1. HD lunch talk, 30 Apr 2008 Kai Schweda 1 Heavy-Quarks with ALICE  Some Highlights from the ALICE Physics Week in Prague March 2008 Kai Schweda, University of Heidelberg / GSI Darmstadt

2. HD lunch talk, 30 Apr 2008 Kai Schweda 2 Outline  Motivation  Total charm cross section with ALICE  B  J/  + X feeddown  1 st day Detector Performance in p+p  Summary

3. HD lunch talk, 30 Apr 2008 Kai Schweda Quark Masses 1)Higgs mass: electro-weak symmetry breaking. (current quark mass) 2)QCD mass: Chiral symmetry breaking. (constituent quark mass) éStrong interactions do not affect heavy-quark masses. éImportant tool for studying properties of the hot/dense medium at RHIC and LHC. éTest pQCD predictions at RHIC and LHC. Total quark mass (MeV) X. Zhu, M. Bleicher, K.S., H. Stoecker, N. Xu et al., PLB 647 (2007) 366.

4. HD lunch talk, 30 Apr 2008 Kai Schweda 4 Heavy  Quark Production 1)Charm x 10 2)Beauty x 100 3) Heavy-quarks abundantly produced at LHC ! STAR data: A. Suaide, P. Djawothoto QM2006; Calcs.: R. Vogt.

5. HD lunch talk, 30 Apr 2008 Kai Schweda 5 J/  Production  suppression, compared to scaled p+p  regeneration, enhancement Low energy (SPS):few ccbar quarks in the system  suppression of J/  High energy (LHC): many ccbar pairs in the system  enhancement of J/   Signal of de-confinement + thermalization of light quarks ! (SPS) P. Braun-Munzinger and J. Stachel, Nature 448 (2007) 302.

6. HD lunch talk, 30 Apr 2008 Kai Schweda 6 Predictions for LHC  large ccbar production at LHC  corona effects negligible  regeneration of J/  dominates  striking centrality dependence Signature for QGP formation !  Initial conditions at LHC ? A. Andronic et al., nucl-th/0701079.  cc

7. HD lunch talk, 30 Apr 2008 Kai Schweda 7 Charm at the LHC: testing pQCD at  s = 14 TeV Important test of pQCD in a new energy domain D production not yet fully understood at Tevatron and RHIC Need displaced vertex technique for precise heavy-flavor measurements Tevatron data: CDF PRL91 (2003) 241804, RHIC data: Y. Zhang, QM2008, FONLL calcs. R. Vogt, Eur. Phys. J.ST 155 (2008) 213.

8. HD lunch talk, 30 Apr 2008 Kai Schweda 8 Hadronic charm in ALICE TPC (tracking) TOF (K/  id) ITS (vertexing) K  D 0  K   D +  K  D s  KK  D*  D 0  D 0  K   c   Kp under study

9. HD lunch talk, 30 Apr 2008 Kai Schweda 9 Plot: A. Shabetai D 0   + + K - Reconstruction D 0, c  = 123  m ++ K-K-

10. HD lunch talk, 30 Apr 2008 Kai Schweda 10 Charm cross section in pp D 0  K  Expected sensitivity in comparison to pQCD: 1 year at nominal luminosity (10 9 pp events) Detector configuration: ITS + TPC + TOF ~1 month stat. err. vs # events Slide: A. Dainese, INFN - Italy.

11. HD lunch talk, 30 Apr 2008 Kai Schweda 11 Inner Tracking System (ITS) Silicon Pixel Detector (SPD): ~10M channels 240 sensitive vol. (60 ladders) Silicon Drift Detector (SDD): ~133k channels 260 sensitive vol. (36 ladders) Silicon Strip Detector (SSD): ~2.6M channels 1698 sensitive vol. (72 ladders) SPD SSD SDD ITS total: 2198 alignable sensitive volumes  13188 d.o.f. Slide: A. Dainese, INFN - Italy.

12. HD lunch talk, 30 Apr 2008 Kai Schweda 12 Effect of ITS misalignment on d 0 resolution Impact parameter resol:  track = a scatter /p t  b meas  c misalign Effect studied with full simulation of exptected initial (full+) and residual (after realignment) misalignments See talk tomorrow Effect on D 0 measurement studied (next slides) null residual full full+ Slide: A. Dainese, INFN - Italy.

13. HD lunch talk, 30 Apr 2008 Kai Schweda 13 Effect of misalignment on S/B and significance (S/  S+B) Residual misalignment: negligible effect “Full” misalignment: 15-20% worsening of statistical errors

14. HD lunch talk, 30 Apr 2008 Kai Schweda 14 Kinematical distributions: prompt J/  versus secondary J/  rapidity and transverse momentum (all distribution normalized to 1 m.b. event) y but p T dependent Primary J/ Secondary J/ Slide: Giuseppe E Bruno, Università di Bari and INFN - Italy. B  J/  + X

15. HD lunch talk, 30 Apr 2008 Kai Schweda 15 product of impact parameters d 0 xd 0 Kinematical distributions: prompt J/  versus secondary J/  Primary J/ Secondary J/ Slide: Giuseppe E Bruno, Università di Bari and INFN - Italy, also: Wolfgang Sommer, Uni Frankfurt. Disentangle primordial J/  from B  J/  decay Determine  bbar

16. HD lunch talk, 30 Apr 2008 Kai Schweda 16 J/   e + + e - Reconstruction  J/   e+ + e- (BR = 6%)  Reconstruct invariant mass  TRD identifies electrons  4/18 SM installed for first p+p run  Identify quarkonia J/  : c c  : b b

17. HD lunch talk, 30 Apr 2008 Kai Schweda 17 Summary  Heavy-quarks (c,b) carry important information on de-confinement and light-quark thermalization  Measure yield, spectra, correlations and v 2 of: D 0, D +, D* +, D s, J/  b,  to identify and characterize QGP !  ALICE is well suited for these studies

18. HD lunch talk, 30 Apr 2008 Kai Schweda 18 Average Momentum Correlator – angular dependence  Enhanced correlations  Only FC produces correlations at high   Distinction of the baseline at middle  – flat to 0  Average Momentum Correlator as a sensitive measure of back to back correlations Same event Mixed event  At full  : = 199.5 +/- 6 (MeV/c) 2 or  p t ~30 %

20. HD lunch talk, 30 Apr 2008 Kai Schweda 20 D Meson Pair Correlations : Some Results   =  (D) –  (Dbar) E791 : Eur. Phys. J. direct C1 (1999) 4 WA92 : Phys. Lett. B385 (1996) 487 NA32 : PLB257 (1991) 519, PLB302 (1993) 112, PLB353 (1995) 547  Correlation variable studied: 10 3 /N * dN/d(  ) At low energies, D-Dbar production correlated! Pythia describes these correlations!  How about LHC energies? p p c c D D Georgios Tsildeakis,HD.

21. HD lunch talk, 30 Apr 2008 Kai Schweda 21 Charm correlations c-cbar are correlated Flavor creation: back to back Gluon splitting: forward Flavor excitation: flat Correlations vanish  frequent interactions among partons !  probe light-quark thermalization !