Belle and Belle II Christoph Schwanda Institute of High Energy Physics (HEPHY) Austrian Academy of Sciences RECFA Meeting Open Session - Austria

KEK Tsukuba site Linac KEKB rings (HER+LER) Belle detector Mt. Tsukuba 2

The KEKB collider KEKB collides 8 GeV electrons on 3.5 GeV positrons Center of mass energy: GeV (Y(4S) resonance)  production of B pair at threshold One interaction point (Belle) 3 e + source Ares RF cavity Belle detector SCC RF(HER)‏ ARES(LER)‏ First physics run on June 2, 1999 Last physics run on June 30, 2010 L peak = 2.1x10 34 /cm 2 /s L total > 1ab -1

 / K L detection 14/15 lyr. RPC+Fe CsI(Tl) 16X 0 Si vtx. det. 3(4) lyr. DSSD SC solenoid 1.5T 8 GeV e  3.5 GeV e  Aerogel Cherenkov cnt. n=1.015~1.030 C entral D rift C hamber small cell +He/C 2 H 5 TOF counter The Belle detector 4

Belle: 772 million BB events BaBar: 470 million BB events 5

B factories: a success story B 0 →J/ψK 0 _ Discovery of CP violation in the B meson system (2001) Confirmation of CKM mechanism Rate of the decay B 0 (B 0 ) →J/ψK 0 as a function of the decay time difference of the two Bs in Y(4S) → BB events 6

“… As late as 2001, the two particle detectors BaBar at Stanford, USA and Belle at Tsukuba, Japan, both detected broken symmetries independently of each other. The results were exactly as Kobayashi and Maskawa had predicted almost three decades earlier.” 7

Vienna’s contributions to Belle Belle member since 2001 Hardware – Readout system for the silicon vertex detector (SVD), installed 2003 – 110,592 readout channels in total – Worked flawlessly for 7 years Physics analysis – Leading the Belle CKM group (measurements of |V cb | and |V ub | with semileptonic B decays, search for the charged Higgs) – Charmed meson spectroscopy (semileptonic and leptonic D decays) 8

Vienna results: B semileptonic First evidence for B   l [PRL 93, (2004)] Hadronic mass moments in B  X c l [PRD 75, (2007)] Measurement of |V cb | and m b from inclusive semileptonic B decays [PRD 78, (2008)] 9

Vienna results: charm spectroscopy Measurement of D  K  l [PRL 97, (2006)] Measurement of D s   [PRL 100, (2008)] 10

Most recently: |V cb | from B 0  D *- l + The most precise measurement of |V cb | using exclusive decays (3.0% experimental error) 11 [PRD 82, (2010)]

KEK B factory upgrade The KEK Super B factory aims at accumulating 50 times the Belle data set by /ab/month (4x10 35 /cm 2 /s) 0.9/ab/month (6x10 35 /cm 2 /s) 1.2/ab/month (8x10 35 /cm 2 /s) 50/ab 1/fb Y(4S) data = 1.1 million BB events 1/ab Y(4S) data = 1.1 billion BB events 12

Searching for physics at the TeV scale with precision flavor physics ??? 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  tau nu and B  D(*) tau nu decays Search for lepton flavor violation in B and tau decays (SUSY breaking mechanism, right-handed neutrino couplings) 13

From Belle to Belle II The Belle II detector will be built by upgrading the present Belle spectrometer Requirements for Belle II – 40x higher physics rate  faster detector – Higher backgrounds  more radiation damage, higher occupancy – Need better detector hermeticity for lepton flavor violation searches 14

Particle ID ring imaging Cherenkov devices (TOP in the barrel, ARICH in the forward) Belle II detector Pixel detector (2 layers) Silicon strip detector (4 layers) Drift chamber smaller cell size Em. calorimeter wave form sampling pure CsI (endcaps) Muons, neutrals scintillator strips (endcaps) 15

Belle II Silicon Vertex Detector (SVD) Vienna is leading for the design, development and construction of the entire Belle II 4-layer SVD system This includes – Double-side silicon sensors – Ladder mechanics and cooling – Readout electronics for 240,000 channels 16

Challenges in the Belle II SVD design Background – The Belle II SVD must be able to handle trigger rates up to 30 kHz Material – Charged particles down to a transverse momentum of 50 MeV must be tracked  ultra-low mass design Space – The entire system including cabling, cooling, support and services must fit into a narrow, 10 cm wide gap.  Our design is documented in the Belle II TDR (KEK Report , arXiv: ) 17

4-layers of double-sided silicon sensors (DSSDs) read out by a fast front-end chip (APV25) Flash analog-digital converter (FADC) with hit time finding Low mass ladder design: Carbon fiber ribs CO 2 cooling Slanted forward sensors Belle II SVD design 1.2 m 2 of double-sided silicon detectors 4 layers (r=3.8cm…14cm) – surrounding pixel detector 243k readout channels CO 2 cooling Low-mass: 0.55% X 0 per layer (including services) 18

Why hit time finding? Occupancy Reduction With hit time reconstruction, we can cope with 50-fold increase in luminosity 19

Origami chip-on-sensor concept 20

Manpower and funding 12 FTE working in the Vienna Belle/Belle II group – 5 FTE on Belle physics analysis, 7 FTE on Belle II SVD construction – 3 female staff (25%) Funding – Belle physics analysis funded by the Austrian science fund FWF – Funding for Belle II SVD construction has yet to be secured 21

Summary The Vienna Institute of High Energy Physics plays an active and visible role in both the Belle and the Belle II experiments Belle activity – Construction of the Silicon Vertex Detector readout electronics – Now main focus on physics analysis Belle II – Leading the design, development and construction of the entire 4-layer Silicon Vertex Detector system 22

Backup 23

Charged current interaction in the Standard Model V CKM is the unitary 3x3 matrix of coupling constants of weak transitions It also contains the KM phase, responsible for all CP violating phenomena observed so far! The Cabibbo-Kobayashi-Maskawa theory [Kobayashi, Maskawa, Prog. Theor. Phys. 49, 652 (1973)] Existence of CP violation implies (at least) 6 quark flavors! 24

Main physics goals of the B factories Find CP violation in B decays, as predicted by the CKM theory Confirm the unitarity of the CKM matrix 25  The CKM unitarity triangle

The Belle collaboration 15 countries, 62 institutes, ~400 collaborators HEPHY Vienna ITEP Kanagawa U. KEK Korea U. Krakow Inst. of Nucl. Phys. Kyoto U. Kyungpook Nat’l U. EPF Lausanne Jozef Stefan Inst. / U. of Ljubljana / U. of Maribor U. of Melbourne Aomori U. BINP Chiba U. Chonnam Nat’l U. U. of Cincinnati Ewha Womans U. Frankfurt U. Gyeongsang Nat’l U. U. of Hawaii Hiroshima Tech. IHEP, Beijing IHEP, Moscow Nagoya U. Nara Women’s U. National Central U. National Taiwan U. National United U. Nihon Dental College Niigata U. Osaka U. Osaka City U. Panjab U. Peking U. U. of Pittsburgh Princeton U. Riken Saga U. USTC 26

e- 2.6 A e+ 3.6 A To get x40 higher luminosity Colliding bunches Damping ring Low emittance gun Positron source New beam pipe & bellows Belle II New IR TiN-coated beam pipe with antechambers Redesign the lattices of HER & LER to squeeze the emittance Add / modify RF systems for higher beam current New positron target / capture section New superconducting /permanent final focusing quads near the IP Low emittance electrons to inject Low emittance positrons to inject Replace short dipoles with longer ones (LER) KEKB to SuperKEKB

Machine design parameters parameters KEKBSuperKEKB units LERHERLERHER Beam energy EbEb GeV Half crossing angle φ mrad Horizontal emittance εxεx nm Emittance ratio κ % Beta functions at IP β x * /β y * 1200/5.932/0.2725/0.31 mm Beam currents IbIb A beam-beam parameter ξyξy Luminosity L2.1 x x cm -2 s -1 Small beam size & high current to increase luminosity Large crossing angle Change beam energies to solve the problem of LER short lifetime 28

New Physics reach with 50/ab compared to energy frontier experiments See T. Aushev et al., “Physics at Super B Factory”, arXiv: [hep-ex] for more details 29

Complementarity LHC/Super B factory Precision flavor data allows to exclude wide areas of the NP parameter space This allows to focus searches at the LHC and properly interpret the results 30 MSSM with minimum flavor violation G. Eigen, arXiv:

LFV and New Physics   l  SUSY + Seasaw Large LFV Br(    )=O(10 -7~9 )   3l,l h Neutral Higgs mediated decay. Important when M SUSY >> EW scale. model Br(  →  ) Br(  → lll ) mSUGRA+seesaw SUSY+SO(10) SM+seesaw Non-Universal Z’ SUSY+Higgs =

Rare  decays LF violating  decay? Integ. Lum. （ ab -1 ） Reach of B factories Super B factories Upper limits    ee ee T.Goto et al., 2007 Theoretical predictions compared to present experimental limits

LP 2009 Charm FCNC Charm mixing and CP B Y(4S) B s Y(5S) t Physics M. Giorgi, ICHEP2010

Belle II SVD readout electronics Full readout chain to DAQ To be designed and built by HEPHY Prototypes exist for all stages Origami module Repeater box FADC+PROC VME Data processing and hit time finding (~3ns) in FPGA firmware 34

Belle-II collaboration SuperKEKB LoI KEK Roadmap st Proto collaboration meeting Detector study report New collaboration, Belle-II, started ~300 collaborators from 43 institutions in 13 countries ~ Technical Design Report available 35

SuperKEKB/Belle II costs Construction Cost : $340M – Appropriated FY2009 stimulus money $35M FY2010 line item : $5M for a positron accumulator ring FY2010 stimulus money $100M – Soon to be approved FY2011 ~$200M Operation cost ~$70M/year Belle II SVD costs ~EUR 2.6M (Vienna share ~EUR ) 36