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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 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 • 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
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%)
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 _ B0J/ψK0 B0J/ψK0 _ _ Asymmetry =(N-N)/(N+N)
Upgrades KEKB collider Belle detector SuperKEKB collider Belle II detector
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
Peak Luminosity SuperKEKB
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
Detector Upgrade 9 H.Nakayama (KEK)
Detector Upgrade Vertex detector: 4 lyr. Si strip 2 lyr. pixel + 4 lyr. Si strip 10 H.Nakayama (KEK)
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)
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)
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)
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)
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.
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
More information of Belle II detector: “Belle II Technical Design Report” at arXiv:1011.0352.
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, …).
Btn • 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 Btn mayrevealsource of the tension. Tag-side information is vital for ≥ 2n’s. ~2.8s discrepancy
Btn at Belle II • In Two-Higgs Doublet Model (THDM) Type II,the branching ratio of Btn 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.
Direct CP Violation for BKp 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- BKpw/ 0.5 ab-1 Nature 452, 332 (2008) K-p0 K+p0
Direct CP Violation for BKpat 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
Decays of t Example: tmg • Can be enhanced by the effectsof new physics in the loop diagram. Belle II provides good sensitivities on the t decays. g ○tmg □tmh △tmmm t m Integrated luminosity (ab-1)
More information of physics prospects: “Physics at Super B Factory” atarXiv:1002.5012.
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. (Btn, BKp, t decays, etc.)
KEKB Collider 2.1x1034 cm-2s-1 Crab crossing:
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.
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
Other Upgrades for Belle II Silicon vertex detector: new readout chip (APV25) shorter integration time (800 ns50 ns) Drift chamber: smaller cells Belle Belle II Calorimeter: new readout system with waveform sampling (x1/7 BG reduction) KL/Muon detector RPCScintillator+MPPC Better performance against neutron BG