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Status and Physics Prospects of the SuperKEKB Project

Status and Physics Prospects of the SuperKEKB Project. 5th March 2011, La Thuile 2011. Y. Horii Tohoku Univ. (Japan). KEKB Collider. KEKB parameters HER ( e - ): 8.0 GeV LER ( e + ): 3.5 GeV E CMS = U (4S) mass  B meson pair Peak luminosity = 2.1 x 10 34 /cm 2 s

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Status and Physics Prospects of the SuperKEKB Project

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  1. Status and Physics Prospects of the SuperKEKB Project 5th March 2011, La Thuile 2011 Y. Horii Tohoku Univ. (Japan)

  2. KEKB Collider KEKB parameters • HER (e-): 8.0 GeV • LER (e+): 3.5 GeV • ECMS = U(4S) mass  B meson pair • Peak luminosity=2.1 x 1034 /cm2s • Integrated luminosity > 1 ab-1(June 1999 - June 2010) Tsukuba city (40 minutes from Tokyo by train) LER HER Belle World records

  3. Belle Detector KL and MuonDetector Electromagnetic Calorimeter e+ e- Time of Flight AerogelCherenkov Silicon Vertex Detector (Double-sided silicon strips) Drift Chamber K±/p± identification (Eff. ~ 90%, fake ~ 10%)

  4. A Success Story at B-Factories Discovery of CP violation in the B system Measurements of the CKM matrix elements PRL 98, 031802 (2007), 0.5 ab-1 _ B0J/ψK0 B0J/ψK0 _ _ Asymmetry =(N-N)/(N+N)

  5. Upgrades KEKB collider Belle detector SuperKEKB collider Belle II detector

  6. SuperKEKB Collider Approved in 2010. Belle II Larger crossing angle 2f = 22 mrad  83 mrad for separated final-focus magnets. e- Smaller asymmetry 8/ 3.5 GeV  7 /4 GeV e+ High currents e-: 2.6 A e+: 3.6 A Replace short dipoles with longer ones (LER). Small beam sizes sx~10mm, sy~60nm Damping ring Redesign the lattices of HER & LER toreducethe emittance. TiN coated beam pipewith antechambers L = 8 x1035 cm-2 s-1

  7. Peak Luminosity SuperKEKB

  8. Schedule Milestone of SuperKEKB 9 months/year 20 days/month We will reach 50 ab-1 in 2020-2021. Integrated Luminosity (ab-1) Commissioning starts in 2nd halfof FY2014. Peak Luminosity (cm-2s-1) Shutdown for upgrade Year

  9. Detector Upgrade 9 H.Nakayama (KEK)

  10. Detector Upgrade Vertex detector: 4 lyr. Si strip  2 lyr. pixel + 4 lyr. Si strip 10 H.Nakayama (KEK)

  11. Detector Upgrade Drift chamber for tracking: smaller cells Vertex detector: 4 lyr. Si strip  2 lyr. pixel + 4 lyr. Si strip 11 H.Nakayama (KEK)

  12. Detector Upgrade Drift chamber for tracking: smaller cells Vertex detector: 4 lyr. Si strip  2 lyr. pixel + 4 lyr. Si strip New PID system: Cherenkov imaging, very fast readout 12 H.Nakayama (KEK)

  13. Detector Upgrade Drift chamber for tracking: smaller cells Vertex detector: 4 lyr. Si strip  2 lyr. pixel + 4 lyr. Si strip Calorimeter: new readout with waveform sampling New PID system: Cherenkov imaging, very fast readout 13 H.Nakayama (KEK)

  14. Detector Upgrade Drift chamber for tracking: smaller cells Vertex detector: 4 lyr. Si strip  2 lyr. pixel + 4 lyr. Si strip Calorimeter: new readout with waveform sampling New PID system: Cherenkov imaging, very fast readout Endcap KL/muon: RPC Scintillator +MPPC 14 H.Nakayama (KEK)

  15. Vertex Detector Improve decay-time precision and acceptance (KS’s). 4lyr. Si strip  2lyr. pixel(DEPFET) + 4lyr. Si strip 6th lyr. Si strip 5th lyr. 4th lyr. 3rd lyr. 2nd lyr. pixel 1st lyr. Pixel: r=14,22mm Si strip: r=38,80,115,140mm Belle II Belle 4th lyr. 3rd lyr. 2nd lyr. 1st lyr.

  16. Endcap PID: Aerogel RICH (ARICH) Particle Identification System at Belle II Barrel PID: Time of Propagation Counter (TOP) Quartz radiator TOP Focusing mirror Hamamatsu MCP-PMT (measure t, x and y) 200mm Cherenkov photon sq(1p.e.) = 14.4 mrad Npe ~ 9.6 sq(track) = 4.8 mrad n1 n2 Aerogel radiator n~1.05 Completely different from PID at Belle, with better K/p separation, more tolerance for BG, and less material. Hamamatsu HAPD + new ASIC Multiple aerogel layers with different indices

  17. More information of Belle II detector: “Belle II Technical Design Report” at arXiv:1011.0352.

  18. Physics at SuperKEKB/Belle II • A benefit to use One B meson (“tag” side) can be reconstructed in a common decay. Flavor, charge, and momentum of the other B can be determined. Effectivefor the modesincluding missing energy. Missing Also possible to partially reconstruct (semileptonically, …).

  19. Btn • Evidence obtained at the B factories. • Tension between the global CKMfit and direct measurement. BG only Sig + BG Example w/ semileptonic tag, 0.6 ab-1 PRD 82, 071101 (2010) Better measurement of Btn mayrevealsource of the tension. Tag-side information is vital for ≥ 2n’s. ~2.8s discrepancy

  20. Btn at Belle II • In Two-Higgs Doublet Model (THDM) Type II,the branching ratio of Btn can be modified. H- Constrains on mH± and tanb can be obtained. 5 ab-1 assuming 5% errors for |Vub| and fB. 50 ab-1 assuming 2.5% errors for |Vub| and fB.

  21. Direct CP Violation for BKp If the only diagrams are a and b, we expect However, significant difference is obtained. Missing diagrams?Large theoretical uncertainty… a b K-p+ K+p- BKpw/ 0.5 ab-1 Nature 452, 332 (2008) K-p0 K+p0

  22. Direct CP Violation for BKpat Belle II • We can compare to a model-independent sum rule: Can be represented as diagonal band (slope precisely known from B and lifetimes): Belle II provides a good environment for the all neutral final state (K0p0). sum rule sum rule measured measured expected Current measurement larger error for ACPK0p0 50 ab-1assuming current central value expected

  23. Decays of t Example: tmg • Can be enhanced by the effectsof new physics in the loop diagram. Belle II provides good sensitivities on the t decays. g ○tmg □tmh △tmmm t m Integrated luminosity (ab-1)

  24. More information of physics prospects: “Physics at Super B Factory” atarXiv:1002.5012.

  25. Summary • Significant opportunities to search for new physicsat SuperKEKB/Belle II. • More information: • “Belle II Technical Design Report” at arXiv:1011.0352. • “Physics at Super B Factory” at arXiv:1002.5012. KEK collider Belle detector SuperKEKB collider Belle II detector Operation from1999 to 2010. Peak luminosity = 2.1 x 1034 / cm2s. Integrated luminosity = 1.0 ab-1. Aim to start commissioning in 2014. Target of peak luminosity =8 x 1035 / cm2s. Target of integrated luminosity = 50 ab-1 by 2021. (Btn, BKp, t decays, etc.)

  26. Backup Slides

  27. KEKB Collider 2.1x1034 cm-2s-1 Crab crossing:

  28. Funds for SuperKEKB • 100 oku-yen (~100 million dollars) approved in summer 2010. • Upgrade approved by the cabinet in December 2010. • Waiting for the final approval by the Diet.

  29. Belle II Detector • Have to deal with: • Higher background (10-20x) • radiation damage, • higher occupancy • Higher event rates • DAQ (L1 trigg. 0.5 20 kHz) • Improved performance • hermeticity Calorimeter: waveform sampling KL, m: scintillatorstrips for endcaps Drift Chamber: smaller cell size improved read-out PID: TOP barrel ARICH forward Vertexing: 2 lyrs DEPFET pixel 4 lyrs DSSD

  30. Other Upgrades for Belle II Silicon vertex detector: new readout chip (APV25) shorter integration time (800 ns50 ns) Drift chamber: smaller cells Belle Belle II Calorimeter: new readout system with waveform sampling (x1/7 BG reduction) KL/Muon detector RPCScintillator+MPPC Better performance against neutron BG

  31. Expected Performance for Belle II

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