No abstract available

No abstract available

[en] This contribution presents the RK measurement and angular analysis of the B"0 → K"∗"0e"+e"− decay performed by the LHCb collaboration and gives an overview of the ongoing and future measurements of rare decays proceeding through a b→sℓ"+ℓ"− transition.

[en] We propose the scheme in which < e>, <μ>, < tau> and < tau'> are grouped into pairs in order (where < tau'> are the yet undiscovered fourth generation), and the theory is invariant under the discrete transformation (<μ> reversible < e>) and (< tau> reversible < tau'>). We investigate this scheme explicitly on the base of SO(10). (orig.)

[en] A new measurement of the π → eν branching ratio yields GAMMA(π→eν + π→eνγ) / GAMMA(π→μν + π→γνμ) = (1.218 +- 0.014) x 10^-4. The measured value is in good agreement with the standard model prediction incorporating electron-muon universality

[en] In this paper, we study the phenomenology of right-handed neutrino isosinglets. We consider the general situation where the neutrino masses are not necessarily given by m_D²/M, where m_D and M are the Dirac and Majorana mass terms, respectively. The consequent mixing between the light and heavy neutrinos is then not suppressed, and we treat it as an independent parameter in the analysis. It turns out that μ-e conversion is an important experiment in placing limits on the heavy mass scale (M) and the mixing. Mixings among light neutrinos are constrained by neutrinoless double-β decay, as well as by solar and atmospheric neutrino experiments. Detailed one-loop calculations for lepton-number-violating vertices are provided

[en] We give analytical expressions for the collinear photon emission in Z⁰ -> l⁺l^- γ and W -> lνγ and for the radiative corrections to Z⁰ and W decays corresponding to possible experimental set-ups. We find that the correct definition of the 'elastic' events increases remarkably the ratio of bremsstrahlung to 'elastic'. It also reduces the amount of the apparent violation of lepton universality originated from radiative corrections. (orig.)

[en] A gauge model for the weak interactions of the leptons (vsub(e),e, μ, vsub(μ)) and the quarks (qsub(p), qsub(n), qsub(lambda), qsub(p')) is presented in which deviations from universality, such as the Cabibbo suppression, are explicitly and spontaneously generated. The gauge group is, to begin with SU(4). There are three quartets of Higgs scalars with suitable vacuum expectation values, sufficient and necessary to give masses to all gauge bosons. It turns out that this gauge group is too 'large' and fails to account for many observed symmetries of weak interactions, especially electron-muon symmetry. This symmetry corresponds to a discrete transformation R which is an element of SU(4). To accommodate it, the gauge group is restricted to the subgroup of SU(4) which commutes with R. There are now 7 gauge bosons, 4 charged and 3 neutral. One pair of charged bosons is necessarily heavier than the other pair (denoted Wsup(+-)) and two neutrals are necessarily heavier than the third (Wsup(o)). The electron and the muon become massive while the neutrinos and the quark fields remain massless. The Cabibbo angle THETAsub(c) itself is determined by minimising a very general class of Higgs potentials, leading to a numerical value THETAsub(c) = +- π/8, absolute value of tanTHETAsub(c) =√2 - 1 (an alternative solution absolute value of tanTHETAsub(c) = (√2 + 1) is rejected), independent of the parameters and of the precise form of potential. This the bare' THETAsub(c); in low energy/momentum transfer processes, this value is renormalised by the structure of the hadrons. A model is given for this renormalisation which reduces the renormalised value of absolute value of tanTHETAsub(c) to about 0.2-0.3 from the bare value 0.41. Recent data on highly inelastic neutrino interactions are shown to be not inconsistent with absolute value of tanTHETAsub(c) = 0.4. (auth.)

[en] We incorporate possible violation of μ - e universality in π-decay into neutrino oscillations. We found compatibility with reactor anti νsub(e), solar neutrino, deep mine and accelerator neutrino flux measurements, assuming a 0.5 MeV/c² neutrino plus two light mass neutrinos. (orig.)

[en] An analysis is given of the contributions to the effective Hamiltonian that describes the recoil corrections to the hyperfine splitting that are logarithmic in the electron-to-muon mass ratio