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Belle の最近の物理結果

Belle の最近の物理結果. 堀井泰之　名大 KMI 日本物理学会　第 67 回年次大会 2012 年 3 月 24 日. KEKB Collider. Loca ted at KEK in Tsukuba. 8.0 GeV e −. 3 .5 GeV e +. _. ϒ (4S)→BB. Designed for ϒ (4S). Data also taken for ϒ (1S), ϒ (2S), ϒ (3S), and ϒ (5S). Peak luminosity = 2.1 x 10 34 cm −2 sec −1 .

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Belle の最近の物理結果

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  1. Belleの最近の物理結果 堀井泰之　名大KMI 日本物理学会　第67回年次大会 2012年3月24日

  2. KEKB Collider Located at KEK in Tsukuba. 8.0 GeVe− 3.5 GeVe+ _ ϒ(4S)→BB Designed for ϒ(4S).Data also taken forϒ(1S), ϒ(2S), ϒ(3S), and ϒ(5S). Peak luminosity = 2.1 x 1034 cm−2sec−1. world record for e+e− collider

  3. Integrated Luminosity Integrated luminosity [fb-1] Data taking ended in 2010, and was reprocessed with better tracking by 2011.

  4. Belle Detector Resistive plate chamber + Fe(detection of μ and KL) CsI(Tl) calorimeter(detection of e± and γ) e+ e- Four layers of double-sided-silicon-strip (vertexing) Time-of-flight counter (K/π separation) Aerogel Cherenkov counter (K/π separation) Drift chamber(tracking and dE/dx)

  5. Belle Collaboration ~400 members, 67 institutes, 16 countries

  6. Recent Results at Belle • sin2ϕ1from B→(cc)K, B→D(*)±D • ϕ3 from B±→D(*)K± • |Vub| from B→πlν • Bs→J/ψ(ss) branching ratios • Charm physics (example: ACP for D±→KSπ±) • Tau physics (example: LFV decays τ→lhh’) • Charmonium-like states • Bottomonium-like states • … _ ± _ 27aFA-1, B. Vishal

  7. CKM Matrix and Unitary Triangle • Charged-current interaction Lagrangian: • CKM matrix and unitary triangle: orthogonal

  8. Global Fit to CKM Elements • Agreements between various measurements (~5% precision). • ~2.5σ of tension for related to BR(B→τν) and sin2ϕ1. • Related recent results by Belle • sin2ϕ1from B→(cc)K, etc. • ϕ3from B±→D(*)K± • |Vub| from B→πlν, etc. _ direct (±1σ) BR(B→τν) CKM fit sin2ϕ1

  9. Method of Measuring ϕ1 Neither Vub nor Vtd. Interference betweenB0→X and B0→B0→X depending on Δt = t1 − t2. Relative weak phase = 2ϕ1. _ X _ _ b d W t t W d b B2 tagged by charges ofK, μ, etc. (exploit bcW−). Method Extract signal of B1→X from B2-tagged events. Fit signal yields depending on Δz (∝Δt) with sin2ϕ1 as one of parameters.

  10. Two Types of Modes Analyzed _ CPV to be compared with B→(cc)K. b→d penguin diagrams carryingdifferentweak phases could contribute. “Golden” mode. First observation of CPVin B system obtained by this mode.Relatedto “tension” of CKM fit.

  11. ϕ1 from B→(cc)K _ Accepted by PRL,full data sample Signal extraction. Fit on Δt. Asymmetry(Δt) = [N(Δt) − N(Δt)] / [N(Δt) + N(Δt)] = S sin (ΔmdΔt) + A cos (ΔmdΔt)where S = sin2ϕ1. _ _ _ Combining (cc)KL, we obtain sin2ϕ1 = +0.667 ± 0.023 ± 0.012 Most precise measurement of sin2ϕ1. No significant difference btw modes. Still tension with B→τν by ~2.5σ. all (cc)KS modes B mass calculated with beam energy

  12. ϕ1 from B→D(*)±D ± Combined paper to be submitted to PRD(RC) Signal extraction Fit on Δt Result 2011 preliminary B→DD A sin2ϕ1 = +1.06 ± 0.21 ± 0.07 Direct CPV parameter A = +0.43 ± 0.17 ± 0.04(previous value = +0.91 ± 0.23 ± 0.06.) 2012 preliminary B→D*D sin2ϕ1 = +0.78 ± 0.15 ± 0.05 _ Both are consistent with B→(cc)K: sin2ϕ1 = +0.667 ± 0.023 ± 0.012

  13. Methods for Measuring ϕ3 • Golden mode: B±DK± • Exploit interference of the two processes. • DKK, ππ, KSπ0, KSφ, KSω, … (GLW) • DKπ, Kππ0, … (ADS) • DKSππ, KSKK, … (GGSZ) ϕ3 ~ −arg(Vub) • Color allowed. • Final state contains D. _ D and D decay to common final state. Tree processes • Color suppressed. • Final state contains D. _ Not likely to be affected by NP(Good “reference point”)

  14. GLW and ADS Modes for ϕ3 2011 preliminary,full data sample B−DCP+K− B+DCP+K+ B−D*Dπ, ADSK− B+D*Dγ, ADSK+ Signal B→Dπ Signal B→Dπ CP asymmetry for CP+ mode Decay rate relative to the favored D→Kπ Significant CP asymmetry for GLW mode. First evidence of B→D*K ADS signal. Both would be due to interference terms including ϕ3.

  15. ϕ3 from Model-Independent GGSZ • Most stringent constraint on ϕ3 is provided by B→DK, D→KSπ+π−. • Uncertainty due to D decay modeling in the previous method. • New method: divide Dalitz plot of D→KSπ+π− into several regions. • Optimal binning: uniform division ofthe strong-interaction phases (Fig.). • For each bin, • Strong-interaction phase is obtainedby using ψ(3770)→D0D0 at CLEO. • B− and B+ yields are obtained at Belle. • ϕ3 is extracted from above information. PRD81, 112002 (2010) _

  16. ϕ3 from Model-Independent GGSZ 2011 preliminaryto be submitted to PRD • Signal yields and asymmetry in each bin: • Result: Black: flavor sample Third error due to uncertainty on strong-interaction phases for D decaysmeasured by CLEO.Will decrease to 1° or less by BES-III. Method useful for super B factories established. Using full data sample.

  17. Global Fit for ϕ3 Including Belle, BaBar, CDF, and LHCb. Summer 2010 Summer 2011 (Statistical treatmentslightly changed.) Belle DK ADS Belle D*K ADS Belle DK GLW LHCb DK ADS … ϕ3 = (71 +21−25)° ϕ3 = (68 +10−11)° Significant improvement. Consistent with other CKM measurements.

  18. |Vub| from B→πlν • Motivation • Improved tagging of the other B by hadronic decays: B→D(*)nπ, etc. q2 = (pB − pπ)2 l = e, μ ν B |Vub| is extracted using theoretical calculation for f+(q2). π ~2 times larger tagging efficiencyfor the same purity. Achieved by NeuroBayes package(neural network based on Bayesian statistics).

  19. |Vub| from B→πlν 2012 preliminary Signal extraction Signal yield depending on q2 and |Vub| signal,B→ρlν, other b→ulν, b→clν This: 710 fb−1 (full ϒ(4S)), new hadronic tag Previous: 605 fb−1, old hadronic tag Global fit before this analysis: (3.5 +0.2 −0.1) x 10−3 Expect a big improvement for upcoming B→τν measurement.

  20. Bs→J/ψϕ LHCb measures CPV parameter ϕs = −0.001±0.101±0.027. (−0.036 in SM.) Belle has smaller uncertainty of ratio of J/ψKK over J/ψϕ in J/ψϕ phase space. J/ψϕ J/ψKK Comb. BG 2012 preliminary ϕ N of Events e+e− J/ψϕ J/ψKK Comb. BG S+P-wave fit using wide M(KK) region. μ+μ− N of Events M(KK) around ϕ region M(KK) for higher region ΔE = Esignal − Ebeam (GeV) (J/ψKK)/(J/ψϕ) = (0.61±0.07±0.06)%,LHCb: (2.2±1.2±0.7)%

  21. Bs→J/ψη(’) Branching ratios are measured to be Difficult for LHCbdue to γ’s in final states. Signal seen at Belle using full ϒ(5S) data: η(’) BR(J/ψη) = (5.10±0.50±0.25+1.14−0.79) x 10−4 BR(J/ψη’) = (3.71±0.61±0.18+0.83−0.57) x 10−4 Third error due to NBs(*)Bs(*). (Inclusive production of Ds.) First observation. (low background) Submitted to PRL

  22. CP Asymmetry (ACP) for D±→KSπ± _ • SM prediction, due to K0 – K0 mixing: ACP = (−0.332 ± 0.006)%. • NP could generate ACP = O(1)%. • Result of Belle using 977 fb−1:ACP = (−0.363 ± 0.094 ± 0.067)%. • First evidence for CPV of charmed meson decaysfrom a single experiment and a single decay. • Consistent with SM. • Systematic uncertainty dominated bydetection asymmetry of π±.(Estimated by D+→K−π+π+ and D0→K−π+π0.) I. I. Bigi and H. Yamamoto, PLB 349, 363 (1995). 2012 preliminary

  23. Published Results on ACP for Charmed Meson Decays • D0 tagged by D*+→D0π+. Momentum-dependent correction for π± asymmetry. _ All results consistent with SM: |ACP| < O(0.1)%. (−0.3% for K0 – K0 mixing.) Detection asymmetries for K± and π±well understood. (Results statistically limited.)

  24. τ → lhh’ (l = μ, e) (h, h’ = K±, π±) 2011 preliminary to be submitted to PLB FCNC suppressed by SM. • No significant signal. Upper limits of O(10−8). • Upper limits improved by a factor of 1.8compared to the previous analysis. • Increased luminosity: 671 fb−1 → 854 fb−1. • Improved analysis: veto of τ→πππν, etc. Dots: data Boxes: Sig. MC Use ΔE = Esignal − Ebeamand Msignal. Veto τ→Xν by usingmissing momentum. Dots: data Boxes: Sig. MC

  25. Lepton-Flavor-Violating τ Decays Summer 2011 Reach upper limits around 10−8. 2011 preliminary

  26. Summary • Most precise measurement of sin2ϕ1 from B→(cc)K. • Precision of ϕ3improved by various approaches on B→D(*)K. • |Vub| from B→πlνagrees with other exclusive measurements. • First observation of Bs→J/ψη. • First evidence for CPV in D±→KSπ±from single experiment. • Completing updates for LFV τ decays. • New resonances and exotic hadrons: 27aFA-1, B. Vishal. • Many ongoing analyses: other presentations. Final analyses using full data and improved method are ongoing at Belle.

  27. Backup Slides

  28. K±/p±識別 飛行時間 ドリフトチェンバー (dE/dx) エアロジェルチェレンコフ 屈折率1.01-1.03 質量分布 p p p K K (< 1.2 GeV/c) p Histo: MC K p e 質量 [GeV] 光電子数 飛行距離と運動量を用い 質量を計算できる（上図）。 （D*D0サンプル） Likelihoodは、eまたは1-e （eは、しきい値基準の効率）。 光電子数しきい値で分離。 Landau tailを除く20%カットを行い Likelihoodはガウス関数とする。 Likelihoodはガウス関数。 > < Likelihood比LK / ( LK + Lp )を用い、効率~90%、誤識別確率~15%で分離できる。 3つの検出器の情報を、Likelihood法で結合する。

  29. CKM fit, 2010 summer and 2011 summer

  30. ϕ1 from B→(cc)K _ Accepted by PRL,full data sample Clear signal peaks. Fit on Δt. (cc)KS (cc)KL Asymmetry shown for good-tag sample.

  31. ϕ1 from B→(cc)K, systematic uncertainties Uncertainties due to vertexingreduced by a factor of twoby introducing three-dimensionalgoodness-of-fit indicator ratherthan χ2 in beam axis using IP tube. Tag-side interference: interferencebtw b→u and b→c transitions in B→D. Estimated by fitting nominal PDF totoy MC generated by using D*lν signaldata (no interference in signal side).

  32. ϕ1 from B→D±D ± S measures mixing-induced CPV, and C measures direct CPV.

  33. ϕ1 from B→D*±D ± A, C, ΔS, and ΔC consistent with 0. If A = C = ΔS = ΔC = 0, S = −sin2ϕ1.

  34. ϕ1 from B-π tag Accepted by PRL,full ϒ(5S) data • Initial flavor of neutral B tagged by pion charge: • Result: Comparison with ϒ(4S)→BB: Corresponds to (b). Corresponds to (a). Assuming no direct CPV, sin2ϕ1 = 0.57 ± 0.58 ± 0.06. Good program at super B factories.

  35. Method of ϕ3 Measurement _ ① B-D0K- D0f B- f K- φ3 _ _ B-D0K- D0f If no interference, angle disappears. ② Decay rate ∝ |A(①) + A(②)|2 • Exploit the interference betweenthe decay chains through D and D. • Angle ϕ3 (as well as strong phases)appears in the decay rates. • Several choices of the D decays: • DKK, ππ, KSπ0, KSφ, KSω, … (Gronau, London, and Wyler: GLW) • DKπ, Kππ0, … (Atwood, Dunietz, and Soni: ADS) • DKSππ, KSKK, … (Giri, Grossman, Soffer, and Zupan: GGSZ)

  36. GLW: Amplitude Triangles and Observables • Amplitude triangles: • Usually-measured observables: Magnitude of one sideis ~0.1 of the otherswhile relative magnitude ofthe others help ϕ3 constraint.

  37. ϕ3 from GLW LP 2011 preliminary,772 x 106 BB pairs CP+ (K+K−, π+π−): 582 ± 40 events CP− (KSπ0, KSη): 476 ± 37 events B-DCP+K- B+DCP+K+ B-DCP-K- B+DCP-K+ Red: signal Magenta: BDπ Green: BB BG Blue: qq BG (q=u, d, s, c) Light blue: peaking BG Significant CP asymmetry for CP+ mode. Opposite asymmetry btw CP+ and CP−. Systematics dominated by peaking BG.

  38. ADS: Amplitude Triangles and Observables • Amplitude triangles: • Usually-measured observables: Magnitudes of the sides are small relatively to the GLW ones (small signal)while three sides of the triangleshave similar magnitudes (large CPV). Larger contribution from continuum BG. Additional parameters: Inputs from charm factories.

  39. ϕ3 from BDK, Dsuppressed states (ADS) Y. Horii et al. (Belle),published in PRL 106, 231803 in June 2011 First evidence (4.1σ) obtained.Indication of negative asymmetry. LHCb also reported the evidence. Promising method for ϕ3 determination.

  40. ϕ3 from ADS LP 2011 preliminary,772 x 106 BB pairs • Continuum suppression with: • Signal seen with 3.5σsignificance for D*Dγ mode. • Ratio to favored mode: • Difference between RDπ0 and RDγ: indication of the effect of the interference term 2rB*rDcos(δB*+δD)cosϕ3 (opposite sign for RDπ0 and RDγ). continuum continuum Signal Signal D*π D*π DK/Dπ DK/Dπ BB BB

  41. ϕ3 from ADS RADSfor DK AADSfor DK Signal established. Negative asymmetry. Promising for ϕ3 determination. RADSfor D*K AADSfor D*K Signal seen also for BD*K ADS. Encouraging for improving ϕ3 measurement.

  42. B0DK*0 ADS by Belle To be submitted to PRD(RC) • ADS method can be extended toB0DK*0 by tagging B0 from K*0. • K*0 cannot be separated by K+π−and effective parameters rS andδS are included in ‘ADS fit’. • Result: DK*0 qq Dρ BB No significant signal for main mode: 7.7+10.6-9.5. Both color suppressed. DK*0 Dρ qq BB Dh… Signal seen for calibration mode: 190+22-21. (NB’: variable for continuum suppression.)

  43. GGSZ, Model-Dependent Approach • Amplitude of B±DK± process can be expressed by • Procedure of analysis: • Fit tom± by M± to obtainx± = rBcos(±ϕ3+δB) and y± = rBsin(±ϕ3+δB). • Extract ϕ3 (as well as rB and δB) from x± and y±. DKSπ+π− Amplitude of DKSh+h- decaydetermined from Dalitz plot of large continuum data(Flavor is tagged by soft-pion charge in D*±Dp±soft). Isobar-model assumption with BW for resonances.

  44. GGSZ by Belle PRD81, 112002 (2010),657M BB • Examples of Dalitz plots and confidence contours onxandy: • Result on ϕ3 obtained by combiningDK and D*K: B− B+ Dalitz plots for BDK. D decay modeling (isobar model)

  45. ϕ3 from Model-Independent GGSZ • Divide the Dalitz plot of D→KSππ into several regions(averaged strong phase of DKShh obtained without assuming model). Number of events in ith bin is a function of x±/y± where ψ(3770) by CLEO DKSπ+π− Optimal binning: uniform divisionof the strong phase difference.(Binning is model-dependent while result model-independent.) Values of ϕ3, rB, and δB are extracted from Ni±’s(simultaneous equations for ϕ3, rB, and δB).

  46. ϕ3 fit from 2010 to 2011 BD*K, D*Dπ0/γ, DKπ from Belle (Prelim.) BDK, DCP eigenstates from Belle (Prelim.) BDK, DKπ from Belle (PRL) BDK, DKπ from LHCb (Prelim.) Not full fits, Gaussian assumption for observables. (Recently more Gaussian-like.)

  47. B→τν at Belle II • In Two-Higgs Doublet Model (THDM) Type II,the branching ratio of Btn can be modified. H- Figures: constrains onmH± and tanb at Belle II. 5 ab-1 assuming 5% errors for |Vub| and fB. 50 ab-1 assuming 2.5% errors for |Vub| and fB. Bmn is helicity-suppressed, and we need 1.6 ab-1 (4.3 ab-1) for 3s evidence (5s discovery).

  48. _ Bs→J/ψ(ss) J/ψϕ J/ψKK Comb. BG ϕ, η(’) Events/0.006 J/ψϕ J/ψKK Comb. BG Events/0.006 BR(J/ψη) = (5.10±0.50±0.25+1.14−0.79) x 10−4 BR(J/ψη’) = (3.71±0.61±0.18+0.83−0.57) x 10−4 Syst. due to NBs(*)Bs(*). BR(J/ψϕ) = (1.25±0.07±0.20) x 10−3 ΔE (GeV) First observation! (low-background environment) Both on full ϒ(5S) data. 2012 preliminary Submitted to PRL

  49. CP Asymmetry (ACP) for D0→KSπ0 _ • SM prediction, due to K0 – K0 mixing: ACP = (−0.332 ± 0.006)%. • NP could generate ACP = O(1)%. • Direct CPV: I. I. Bigi and H. Yamamoto, PLB 349, 363 (1995). • Indirect CPV: Y. Grossman, A. L. Kagan, and Y. Nir, PRD 75, 036008 (2007). • Analysis of Belle using 791 fb−1 • D0 tagged by soft pion charge in D*+→D0π+.(Detection asymmetry of pion corrected depending on momentum.) • Result is ACP = (−0.28 ± 0.19 ± 0.10)%. • Consistent with SM. • Systematic uncertainties from asymmetries of slow pion in D*+→D0π+and K0/K0 material effects. Former estimated by D*+→D0π+, D0→K−π+ and untagged D0→K−π+. Latter same as D+→KSπ+. PRL 106, 211801 (2011) _

  50. LFV at Super B Factories g ○tmg □tmh △tmmm t m 10−9 level at 50 ab−1. 積分ルミノシティ（ab-1） http://agenda.hepl.phys.nagoya-u.ac.jp/conferenceDisplay.py?confId=289

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