# Presentation: 656630

## PHENIX Heavy Flavor Production in Heavy-ion Collisions 

- W. Xie
*(UC. Riverside)*
**PHENIX Collaboration**

***QWG at Fermilab on Sep. 2003***

## PHENIX Heavy Flavor Physics:results and perspectives

- W. Xie
*(UC. Riverside)*
**PHENIX Collaboration**

***QWG at Fermilab on Sep. 2003***

**2 counter-circulating rings, 3.8 km circumference**
**Any nucleus on any other.**
**Top energies (each beam):**
**100 GeV/nucleon Au-Au.**
**250 GeV polarized p-p.**

**P****ioneering ****H****igh ****E****nergy ****N****uclear ****I****nteraction e****X****periment   **
*           **(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.**

**QGP & Proton Spin**

## PHENIX  Ability to Study Heavy Flavor-- electron and muon measurenent 

- high resolution tracking and momentum measurement from  Drift chamber.

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

- Good  momentum resolution and muon identification from ID and Trk.

- Yield of Open Charm, Bottom from single leptons.
- flow of charm.
- J/’
- Upsilon

## Collision Topology

-     Soft interactions where production scales with Npart
-     Hard interactions where production scales with Ncoll

- Wang, Gyulassy: nucl-th/0008014
- Kharzeev, Nandi:  nucl-th/0012025

- The impact parameter determines the number of nucleons that participate in the collision.

**Participating nucleons**

- Spectators

## Motivation
Mainly produced from gluon fusion. Sensitive to initial gluon density and gluon distribution
Energy loss when propagating through dense medium
baseline measurement for charmonium suppression

- Mainly produced from gluon fusion. Sensitive to initial gluon density and gluon distribution
- Energy loss when propagating through dense medium
- baseline measurement for charmonium suppression

- Open Charm measurements

**PHENIX has measured charm cross section via single electron in run1 and run2**

- K+

- -

- 

- e+

**D*****0**

********

## Inclusive e± spectra from Au+Au at 130 GeV

-    main sources contributing to the e± spectra
- “photonic” sources
- conversion of photons from hadron decays in material
- Dalitz decays of light  mesons  (0, , , ’, )
- “non-photonic” sources
- semi leptonic decays of open charm (beauty)

- “non-photonic” sources are picked-up via cocktail methods.

## Non-photonic e± spectra from Au-Au at 130 GeV 

- Comparison with  PYTHIA
- tuned to fit SPS, FNAL, ISR data
- (s<63 GeV)
- cc = 330 b for pp at 130GeV
- scale to Au+Au using the <Ncoll>
- PYTHIA calculation consistent
- with data.

- Non-photonic e± spectra from Au-Au at 130 GeV

- Charm cross section per binary collision from data
- assumption: all e± are from charm decays
- fitting PYTHIA to data for pT > 0.8 GeV/c
- consistent with binary scaling (within large uncertainties)

## Energy dependence of charm production 

- PHENIX data is consistent with the prediction of PYTHIA and NLO pQCD calculation.

## Converter method for RUN2 single electron measurement

- e±  spectra with converter: Nc
- e± spectra without converter: N
- if no contribution to e± from non-photonic sources  N/Nc  const.
- but spectra approach each other with increasing pT
- indication for strong non-photonic source

## Non-photonic e± spectra from Au-Au at 200 GeV

- Non-photonic e± spectra from Au-Au at 200 GeV

- non-photonic e± yield at 200 GeV
- larger than at 130 GeV
- consistent with  PYTHIA,  assuming binary scaling
- PYTHIA for pp at      200 GeV: cc = 650 b

- inclusive e± are consistent with binary scaling within the current statistical and systematical uncertainties
- no large suppression observed in e± from charm decay, possibly due to “dead cone” effect which result in less energy loss(*Y.L. Dokshitzer and D.E. Kharzeev, Phys. Lett. B519(2001)199*)

## J/ Measurement

**When Quark-Gluon plasma (QGP) is formed****:**
-       Color  screening will lead to suppression of charmonium production in heavy ion collisions(*T. Matsui, H. Satz, Phys. Lett. B178(1986)416)*.
-       More recent predictions of increased J/ production at RHIC from recombination(*R.L. Thews  et al, Phys. Rev. C63(2001)054905*)
**A promising signal for the observation of QGP**

## J/ Signal in RUN2 p-p Collisions at s=200 GeV

-  One of the baseline for understanding J/ production in AuAu collisions.
-  Constrain models for J/ production( for results and discussion, see Hiroki Seto’s talk in production session)

- 82nb-1

- 67nb-1

- BdN/dy|y=0 = 1.46±0.23(stat) ± 0.22(sys) ± 0.15(abs)x10-6

## J/ Measurement in Au-Au Collisions at snn=200GeV

**NA50 points normalized to pp point  **

- Incl. systematic errors

- 90% C.L.

- One standard deviation

- Most probable value

- Binary scaling

- Expectation with absorption (4.4 and 7.1 mb)

## Comparison with Model 

- Comparison with Model

- Coalescence model (Thews et al)

- y = 1.0

- y = 4.0

- Stat. Model (Andronic et al.)

- Absorption model (Grandchamp et al.)

## Charm Measurement in RUN3 d-Au Collision at snn=200GeV

- There’re also suppression or enhancement due to normal nuclear effect:
- Gluon (anti)shadowing:
-  depletion of the small x gluons (very low momentum fraction partons have large size, overlap with neighbors, and fuse to thus enhancing higher population at higher momentum at the expense of lower momentum).

- Nuclear effect can be understood through p-A collisions.

- Nuclear absorption:
- ccbar dissociation through interaction with nucleons when passing through nucleus.

## J/ Signal in RUN3 d-Au Collisions

-  Number of J/’s expected from the d-Au run (w/o shadowing) is about  1000/arm for +

- Number of J/’s expected from the d-Au run about  400 for central arm for e+e-

- North Muon arm

## PHENIX Proposal for Future Heavy Flavor Measurement in Heavy-ion Collisions

- RUN4:   Au+Au at ***s**nn**=200GeV  to measure charmonium, open charm with the maximum possible integrated luminosity.*

- RUN5* :  **Si+Si *at ***s**nn**=200GeV  to study charmonium production in a lighter system.*

- RUN6* :  **Au+Au at ****s**nn**=62.4GeV to study the energy dependence of charm production.*

- RUN8:  Au+Au at***s**nn**=200GeV *with Silicon Vertex Detector, which will enable PHENIX in the future runs :
-     to have robust measurement of gluon shadowing in p+A collisions
-     to measure charm and beauty with pt above 4GeV/c
-     to quantify J/ suppression relative to open charm production
-     to improve mass resolution of J/ and tobetter separate different state

- Muon Trigger Upgrade to enable PHENIX consume future high luminorsity runs for rare event.

## BACK-UP SLIDE 

## light hadron cocktail input:
0 (dominant source at low pT)
pT spectra from PHENIX 0, ± data  
power law parameterization                                                                      
other hadrons
mT scaling:                                                                                                                          
relative normalization to  at high pT                                                                                      from other measurements at SPS,                                                                                          FNAL, ISR, RHIC
photon conversions
material known in acceptance
excess above cocktail
increasing with pT
expected from charm decays

- 0 (dominant source at low pT)
- pT spectra from PHENIX 0, ± data
- power law parameterization
- other hadrons
- mT scaling:
- relative normalization to  at high pT                                                                                      from other measurements at SPS,                                                                                          FNAL, ISR, RHIC
- photon conversions
- material known in acceptance
- excess above cocktail
- increasing with pT
- expected from charm decays

- Separation of non-photonic e±: cocktail method

## Photon converter in Run-2 

- additional photon converter installed in parts of the 200 GeV run in PHENIX central arms
- 1.7 % X0 brass close to beam line
- additional material increases the number of e± from photon conversions by a fixed factor
- ratio between Dalitz decays and photon conversions is fixed by relative branching ratios Dalitz/, which is very similar for 0 and 

- comparison of spectra with and without converter allows for complete separation of contributions from non-photonic and photonic sources
- complementary to cocktail method
- completely different systematics

## J/ Kinematic Coverage for present PHENIX d-Au (run-III)

_**J/**__****__** Kinematic Coverage for present PHENIX d-Au (run-III)**_

- 	PHENIX has very broad coverage in xF, pT and x2 by combining
- North Arm
- Central Arm
- South Arm

## Dead Cone Effect ??

- Gluon radiation from a massive parton  is suppressed at angles
-    < Mq/Eq  (manifestation of causality as Q < c)
-  D. Kharzeev et al. **Phys.Lett.B 519:1999,2001**
- The slower moving quark also samples a more dilute density profile as
-   the medium expands
-   reduced energy loss E since most radiation is in the forward region
-   is E inhibited enough for produced medium to be
-       transparent to heavy quarks  (Q > LN) ?

## Flowing D Meson Calculation.

- J. Nagle, S. Kelly, M. Gyulassy, S.B. JN, Phys. Lett. B 557, pp 26-32.

- Electon data are consistent
- with both:
- 1. Medium transparent to
-    heavy quarks which then
-    fragment into D/B mesons
-    outside the system(scaled Pythia)
- 2. Highly opaque medium
-     with charm boosted via
-     rescattering and
-     hadronizing in the system

- Flowing D Meson Calculation.

## Centrality dependence at 200 GeV 

- Centrality dependence at 200 GeV

## Silicon Vertex Tracker in PHENIX

**Pixel barrels**** **** (50 ********m x 425 ********m)**
**Strip barrels****  (80 ********m x 3 cm)**
**Pixel disks****      (50 ********m x 2 mm)**

**~1.0% X****0 ****per layer**
**barrel resolution  < 50 ********m forward resolution < 150 ********m**

**1.2<|********|<****2.4**

**|********|<****1.2**

**Strawman design under investigation**

## Charm/Beauty measurements in Au+Au with SVT

- Charm Measurement by barrel + central arm

- BBeauty e by barrel+central arm

- HIJING Au+Au

- Au+Au
- Robust charm/beauty measurement in Au+Au
- Energy loss of charm at high Pt
- Energy loss of beauty

## Measurement of gluon shadowing with SVT

- Heavy-flavor measurement in p+A
- Single lepton and J/ with displaced vertex
- Heavy-flavor production via g+g  q+q
- Extracting gluon structure function nuclei, shadowing
- vertex detector provides broader range in x into predicted shadowing region (x ~ 10-2 - 10-3)