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Over view of charm production at RHIC

All nice talks on data are Over I am offering my own view. Over view of charm production at RHIC. Presentions: Xiaorong Wang, PHENIX (Forward muon) Yifei Zhang, STAR (mid-rapidity, muon, electron) Haibin Zhang, STAR (STAR overview)

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Over view of charm production at RHIC

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  1. All nice talks on data are Over I am offering my own view Overview of charm production at RHIC • Presentions: • Xiaorong Wang, PHENIX (Forward muon) • Yifei Zhang, STAR (mid-rapidity, muon, electron) • Haibin Zhang, STAR (STAR overview) • Adrew Glenn, PHENIX (PHENIX overview) • Posters: • Chen Zhong, STAR (Low-pt muon) • H.D. Liu et al., nucl-ex/0601030 • X. Dong, thesis, nucl-ex/0509011 Zhangbu Xu (BNL) Thank the organizers SQM06, Zhangbu Xu (BNL)

  2. Outline • Charm Total Cross Sections • Are we alone? • What’s right and what’s wrong? • Are lepton spectra sensitive to flow? • Form Factors • What scale? (30%, x3) • Does it make senses? • Color, flavor (dE/dx)? • Is pp/FONLL off by 3—6 serious? • Wild Speculations and Outlook Mc1.5 GeV>>Tc, LQCD, Muds M/E>>0 SQM06, Zhangbu Xu (BNL)

  3. Are we alone? Data provide reference for Au+Au data and J/psi from charm coalescence STAR >3x PYTHIA,pQCD Energy dependence mR and mF? Need smaller errors to constrain pQCD and determine the effects in Cosmic Ray Showers X. Dong USTC Can we confirm or rule out Cosmic Ray experiments (Pamir, Muon, Tian Shan) under similar conditions? Pamir, Nuovo Cim 24c (2001) 557; NPB 122(2003) 353c SQM06, Zhangbu Xu (BNL)

  4. Pamir EM shower depth With charm XREC upgrade Without charm Pamir, Nuovo Cim 24c (2001) 557 SQM06, Zhangbu Xu (BNL)

  5. Muons on the Side What is the problem? Incorrect Model of Detector? Incorrect Model of Showers? Heavy Primaries? New Physics? Two techniques, Two Spectra Fluorescence vs Muon/scintillator A. Olinto, PANIC05 SQM06, Zhangbu Xu (BNL)

  6. Can we get rid of data points we don’t like? if the data points shouldn’t be there in the first place? R. Vogt SQM06, Zhangbu Xu (BNL)

  7. What’s right and what’s wrong X. Dong (USTC) PH.D. Thesis SQM06, Zhangbu Xu (BNL)

  8. CDF directy D measurement -- high pT hep-ex/0307080 CDF/ISR ce Spectra X. Dong, Thesis, nucl-ex/0509011 SQM06, Zhangbu Xu (BNL)

  9. dNe/dy[0.8<pT<4.0]/Ncoll Discrepancy at RHIC? PHENIX, PRL 94, 082301(2005) Y.F. Zhang, H.B.Zhang, C. Zhong, SQM06 SQM06, Zhangbu Xu (BNL)

  10. 90% 15% Which part of the lepton spectrum is sensitive to scc ? σcc = 1.1  0.1  0.3 mb Change (n, <pT>), Left: 0.16<pT (m) <0.26, ±10% Right: pT(e)>1.0 GeV/c, x8 SQM06, Zhangbu Xu (BNL)

  11. Measure scc vs sqrt(s) Propose to measure total cross sections with low-pt muons: CDF, ALICE, Energy Scans at STARH.D. Liu et al.,nucl-ex/0601030 • Constrains pQCD • Baseline for charm Coalescence Model • Test PBM thermal model x4 below STAR measurements SQM06, Zhangbu Xu (BNL)

  12. Are they talking about the same thing? PHENIX, PRL 94, 082301(2005) FSI Dynamics • consistent with Nbin scaling! • Produced at initial impact! • Large values: • pQCD • J/psi coalescence H.B. Zhang, Y.F. Zhang, C. Zhong SQM06 No sensitive to FSI Dynamics SQM06, Zhangbu Xu (BNL)

  13. Are lepton spectra sensitive to flow? X. Dong QM05 Electrons: Smearing in pT axis S. Batsouli, et al, Phys.Lett.B 557 (2003) 26 • Electron spectra cannot disentangle different charm hadron shapes at low pT SQM06, Zhangbu Xu (BNL)

  14. Preserve the Orientation for v2? B. Zhang nu-th/0502056 v2 and other calculations shows sensitivity? Is it by accident? H. Va Hees hep-ph/0601166 SQM06, Zhangbu Xu (BNL)

  15. e n s c u,d,ud Charm Decay Form Factors PDG Form factor is different between PYTHIA and PDG Electron spectrum depends strongly on charm spectrum shape at pT~1—2 GeV/c H.D. Liu, nucl-ex/0601030 SQM06, Zhangbu Xu (BNL)

  16. AuAu Central charm hadron AuAu Central , K, p Charm flows, but not quite as large H.B. Zhang, Y.F. Zhang BlastWave model-dependent fit shows sensitivity of electron spectrum to charm spectrum shape Likely, Freeze-out early with less flow S. Esumi: (Next session)Overview of non-photonic electron v2 SQM06, Zhangbu Xu (BNL)

  17. RAA of non-photonic electrons PHENIX, PRL96 STAR Highlight talk • Evidence of large heavy quark energy loss! SQM06, Zhangbu Xu (BNL)

  18. Flavor or Color factor? • Radiative dE/dx and Radiation+Elasitic The bigger difference is gluon vs quarks charm vs u/d is quite small • The biggest difference between p and charm RAA is due to gluon • dE/dx(g) ~=9/4 dE/dx(uds)pbar, p vs p • dE/dx(c/b)<dE/dx(uds) S. Wicks, nucl-th/0512076 The ten thousand things rise and fall without cease–道德经 http://www.actus.org/laotzu.html SQM06, Zhangbu Xu (BNL)

  19. STAR nucl-ex/0601033 Gluon vs light quarks • dE/dx(g) ~=9/4 dE/dx(uds)pbar, p vs p • dE/dx(c/b)<dE/dx(uds) p from quarks, pbar (p) from gluonsat pT~=10 GeV/c SQM06, Zhangbu Xu (BNL)

  20. STAR Preliminary Pbar(p),p same suppression Same suppression L.J. Ruan, WWND06 SQM06, Zhangbu Xu (BNL)

  21. Cacciari, PRL95 First thing first! STAR |y|<1 p+p (PHENIX,STAR)/FONLL=(3,5.7) Are we worried? What if charm is off, but bottom is correct PHENIX, X.R. Wang, SQM06 SQM06, Zhangbu Xu (BNL)

  22. Speculations • Gluon and light quark have similar dE/dx • color-factor 9/4 doesn’t work for large dE/dx?But, I. Vitev hep-ph/0601010: dE/E(g)=50%, (q)=25% • NLO underpredicts charm but predicts bottom correctly • Mc~ 1.5 GeV/c too small • Other processes? • These will explain:pbar(p), pion,electron RAA SQM06, Zhangbu Xu (BNL)

  23. Outlook • Measure scc by low-pt muonsLHC, Tevetron and energy scan at RHIC • Measure D, Lc, and B separately and cleanly • Explain why gluons and light quarks have same dE/dx • Does pQCD dE/dx work all the way to pT(e)~=1 GeV/c? SQM06, Zhangbu Xu (BNL)

  24. A same ending of charm production at RHIC?? Whatever the truth,Triumph over mistrust! Thanks to PBM SQM06, Zhangbu Xu (BNL)

  25. Effects related to Open Charm Down Down Up Up Down Up Up Down Down Up? • Radiation Energy Loss • Collision Energy Loss • Dead Cone Effect • Ter-Mikayelian Effect • Transition Radiation • Flow (radial & elliptic) • (quark) Coalescence • Death of “dead cone” • Charm Resonance • CGC All these happen at intermediate pTEmphasize on experimental measurements SQM06, Zhangbu Xu (BNL)

  26. M. Djordjevic, et. al. nucl-th/0507019 N. Armesto et. al. private comm. any beauty? Challenges to theory X. Dong QM05 Current energy loss mechanisms can only account for part of strong suppression of RAA for electrons. SQM06, Zhangbu Xu (BNL)

  27. SQM06, Zhangbu Xu (BNL)

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