1. Recent results from the ALICE experiment on open heavy flavours Sarah Porteboeuf-Houssais for the ALICE collaboration 52th International Winter Meeting on Nuclear Physics 27-31 January 2014, Bormio, Italy  The ALICE experiment @ LHC  Open heavy flavours (HF): physics motivations

2. sarah@clermont.in2p3.fr 2 Open heavy flavours (HF): physics motivations HF in pp collisions -Test of pQCD-based calculations (production cross sections) -Investigation of charm production mechanisms -Reference measurement for p-Pb and Pb-Pb HF in p-Pb collisions - Control experiment for Pb-Pb measurement via understanding of cold nuclear matter (CNM) effects HF in Pb-Pb collisions Heavy quarks produced in initial hard scatterings. HF sensitive to hot medium effects. Energy loss ( Δ E) Collectivity in the QGP Colour-charge dependence: α C R Quark mass dependence: Δ E uds > Δ E c > Δ E b Δ E g > Δ E uds > Δ E c > Δ E b R AA ( π ) < R AA (D) < R AA (B) JPG 17 (1991) 1602;, PLB 519 (2001) 199; PRD 71 (2005) 054027; NPA 783 (2007) 493 ? C R (g)= 3, C R (q)= 4/3 Initial spatial anisotropy momentum anisotropy of particles If heavy quarks participate in the expansion of QGP : v 2 (c,b) > 0 => v 2 (D, HF-e, HF- μ ) > 0 The anisotropy is quantified via a Fourier expansion in azimuthal angle φ with respect to the reaction plane Ψ RP The second coefficient is v 2 (elliptic flow) R AA and v 2 are the experimental observables.

3. The Alice experiment @ LHC D mesons D 0 -> K - π + D + ->K - π + π + D *+ -> D 0 π + D s + -> φ π + ->K - K + π + | ƞ | < 0.9 ITS: tracking, vertexing TPC: tracking PID TOF: PID HF decay electrons D, B, Λ c, … -> e + X | ƞ | < 0.9 ITS : tracking, vertexing TPC : tracking PID TOF, EMCAL, TRD : e-ID HF decay muons D, B, Λ c, … -> μ + X -4 < ƞ < -2.5 Muon Spectrometer : trigger and μ -ID sarah@clermont.in2p3.fr VZERO: Trigger, centrality determination 3

4. Data Samples SystemEnergyLHC Run D mesonsHF electronsHF muons pp2.76 TeV2011 1.1 nb -1 (MB trigger) JHEP 1207 (2012) 191 - cross sections 0.5 (11.9) nb -1 MB (EMCAL) triggers Cross sections 19 nb -1 ( μ trigger) PRL 109 (2012) 112301 - cross sections pp7 TeV2010 5 nb -1 (MB trigger) JHEP 01 (2012) 128 - cross sections D-h correlation D vs. mult PLB 718 (2012) 279 2.6 nb -1 (MB trigger) PRD 86 (2012) 112007 2.2 nb -1 PLB 721 (2013) 13 - cross sections 16.5 nb -1 ( μ trigger) PLB 708 (2012) 265 - cross sections p-Pb5.02 TeV2013 48.6 μ b -1 (MB trigger) R pPb 48.6 μ b -1 (MB trigger) R pPb e-h correlation Work in progress Pb-Pb2.76 TeV2010 2.12 μ b -1 (0-80%) JHEP 09 (2012) 112 - R AA 2.0 μ b -1 (0-80%)2.7 μ b -1 (MB trigger) PRL 109 (2012) 112301 - R AA Pb-Pb2.76 TeV2011 23 μ b -1 in 0-10% 6.2 μ b -1 in 10-50% PRL 111 (2013) 102301 - v 2 R AA 22(37) μ b -1 in 0-10% 6(34) μ b -1 in 20-40% MB(EMCAL)trig. R AA, v 2 11.3 μ b -1 in 0-10% 3.5 μ b -1 in 10-40% v 2 Green: recent published results discussed in this talk Purple: recent preliminary results discussed in this talk Black: ALICE published results for HF observables sarah@clermont.in2p3.fr Large amount of data collected by ALICE for HF observables Several analyses, results, plots In this talk: a selection 4

5. sarah@clermont.in2p3.fr pp: the baseline for heavy ion study, reference measurement, test of pQCD D mesonsHeavy-flavour decay muons JHEP 1201 (2012) 128 Phys. Lett. B 718 (2012) 279 Phys. Rev. D 86 (2012) 112007 for HF decay electrons Phys. Lett. B 721 (2013) 13 Phys. Lett. B 708 (2012) 265 pQCD-based calculations compatible with data FONLL: JHEP 1210 (2012) 137; GM-VFNS: Eur. Phys. J. C 72 (2012) 2082 5 Heavy-flavour decay electrons

6. sarah@clermont.in2p3.fr D mesons Heavy-flavour decay electronsHeavy-flavour decay muons JHEP 1207 (2012) 191Phys. Rev. Lett. 109 (2012) 112301 pQCD-based calculations compatible with data FONLL: JHEP 1210 (2012) 137; GM-VFNS: Eur. Phys. J. C 72 (2012) 2082 HF muon data used as reference for Pb-Pb at the same energy For other channels, a scaling based on pQCD calculations is used arXiv:1107.3243 pp: the baseline for heavy ion study, reference measurement, test of pQCD 6

7. sarah@clermont.in2p3.fr pp: looking at more exclusive observables to better understand production mechanisms D-hadron correlation Correlation measurements well described by PYTHIA6.4 within statistical and systematic uncertainties Precise measurement expected from LHC Run2 7 Reference for Pb-Pb studies of charm jet modification due to hot medium effects Insight into charm production mechanisms in pp by measuring the associated hadron yields in the near and away side region

8. sarah@clermont.in2p3.fr 8 pp: looking at more exclusive observables to better understand production mechanisms D and non-prompt J/ Ψ vs. multiplicity Approximately linear increase with charged particle multiplicity within statistical and systematic uncertainties Observable related to the underlying event accompanying heavy-flavour production Connected with Multi Parton Interaction (MPI) and possible contributions from hadronic activity associated with heavy-flavour production and gluon splitting (g->cc)

9. sarah@clermont.in2p3.fr D mesons Heavy-flavour decay electrons HF e R pPb measurement is compatible with unity within uncertainties Consistent with predictions from FONLL +EPS09 Similar results for the four D-meson species (and for the D s, not shown here) D R pPb measurement is compatible with unity within uncertainties Consistent with predictions from: MNR (HF production) + EPS09 (Shadowing) Nucl. Phys. B 373 (1992) 295 + JHEP 0904 (2009) 065 CGC arXiv:1308.1258 Two analyses based on different PID strategies TPC + TOF at low p T TPC + EMCAL at high p T Phys. Rev. Lett. 109 (2012) 242301 9

10. sarah@clermont.in2p3.fr Correlation between trigger particles (electron from HF hadron decay) and associated particles (charged hadrons) Analysis performed in 3 multiplicity classes defined with signal multiplicity in the region 2.8 < ƞ < 5.1 in the Pb hemisphere A double-ridge structure observed also for HF e-h correlations as in h-h correlations when subtracting low mult to high mult. For h-h, possible interpretation: hydrodynamical evolution of the system or CGC Phys. Lett. B 719 (2013) 29 In the highest multiplicity event class (0- 20%), stronger correlation than the one observed in pp minimum bias 10

11. sarah@clermont.in2p3.fr 40-50% for electrons and 40-80% for muons Central Collisions (0-10%)Semi-peripheral collisions Clear suppression observed for 3(4) <p T <18(10) GeV/c for the most central collisions Final state effects: HF decay e R pPb compatible with unity (cf. S.9) Similar suppression at central (electrons) and forward (muons) rapidity Muons results: Phys. Rev. Lett. 109 (2012) 112301 11

12. as a function of p T sarah@clermont.in2p3.fr Suppression up to a factor of 5 at p T ~10 GeV/c for 0-7.5% central collisions. Hot medium effect: D R pPb measurement compatible with unity (cf. S.9) R AA (D) ~ R AA (charged π ) within large uncertainties Not trivially linked to ΔΕ (g) and ΔΕ (c): different fragmentation, spectral shape, bulk properties arXiv:1307.4702 12

13. sarah@clermont.in2p3.fr 13 Smaller suppression in peripheral than in central collisions at high-p T for D mesons Indication of a larger suppression for charm than for beauty Supported by predictions from energy-loss models for R AA D and non-prompt J/ Ψ => Hint of the quark-mass dependence of energy loss: ΔΕ (c) > ΔΕ (b) as a function of N part J. Phys. G 38 (2011) 124152; J. Phys. G 38 (2011) 124114; Phys. Rev. C 80 (2009) 054902

14. sarah@clermont.in2p3.fr D mesonsHF decay electrons and muons v 2 (D) ~ v 2 (charged π ) within uncertainties v 2 (HF-e) ~ v 2 (HF- μ ) within uncertainties in different rapidity regions All channels show positive v 2 (>3 σ effect) Information on the initial azimuthal anisotropy transferred to charm quarks Phys. Rev. Lett. 111 (2013) 102301 The anisotropy is quantified via a Fourier expansion in azimuthal angle φ with respect to the reaction plane Ψ RP 14

15. sarah@clermont.in2p3.fr A global picture of QGP from the D mesons Simultaneous description of R AA and v 2 gives insight on quark transport coefficients of the medium Still a challenge for models Low p T D mesons thermalized in the formed medium and acquire properties of the expanding bulk Only models with predictions for both RAA and v2 are shown J. Phys.G38 (2011) 124064, Eur. Phys J. C 71 (2011) 1666; arXiv:1308.0617; Phys. Rev. C 79 (2009) 044906; arXiv:1112.1559; arXiv:1204.4442; arXiv:1204.4442 JHEP 09 (2012) 112PRL 111 (2013) 102301 15

16. sarah@clermont.in2p3.fr Conclusions HF measurements in pp collisions HF measurements in p-Pb collisions HF measurements in Pb-Pb collisions  Production cross sections in all channels described within uncertainties by pQCD-based calculations (at both 7 and 2.76 TeV)  More exclusive study ongoing (D and non prompt J/ Ψ vs. mult and D-h correlations)  Good agreement with pQCD calculations including nuclear modification of PDFs and CGC predictions  R pPb (D,e) ~ 1 within uncertainties  HF decay e-h correlations show similar structure as for h-h correlations in p-Pb collisions (double ridge structure)  R AA < 1 at high p T for all HF channels for central Pb-Pb collisions final state effects due to parton energy loss in the hot and dense medium  R AA (D) ~ R AA (charged π ) for central collisions  R AA (D) > R AA (B->J/ Ψ ) for central collisions Difference between charm and beauty hadrons at high p T  v 2 > 0 for all HF channels measured at low p T Suggests that charm takes part in the anisotropic evolution of the system 16

17. sarah@clermont.in2p3.fr BACK-UP SLIDES 17

18. sarah@clermont.in2p3.fr LHC schedule belong LS1 18 LS2 starting in 2018 (July) 18 months + 3months BC (Beam Commissioning) LS3LHC: starting in 2023 => 30 months + 3 BC injectors: in 2024 => 13 months + 3 BC approved by CERN management and LHC experiments spokespersons and technical coordinators Monday 2 nd December 2013 Run 2Run 3 Run 4 LS 2 LS 3 LS 4LS 5Run 5

19. ALICE running conditions during RUN II (2015-2017) sarah@clermont.in2p3.fr 19 Values to be compared to:  L = 2 10 31 cm -2 s -1 in pp collisions 2012 (8 TeV)  L = 4.6 10 26 cm -2 s -1 in Pb-Pb collisions 2011 (2.76 TeV)  L = 10 29 cm -2 s -1 in p-Pb/Pb-p collisions 2013 (5.02 TeV)

20. sarah@clermont.in2p3.fr Centrality Measurement 20 Collision centrality determine the number of participating nucleons and the remaining spectators.  ZDCs (~116m from IP) measure spectator nucleons  V0, SPD, TPC are sensitive to participating nucleon “Fit” multiplicity distributions with a Glauber MC (V0 amplitude, SPD clusters, TPC tracks) Energy deposit on the ZDCs and ZEMs

21. sarah@clermont.in2p3.fr D mesons reconstruction strategy 21 D 0 -> K - π + M = 1864.86 ± 0.13 MeV; c τ = 122.9 μ m D + ->K - π + π + M = 1869.62 ± 0.15 MeV; c τ = 311.8 μ m D *+ -> D 0 π + M = 2010.28 ± 0.13 MeV Invariant mass analysis mainly based on secondary vertex reconstruction and kaon identification.  Vertex reconstruction Impact parameter resolution ~ 60 μ m for p T = 1 GeV/c JHEP 09 (2012) 112 Main topological cuts: Impact parameter of the tracks Angle between the meson flight line and the particle momentum

22. sarah@clermont.in2p3.fr D mesons reconstruction strategy 22  Kaon identification Energy loss deposit in the TPCVelocity measurement in TOF TPC allows K/ π separation up to ~0.6 GeV/c TOF allows K/ π separation up to ~2 GeV/c

23. sarah@clermont.in2p3.fr Heavy-flavour decay electrons sarah@clermont.in2p3.fr 23 Low p T : TPC (dE/dx) + TOF + TRD High p T : TPC (dE/dx) + EMCAL  Electron identification  Background subtraction Cocktail method: MC hadron generator for different background sources e + e - invariant mass method to remove Dalitz decay and photon conversion

24. 24 sarah@clermont.in2p3.fr Heavy-flavour decay muons sarah@clermont.in2p3.fr Phys. Lett. B 708 (2012) 265 24 Main source: muon from pions and kaons decay, subtracted by MC dN/dp T normalized to data at low p T Background contribution decreases with p T => measurement for p T > 2 GeV/c Remove beam-gas and secondary muons by requiring a muon trigger signal + a cut on the p x DCA Remove punch-through hadrons by muon trigger matching  Muon track selection  Background subtraction In Pb-Pb: no subtraction of decay muons, but analysis restricted to high p T region where background is small

25. Charm and Beauty cross sections sarah@clermont.in2p3.fr Evaluation of the total charm and beauty production cross sections 25

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27. sarah@clermont.in2p3.fr 27

28. sarah@clermont.in2p3.fr Compatible results for the four D-meson species (including the D s ) All measurements compatible with unity within uncertainties 28

29. sarah@clermont.in2p3.fr No rapidity dependence observed in -1.265<y CMS <0.355 29

30. sarah@clermont.in2p3.fr Compatible D meson production ratios between pp at 7 TeV and p-Pb at 5.02 TeV 30

31. sarah@clermont.in2p3.fr 31

32. sarah@clermont.in2p3.fr Upgrades Inner Tracking System 32 Reduces the material budget (X/X0 per layer): from 1.14% to 0.3% for the inner layers. Get closer to IP (first layer): 39 mm to 22 mm. Improves the pointing resolution by x3 (r φ ) and x5 (z). Increase granularity (6 layers to 7 layers) and reduce pixel size (from 50 x 425 μ m to 20 x 20 μ m). Fast readout: pp at 1 MHz and Pb-Pb at 50 kHz.

33. sarah@clermont.in2p3.fr Upgrades Muon Forward Tracker 33 ψ ’: improve the S/B by x6 with respect to the current performance. B->J/ ψ : prompt/displaced J/ ψ separation for measuring B down to zero p T. MFT 5 silicon pixel discs located in front of the absorber. MFT will improve the pointing accuracy in the vertex region. OHF: separate charm and beauty contributions at the (di)muon level.