Conference Summary. K.K. Gan The Ohio State University. K.K. Gan Tau2000 1

Transcription

1 Conference Summary K.K. Gan The Ohio State University K.K. Gan Tau2000 1

2 many interesting results can only summarize some highlights include a few interesting results not presented here apologize to those whose results are not mentioned congratulation to organizers for a successful conference! K.K. Gan Tau2000 2

3 Outline test of lepton universality measurement of Michel parameters measurement of hadronic decays direct evidence of tau neutrino status of neutrino oscillations search of neutrinoless decays conclusion Tau2002 K.K. Gan Tau2000 3

4 Lepton Universality of Charge Current Couplings measurements of τ lifetime and leptonic branching ratios: g τ / g e = ± g τ / g µ = ± measurements of W leptonic branching ratios: g τ / g e = 1.021± g τ / g µ = ± lepton universality is respected from Q of 4 to 6500 GeV 2 K.K. Gan Tau2000 4

5 Lepton Universality of Charge Current Couplings τ lifetime (fs g τ / e,µ g = ± m τ =± 0.26 MeV VEPP to rescue? B(τ lνν ) (%) universality is tested to 0.2% precision K.K. Gan Tau2000 5

6 0 Z couplings: Asymmetry Parameters A e (LEP) ± Prob(χ 2 )= 0.38 ALEPH(prelim) ± e Z 0 τ DELPHI L3 OPAL(prelim) ± ± ± A e + τ + e A τ A τ (LEP) ± Prob(χ 2 )= 0.83 ALEPH(prelim) DELPHI L3 OPAL(prelim) ± ± ± ± universality of Z couplings K.K. Gan Tau2000 6

7 Michel Parameters ρ Electrons Muons ξ ξδ η χ 2 /ndf = 3.6 / 7 results are consistent with lepton universality K.K. Gan Tau2000 7

8 Michel Parameters (e/µ combined) ρ ALEPH DELPHI L3 OPAL SLD CLEO ARGUS 0.752± ± ± ± ± ± ±0.031 η ALEPH DELPHI L3 OPAL SLD CLEO ARGUS 0.086± ± ± ± ± ± ±0.22 World average 0.752± χ 2 /ndf = 2.2 / 6 World average 0.031±0.031 χ 2 /ndf = 3.3 / ξ ALEPH DELPHI L3 OPAL SLD CLEO ARGUS 1.002± ± ± ± ± ± ±0.11 ξδ ALEPH DELPHI L3 OPAL SLD CLEO ARGUS 0.782± ± ± ± ± ± ±0.09 World average 0.984±0.031 χ 2 /ndf = 4.2 / World average 0.745±0.022 χ 2 /ndf = 3.1 / all parameters are consistent with SM expectations looking forward to results from b factories K.K. Gan Tau2000 8

9 Limits on Coupling Constants Scalar Vector Tensor S V τ R l R RR S 0.35 RR V 0.17 T τ R l L LR S 0.37 LR V 0.18 LR T 0.11 τ L l R RL 2 limits on tau are still less stringent than limits on muon no measurement of σ(v τ e τ v e ) no limit on scalar and vector LL couplings RL 0.51 K.K. Gan Tau RL % CL

10 Test of CVC: B(τ π π 0 ν ) τ PDG(2000): B = (25.32 ± 0.15)% CVC(Tau98): B = (24.52 ± 0.33)% = (3.2 ± 1.5)% CVC(Tau2000): B = (24.94 ± 0.23)% = (1.5 ± 1.1)% L3(Tau2000): B = (25.38 ± 0.18 ± 0.12)% (not included) K.K. Gan Tau

11 Test of CVC:B(τ 2π π + π 0 ν τ ) E (GeV) CVC(Tau2000): B = (3.55 ± 0.20)% CLEO(Tau2000): B = (4.19 ± 0.10 ± 0.21)% CVC prediction is somewhat low K.K. Gan Tau

12 Test of CVC:τ π ων τ σ (nb) E (GeV) CVC(Tau2000): B = (1.73 ± 0.06)% PDG: B = (1.92 ± 0. 07)% CVC prediction is somewhat low K.K. Gan Tau

13 CLEO: τ π ων τ ρ and ρ' required for good fit: M ρ' =1523 ±10 MeV Γ ρ' = 400 ± 35 MeV fit from τ π π 0 ν τ : M ρ' =1406 ±15 MeV Γ ρ' = 455 ± 41 MeV PDG: M ρ' =1465 ± 25 MeV Γ ρ' = 310 ± 60 MeV origin of difference is unresolved K.K. Gan Tau

14 CLEO: τ 2π π + 3π 0 ν τ and τ 3π 2π + π 0 ν τ decays are saturated by η and ω intermediate states B(τ π 2π 0 ων τ ) = (1.5 ± 0.4 ± 0.3) 10 4 B(τ 2π π + ων τ ) = (1.2 ± 0.2 ± 0.1) 10 4 somewhat lower than B.A. Li predictions: B(τ π 2π 0 ων τ ) = B(τ 2π π + ων τ ) = (1st observation) K.K. Gan Tau

15 Test of Isospin Symmetry B( ) /B(5( ) 0 ) I I (3) CLEO result isospin allowed 321 ( ) 510 (4 ) 411 (3 ) B( )/B(5() 0 ) result consistent with isospin symmetry I I looking forward to similar analysis on five-pion decays K.K. Gan Tau

16 Anomalous Magnetic Moment a µ ππ (10 10 ) e + e π + π 498.8± 5.0 τ π π 0 ν τ (ALEPH) ± 6.9 τ π π 0 ν τ (CLEO) 513.1± 5.8 combined ± 3.3 τ decays provide measurement of different systematic error ALEPH and CLEO are not inconsistent given the errors but the difference is three times the expected precision of the new g-2 experiment at BNL need measurements from other LEP and b-factory experiments K.K. Gan Tau

17 Strange Quark Mass measurements of strange quark mass (MeV) using ALEPH data: Scale Davier Maltman Lattice2000 m τ 112 ± ± 16 2 GeV 107 ± ± 13.6 ± 11.8 ± ± 15 Lattice 2000 result is quenched, i.e. neglects virtual quark loops: expect 10-15% reduction for unquenched mass good consistency in estimate of strange quark mass need more precise measurement of spectral function to eliminate theoretical uncertainty in de-weighting of high mass region K.K. Gan Tau

18 Direct Measurement of Electric Dipole Moment No CP violation in Standard Model CP violation interactions contribute to EDM charge dependent momentum correlation Argus (00): Re(d τ ) < e 95%CL Im(d τ ) < e cm L3 (98): d τ < e 90%CL for zero anomalous magnetic dipole moment K.K. Gan Tau

19 Direct Evidence for ν τ DONUT find the decay ν τ N τx e τ ν τ 4.5 µm emulson K.K. Gan Tau

20 Direct Evidence for ν τ found 4 events with long decay expect: 4.1 ± 1.4 events background: 0.41 ± 0.15 events background probability: Events p (GeV) T c τ K.K. Gan Tau

21 Neutrino Oscillations Super-Kamiokande observed deficit of atomspheric νµ interpreted as ν µ ν τ MINO (2003): OPERA (2005): ν disappearance µ ν appearance using emulson τ K.K. Gan Tau

22 Neutrino Oscillations: implication on τ decay W τ µ ν τ ν µ γ B(τ µ γ )~10 54 CLEO(Tau2000): B(τ µ γ ) ~ K.K. Gan Tau

23 Forbidden Decays 90% C.L. limits on neutrinoless decays: ~10 6 new limits (ICHEP/DPF2000): Belle (00) Mark II (82) e K 0 < < µ K 0 < < K.K. Gan Tau

24 Forbidden Decays Ilakovac calculated rates for model with heavy neutral leptons: Expt. Theory e e + e < < y τe e µ + µ < < y τe e π 0 < < y τe e ρ < e φ < < y τe < y τe e K 0 K 0 < z τe µ K 0 K 0 < z τµ K.K. Gan Tau

25 Search for Forbidden Decays at Hadron Colliders LHCb expected sensitivity: ~10 need 10x improvement in sensitivity to be competitive with B factories at 2005 repeat my suggestion at Tau98: CDF and D0 should look for forbidden tau decays 7 K.K. Gan Tau

26 Conclusions tremendous progress in the last two years no hint of physics beyond the Standard Model other than ν µ ν τ oscillation challenge of Standard Model continue... K.K. Gan Tau

27 Tau2002! major advance on Cabibbo-suppressed decays from Babar/Bello/CLEO with kaon identification! observation of second class current τ π ην τ! sensitive to! surprise... m ντ ~ 10 MeV K.K. Gan Tau

28 τ workers busy analyzing data with papers and pens... This could be you! Anything new yet, Mr. Tau? K.K. Gan Tau