PHENIX results and prospects regarding strangeness and charm

1. PHENIX results and prospects regarding strangeness and charm David Morrison (Brookhaven National Laboratory) for the PHENIX Collaboration

2. s, c, b • select strangeness results from first year PHENIX data • single electrons, electron pairs from first year PHENIX data showing capabilities for heavy quark measurement • expectations for heavy quarks in current run mass David Morrison

3. PHENIX in its first year Acceptance as it will be when PHENIX is fully installed and instrumented David Morrison

4. FeNIX David Morrison

6. First year data set • energy ÖsNN = 130 GeV • 5M minimum bias triggers recorded • essentially all data from final 3 weeks of run • simple vertex location and other quality cuts yield 1.6M useful events • global observables, hadron spectra, HBT, lepton(s), ... David Morrison

7. 25-30% Centrality Collisions Participants 20-25% 0-5% 945  15% 347  15% 15-20% 10-15% 5-15% 673  15% 271  15% 5-10% 15-30% 383  15% 178  15% 0-5% 30-60% 123  15% 76  15% 60-80% 19  60% 19  60% 80-92% 3.7  60% 5  60% Centrality determination Normalized ZDC energy Normalized BBC energy David Morrison

8. Particle identification In first year analyses TOF resolution 120ps. Allows pK separation to ~1.6 GeV/c. For coming analyses, TOF resolution improved to ~96ps. Allows pK separation to better than 2.3 GeV/c. David Morrison

9. pT spectra Julia Velkovska QM01 David Morrison

10. <pT> versus centrality David Morrison

11. Inverse slope systematics David Morrison

12. Comparison of inverse slopes Hijing shows weaker dependence on mass and centrality than seen in data. No surprise here: some aspects of data are better described by prescription including copious reinteraction. The limit in that regard is to look to a hydrodynamic model. HIJING Hijing with default parameters David Morrison

13. Hydrodynamic parameterization 1/mt dN/dmt = A  f()  d mT K1( mT /Tfo cosh  ) I0( pT /Tfo sinh  ) freeze-out temperature Tfo surface velocity t linear velocity profile t() = t surf. velocity t <t > = 2/3 t boost () = atanh( t() ) This is the usual result when integrating Boltzmann over large rapidityrange. With assumption of hyperbolic Bjorken-like freeze-out surface, same result holds for differential yield. to minimize contributions from hard processes fit mt-m0<1 GeV David Morrison

14. PHENIX Preliminary 5% most central Tfo ~ 104  21 MeV t ~ 0.7  0.1 < t > ~ 0.5  0.1 Systematic errors: ~8% in Tfo ~5% in t Arrows indicate upper pt in fit PHENIX Preliminary PHENIX Preliminary thesis work of Jane Burward-Hoy David Morrison

15. 2 contour overlap Tfo ~ 125 - 83 MeV ~ 104 MeV t ~ 0.6 - 0.8 ~ 0.7 < t> ~ 0.4 - 0.6 ~ 0.5 CERN Pb-Pb NA49: T ~ 132 - 108 MeV ~ 120 MeV t ~ 0.43 - 0.67 ~ 0.55 Systematic error estimate: ~8% Tfo, ~5% t

16. K+/K-ratio at mid-rapidity PHENIX Preliminary K+/K- = 1.08  0.03(stat.)  0.22(sys.) `p/p = 0.64  0.01(stat.)  0.07(sys.) consistent across RHIC experiments David Morrison

17. K-/K+ versus participants Phys. Rev. C 60, 044904 (1999) PHENIX Preliminary Ratio of total yields at AGS energies (E866) also centrality independent Weak (or no) dependence on centrality. Major contribution to systematic error is from uncertain decay, acc. corrections. Much improved in current analyses. David Morrison

18. near-net baryon free regime associated production of K+ off existing baryons and baryon resonances is a large contribution at lower energies K-/K+ versus Ös K+/K- C+C KaoS PHENIX Preliminary Ni+Ni NA44 Pb+Pb E866/E917 Au+Au S+S Si+Au PHENIX Preliminary  s [GeV] David Morrison

19. K/p versus participants • measurements at mid-rapidity • rises from values for p+p at Ös = 63 GeV at pT = 0.8 GeV/c • Alper et al, NP B87(1975) • K-/p- = 0.10, K+/p+ = 0.14 PHENIX Preliminary David Morrison

20. K+/p+ versus pT E866 Au+Au • ratio rises with pT, as at AGS, SPS • low pT pions drive down ratio • not enough pT reach in current result to observe trend as in p+p K+/p+ NA44 Pb+Pb p+p Ös = 20GeV PHENIX preliminary p+p Ös = 25 GeV pT [GeV/c]

21. further pT dependence nucl-ex/0109003, submitted to PRL X. N. Wang, Phys. Rev C58, 2321 (1998) David Morrison

22. quarks and gluons in medium • particles w/o valence quarks mainly by gluon mediated production • K, p separation from p from about 6 to 15 GeV/c using RICH • (K- +`p)/(K+ +p) sees gluon-quark difference in energy loss • possible with 2001 data • high pT 2nd level trigger to enhance signal ? 6 15 pT range of possible measurement David Morrison

23. high pT electrons and heavy quarks • in p+p at RHIC energies, the signal (from c-quark decay) is expected to be about e/p ~ 3-4x10-4 • in Au+Au collisions at RHIC e/p may be as high as 10-3, given the observed suppression of high pT hadrons. • charm is principal source around pT = 1-2 GeV/c; b-decay becomes main source above pT = 3-4 GeV/c p e from p0 Dalitz e from c decay e from b decay Y. Akiba, QM’95

24. single electrons • RICH and EMCal together with tracking in central arms are used to identify electrons • with the statistics from year 200 run, it has been possible to measure the electron spectrum up to 4 GeV/c • very detailed subtraction of conversion electrons required in order to obtain useful signal D0 K-p+ D0 K- e+ ne D0 K-m+ nm Y. Akiba (QM01)

25. electron pairs • extends to J/y region • statistics obtained from ÖsNN = 130 GeV too limited to measure J/y • backgrounds small enough that successful measurement in current run looks certain Y. Akiba (QM’01)

26. prospects for current run • lvl2 trigger tailors event mix • 300 mb-1 Au+Au at ÖsNN = 200 GeV should provide • 60M minimum bias events • 30K J/Y  m+m- in muon arm • 6K J/Y  e+e- in central arm • 15K (charm) e’s with pT > 2 GeV/c (central 10%) • p-p comparison data: • same probes as in Au-Au with roughly half the statistical precision from PHENIX design documents

27. was then is now

28. strange so far, charm coming • in the moderate pT part of phase space measured so far, K- yields very closely track K+ yields • can test this trend to much higher pT in current run (TOF, RICH) • consistency with significant reinteraction, approach to statistical equilibrium • !Hijing slopes, hydro. for singles, rise in <pT>, radial and elliptic flow • drives interest in more sensitive tests of strangeness production ... • multi-strange particles, HBT, balance functions • ... and in production of heavier quarks • single electron and electron pair measurements demonstrate ability • newly installed muon arm • open charm, J/y David Morrison

29. David Morrison

30. PHENIX Preliminary PHENIX Preliminary 3 2/NDF 102 2 10 1 1 2 contours of -K-p

31. K+/K- versus pT • weak (or no) dependence on pT within errors • differential K- yields track those of K+ throughout phase space

32. Participant Scaling Ncoll pA as baseline for strangeness E910 preliminary PHENIX Preliminary

33. chemical freeze-out PHENIX preliminary hep-ph/0002267: F.Becattini, et al.

34. Corrections to the Raw Spectra Used MC single particles and track embedding to correct for Tracking inefficiencies and momentum resolution Geometrical acceptance Decays in flight (’s and K’s) Correction is p and PID dependent Particle Acceptance 0.2 GeV/c -0.35 <  < 0.35

35. mT spectra David Morrison