[en] The precision of τ lifetime measurements have increased remarkably in the last several years. The techniques which lead to these results are summarized and compared, together with results obtained by different experiments from use of these methods. By combining the recent, and previous lifetime values an updated world average lifetime of τ_τ = (291.7 ± 1.6) fs is obtained, which is in good agreement with the prediction derived from the τ electronic branching ratio through the assumption of τ-μ lepton universally

[en] In this paper the author discusses the issue of universality with respect to the tau particle. Present work is trying to attack this by looking at τν_τW and Zτ bar τ couplings. Some models predict that non-universality will be such a small effect that it may be only tractable with a device such as a tau-charm factory. The issue of universality has impacts in other electroweak reactions, and in many models. The observation of such effects may require very high luminosity however

[en] We present a review of BaBar results on e⁺e^- → hadrons using the initial state radiation technique. Cross sections over the √s range from threshold to 4-5 GeV, with very small point-to-point systematic errors, are presented for the π⁺π^-π⁰, 2(π⁺π^-), 2(K⁺K^-), 3(π⁺π^-), 2(π⁺π^-)2π⁰, 2(π⁺π^-)K⁺K^-, and p(bar p) final states. The preliminary results of e⁺e^- → K⁺K^-π⁺π^- and e⁺e^- → K⁺K^-π⁰π⁰ cross sections are also presented

[en] Based on 3.26 fb^-1 data sample collected at CLEO III, we study the decay τ^- a K⁺ K^- π^- ν_τ and improve the measurement of the branching ratio B(τ^- a K⁺ K^- π^- ν_τ) = (1.59 ± 0.06 ± 0.13) x 10^-3, the results preliminary

[en] The present status of the tau one prong problem is reviewed. Emphasis is placed on recent published branching fraction measurements, the status and implications of tau lifetime measurements, and measurements which constrain the sum of branching fractions to be unity

[en] The status of the Monte Carlo programs for the simulation of the τ-lepton production and decay in high energy accelerator experiments is reviewed. In particular, the status of the following packages is discussed: (i) TAUOLA for τ-lepton decay and PHOTOS for radiative corrections in decays, (ii) MC-TESTER for universal tests of the Monte Carlo programs describing particle decays, (iii) KORALB, KORALZ, KKMC packages for τ-pair production in e⁺e^- collisions, and (iv) universal interface of TAUOLA for the decay of τ-leptons produced by 'any' generator

[en] We have searched for the violation of baryon number B and lepton number L in the (B - L)-conserving modes τ^- → (bar Λ)π^- and τ^- → (bar Λ)K^- as well as the (B - L)-violating modes τ^- → Λπ^- and τ^- → ΛK^- using 237 fb^-1 of data collected with the BaBar detector at the PEP-II asymmetric-energy e⁺e^- storage rings. We do not observe any signal and we determine preliminary upper limits on the branching fractions Β(τ^- → (bar Λ)π^-) < 5.9 x 10^-8, Β(τ^-→ Λπ^-) < 5.8 x 10^-6, Β(τ^- → (bar Λ)K^-) < 7.2 x 10^-8, and Β(τ^- → ΛK^-) < 15 x 10^-8 at 90% confidence level

[en] The τ lifetime was measured with the Mark II vertex detector at the storage ring PEP. τ_τ = (3.20 ± 0.41 ± 0.35) × 10^-13 sec was found, which agrees well with e – μ – τ university.

[en] The τ lepton arising from the scalar tau (τ) decay is naturally polarized. P_τ depends on the left-right mixing of the τ and the gaugino-Higgsino mixing of the neutralino. The polarization P_τ could be measured from the energy distribution of the decay products of τ at future e⁺e^- colliders. A measurement of P_τ and of the τ production cross section allows us to determine both these mixing angles

[en] We propose a simple set of hypotheses governing the deviations of the leptonic mapping matrix from the Harrison-Perkins-Scott (HPS) form. These deviations are supposed to arise entirely from a perturbation of the mass matrix in the charged lepton sector. The perturbing matrix is assumed to be purely imaginary (thus maximally T-violating) and to have a strength in energy scale no greater (but perhaps smaller) than the muon mass. As we shall show,it then follows that the absolute value of the mapping matrix elements pertaining to the tau lepton deviate by no more than O((m_μ/m_τ)²) ≅ 3.5 x 10^-3 from their HPS values. Assuming that(m_μ/m_τ)² can be neglected, we derive two simple constraints on the four parameters θ12, θ23, θ31, and δ of the mapping matrix. These constraints are independent of the details of the imaginary T-violating perturbation of the charged lepton mass matrix. We also show that the e and μ parts of the mapping matrix have a definite form governed by two parameters α and β; any deviation of order m_μ/m_τ can be accommodated by adjusting these two parameters. (authors)