May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) sin2  1 atBelle sin2  1 at Belle Status of KEKB and Belle sin2  1 Winter ’02 Update Conclusion Masashi Hazumi (KEK) for the Belle Collaboration Outline

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) Belle The Belle Collaboration A World-Wide Activity Involving ~50 Institutions ~300 members

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) Belle The Belle Collaboration A World-Wide Activity Involving ~50 Institutions KEK Hawaii Cincinnati Princeton VPI ~300 members

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) Belle The Belle Collaboration A World-Wide Activity Involving ~50 Institutions KEK Hawaii Cincinnati Princeton VPI ~300 members

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) B Factory at KEK: 1-page Introduction 8GeV electron3.5GeV positron KEKB Collider

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) B Factory at KEK: 1-page Introduction 8GeV electron3.5GeV positron  (4s) (10.58GeV/c 2 )  =  (4s)  B B KEKB Collider B B ~200  m (average) J/  Ks flavor tagging

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) B Factory at KEK: 1-page Introduction 8GeV electron3.5GeV positron  (4s) (10.58GeV/c 2 )  =  (4s)  B B KEKB Collider B B ~200  m (average) J/  Ks flavor tagging Rate = exp(-|  t|/  B )/2  B  {1  (  q)sin2  1 sin(  m  t)}  : CP eigenvalue (e.g.  1 for J/  Ks) q : Flavor tagging (= +1 for B0-bar(  t)) proper time difference  t (ps) decay rate

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) Experimental Challenges Δz  cβγΔt (~200  m at Belle) 1) Copious B pair production, efficient B reconstruction 2) Efficient and correct flavor tagging 3) Observation of time-dependent CP asymmetry in B decays to a CP eigenstate with good vertex resolution decay rate proper time difference  t (ps)

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) sin2  1 = 0.99  0.14(stat)  0.06(sys) (Belle, July 2001) July 2001 : the Beginning of New Age World average (as of July 2001) 29.1fb -1 (31.3 million B pairs) PRL 87, (2001) hep-ex/ (submitted to PRD) sin2  1 = 0.79  0.10 First CPV observed outside the kaon system Strongly support the KM machanism of CPV –CP is not an approximate symmetry anymore

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) KEKB Luminosity: the world’s best ! Peak L 7.25  cm -2 s -1 (Mar. 28, ’02) Daily Integrated L 387 pb -1 /day(May. 11, ’02) Weekly Integrated L 2.14 fb -1 /week(Apr. 28, ’02) 76fb-1 recorded (May 13,’02) Daily Integrated luminosity history Integrated luminosity history

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) Belle Detector Silicon Vertex Detector (SVD) Impact parameter resolution  55  m for p=1GeV/c at normal incidence Central Drift Chamber (CDC) (  Pt/Pt)2 = (0.0019Pt)2 + (0.0034)2 (Pt in GeV/c)2 K/  separation with dE/dx in CDC (  dE/dx =6.9%) TOF (  TOF = 95ps) Aerogel Cerenkov (ACC) Efficiency = ~90%, Fake rate = ~6% up to 3.5GeV/c , e  with CsI crystals (ECL)  E/E ~ E=1GeV e  : efficiency > 90% (~0.3% fake for p > 1GeV/c) KL and  with KLM (RPC chambers)  : efficiency > 90% ( 1GeV/c) Quite stable performance up to now ACC All components are importantfor the sin2  1 measurement.

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) Belle Detector Silicon Vertex Detector (SVD) Impact parameter resolution  55  m for p=1GeV/c at normal incidence Central Drift Chamber (CDC) (  Pt/Pt)2 = (0.0019Pt)2 + (0.0034)2 (Pt in GeV/c)2 K/  separation with dE/dx in CDC (  dE/dx =6.9%) TOF (  TOF = 95ps) Aerogel Cerenkov (ACC) Efficiency = ~90%, Fake rate = ~6% up to 3.5GeV/c , e  with CsI crystals (ECL)  E/E ~ E=1GeV e  : efficiency > 90% (~0.3% fake for p > 1GeV/c) KL and  with KLM (RPC chambers)  : efficiency > 90% ( 1GeV/c) Quite stable performance up to now ACC All components are importantfor the sin2  1 measurement. Kaon efficiency  contamination 87% 8% PID(K)>0.6

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) Mass Resolutions (1) J/   +  -  = 9.6 MeV/c 2 J/   e + e - (  )  = 10.7 MeV/c 2 MKp(GeV/c2) B -  D 0  -  K -  +  1 = 4.8MeV/c 2 (66%)   = 12.3MeV/c 2 (34%)

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) Mass Resolutions (2)  0   =4.8MeV/c 2   =12.1MeV/c 2 Ks   0  0   =12.1MeV/c 2

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) Fully-reconstructed Event Example

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) sin2  1 Winter ’02 Update [ Major update  Summer 2002 (~90fb-1) ]

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) Data Set Belle 2000~2001 (41.8fb-1) (LP01 (published) 29.1fb-1) 2002

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) Reconstruction of CP Eigenstates Mode# of Ev.Purity J/yKS(p+p-)J/yKS(p+p-) J/yKS(p0p0)J/yKS(p0p0) y(2S)( l + l - )K S y(2S)(J/yp + p - )K S c c1 (J/yg)K S hc(KSK+p-)KShc(KSK+p-)KS hc(K+K-p0)KShc(K+K-p0)KS J/yK*0(KSp0)J/yK*0(KSp0) J/yKLJ/yKL Total1772 CP-odd (  =  1) even/odd mix. CP-even (  = +1)

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) All Modes (except B 0  J/  K L ) cand candidates 636 candidates ~31 background (Purity = 95%) B 0  J/  Ks(  +   ) 369 candidates ~59 background (Purity = 84%) B 0  other modes (  E cut applied)

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) B 0  J/  K L 1)J/   l + l  + K L 2) Assume B  J/  K L : compute P KL 3) Remove reconstructed B  J/  K, J/  K*, … 4) Cut on a likelihood based on kinematical and shape quantities 5) Plot P* =|P J/  + P KL | B K L direction + 2-body decay kinematics

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) B 0  J/  K L 767 total events 462 signal (Purity = 60%) B 0  J/  K L P B =| P J/  + P KL | Belle P B (cms) * ** N bkg = 305 evts Total 1772 CP events N sig = 462 events 1316 LP01 run-dep. E beam correction LP sig. 346 bkg

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) Flavor Tagging (no change from LP01)  Inclusive Leptons:  high-p l  b  c l   intermed-p l + s l    Inclusive Hadrons:  high-p  + B 0  D (*)   +, D (*)   +, etc.  intermed-p K + K + X,      low-p   D 0   Also include correlations Use inclusive flavor-specific properties:

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) Belle Flavor Tagging Method Look-up tables

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) Wrong-tag Fraction Determination Wrong tag fractions in 6 tagging categories Efficiency > 99.5%  effective = 27.0  1.2% determined by data Asym = OF - SF OF + SF Flavor specific decays + Tagging B 0  D*l, D (*)  (  mixing) OF = Opposite Flavor SF = Same Flavor (i.e. oscillated)

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) Related topic:  m d (4 methods) Dilepton (5.9fb -1 )   Hadronic  D*l  D*  partial   0.020

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) Event-by-event Likelihood Taken from data double Gaussian

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) Improved Resolution Functions Separate response functions for “vtx with 1-track + IP constraint” and other Outlier treatment Already adopted for the B lifetime analysis More sensitive to R(  t) Simultaneous fit to B 0,B - Pdf(  t) = P sig R sig + P BG + P OL R sig = R det R NP R Kin PRL 88, (2002)  B0) = ±0.030 ±0.019 (ps)  B–) = ±0.026 ±0.015 (ps)  B–) /  B0) =1.091 ±0.023 ±0.014

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) sin2  1: Unbinned Maximum-likelihood Fit sin2  1 = 0.82  0.12 (stat)  0.05 (sys) Raw data Asymmetry ! N(q  f =-1) - N(q  f =+1) N(q  f =-1)+ N(q  f =+1) 1550 events 1137 LP01 Preliminary

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) sin2  1: Unbinned Maximum-likelihood Fit sin2  1 = 0.82  0.12 (stat)  0.05 (sys) Raw data Asymmetry ! N(q  f =-1) - N(q  f =+1) N(q  f =-1)+ N(q  f =+1) 1550 events 1137 LP01 Preliminary Test of direct CPV | | = 1.01 (stat) “sin2  1” = 0.82  0.12 (stat)  0.07

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) Raw Asymmetries CP-1 CP+1 sin2   1.14  (statistical errors only) opposite! [N (B 0 tag) -N (B 0 tag) ] / [N (B 0 tag) +N (B 0 tag) ]

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) Test of Null Asymmetry “sin2  1 ” 0.05  0.04 (statistical error only) use: B 0  D (*)   , D *   , J/  K*(K    

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) sin2  1 from various subsamples q=  evts q=  evts (statistical errors only)

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) sin2  1 : Systematic Errors  Total  m d and  B0 errors  Background (non K L )  Background fraction(K L )  Resolution function  Flavor tagging  0.03 Vertexing Preliminary   LP01

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) Why better precision required ? sin2  1 in J/  Ks (and related) –Insensitive to New Physics: Boring ? No ! Important as the Standard Model “Anchoring Point” Combination with other rare-decay CPV: a promissing road to the Physics beyond the Standard Model Examples of rare decays –B 0  ’Ks : New CPV phase search in penguin decays  sin2  1(J/  Ks) = “sin2  1(  ’Ks )” ??  Talk by K-F. Chen in the “hot topics” session with 73 signal events –One of the most important inputs to the CKM fit

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) Conclusion KEKB: Great Achievement ! Lpeak = 7.25 x cm -2 s -1 Belle: Very Stable Operation sin2  1 = 0.82  0.12 (stat)  0.05 (sys) (41.8fb -1 ) Summer update with ~90fb -1 ! Test the SM with other CPV in rare B decays ! Exciting time will yet to come !

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) Backup Slides

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) Kobayashi-Maskawa model of CPV CPV due to the complex phase in CKM matrix 11 22 33 V td V tb V cd V cb V ud V ub * * * Physics at Belle Unitarity triangle Discover CPV in B meson system (done !) Measure CKM elements (angles and lengths) with unprecedented precision to overconstrain Beyond the SM (e.g. a new CPV phase) CKM

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) KEKB Luminosity

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) Control Samples Used to evaluate performance of flavor tagging ~6 x 10 3 events Semileptonic decays B 0  D* + (  D 0  + )l – Hadronic decays B 0  D ( * )+  –,D* +  – D 0  K –  + D 0  K –  +  0 D 0  K –  +  –  +

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) For CP-side, use J/   l  l  –Reject poorly fit events.  z CP  75  m (rms) For Tag-side –use well fit tracks –iterate: discard worst track –  z tag  140  m (rms) Require |z CP - z tag |<2mm (  10  B )   t  1.5 ps Tails  3%; Effic.  85% Vertex Reconstruction

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) (See BELLE-CONF-0105) J/  K* Transversity Analysis P sig （  t,  tr ） = (1-R T )P CP=-1 (1+cos 2  tr ) 3/8 + R T P CP=+1 (sin 2  tr ) 3/4 B  VV usable !

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) B0  ’Ks Time-dependent CPV Precise measurement of CPV in penguin decays : a powerful tool to search for a new CPV phase beyond the Standard Model (SM) Large branching fractions for inclusive and exclusive B   ’ transition may be a hint. B 0  J/  Ks w b c s c A CP (  t) = –  f sin2  1 sin(  m d  t) Motivation

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) B0  ’Ks Time-dependent CPV Precise measurement of CPV in penguin decays : a powerful tool to search for a new CPV phase beyond the Standard Model (SM) Large branching fractions for inclusive and exclusive B   ’ transition may be a hint. B 0  J/  Ks w b c s c A CP (  t) = –  f sin2  1 sin(  m d  t) W b s s s g B 0   Ks,  ’Ks Motivation

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) B0  ’Ks Time-dependent CPV Precise measurement of CPV in penguin decays : a powerful tool to search for a new CPV phase beyond the Standard Model (SM) Large branching fractions for inclusive and exclusive B   ’ transition may be a hint. B 0  J/  Ks w b c s c A CP (  t) = –  f sin2  1 sin(  m d  t) W b s s s g B 0   Ks,  ’Ks A CP (  t) = –  f sin2(  1 +  NP )sin(  m d  t) New diagram and phase Motivation

May , 2002 FPCP02, Philadelphia, U.S.A. Masashi Hazumi (KEK) Reconstruction B0   ’Ks  +  - (   0.27 )%  (29.5  1.0)%  +  - (~100)%  +  - (44.3  1.5)%  (39.33  0.25)% Belle 41.8fb-1 B0 Yields N(  Ks) = 45.5 N(  Ks) =  B0 B+ More will be given in the “hot topic” session (K-F. Chen)