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CP Asymmetry in B 0 -> + at Belle Kay Kinoshita University of Cincinnati Belle Collaboration B 0 -> + and CP asymmetry in CKMB 0 -> + and CP asymmetry in CKM e + e -> (4S) at KEKB and Belle e + e -> (4S) at KEKB and Belle Belle data Belle data Measurement of CP asymmetry in B 0 -> + Measurement of CP asymmetry in B 0 -> + Interpretation vis-a-vis CKM Interpretation vis-a-vis CKMFuture

Slide 2 + involves 2 ( ) of CKM: V ub *V ud V cb *V cd V tb *V td V "> + involves 2 ( ) of CKM: V ub *V ud V cb *V cd V tb *V td V cb *V cd + 1 += 0 CKM: matrix of W-quark couplings - 3x3, unitary One condition of unitarity: "> + involves 2 ( ) of CKM: V ub *V ud V cb *V cd V tb *V td V " title="DPF, April 5, 2003 2 Represented in complex plane as "unitarity triangle" B 0 -> + involves 2 ( ) of CKM: V ub *V ud V cb *V cd V tb *V td V ">

DPF, April 5, 2003 2 Represented in complex plane as "unitarity triangle" B 0 -> + involves 2 ( ) of CKM: V ub *V ud V cb *V cd V tb *V td V cb *V cd + 1 += 0 CKM: matrix of W-quark couplings - 3x3, unitary One condition of unitarity:

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DPF, April 5, 2003 3 V tb *2 V td 2 V ub V ud * V ub * V ud B 0 -> + 2 =arg 2 paths, each w/wo mixing: Tree Penguin V tb * V td V tb *2 V td 2 V tb V td * "direct" asym V td V tb * V ud V ub * mixing+ " Bottom line: CP-asymmetric time-dependent rate from x-terms

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DPF, April 5, 2003 4 Uncertainty: relative amplitudes of Tree, Penguin if T dominates, A =0, S =sin2 2 if T dominates, A =0, S =sin2 2 if P, T comparable, A 0, S ~sin(2 2 +2 )2/(| | 2 +1) if P, T comparable, A 0, S ~sin(2 2 +2 )2/(| | 2 +1) Direct CP violation Now: more data - 78 fb 1 more data - 78 fb 1 improved analysis - tracking, improved analysis - tracking, t resolution, event selection t resolution, event selection statistical analysis statistical analysis (total 126 fb 1, ~1.3x10 8 B events) Each 2.9 from zero; note physical region is difference of strong phase 1 if direct CP violation+0.38+0.160.270.13+0.25+0.09 0.31 0.09 S = 1.21 A = +0.94 Previous Belle result {PRL 89, 071801 (2002)} (42 fb 1 ~45M B pairs)

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DPF, April 5, 2003 5 B production: } B BB threshold e-e-e-e- e+e+e+e+ CP=1,conserved + e - -> (4S) { = 0.425} z t c ~200 m CP mode @ t= t flavor tag @t= : e, , K ,... As with sin2 1 via J/ K: reconstruct CP mode reconstruct CP mode tag flavor tag flavor reconstruct vertices reconstruct vertices unbinned max. unbinned max. likelihood fit to t likelihood fit to t B2B2B2B2t=0 B1B1B1B1 first B decay (t=0), break CP

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DPF, April 5, 2003 6 Belle detector Charged tracking/vertexing - SVD: 3-layer DSSD Si strip CDC: 50 layers (He-ethane) Hadron identification CDC: dE/dx TOF: time-of-flight ACC: Threshold Cerenkov (aerogel) Electron/photon ECL: CsI calorimeter Muon/KL KLM: Resistive plate counter/iron

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DPF, April 5, 2003 7 the people 274 authors, 45 institutions many nations many nations

Slide 8 K + "physics bg" B 0 ->K + => hadron ID, kinematics dE/dx, TOF, Aerogel positive ID =91%, K =10% continuum => event shape {qq jet-like vs BB spherical) continuum => event shape {qq jet-like vs BB spherical) Fisher discriminant from modified Fox-Wolfram moments Fisher discriminant from modified Fox-Wolfram moments B candidate direction relative to beam axis B candidate direction relative to beam axis Construct Likelihood ratio LR=L BB /[L BB +L qq ], 2 selections: Construct Likelihood ratio LR=L BB /[L BB +L qq ], 2 selections: LR > 0.825 {} LR > 0.825 { BB =53%, qq =5%} 0.825 > LR > LR min (cut depends on flavor tag classification)">

DPF, April 5, 2003 8 B 0 -> + reconstruction final selection: E E* cand E* beam : 00.057 GeV(E* beam s 1/2 /2) {K shift 45 MeV} E E* cand E* beam : 00.057 GeV(E* beam s 1/2 /2) {K shift 45 MeV} M bc (E* beam 2 -p* cand 2 ) 1/2 : 5.271 5.287 GeV/c 2 (Beam-constrained) M bc (E* beam 2 -p* cand 2 ) 1/2 : 5.271 5.287 GeV/c 2 (Beam-constrained) but less clean than B 0 ->J/ K s : "physics bg" B 0 ->K + "physics bg" B 0 ->K + => hadron ID, kinematics dE/dx, TOF, Aerogel positive ID =91%, K =10% continuum => event shape {qq jet-like vs BB spherical) continuum => event shape {qq jet-like vs BB spherical) Fisher discriminant from modified Fox-Wolfram moments Fisher discriminant from modified Fox-Wolfram moments B candidate direction relative to beam axis B candidate direction relative to beam axis Construct Likelihood ratio LR=L BB /[L BB +L qq ], 2 selections: Construct Likelihood ratio LR=L BB /[L BB +L qq ], 2 selections: LR > 0.825 {} LR > 0.825 { BB =53%, qq =5%} 0.825 > LR > LR min (cut depends on flavor tag classification)

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DPF, April 5, 2003 9 B 0 -> + Candidates LR>0.825 0.825>LR>LR min :10616K:4110qq:1286:578K:226qq:40617 Total signal 16324 760 in signal box - 391 B 0, 369 B 0

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DPF, April 5, 2003 10 Flavor tagging: same as for sin2 1 bcs l-l-l-l- l+l+l+l+ KKKK D0D0 ++ D *+ high-p lepton (p*>1.1 GeV): b-> l - net K charge b->K medium-p lepton, b->c-> l + soft b->c{D *+ ->D 0 + } hard b->{c} X * multidimensional likelihood, >99% or wrong-tag fraction w classify events based on expected w (MC) - 6 bins. (B 0 mixing amplitude in data) => effective efficiency = (1-2w): net (28.80.5)% mixing amplitude w

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DPF, April 5, 2003 11 K-K- K-K- sin2 1 z vertex reconstruction: same as for sin2 1 t ~1.43 ps (rms) zz B 0 D , D* , D* , J/ K S, J/ K* 0 Resolution function: validate via lifetime

DPF, April 5, 2003 12 More checks of t resolution+flavor tag B0 = 1.420.14 ps (PDG02: 1.5420.016) B0 = 1.460.08 ps B 0 ->K + mixing m d = 0.550.07 ps 1 (PDG02: 0.4890.008) Fitted bg agrees w sideband

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DPF, April 5, 2003 13 Check for flavor bias Look where zero asymmetry expected: "S "= 0.0450.033 "A "= -0.0150.022 S K = 0.030.11 A K = +0.080.16

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DPF, April 5, 2003 14 Fitting for CP asymmetry Same technique as with sin2 1 unbinned maximum likelihood fit unbinned maximum likelihood fit resolution function event-by-event: tracking, misreconstruction, resolution function event-by-event: tracking, misreconstruction, physics, approximation of t= z/ c physics, approximation of t= z/ c wrong tag fraction w, backgrounds wrong tag fraction w, backgrounds Fit for A , S : rootDiluted +K (set A K = 0) +resolution + bg

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DPF, April 5, 2003 15 5-5 0 5 0 Backgroundsubtracted rawasymmetry LR>0.825 Fit Results display t projection (78 fb 1 ~85M B pairs) display t projection (78 fb 1 ~85M B pairs) Likelihood not parabolic -> statistical errors estimated numerically via MC ensemble S = 1.230.41 A = +0.770.270.08 (stat) (sys) (stat) (sys)+0.080.07 still outside physical region => investigate

Slide 16 + (3.4 ) }">

DPF, April 5, 2003 17 Feldman-Cousins frequentist approach. Acceptance regions from MC ensembles. Systematic errors included. Confidence Level (CL) calculated at each point. Confidence regions (2.2 ) hint of direct CP non-conservation } interpret as evidence for CP non-conservation in B 0 -> + (3.4 ) }

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DPF, April 5, 2003 18 Constraints on the CKM angle 2 S , A depend on 4 parameters: S , A depend on 4 parameters: 2, 1 [21.3-25.9], |P/T| [0.15-0.45], -> plot confidence contours in ( 2, )for various |P/T| -> plot confidence contours in ( 2, )for various |P/T| e.g. e.g. |P/T|=0.3 1 =23.5 2222 From other CKM (CKM fitter group, 2002) : 78.3 2 121.6 78.3 2 121.6 (95% C.L.) => consistent Find: 78 2 152 (95% C.L.) insensitive to

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DPF, April 5, 2003 19 Summary Belle, 2000-2: peak L= 9.5x10 33 cm 2 s 1 - nearly at design (1x10 34 cm 2 s 1 ) peak L= 9.5x10 33 cm 2 s 1 - nearly at design (1x10 34 cm 2 s 1 ) passed 100 fb -1 in Oct. 2002 passed 100 fb -1 in Oct. 2002 with 78 fb 1 on (4S), sensitive to large values of sin2 2 with 78 fb 1 on (4S), sensitive to large values of sin2 2 measure CP asym in B 0 -> + measure CP asym in B 0 -> + constraints on 2, consistent with other CKM constraints. hint of direct CP non-conservation result submitted to PRD. Next ->150 fb 1 by summer, 500 fb 1 by 2005 ->150 fb 1 by summer, 500 fb 1 by 2005 Luminosity >@ design Luminosity >@ design the CP challenge: stay tuned on 2 the CP challenge: stay tuned on 2

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DPF, April 5, 2003 20 additional slides

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DPF, April 5, 2003 21 Systematic uncertainties* source A S +error error+error error Background fractions+0.058 0.048+0.044 0.055 Vertexing+0.044 0.054+0.038 0.012 Fit bias+0.016 0.021+0.052 0.020 Wrong tag fraction+0.026 0.021+0.015 0.016 B, m d, A K +0.021 0.014+0.022 0.022 Resolution function+0.019 0.020+0.010 0.013 Background shape+0.003 0.015+0.007 0.002 Total+0.08 0.08+0.08 0.07 * blind analysis: actual estimations done before seeing fit result.

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DPF, April 5, 2003 22 convention taken from M.Gronau & J.L.Rosner Phys Rev D65, 093012 (2002) Constraints on the CKM angle 2 4 parameters |P/T| 0.15-0.45 (representative) Theory ~0.3 1 21.3 - 25.9deg (Belle & BaBar combined)