17 Sep 2012 Erice, 34th Course Open charm production with ALICE at the LHC Kai Schweda (for the ALICE Collaboration) Physikalisches Institut University of Heidelberg / GSI Darmstadt Thanks to Directors of this school !

17 Sep 2012Erice, 34th Course Outline Introduction Heavy-quark production in pp Heavy-quark production in Pb-Pb Summary 1/20

17 Sep 2012Erice, 34th Course Time Scales QGP life time 10 fm/c ≈ 3  s thermalization time 0.2 fm/c ≈ 7  s formation time (e.g. charm quark): 1/2m c = 0.08 fm/c ≈ 3  s collision time 2R/ = fm/c ≈ 2  s Plot: courtesy of R. Stock. 2/30

17 Sep 2012Erice, 34th Course X. Zhu, M. Bleicher, S.L. Huang, K.S., H. Stöcker, N. Xu, and P. Zhuang, PLB 647 (2007) 366. m c,b » QCD : new scale m c,b ≈const., m u,d,s ≠ const. initial conditions: test pQCD probe gluon distribution early partonic stage: diffusion (), drag () flow, jets, correlations probe thermalization hadronization: chiral symmetry restoration confinement statistical coalescence J/ enhancement / suppression Heavy - flavor: a unique probe Q2Q2 time 3/20

17 Sep 2012Erice, 34th Course Where does all the charm go ? D0D0 D±D± DsDs cc J/(charmonium) Total charm cross section: open-charmed hadrons, e.g. D 0, D +, D* +,  c, … and c,b  e() + X Quarkonia, e.g. J/ carries 1% of total charm D *+ 4/20

17 Sep 2012Erice, 34th Course Heavy-quark detection e.g., D 0  K - +  , c = 123 m displaced decay vertex is signature of heavy-quark decay Open-charm reco. in ALICE D 0  K D +  K D *  D 0  D s  KK Under study: D 0  K  c  pK  c    c  K 0 S  plot: courtesy of D. Tlusty. 5/20

17 Sep 2012Erice, 34th Course Open-charm spectra from 7 TeV covers spectrum from 1 up to 24 GeV/c ALICE, JHEP 1201 (2012) 128; arXiv: [hep-ex]; D* analysis: Y. Wang, PhD thesis, Univ. Heidelberg, in preparation; F. Schaefer, bachelor thesis, Univ. Heidelberg (2012). 6/20

17 Sep 2012Erice, 34th Course Open-charm cross section LHC: First collider measurements at TeV scale ATLAS & LHCb agree with ALICE experimental data sits in the upper theory band ALICE, arXiv: [hep-ex]; J. Wilkinson, bachelor thesis, Univ. Heidelberg (2011); S. Stiefelmaier, bachelor thesis, Univ. Heidelberg (2012). 7/20

17 Sep 2012Erice, 34th Course P v : fraction of D-mesons in vector state (V) to all mesons (V+S), P v = V / (V+S) World average: P v = 0.60 ± 0.01 Stat. model, T=164 ± 10 MeV: P v = 0.58 ± 0.13, agrees with data HQET predicts P v = 3/(3+1) = 0.75 Charm hadronization 8/20 ALICE, arXiv: [hep-ex]; J. Wilkinson, bachelor thesis, Univ. Heidelberg (2011); S. Stiefelmaier, bachelor thesis, Univ. Heidelberg (2012).

17 Sep 2012Erice, 34th Course P v independent on collision energy and system Charm quark does not remember how it was created In hindsight, justifies factorization Ansatz Charm hadronization described by stat. model N.B. Lund fragm. + Clebsch-Gordan coupling: P v = 0.63 HQEFT (m= ∞ ), mass differences negligible, NOT justified for charm but exp. checked for B mesons (Δm/m = 40 MeV/5000 GeV) Charm hadronization, cont’ed 9/20

17 Sep 2012Erice, 34th Course In Pb-Pb collisions: Suppresion by factor ~5 when compared to simple binary scaling from pp Covers 1 – 36 GeV/c pp reference measured only up to 24 GeV/c + extrapolation 10/20 Charm: Nuclear Modification

17 Sep 2012Erice, 34th Course Comparison to other hadrons Mass ordering in R AA ? J/ψ  B(upper) D(middle) (lower) ,W,Z-bosons: R AA ≈ 1 (!) checks normalization, does not probe the medium ALICE, arXiv: [nucl-ex], CMS Z-boson: Phys. Rev. Lett. 106 (2011) /20

17 Sep 2012 Erice, 34th Course Model calculations 12/20 Rising R AA solely due to spectrum in pp Still have to learn from theory about medium properties, i.e. qhat, ehat Not an initial state effect

Anisotropy Parameter v 2 y x py px coordinate-space-anisotropy  momentum-space-anisotropy Initial/final conditions, EoS, degrees of freedom

17 Sep 2012Erice, 34th Course 2 nd Fourier Coefficient – v 2 Substantial v 2 of charm, comparable to charged hadrons 14/20 D-meson v2 analysis: R. Grajcarek, PhD thesis, Univ. Heidelberg, in preparation.

17 Sep 2012Erice, 34th Course v 2 - Model calculations 15/20 Models needs to simultaneously describe v 2 and R AA Stringent constraint, gets tougher with more precision/data

17 Sep 2012Erice, 34th Course Next steps Extract power spectrum of vn, like WMAP* Compare pp high multiplicity vs Pb+Pb Mach cone vs medium response for heavy-quarks (well defined probes) /s *WMAP data: The NASA/WMAP Science team; QGP plot: B. Schenke, S. Jeon, and C. Gale, arXiV: /20

17 Sep 2012Erice, 34th Course Heavy  quark Correlations PYTHIA: p + 14 TeV X. Zhu, M. Bleicher, S.L. Huang, K.S., H. Stöcker, N. Xu, and P. Zhuang, PLB 647 (2007) 366. G. Tsildeakis, H. Appelshäuser, K.S., J. Stachel, NPA 858 (2011) 86; arXiv: [nucl-ex]. Charm and anti-charm quarks created in pairs and thus correlated Look for modifications in Pb+Pb collisions Study transport properties / thermalization 17/20

17 Sep 2012Erice, 34th Course Heavy  quark Correlations* *CMS collaboration:JHEP 1102 (2011) 136; arXiv: v2 [hep-ex]. CMS trigger: inspected 200 x 10 9 p+p collisions BBbar, establish correlations exist in p+p ! Look out for modifications in Pb+Pb 18/20

17 Sep 2012Erice, 34th Course Upgrading the Inner Detector upgrade Concept recently approved by the ALICE Collaboration targeted for LHC shutdown Conceptual Design Report CERN-LHCC /20

17 Sep 2012Erice, 34th Course LHC: Tentative Schedule 2010/11:long run with pp collisions at 7 TeV 1 month of Pb+Pb collisions each year 2012:long run with pp at 8 TeV 2012/13:p+Pb control measurement 2013/14:Machine consolidation and training 2014:pp and Pb+Pb at full energy 2017/18:long shutdown, luminosity + detector upgrades 2019:pp and Pb+Pb at high luminosity 20/20