

medium

light

ENERGY LOSS

%07.080.3..

,, 00

RB

KDKD

Direct: reconstruction of all decay products

Indirect: charm and beauty via electronsc e+ + anything (B.R.: 9.6%)b e+ + anything (B.R.: 10.9%)issue of photonic background

charm (and beauty) via muonsc + + anything (B.R.: 9.5%)

Introduction : Introduction : (open) heavy flavor measurement (open) heavy flavor measurement

Total cross sections,PHENIX vs STARTotal cross sections,PHENIX vs STAR

Binary scalingSTAR results ~ 2 times larger than PHENIX

Forward prompt Forward prompt -- production production (PHENIX) (PHENIX)

PPG057 : PRD76, 092992(2007)

Leptons from HLeptons from Heavy flavor,eavy flavor, PHENIX PHENIX

PHENIX Preliminary

PRL, 98, 172301 (2007)

Systematically higher than FONLL calculation

e yield shows binary scaling, high pT suppression in central Au+Au

p+p 200GeV/c

8

Leptons from Leptons from heavy flavor, heavy flavor, STARSTAR

STAR Preliminary

• Combined fit of , D0, low pT e

• Low pT muon constrains charm cross-section

c dominant

b dominant

Heavy quarks in p+p from eHeavy quarks in p+p from e++ee-- at PHENIX at PHENIX

d+Au: no suppression expected slight enhancement

expected (Cronin effect) Peripheral Au+Au:

no suppression expected Semi-Central Au+Au: very little suppression expected

STAR hadrons pT> 6 GeV/c

Central Au+Au: less suppression expected ?

RRAAAA

t

pp

t

AA

colltAA

dp

dNdp

dN

NpR

1)(

Nuclear modification factor

Energy Loss?Energy Loss?

Elliptic flow vElliptic flow v22 – NPE from HF decays – NPE from HF decays

PHENIX RUN4 : PRL, 98, 172301 (2007)

How do we obtain the result?How do we obtain the result?

STAR Preliminary

Direct D-meson reconstruction Direct D-meson reconstruction ((STARSTAR))

D0

Phys. Rev. Lett. 94 (2005)

No displaced vertex used

7.4~/ NS

Non-photonic electrons

Inclusive electrons = photonic + non-photonic electron

Direct measurement :converter method

Estimation based on other(PHENIX) measurement :

Cocktail method

Dominant background : 0 Dalitz decay, conversion

Mostly from heavy quark

TrackerIdentifier Absorber

Collision vertex range

Collision

Muon HadronAbsorber

Symbols

Detector

-measurement, sources

1

1 : Hadrons, interacting and absorbed (98%),

3

3 : Hadrons, penetrating and interacting (“stopped”)

4

4 : Hadrons, “punch-through”, 5 : Prompt ,”desired signal”

5

2

2 : Charged /K's, “decaying into ” before absorber (≤1%),

PRELIMINARY

Generator ( Decay + punch-through )1. Light hadron measurement by PHENIX central arm (y = 0)2. Gaussian extrapolation in rapidity to muon arm acceptance

( = 2.5)3. Simplified spectrometer geometry.

-measurement,-measurement, Signal composition Signal composition

Forward prompt Forward prompt -- production production (PHENIX) (PHENIX)

PPG057 : PRD76, 092992(2007)

Leptons from Leptons from heavy flavor, heavy flavor, PHENIXPHENIX

PHENIX Preliminary

PRL, 98, 172301 (2007)

Systematically higher than FONLL calculation

Integral e yield follows binary scaling, strong high pT suppression at central AuAu collisions

p+p 200GeV/c

20

Leptons from Leptons from heavy flavor,heavy flavor, STAR STAR

STAR Preliminary

• Combined fit of , D0, low pT e

• Low pT muon constrains charm cross-section

High pT electrons (EMC trigger) FONLL * 5 p+p spectra

STAR high pSTAR high pTT non-photonicnon-photonic electrons electrons

STAR

Phys. Rev. Lett. 98 (2007) 192301

Bottom contribution to Bottom contribution to non-photonic enon-photonic e

Data consistent with FONLL.

(b

e)/(

ce+

b

e)

Results at higher energyResults at higher energy

Differential charm cross sectionDifferential charm cross section

Differential bottom cross sectionDifferential bottom cross section

A question?A question?

• STAR high pT electrons?STAR high pT electrons?

• If it’s problem, normalization (efficiency)?If it’s problem, normalization (efficiency)?– Detector thickness must be varying a lot!Detector thickness must be varying a lot!