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Chapter 2: Physics Motivation

Chapter 2: Physics Motivation. A. Dainese, G. Usai (INFN) Chapter authors: G.E. Bruno, A. Dainese, C. Di Giglio, M. Kweon, M. Mager, A. Mastroserio, S. Moretto, A. Rossi, C. Terrevoli, G. Usai. Chapter Outline. Physics Motivation.

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Chapter 2: Physics Motivation

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  1. Chapter 2:Physics Motivation A. Dainese, G. Usai (INFN) Chapter authors: G.E. Bruno, A. Dainese, C. Di Giglio, M. Kweon, M. Mager, A. Mastroserio, S. Moretto, A. Rossi, C. Terrevoli, G. Usai ITS Upgrade, CERN, 14.11.11 Andrea Dainese, Gianluca Usai

  2. Chapter Outline ITS Upgrade, CERN, 14.11.11 Andrea Dainese, Gianluca Usai

  3. Physics Motivation • Study properties of QCD in extended high-density systems via the probe-medium interaction • Interaction depends on colour charge and mass • Heavy quarks test both these aspects • Do we observe this pattern? • Study the QGP thermalization and collectivity via heavy quark hadronization and flow • Are the quenched heavy quarks thermalized in the system? • Do they carry elliptic flow? • Do they hadronize via recombination? ITS Upgrade, CERN, 14.11.11 Andrea Dainese, Gianluca Usai

  4. Energy Loss • Goal: measure charm and beauty separately with high accuracy over a broad pt range D/p RAA (Armesto et al.) B/D RAA (Armesto et al.) D/B RAA (Horowitz et al.) Colour charge? AdS/CFT? Mass? ITS Upgrade, CERN, 14.11.11 Andrea Dainese, Gianluca Usai

  5. Energy Loss • Current capability: • ALICE uniqueness: PID ( charm); low pt (low material and field); • ALICE limits: B/D separation difficult, especially at low pt (electron PID + vertexing); indirect B measurement via electrons; charm difficult for pt0 (background is too large); • CMS has measured J/psi from B starting from 6.5 GeV/c ITS Upgrade, CERN, 14.11.11 Andrea Dainese, Gianluca Usai

  6. Hadronization and Flow • Goal: measure v2 and RCP for HF mesons and baryons v2 constituent scaling and baryon/meson for charm (beauty?)  Lc Strange Baryon/Meson mu,d~0 ms~0.3 GeV Light-flavour Mesons, baryons Lc/D in central and periph. Lc and D elliptic flow mc~1.5 GeV Lb vs B? mb~5 GeV ITS Upgrade, CERN, 14.11.11 Andrea Dainese, Gianluca Usai

  7. Hadronization and Flow • Current capability: • ALICE uniqueness: PID; low pt (low material and field); • ALICE limits: resolution not sufficient (Lc ct = 1/2 D0 = 1/5 D+); Lc at the limit in pp (only high pt), impossible in Pb; • CMS limits: no PID  no Lc?; no dramatic resolution improvement with upgrade (25%?) Hint of D meson flow from Pb 2010 Lc signal above 3 GeV in pp 2001 ITS Upgrade, CERN, 14.11.11 Andrea Dainese, Gianluca Usai

  8. Possible measurements and expected yields • Start to put together some numbers on the possibility to trigger • Compute the expected raw yields (after selections) • Estimate the signal yields for two cases: • Dedicated trigger running • Minimum bias running • Caveats: • Acc x Eff from current data analysis + hydrid sim + guesses • Assume we can do at the trigger level the same selections done offline (PID + topology) • And that they have the same efficiency and bkg-rej. power USTF, CERN, 25.10.11 Andrea Dainese

  9. Yields and possible channels USTF, CERN, 25.10.11 Andrea Dainese

  10. Pb-Pb running scenario Within the Upgrade Strategy task-force, a more ambitious scenario is being defined, which corresponds to a LHC luminosity increased by x10  ~1028 cm-2s-1 i.e. ~50-80 kHz This could be added to the section for December release USTF, CERN, 25.10.11 Andrea Dainese

  11. Signal statistics: Pb-Pb m.b. 8 kHz • The trigger rates are in the range 10-2-102 Hz • Factor 15 more signal with trigger • Lb and reco-B signals interesting in view of 50 kHz or higher efficiency… • To be continued: • Minimum pt threshold • Realistic cut and PID efficiencies and bkg rejection USTF, CERN, 25.10.11 Andrea Dainese

  12. Ongoing update: trigger rates vs pt • Add a set of figures with rate, purity, yield vs. ptmin • for the D0 as an example • + Add the cases Pb-Pb minimum-bias at 50 kHz? (80 kHz?) D0, 5.5 TeV PbPb m.b. 8 kHz ITS Upgrade, CERN, 14.11.11 Andrea Dainese, Gianluca Usai

  13. “Hybrid” simulation method M. Mager • Baseline upgrade scenario: “AllNew”, 7 layers of pixels with resolution 4x4mm2 and thickness 0.3% x/X0 • Impact parameter and pt resolutions from Fast Estimation Tool applied to existing ALICE simulations by rescaling the track parameter residuals (wrt MC truth) D0Kp vertex resolution upgrade ITS Upgrade, CERN, 14.11.11 Andrea Dainese, Gianluca Usai

  14. D0 as a benchmark channel A. Rossi, S. Moretto • D0Kp in Pb-Pb: • ~0 pt • S/B x10 With partial cuts optimization upgrade ITS Upgrade, CERN, 14.11.11 Andrea Dainese, Gianluca Usai

  15. Charm baryons: Lc C. Terrevoli, M. Mager • LcpKp: • pt>4 in Pb-Pb • pt>3 in pp With partial cuts optimization upgrade USTF, CERN, 25.10.11 Andrea Dainese

  16. Ongoing updates:D0 and Lc with other scenarios • Show the dependence of the performance on the detector thickness. Consider a case with 0.1% x/X0 instead of 0.3% • Consider a "high-rate" scenario in which tracking and PID are performed without TPC (ITS+TRD+TOF) • This configuration could run with L~1028 cm-2s-1 • Try to include Lc results from the new dedicated simulations at 5.5 TeV, with enhanced Lc signal (cuts tuning), and ITS fully active (no dead areas) ITS Upgrade, CERN, 14.11.11 Andrea Dainese, Gianluca Usai

  17. Beauty via displaced D0 A. Rossi • Measure prompt charm • And measure beauty production upgrade USTF, CERN, 25.10.11 Andrea Dainese

  18. Beauty via displaced J/y C. Di Giglio • Measure prompt J/y • And measure beauty production upgrade USTF, CERN, 25.10.11 Andrea Dainese

  19. Beauty via displaced electrons M. Kweon • The impact of the ITS upgrade is two-fold: • Reduced x/X0 decreases g conversions, one of the main background sources • Better impact parameter resolution improves the separation of displaced electrons (from B) background B signal upgrade ITS Upgrade, CERN, 14.11.11 Andrea Dainese, Gianluca Usai

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