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f 1 measurements from b c decay at Belle

f 1 measurements from b c decay at Belle. K. Sumisawa (KEK) Belle collaboration PANIC05 Oct. 27, 2005. Introduction sin2 f 1 from B 0  J/ y K 0 f 1 from B 0  D[K S p + p - ] p 0 (w,h) Summary. _. f 1  b A  -C. _. _. _. _. c. _. J/ y. q p. -i2 f 1. _. ~ e. d.

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f 1 measurements from b c decay at Belle

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  1. f1 measurementsfrom bc decay at Belle K. Sumisawa (KEK) Belle collaboration PANIC05 Oct. 27, 2005 • Introduction • sin2f1 from B0 J/y K0 • f1 from B0  D[KSp+p-] p0(w,h) • Summary _ f1 b A  -C

  2. _ _ _ _ c _ J/y q p -i2f1 _ ~e d b b c t w B0 B0 _ B0 w w t s b d d K0 d if1 V*td =| Vtd|e = -xcpsin2f1 sin(DmDt) + A cos (DmDt) A CP Mixing induced CPV Direct CPV sin2f1 measurement B0 fCP B0 V*td Time dependent CP asymmetry ACP A~0 for J/yK0 xCP: CP eigenvalue, +1 (-1) for CP even (odd) We can measure CPV (asym.) as a function of proper time diff (Dt).

  3. Principle of TCPV measurement CP-side m+ J/y m- (4S) resonance B1 electron (8GeV) KS/L positron (3.5GeV) B2 bg = 0.425 (Belle) 0.56 (BaBar) • Fully reconstruct one B-meson which decays to CP eigenstate

  4. _ B0 -xcpsin2f1 = 0.65 A = 0.00 B0 tag _ B0 tag Principle of TCPV measurement CP-side m+ J/y m- (4S) resonance B1 electron (8GeV) KS/L B0 positron (3.5GeV) nm B2 p- bg = 0.425 (Belle) 0.56 (BaBar) K+ p- Flavor tag and vertex reconstruction Dz ~ 200mm (Belle) m+ • Fully reconstruct one B-meson which decays to CP eigenstate • Tag-side determines its flavor • Proper time (Dt) is measured from decay-vertex difference (Dz)

  5. 13 countries, 55 institutes, ~400 collaborators International Collaboration: Belle Seoul National U. Shinshu U. Sungkyunkwan U. U. of Sydney Tata Institute Toho U. Tohoku U. Tohuku Gakuin U. U. of Tokyo Tokyo Inst. of Tech. Tokyo Metropolitan U. Tokyo U. of Agri. and Tech. Toyama Nat’l College U. of Tsukuba VPI Yonsei U. 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 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 IHEP, 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

  6. Lpeak= (1.581034)/cm2/sec  > 1M BB pairs/day _ _ 386 M BB pairs analysis are shown, today KEKB B-Factory & Belle Detector

  7. _ B0 J/y K0 : 386 M BB pairs B0 J/y KS 0 B0 J/y KL 0 Nsig = 5264 Purity 98 % CP odd Nsig = 4792 Purity 60 % CP even Belle preliminary

  8. B0 tag _ _ B0 tag B0 tag -xCPsin2f1 B0 tag S = 0.65 A = 0.00 R : detector resolution w : wrong tag fraction (misidentification of flavor)  (1-2w) quality of flavor tagging They are well determined by using control sample D*ln, D(*)p etc…

  9. B0 J/y KS 0 B0 J/y KL 0 _ _ B0 tag B0 tag B0 tag B0 tag Belle preliminary CP odd : xCP=-1 CP even : xCP=+1 Asym. = -xCPsin2f1sinDmDt+AcosDmDt sin2f1= +0.668 ±0.047 A = - 0.021 ±0.034 sin2f1= +0.619 ±0.069 A = +0.049 ±0.039

  10. _ B0 tag B0 J/y K0 : combined result sin2f1= 0.652 ±0.039 (stat) ±0.020 (syst) A = 0.010 ±0.026 (stat) ±0.036 (syst) _ 386 M BB pairs B0 tag Belle preliminary BG subtracted distributions (good tag region) previous measurement sin2f1= 0.728  0.061 (152 M BB pairs) _ Asym=sin2f1sin{Dm(-xCPDt)}

  11. Constraint on the Unitarity Triangle ? ? f1~70o f1~20o Intrinsic ambiguity still remains … 2f1 p-2f1

  12. _ _ State of neutral B meson at time tsig which was tagged as B0 at time ttag (Dt = tsig–ttag) _ B0 D0 p0 B0  D0 p0 _ B0  D[KSp+p-]p0Direct measurement of f1 hh0 : CP eigenvalue, l : orbital angular momentum

  13. _ f-+ f+- m2(KSp-) m2(KSp-) m2(KSp+) m2(KSp+) B0  D[KSp+p-]p0Direct measurement of f1 We can measure f1 with Time-dependent Dalitz fitting hep-ph/0503174, A.Bondar, et al. |q/p|=1, arg(q/p)=2f1 D0KSp+p- solve the ambiguity sin2f1 , cos2f1 q, Dt m2(KSp+), m2(KSp-) +

  14. _ Reconstruction of B0  D[KSp+p-]p0 D0 p0 D0 w D0 h D*0 p0, h Nsig = 157 ±24 purity : 59% Nsig = 67 ±10 purity : 86% Nsig = 58 ±13 purity : 60% Nsig = 27 ±11 purity : 52% D*0 D0p0 D*  D0 pi0 D*pi0 : 22 +- 9 D*eta : 5+- 6 TOTAL Nsig = 309 ±31 purity : 63% Belle preliminary

  15. Dalitz plot for the signal candidates f-+ m2(KSp-) m2(KSp+) _ f+-/-+ are determined using D*+ D0(KSp+p-) p+slow sample. Charge of slow p± distinguish D0 or D0. (e+e-cc) _ _

  16. Time-Dependent Dalitz fit results Belle preliminary -30o < f1 < 62o(95% C.L.)

  17. Impact for f1 : T-Dep. Dalitz analysis Consistent with B0J/yK* results cos2f1 = 0.87 ±0.75, hep-ex/0504046 ? Disfavored >2s (^_^) ? f1~70o f1~20o Intrinsic ambiguity almost solved !! 2f1 p-2f1

  18. Summary _ hep-ex/0507037 • Belle results with 386 M BB pairs • B0 J/y K0 Time-dependent analysis sin2f1= 0.652±0.039(stat)±0.020(syst) • Ambiguity 2f1  p-2f1 is solved by B0  D[KSp+p-] p0 Time-dep. Dalitz analysis f1 =16 ±21(stat)±11(syst) (o) • The f1 value is the most precise UT parameter f1 = (20.3 ±1.8)o (Belle only) _ hep-ex/0507065 All new results are preliminary

  19. Consistency of TCPV results with indirect constraints f1 = (20.3 ±1.8)o (Belle only)

  20. M(p+p-) distributions MC(2f1=47) real data events with qDt<-tB/2 events with qDt>+tB/2

  21. _ • Checked with life-time measurement • B+  D[KSp+p-]p+ • tB+= 1.68 ±0.04 (ps)  W.A. 1.64 ±0.01 (ps) • B0  D[KSp+p-] p0 • tB0= 1.66 ±0.09 (ps)  W.A. 1.53 ±0.01 (ps) _ Belle preliminary _ Background of B0  D[KSp+p-]p0 _ _ Consistent with World Average

  22. f-+ Dalitz PDF is calibrated with real data _ D*+ D0(KSp+p-) p+slow in real data Charge of slow p± distinguish D0 or D0 _ Modeled with 18 resonances & one non-resonant amplitude Phys. Rev. D 70, 02003 (2004) f3 measurement with Dalitz

  23. Kobayashi-Maskawa Phase l ~ 0.22 CP violation is due to a complex phase in quark mixing matrix CP violation parameters (f1, f2, f3) = (b, a, g )

  24. Belle Detector K/pseparation • , p0 reconstruction e+-, KLidentification Aerogel Cherenkov Counter n = 1.015~1.030 Electromagnetic Calorimeter CsI(Tl) 16X0 3.5 GeV e+ TOF counter K/pseparation charged particle tracking 8.0 GeV e- Central Drift Chamber momentum, dE/dx 50-layers + He/C2H6 B vertex Muon / KLidentification Si Vertex Detector 4-layer DSSD KLm detector 14/15 layer RPC+Fe

  25. KEKB : the highest luminosity in the world Located in Tsukuba, Japan Belle detector 3.5 GeV e+8.0 GeV e- e+e-(4S) with bg = 0.425 22 mrad crossing angle Lpeak= (1.581034)/cm2/sec  > 1M BB pairs/day integrated L= 467 /fb _ _ 386 M BB pairs analysis are shown, today

  26. _ B0 Principle of TCPV measurement CP-side m+ J/y m- (4S) resonance B1 electron (8GeV) KS/L B0 positron (3.5GeV) nm B2 p- bg = 0.425 (Belle) 0.56 (BaBar) K+ p- Flavor tag and vertex reconstruction Dz ~ 200mm (Belle) m+ • Fully reconstruct one B-meson which decays to CP eigenstate • Tag-side determines its flavor • Proper time (Dt) is measured from decay-vertex difference (Dz)

  27. B0 fCP q p B0 2ImlCP 1+ |lCP|2 S = |lCP|2 -1 |lCP|2 +1 A = A(B0 fcp) A(B0 fcp) q p lCP = Observables for TCPV CP Violation manifests itself in proper-time difference (Dt)distributions of two B meson decays. ACP = S sin(DmDt) + A cos (DmDt) Direct CPV Mixing induced CPV (BaBar: A = -C)

  28. Event DisplayB0 J/Y KS J/Ym+m-KSp+p- 3.5 GeV e+ 8.0 GeV e-

  29. Systematic Errors for J/PsiK0 Belle preliminary

  30. History of sin2f1 fromB0  J/PsiK0 • 152 M B meson pairs sin2f1= 0.693 ±0.065 (stat) • 386 M B meson pairs sin2f1= 0.652 ±0.039 (stat) ±0.020 (syst)

  31. History of sin2f1 fromB0  J/PsiKs • 152 M B meson pairs sin2f1= 0.67 ±0.08 (stat) • 386 M B meson pairs sin2f1= 0.67 ±0.05 (stat)

  32. History of sin2f1 fromB0  J/PsiKL • 152 M B meson pairs sin2f1= 0.77 ±0.13 (stat) • 386 M B meson pairs sin2f1= 0.62 ±0.07 (stat)

  33. D0KS r(p+p-) Time-Dependent Dalitz fit results Belle preliminary Asym.(Dt) = -sin2f1sinDmDt In case of D0KS r(p+p-) 0.62 < Mpp < 0.92 GeV/c2 -30o < f1 < 62o (95% C.L.)

  34. _ Systematic Errors for B0  D[KSp+p-]p0 Belle preliminary  Mainly Dalitz f1 =16 ±21(stat)±11(syst) (o)

  35. Stat. Error of Time-Dep Dalitz Fit fitting result fitting error

  36. PDF of Time-Dependent Dalitz

  37. Flavor Tag NIM A 533, 516 (2004)

  38. r = 1-2w NIM A 533, 370 (2004) for resolution Wrong tag probability Estimate w from time-dependent B0-B0 mixing

  39. Wrong tag probability cont. Total eeff = 0.296 ±0.010

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