Belle II status and plans Christoph Schwanda Institute of High Energy Physics Austrian Academy of Sciences June 11-15, 2012, Prague, Czech Republic

Belle II physics: Searching physics beyond the SM using indirect probes at high energy Flavor changing neutral currents (virtual contributions of new, heavy particles in loops) Precision test of CKM unitarity (search for new CP violating phases) ??? Search for the charged Higgs boson in B  t nu and B  D(*) t nu decays Search for lepton flavor violation in B and tau decays (SUSY breaking mechanism, right-handed neutrino couplings) How does the Belle II New Physics reach compare to present facilities (high pT searches at CMS and ATLAS, flavor physics at LHCb)?

Search for the charged Higgs boson with B+ ® t+ n Standard model Type II Higgs doublet models H- W.S.Hou, PRD 48, 2342 (1993) Belle II 5s H+ discovery (50/ab) 14 TeV ATLAS 5s H+ discovery (30/fb) arXiv:0901.0512 [hep-ex]

t lepton flavor violation t ® lg SUSY + seesaw Large LFV t ® 3l, lh Neutral Higgs mediated decay Important when MSUSY >> EW scale experimental sensivity mode Br(t ® mg) Br(t ® 3l) mSUGRA + seesaw 10-7 10-9 SUSY + SO(10) 10-8 10-10 SM + seesaw Non-universal Z’ SUSY + Higgs The full range of t LFV modes is only accessible at a Super B factory!

Belle II physics sensitivity [arXiv:1002.5012[hep-ex]]

Building on the success of the KEK B factory… … accelerator / detector are constructed by upgrading the present facilities

SuperKEKB machine parameters units LER HER Beam energy Eb 3.5 8 4 7 GeV Half crossing angle φ 11 41.5 mrad Horizontal emittance εx 18 24 3.2 5.0 nm Emittance ratio κ 0.88 0.66 0.27 0.25 % Beta functions at IP βx*/βy* 1200/5.9 32/0.27 25/0.31 mm Beam currents Ib 1.64 1.19 3.60 2.60 A beam-beam parameter ξy 0.129 0.090 0.0886 0.0830 Luminosity L 2.1 x 1034 8 x 1035 cm-2s-1 - sx~10mm,sy~60nm Small beam size (“nano-beam”) and higher currents to increase luminosity Smaller boost to improve LER lifetime e- 60nm 10mm e+

From KEKB to SuperKEKB Belle II luminosity goal: Colliding bunches New IR e- 2.6 A New superconducting /permanent final focusing quads near the IP New beam pipe & bellows e+ 3.6 A Belle II luminosity goal: 50 times the Belle dataset Replace short dipoles with longer ones (LER) Add / modify RF systems for higher beam current Low emittance positrons to inject Positron source Redesign the lattices of HER & LER to squeeze the emittance Damping ring New positron target / capture section TiN-coated beam pipe with antechambers Low emittance gun Low emittance electrons to inject

The formal start of the project… Nov 18, 2011: SuperKEKB groundbreaking The formal start of the project…

Feb 7, 2012: Installation of the first SuperKEKB dipole magnet The main purpose of this installation was to debug the tools and methods for installing the 4 m LER dipole over the 6 m HER dipole (remain in place). Installed 2 dipole magnets. The rest of the LER dipoles are scheduled to be installed this year.

Detector upgrade Critical issues at L= 8×1035/cm2/s: Higher background (×10-20) radiation damage and higher occupancy fake hits and pile-up noise in EM calorimeter Higher event rates (×10) higher rate trigger (L1 trigg. 0.5→30 kHz) DAQ, computing Target: Maintain or improve over Belle I data quality in the high background/ high rate environment II

The Belle II detector CsI(Tl) EM calorimeter: waveform sampling electronics, pure CsI for endcaps RPC μ & KL counter: scintillator + Si-PM for end-caps Time-of-Flight, Aerogel Cherenkov Counter → Time-of-Propagation (barrel), prox. focusing Aerogel RICH (forward) 4 layers DS Si vertex detector → 2 layers PXD (DEPFET) + 4 layers DSSD Central Drift Chamber: smaller cell size, long lever arm

Inner tracking (PXD, SVD) PXD + SVD in Belle II (in Belle only strip layers ) Pixels in novel DEPFET technology: thin (75μm) sensors give little multiple scattering, close to the IR Fast strip readout with APV25 chip (50 ns), low occupancy Improved IP resolution and low momentum tracking (pT < 100MeV), 30% larger eff. of Ks→π+π- with vertex info DSSD strip layers pixel layers Belle Belle II σ (μm) rφ IP resolution z IP resolution pβsin5/2θ[GeV/c] pβsin3/2θ[GeV/c] Mechanical mockup of pixel detector DEPFET sensor

Central drift chamber (CDC) Extended outer radius, longer lever arm ® improved momentum and dE/dx resolutions Larger inner radius, smaller cells near beampipe ® more background-hard Belle Belle II inner most sense wire r=88mm r=168mm outer most sense wire r=863mm r=1111.4mm Number of layers 50 56 Total sense wires 8400 14336 Gas He:C2H6 sense wire W(Φ30μm) field wire Al(Φ120μm) Belle normal cell 10~20 mm 18 mm 10 mm 6~8 mm small cell Belle II

Particle Identification (TOP, ARICH) „focusing” aerogel radiator Hamamatsu HAPD + new ASIC Cherenkov photon 200mm n~1.05 Endcap PID: Aerogel RICH Barrel PID: Time of Propagation Counter Quartz radiator Focusing mirror Small expansion block Hamamatsu MCP-PMT (measure t, x and y) TOP: reconstructs Cherenkov rings using 3D info from PMTs: x,y and time of photon propagation (40 ps resolution) ARICH: measures Cherenkov angle. Inhomogeneous aerogel radiator to improve photon resolution Improved K/π separation in wide momentum range Quartz radiator RICH test beam setup p=3GeV/c2

KL and muon detection End-caps upgrade: Resistive Plate Chambers ® scintillator- based detector 20x background increase in RPCs (worse shielding of neutrons along beams) Scintillators + SiPM: better beam-background tolerance Barrel KLM: some RPC layers may be replaced as background increases with luminosity Iron plate Aluminium frame x-strip plane y-strip plane Endcap KLM sector

The Belle II collaboration ~400 members with ~150 participants from Europe

Schedule – beam commissioning starts in JFY 2014 Goal of Belle II/SuperKEKB Integrated luminosity (ab-1) We will reach 50 ab-1 in 2022 9 months/year 20 days/month Commissioning starts in JFY 2014. Peak luminosity (cm-2s-1) Shutdown for upgrade Year

Summary The KEK B factory (KEKB and Belle) undergoes a major upgrade to become a Super B factory (SuperKEKB and Belle II), both accelerator and detector are on schedule for a start in JFY 2014 The upgrade will result in 40x larger event rates, the luminosity goal is 50/ab by 2022 This data sample will allow to probe physics beyond the Standard Model in B and D meson and t lepton decays, these results will complement the searches at hadron colliders References: Belle II Technical Design Report [arXiv:1011.03252 [physics.ins-det]] Belle II Physics [arXiv:1002.5012 [hep-ex]]

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