Heavy Flavor Production in p+p Collisions in PHENX Experiment at RHIC

W. Xie (RBRC) for PHENIX Collaboration

Motivation for Heavy Flavor measurements at RHIC

• An very important probe for study pQCD.

0D

D0

J/

K+

l

l

K-

e-/-

e+/+

e-/-

e+/+

• A very important Probe for studying properties of Hot Partonic Matter and Cold Muclear Matter

(See Xiaorong Wang’s talk in Heavy-ion section)

Pioneering High Energy Nuclear Interaction eXperiment (460 participant from 57 institutions of 12 countries)

• Maximal Set of Observables– Photons, Electrons, Muons, ID-hadrons

• Highly Selective Triggering– High Rate Capability.– Rare Processes.

How PHENIX Measure Heavy Flavor• high resolution tracking and

momentum measurement from Drift chamber.

Good electron identification from Ring Imaging Cherenkov detector (RICH) and Electromagnetic Calorimeter (EMCal).

High rate capability: powerful level-1 electron trigger

E/p

Hadronic background

J/Psi->ee

Good momentum resolution and muon identification from ID and Trk.

High rate capability: powerful level-1 dimuon trigger

How PHENIX Measure Heavy Flavor

J/Psi->uu

J/Psi->uu

Measure Open Heavy Flavor via electrons at midrapidity

Subtraction of “photonic” sources.• conversion of photons from hadron decays in material

• Dalitz decays of light mesons ()

Converter method• Comparison of e+/- spectra with and without converter

allows separation of photonic and non-photonic sources of single electrons.

measurement via -e coincidences • Yield of -e in vicinity of mass with mixed event

subtraction

cocktail

-e invariant mass

γe+

e-ConverterAu

Au

All 3 methods cross check each other and give consistent results

TrackerIdentifier Absorber

Collision vertex range

Collision

Muon HadronAbsorberSymbols

Detector

1

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

2

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

3

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

4

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

5

zcoll zcollzcoll

Measure Open Heavy Flavor via muon at forward rapidity

Prompt electron cross section at midrapidity

PRELIMINARYPRELIMINARY

PRELIMINARY

Prompt Muon cross section at forward rapidity

J/Psi Cross Section Measurement

The total cross section in p-p collisions is:

2.61+/-0.20(fit)+/-0.26(abs) µb

J/Psi pT distribution

Fitting function:

A*[1+(pT/B)2]-6

<pT2>= 4.31±0.85

At midrapidity

<pT2>= 2.51±0.21

at forward rapidity

Run3 (Y=0)

Run3 (Y=0)

<pT2>= 4.31±0.85

CSM

COM

CSM

COM

J/Psi pT distribution

Upsilon Measurement PHENIX accumulated ~3pb-1 p-p collision during 2005 run.

1st Upsilons at RHIC !

Phenix muon arm

Future Measurement

S. Lebedev

• We see Chi_c in run5 with 3pb-1

• We are expecting to accumulate a factor of 3 more luminosity in the current ongoing run6.

•RHICII:

•Detector Upgrade