Thea 1 mass from τ→a 1ν decay

The three recent experiments of the MARK II, DELCO, and ARGUS groups are reanalysed using an analytically correct Breit-Wigner form including apart from the ρπ also (i) the \(K*\bar K + \bar K*K\) thresholds, and (ii) an energy dependent real part (a “running” mass shift function involving Chew-Mandelstam functions) to thea ₁ mass parameter. It is found that all three experiments can be fitted with ana ₁ mass of (1250±40) MeV in agreement with the Particle Data Group value (1275±28) MeV, but in contrast to results presented by the experimental groups. However, the width ofa ₁ determined from the τ→a ₁ν→3πν decay data is considerably larger than the conventional value.     

Search for the decay τ− → vτηπ−

We have searched for the decay τ⁻ → v_τηπ⁻ using data accumulated by the ARGUS detector at the e⁺e⁻ storage ring DORIS II at DESY. No η signal was found in the π⁺π⁻π⁰ subsystems of the decay τ⁻ →v_τπ⁻π⁻π⁺ π⁰. We obtain an upper limit for the branching ratio of the decay τ⁻ → v_τηπ⁻ of 1.3% at the 95% confidence level.     

Upper limit on the branching ratio for the decay τ-→Π-ηvτ

We have searched for the decay τ^-→Π^-ηv_τ using the MARK II detector at the PEP e⁺e^- storage ring. No evidence for the decay is found; the upper limit for the branching ratio is B(τ^-→Π^-ηv_τ)<1.0% at the 95% confidence level.     

Tau Leptonic Decay τ→lVlVτ in Littlest Higgs Model＊

We consider the τ leptonic decay $\tau\rightarrow l\bar{\nu}_{l}\nu_{\tau}$ in the framework of the littlest Higgs (LH) model and calculate the corrections of new particles to this decay. We find that the contributions of the charged scalars can be safely ignored and the LH model is in perfect agreement with the universality of the couplings of the SU gauge bosons to the leptonic charged currents. The corrections of the LH model to the τ leptonic decay $\tau\rightarrow l\bar{\nu}_{l}\nu_{\tau}$ are not sensitive to the parameter c, but depend strongly on the parameters f and x. The precision measured data about the τ leptonic decay demand that the parameter f approximately equal 3.5 TeV and x>0.1, while agree with the general expectation based on other phenomenological explorations.     

Z′particles and e~+ e~- → τ~+ μ~-

We analyze the cross section of e + e-→τ + μ-within the frameworks of SM and its Z extension.The theoretical prediction of the SM on the total cross section is suppressed by the tiny neutrino masses.On the other hand,the contributions from Z to the cross section are enhanced drastically because of the tree level FCNC couplings among Z and leptons.     

Feasibility study of CP violation in τ-→KSπ-vτ decays at the Super Tau Charm Facility

We report a feasibility study for violation in τ-→ KSπ-vτ decays at a Super Tau Charm Facility (STCF).With an expected luminosity of 1 ab-1 collected by STCF pe...     

Bounds on the magnetic moment of the τ-neutrino via the process e~ e-→νγ

Using Breit-Wigner resonance relation, bounds on the magnetic moment of the tau-neutrino are calculated through the reaction e e-→νγ at the neutral boson pole in the framework of a superstring-inspired E6 model which has one extra low-energy neutral gauge boson and a LRSM.     

THE DIFFICULTY OF THE DECAY τ→πντ AND SPIN 3/2 HEAVY LEPTON

We discuss the suppression of the decay of heavy lepton τ into πv_τ,by assuming that τ and/or v_τ carry spin 3/2. For the case of spin 3/2 T and spin 1/2 v_τ, using the weak current ψ_μ^(τ)(a+b_^γ5)Ψ^(v_τ)we find that the πv_τ decay channel relative to the v_τv_ll^-channel is suppressed 12/5 times, while other decay channels are not changed appreciably. △R=σ（e⁺e^-→τ⁺τ^-）/σ（e⁺e^-→μ⁺μ^-） is also discussed.     

Search for CP violation in τ±→K(S)0π±ντ decays at Belle

We report on a search for CP violation in τ(±)→K(S)(0)π(±)ν(τ) decays using a data sample of 699 fb(-1) collected by the Belle experiment at the KEKB electron-positron asymmetric-energy collider. The CP asymmetry is measured in four bins of the invariant mass of the K(S)(0)π(±) system and found to be compatible with zero with a precision of O(10(-3)) in each mass bin. Limits for the CP violation parameter Im(η(S)) are given at the 90% confidence level. These limits are |Im(η(S))| < 0.026 or better, depending on the parametrization used to describe the hadronic form factors, and improve upon previous limits by 1 order of magnitude.     

Z→3γ和γγ→γγ极化张量的一般形式

在标准模型下,讨论了Z→3γ衰变和γ→γ散射过程的单圈极化张量的一般形式.利用S₃对称性和规范不变性对这种极化张量进行限制,从而得到一组约束方程.本文介绍了这种方法的主要步骤,并且将W玻色子圈的结果与费米子圈的结果作了比较.     

Bounds on the magnetic moment of the τ-neutrino via the process e+e－→ννγ

Using Breit-Wigner resonance relation, bounds on the magnetic moment of the     

Measurement of Structure Function of τ→π±2π0v

The structure function of τ→π^±2π⁰v is measured by model independent method. The result is compared with Kuhn-Santamaria model, Isgur-Morningstar-Reader model and Feindt model. Good consistency between data and the three models is shown within the experimental error range. The comparison with the structure function of τ→3π^±v measured by OPAL Collaboration also shows there is no obvious difference within 0.52.