# Presentation: 183781

## Heavy Flavor Measurements at  RHICPast, Present and Future

- Sergey Butsyk
- SUNY at Stony Brook
- for the PHENIX collaboration

## Outline

- Heavy flavor physics motivations
- Signal extraction methods at PHENIX and STAR
- Latest results for Open Charm measurements in p+p, d+Au and Au+Au
- Future outlook
- Summary

## Heavy Flavor Physics

- Production
- gg->QQ “gluon fusion”
- Sensitive to the initial gluon density to the first order s2
- Initial state effects
- Initial parton distribution
- kT broadening
- Intrinsic Flavor
- Energy loss in initial stage

## Why Heavy Flavor?

-  Heavy quark mass is large s(mC2) ~ 0.3  can use perturbative QCD
- Experimentally easy to observe
- DK decays
- Semi-leptonic decays

## Physics motivations

- p-p collisions:
- Check pQCD predictions  at s = 200 GeV
- Measure initial gluon density G(x)
- p-Au collisions:
- Study gluon energy loss in “cold” nuclear matter
- Gluon shadowing
- Au-Au collisions:
- Measure medium modification effects (charm energy loss, collective flow, charm enhancement)
- Study the thermal production of charm from QGP
- Set  the baseline for J/ production

## Enhancement over suppression

**NA50****Pb-Pb **
**158 GeV**
******+********-**

- central collisions

- charm

- DY

- Charm enhancement ?
- NA50 reports increased production of charm in Pb+Pb collisions
- Heavy quark quenching
- Energy loss should be suppressed due to suppression of small angle gluon radiation “dead cone effect”Y. L. Dokshitzer & D.E. Kharzeev, Phys.Lett.B519(2001)199-206

- M. Djordevic & M. Gyulassy QM04, nucl-th/0404006

## Previous measurements

- E769 PRL 77, 2388 (1996)

## Slide 8

## Heavy Flavor program at RHIC

- PHENIX
- Open Charm
- Single electron measurements in p+p, d+Au, Au+Au sNN = 130,200,62.4 GeV
- J/measurements
- e+e-, +- decay reconstruction in p+p, d+Au, Au+Au sNN = 200 GeV

- STAR
- Open Charm
- Direct D mesons decay channels in d+Au
- D0K
- D±K
- D*±D0
- Single electron	 measurements in p+p, d+Au

## PHENIX detector at RHIC

- Electron measurements
- ||<0.35
- Two separate arms 900
- p/p ~ 1%
- Electron ID
- RICH (thr=35)
- e/ separation up to pT ~ 5 GeV/c
- Energy/momentum matching
- Muon measurements
- 1.2 < || < 2.7
- Two separate arms in forward and backward rapidity

## Electron ID in PHENIX

## Electron ID in PHENIX

## Charm electrons in PHENIX

- Signal extraction methods:
- Cocktail subtractionSimulate “photonic” electron background from  decay of 0, light mesons, photon conversion and Ke3 decays
- Converter subtraction	Subtract the “Photonic” component by adding conversion material

## Crosscheck analysis

- Invariant crossection of “Non-photonic” electrons

## Open Charm in Au+Au at sNN=130 GeV

- The first open charm measurements from PHENIX
- cccent = 380 ± 60(stat) ± 200 b
- ccmb   = 420 ± 33(stat) ± 250 b

## Preliminary Open Charm in Au+Au at sNN=200 GeV

**PYTHIA does not describe the data**

## Open Charm in p+p at s=200 GeV

******cc**** = 920 ± 148(stat) ± 524(sys) ********b**
**d********cc**** / dy = 0.196 ± 0.031(stat) ± 0.117(sys) ********b**
- The shape is “harder” then PYTHIA LO predictions
- Central value for NLO predictions by M.Cacciari underpredicts the data

## Open Charm in Au+Au at sNN=200 GeV

- No indication of strong suppression
- Some indication of high pT suppression in central collisions
- Need more statistics for precise RAA

## Open Charm in d+Au at sNN=200 GeV

- No strong modification of the spectral shape compared to p+p
- No significant centrality dependence, scales with binary scaling

- PHENIX PRELIMINARY

## Open Charm in Au+Au at sNN=62.4 GeV

- Good agreement with ISR results
- Scales with number of binary collisions

- PHENIX PRELIMINARY

## Future results for Open Charm from PHENIX

- p+p Run03, Run04
- + 4 times acceptance
- + 5 times ERT trigger statistics
- 20 times total electron statistics allows us to go up to 8-10 GeV/c in pT
- - RICH have 5 GeV threshold for pions – require additional subtraction of  signal at pT > 5GeV/c
- Au+Au Run04
- + at least factor of 100 in MB statistics
- + 2 times the acceptance
-  > 200 times total electron statistics

## STAR detector at RHIC 

- Hadron and electron measurement using TPC, TOF and EMCal

## Open Charm from STAR

- Single electron measurements using TPC dE/dx and TOF
- Measurement of Direct D meson decay channels
- EMC single electron “tagging”

**STAR Preliminary**

## STAR D Mesons in d+Au

- dfg

- NLO pQCD predictions: R. Vogt, hep-ph/0203151

- D*±

## Charm electrons in STAR

- Kinematic selection of  conversion and Dalitz electron background in TPC

## Open Charm electrons in p+p and d+Au at sNN=200 GeV from STAR

- Results are consistent within the systematical and statistical errors

## Open Charm crossection in p+p and d+Au

**STAR Preliminary**

## Open Charm total crossection

- PHENIX and STAR predicts higher total crossection then current  NLO pQCD
- Both results are consistent between experiments

**PHENIX**

## Future Outlook

- PHENIX
- Single muon Heavy Flavor analysis (c(b)±) currently in progress
- Attempt to observer D mesons in hadronic channels.
- PHENIX & STAR
- Upgrade of the Vertex detectors in order to separate Charm from Bottom by vertex displacement
- Bottom measurement through displaced vertex J/ production

## Future Outlook

- Proposed design of PHENIX upgrade of vertex silicon barrel and muon endcaps

## Summary and Conclusions

- PHENIX and STAR experiments at RHIC accomplished a large variety of independent Heavy Flavor production measurements in p+p, d+Au and Au+Au collisions
- Total crossection for Open Charm is ~ factor of 2 higher than current pQCD predictions
- Both experiments results are in good agreement with each other
- Binary scaling of the Charm crossection observed in d+Au and Au+Au collisions
- There is a hint of high pT suppression in central Au+Au collisions, but we need to increase the statistic significantly to obtain sensitive RAA results
***	******	******More interesting results in near future ... ***