t Physics Experimental Review Michael Roney University of

t Physics: Experimental Review Michael Roney University of Victoria

Thanks to LOC for a fantastic conference and an off-the-scale banquet… Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria

Progress on various fronts… • Precision measurements of tau properties • Lepton universality: where are we now • Measurements of hadronic currents • Searches for rare/SM-forbidden decays involving the tau lepton Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria

Goals of this presentation… • Place in a broader context the work presented over the last couple of days • Summarize those results • Stimulate a discussion on where we (the tau community) should be focusing resources over the next two-four years Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria

Precision measurements of tau properties • Tau lifetime • Tau mass • Dipole moments Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria

DELPHI tau lifetime (final) (Attilio Andreazza) nt t Tau Physics: Experimental Summary, TAU 04 Nara Three methods: MD (w=0. 34), IPD(w=0. 22), Decay length(w=0. 45) ττ = 290. 9 ± 1. 4 ± 1. 0 fs J. M. Roney, Victoria

BABAR tau lifetime (preliminary) (Alberto Lusiani) Single method: 2 D Decay length ττ = 289. 4 ± 0. 91 ± 0. 90 fs Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria

BABAR tau lifetime (Alberto Lusiani) With 80/fb, statistics traded for lower systematic errors e. g. Weight to equalize f acceptance in 60 Bins, take error as Variance on 100 subsamples BLINDED ττ = 289. 4 ± 0. 91 ± 0. 90 fs Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria

Systematic errors from modelling tau decay DELPHI: MD (BR, polarisation) 0. 30% Decay length (bias, MC stat) 0. 27% IPD (method bias[colinearity, . . ]) 0. 07% BABAR: decay kinematics bias (MC stat) 0. 2% [effect ~1. 3%] negligible non-MC stat. Estimate correlations between LEP measurements of <0. 2% Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria

New World Average t lifetime CLEO, LEP, BABAR: Ignoring ~0. 1% level correlations: ττ = (290. 15 ± 0. 77) fs χ2/ dof = 2. 3/5 (prob=82%) (assuming 0. 2% correlations between LEP Lifetimes, tt 290. 11± 0. 79 fs) Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria

Future prospects: • BELLE should be able to make measurement with comparable precision as shown by BABAR • BABAR statistical error can go down ~x 2 with data in can now. • BABAR systematic errors dominated by statistics of control samples, MC statistics, alignment errors, koralb description of ISR. Can expect improvements of x 2 overall. • Overall, expect B-factories to bring error down another factor of 2 compared to BABAR results shown here: • At TAU 06 [or TAU 08] could see WA with errors of 0. 4 fs (0. 14%) or less! Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria

CPT • Lifetime: 1 st CPT on lifetime from BABAR (Lusiani) • Mass: OPAL only experiment to publish CPT on mass (mt- - mt+)/mt = (0. 0± 1. 8)x 10 -3 New mass measurement (~10 -4) at threshold is expected at VEPP-4 (Shamov) but CPT test is not a threshold measurement B-factories should publish these asymmetries in the future! Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria

moments of the tau (Lohmann) QED e = F 1(q 2 = 0) at= F 2(q 2 = 0) in QED : at = (g-2)/2 a/2 p + …. = 0. 0012 dt= e. F 3(q 2 = 0) in QED : dt = 0 Tau Physics: Experimental Summary, TAU 04 Nara. P and T violating J. M. Roney, Victoria

(Lohmann) Measurements: DELPHI -0. 018± 0. 017 L 3 0. 004± 0. 035 av. -0. 013± 0. 015 Other determinations: Gtt : -0. 004 < at < 0. 006 (R. Escribano & E. Masso) e+e. Tau Physics: Experimental Summary, TAU 04 Nara t+t-: at ≤ 0. 02 J. M. Roney, Victoria (J. Silverman & G. Shaw)

(Lohmann) -. 22<Re(dt)<. 45 -. 25<Im(dt)<0. 008 BELLE Other determinations: Gtt Measurements: DELPHI L 3 (0 ± 2 ) (0 ± 2) av. (0. 0 ± 1. 4) × 10 -16 e cm Tau Physics: Experimental Summary, TAU 04 Nara : dt < 1. 1 × 10 -17 e cm (R. Escribano & E. Masso) BELLE: (near (4 s), q ≈ 10) Re(dt )= (1. 15 ± 1. 70)× 10 -17 e cm Im(dt )= (-. 83 ±J. M. Roney, 0. 86)× 10 Victoria

(Lohmann) Weak Moments a t W , dt W (q 2 = m. Z 2) dt. W: CP dt W Several measurements in the past by LEP experiments at. W First measurement by L 3 (transverse spin components) New results from : Re ( dt. W ) < 5. 01 × 10 -18 e cm W Im ( dt ) < 11. 15× 10 -18 e cm complete data (19901995) near the Z Re ( a W ) < 1. 14 × 10 -3 t resonance (155 pb-1), -3 Im ( ) < 2. 65 × 10 at. W exclusive final states Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria

(Lohmann) New 2003 results from complete data (19901995) near the Z resonance (155 pb-1), exclusive final states Re ( Im ( Weak Moments : Re ( dt. W ) < 5. 01 × 10 -18 e cm W Im ( dt ) < 11. 15× 10 -18 e cm Re ( a t Im ( a at. W) W ) < 1. 14 × 10 -3 W ) < 2. 65 × 10 -3 t = (-0. 33 ± 0. 49) × 10 -3 = (-0. 99 ± 1. 01) × 10 -3 Re ( dt. W) = (-0. 59 ± 2. 49) × 10 -18 e cm Im ( dt. W) = (-0. 45 ± 5. 57) × 10 -18 e cm Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria

Lepton universality: where are we now • Neutral current universality: a reminder • Charged current universality: q q Direct W decay Leptonic BF, lifetime, mass Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria

• Neutral current universality: a reminder ge. A/ gm. A=0. 9981± 0. 0013 ge. A/ gt. A=0. 9981± 0. 0015 gm. A/ gt. A=0. 9983± 0. 0016 ge. V/ gm. V=1. 040± 0. 065 ge. V/ gt. V=1. 043± 0. 030 gm. V/ gt. V=1. 003± 0. 068 Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria

Lepton universality: where are we now • Charged current universality: direct W decays ge/ gm=1. 001± 0. 011 ge/ gt=0. 972± 0. 013 gm/ gt=0. 971± 0. 013 Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria

Lepton universality: • Charged current universality: tau decays q q q BR(t eνν)= (17. 824± 0. 052)% BR(t mνν)= (17. 331± 0. 048)% F e-m univ: BR(t eνν)= [0. 29%] [0. 28%] (17. 821± 0. 036)% tt= 290. 15 ± 0. 77 fs [0. 27%] [0. 20%] gm/ge=0. 9999 ± 0. 0020 gm/gt=0. 9982 ± 0. 0021 Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria

B-factories must consider measuring leptonic branching ratios at 0. 1% level • Issues of systematic errors: q q q LEP measurements rely on data control samples for establishing the detector response for electrons and muons: same can be done at B-factories Non-tau backgrounds can be controlled at Bfactories: trade-off statistics for reduced systematics as done for tau lifetime measurement Cross contamination from other tau decays: use of control samples & may require improved simultaneous measurements of some non-leptonic modes a la ALEPH Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria

B-factories need to consider leptonic branching ratios • Issues of systematic errors …. q Normalization has been a dominant error at (4 s): (no. of produced taus entering the BR denominator) FNormalize to Nmm but requires s(tt)/s(mm) at <0. 1% level and counting Nmm at 0. 1% level Fs(tt)/s(mm) uncertainties from hadronic vacuum polarization and double photon box diagram – use e+e- data …B-factory ISR and KLOE, VEPP FPrecision cross section ratio measurement may also be interesting Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria

Measurements of hadronic currents • Probes of QCD • Non-strange decays q q q Comprehensive survey Starting to probe small branching ratio modes CVC problem… r+ vs r 0 : more data from Bfactories may help • Strange decays q Access Vus and ms Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria

Hadronic Tau decays Slides from Tau Physics: Experimental Summary, TAU 04 Nara W. Mader J. M. Roney, Victoria

New DELPHI exclusive hadronic Branching Ratios (Dedovich) Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria

Final ALEPH BRs (Davier) Opus to be published soon Strange decays measured separately and BR’s subtracted from /K analysis Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria

ALEPH non-strange Spectral functions (Davier) V Tau Physics: Experimental Summary, TAU 04 Nara A J. M. Roney, Victoria

CVC ‘Problem’ (Davier) e e CVC + isospin breaking (%) ALEPH B 0 24. 52 0. 31 25. 47 0. 13 0. 95 0. 33 B 3 0 1. 09 0. 08 0. 98 0. 09 -0. 11 0. 12 B 3 0 3. 63 0. 21 4. 59 0. 09 0. 96 0. 23 demotivates use of tau data in hadronic vacuum polarisation calculation (seemed a good idea at the time…) Should have more experiments measure the non-strange spectral functions (see Maltman’s talk for e’/e reasons…) Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria

CVC ‘Problem’ (Davier) Relative difference between and e+e – data: zoom No correction for ± – 0 mass (~ 2. 3 ± 0. 8 Me. V) and width (~ 3 Me. V) splitting applied Davier, hep-ex/0312064 Tau Physics: Experimental Summary, TAU 04 Nara Jegerlehner, hep-ph/0312372 J. M. Roney, Victoria

New measurements of high multiplicity tau decays from Bfactories (Sobie, Ter Antonyan) • BABAR probing 5 pion final states Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria

New measurements for TAU 04 from BABAR Channel Preliminary branching fraction BR (t- 4 p- 3 p+ (p 0) nt ) @ 90% CL < 2. 7 × 10 -7 Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria

But now comes some work on understanding decay mechanisms and form-factors …. Background subtracted mass distribution Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria

CLEO results on 3 h modes… (Duboscq) study of Wess Zumino anomaly in KKp mode (first study in this mode) shows 50% effect Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria

Moving on to STRANGE DECAYS…. t Kp 0 n (Mader, Duboscq, Salvatore, Davier) First tau strangness decay measurement from BABAR (fresh for TAU 04) Note: DELPHI showed new inclusive K BR (Dedovich) Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria

B-factories bring new era of Kaon ID… OPAL Jet chamber BABAR d. E/dx cf DIRC statistical separation vs track PID Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria

BABAR Kaon measurement Efficiency and mis-ID computed using D*+ → D 0 p+ data sample K + p- Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria

Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria

Strange spectral function (Mader) Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria

Moments analysis with strange spectral functions yields ms Tau Physics: Experimental Summary, TAU 04 Nara B-factories are now to contribute to this effort J. M. Roney, Victoria

B-factories • Current systematic errors from BABAR represent the starting point p 0 efficiency q Tracking efficiency q Normalization q etc… All expected to come down with additional statistics from control samples and new approaches to solving problems q Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria

Searches for rare/SM-forbidden decays involving the tau lepton • Many new lepton flavour violating decays from BELLE and BABAR • Other searches involving tau leptons q q This morning’s talk from BES and CLEO Tomorrow’s talks: F new particle searches with taus at DELPHI (Matorras) F new particle searches with taus at HERA (Lindfeld) F Z, W couplings, searches: CDF (Safonov) & D 0 (Le Bihan) F LHC (Tanaka) Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria

Junji Hisano b-s penguin v. s. GUT relation: Thus, b-s penguin processes and the SUSY GUTs. CP asymmetry in Tau Physics: Experimental Summary, TAU 04 Nara are correlated in This is non-trivial test for the SUSY GUTs. J. M. Roney, Victoria

BELLE: tgmg Phys. Rev. Lett. 92, 171802 (2004) hep-ex/0310029 (Hayasaka) +5 s - 11% signal MC 1. 71<Minv<1. 82 Ge. V/c 2 • 54 events survived in ± 5 s region • 19 events in ± 3 s region, 20. 2± 2. 1 expected Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria

BELLE t E distribution m Ohshima (ICHEP 04) 3 s region Bayesian method (s 0 w/ 90% CL) e. W=10. 8%, Ntt=78. 5 x 106 Result including systematics: Br(t m ) < 3. 4 x 10 -7 at 90% CL s=0; b=54; s 0(90%CL)=5. 1 ev Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria

Ba. Bar preliminary for TAU 04 Efficiency = (7. 45± 0. 65)% m. EC E Background expected from data SB= 6. 2± 0. 5 events 4 events observed BR(t m ) < 0. 9 x 10 -7 @ 90%CL Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria

BELLE: tgmg Phys. Rev. Lett. 92, 171802 (2004) • After all cuts in ± 3 s region: q 19 events observed, 20. 2± 2. 1 expected: F so=5. 1 events at 90%CL q q Efficiency=11. 1± 0. 6% (sys) Ntt=7. 85 x 107 Limit (no sys)= 2. 9 x 10 -7 90%CL BABAR: tgmg Preliminary • After all cuts in ± 2 s region: q 4 events observed, 6. 2± 0. 5 expected: F so=2. 7 events at 90%CL q q Efficiency=7. 45± 0. 65% (sys) Ntt=1. 97 x 108 Limit (no sys)=0. 9 x 10 -7 90%CL Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria

How do BELLE & BABAR sensitivities compare? define ‘limit sensitivity’ on BR(tgmg) as Limit Sensitivity= Nbkg/ 2 Ntt e BELLE Phys. Rev. Lett. 92, 171802 (2004) • After all cuts in ± 3 s region: 20. 2± 2. 1 background events expected q Efficiency=11. 1± 0. 6% (sys) Limit Sensitivity=2. 6 x 10 -7 q Ntt=7. 85 x 107 BABAR: Preliminary TAU 04 q • After all cuts in ± 2 s region: q q q 6. 2± 0. 5 background events expected Efficiency=7. 45± 0. 65% (sys) Limit Sensitivity=0. 84 x 10 -7 Ntt=1. 97 x 108 Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria

BELLE: tgeg - state of the art (Hayasaka) • fit by unbinned expanded maximum likelihood with signal and BG shape g s 0=0, b 0=20 • Estimation for U. L. of s 90 @ 90%CL uby Toy MC: generate 10000 events Signal yield : s 0 result q s 90=3. 8 events • Branching fraction Br=s 0/2 e. Ntt<3. 8 x 10 -7 e: detection efficiency Ntt: total event number Tau Physics: Experimental Summary, TAU 04 Nara e-ID ineff. 0. 01/0. 02 ev. BG function 0. 13 ev. Efficiency & Luminosity : 2 e. Ntt Track rec. eff. Photon rec. eff. 2. 8% Selection criteria 2. 5% Luminosity Trigger eff. MC statistics Total 2. 0% 1. 4% 5. 0% 0. 2% 6. 8% J. M. Roney, Victoria

t lhh LFV decays BELLE BABAR NEW TAU 04 1. 2 x 10 E-7 2. 9 0. 7 3. 2 1. 7 1. 8 1. 4 1. 5 2. 6 3. 2 2. 5 4. 8 Tau Physics: Experimental Summary, TAU 04 Nara BELLE 158/fb Eff~5% Bkg~some events 93 in total BABAR 221/fb Eff~3% Low backgds 10 in total J. M. Roney, Victoria

t lll LFV decays • BABAR and BELLE have both published results on these decays • Limits are few 10 E-7 q q PLB 589, 103 (2004) BELLE PRL 92, 121801 (2004) BABAR Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria

Search for LFV t decays involving p 0, h, h’ at Belle (Enari) B= s 0 2(e BX Ntt) s 0: signal events e : efficiency Ntt: # of t pairs (140 M tt) Preliminary 10 -70 times tighter limit from PDG 2004 First search!! Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria

Search for Baryonic Decays of the tau (Sato) Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria

Summary • Final LEP measurements being released • CLEO still producing tau physics results • B-factories have now started Focus on LFV But now also have … q precision measurements q Strange decay studies q Non-strange high multiplicity studies q Looking at where to focus efforts for TAU 06… Tau Physics: Experimental Summary, TAU 04 Nara J. M. Roney, Victoria