Hadron radiation in τ-production and the leptonic Z boson decay rate

Hadron Radiation in Τ Production and the Leptonic Z Boson Decay Rate

Hadron Radiation in Leptonic Z Decays

The rate for the final state radiation of hadrons in leptonic Z decays is evaluated, using as input experimental data for σ(e+e− → hadrons) in the low energy region. Configurations with a lepton pair of large and a hadronic state of low invariant mass are dominant. A relative rate Γll̄had/Γll̄ = 6.3×10−4 is calculated. This result is about twice the prediction based on a parton model calculation ...

Charged Scalar Particles and Τ Leptonic Decay

Charged scalar particles introduced in some extensions of the standard model can induce τ leptonic decay at tree level. We find that with some charged SU(2)-singlet scalar particles, like ones introduced in Zee-type models, τ leptonic decay width is always smaller than what is predicted by the standard model, therefore they may offer a natural solution to τ decay puzzle. To be more specific, we...

Finding the leptonic WW decay mode of a heavy Higgs boson at hadron supercolliders.

We reanalyze the extraction of the heavy Higgs boson signal H → WW → l̄ν, lν̄ (l = e or μ) from the Standard Model background at hadron supercolliders, taking into account revised estimates of the top quark background. With new acceptance criteria the detection of the signal remains viable. Requiring a forward jet-tag, a central jet-veto, and a large relative transverse momentum of the two charge...

Radiation zeros in weak boson production processes at hadron colliders

The Standard Model amplitudes for processes where one or more gauge bosons are emitted exhibit zeros in the angular distributions. The theoretical and experimental aspects of these radiation amplitude zeros are reviewed and some recent results are discussed. In particular, the zeros of the WZγ and WZZ production amplitudes are analyzed. It is briefly explained how radiation zeros can be used to...