Modern Physics Letters A

We investigate possible strategies to reduce the experimental uncertainty on the CKM angle α, in the working conditions of an asymmetric e⁺ e^-B-factory. We propose to use information from the time-dependent asymmetry of neutral B-decays to π⁺ π^-, together with the ratio . We also consider the possibility of using information on the ratio . An error analysis on α depending on the expected experimental uncertainties on the input quantities is carried out.

We examine the potential signatures of the Higgs boson when it decays into a tau–lepton pair. We show that with the proper identification of the tau-jet, this decay mode can lead to the identification of the Higgs boson over most of the intermediate mass range (M_W<M_H<2M_W).

We consider a model in which the third family fermions are subjected to an SU(2) interaction different from the first two family fermions. Constrained by the Z-pole data, the heavy gauge boson mass is bounded from below to be about 1.7 TeV at the 2σ level. In this model, the flavor mixing between τ and μ can be so large that and Br(τ→μμμ) provide a better constraint than the LEP/SLC data in some region of parameter space. Furthermore, flavor-changing neutral currents are unavoidable in the quark sector of the model. Significant effects to the mixing and the rare decays of the K and B mesons, such as , , B_s→τ⁺τ^-, μ⁺μ^- and B_s,d→μ^±τ^∓, are expected.

It is shown that T-duality in a σ-model with Kaluza–Klein metric, with or without a torsion term, can be interpreted as electric–magnetic duality for some of their solitonic solutions. Actually Buscher's duality transformation interchanges the topological and Noether charges.

We propose an implicit regularisation scheme. The main advantage is that since no explicit use of a regulator is made, one can in principle avoid undesirable symmetry violations related to its choice. The divergent amplitudes are split into basic divergent integrals which depend only on the loop momenta and finite integrals. The former can be absorbed by a renormalisation procedure whereas the latter can be evaluated without restrictions. We illustrate with the calculation of the QED and -theory β-function to one- and two-loop orders, respectively.

The time evolution and decay of the neutral kaon system can be described using quantum dynamical semigroups. Non-standard terms appear in the expression of relevant observables; they can be parametrized in terms of six new phenomenological constants. We discuss how the presence of these constants affects the determination of the parameter ε′/ε.