C. Jarlskog’s research while affiliated with European Organization for Nuclear Research and other places

In some phenomenological supersymmetric models R-parity (+1 for particles, −1 for sparticles) is spontaneously broken along with tau-lepton number Lτ by a vacuum expectation value υτ of the tau sneutrino ντ. To avoid excess stellar energy loss through majorons, there should also be explicit Lτ violation through right-handed neutrinos. To have a sufficiently light ντ, either υτ is very small which is unnatural and boring, and/or the Higgs mixing parameter ϵ is very small. We find that in the limit ϵ → 0: -both the forward-backward asymmetry in e+e− → τ+τ− and the τ lifetime are unchanged,-Z0 → g̃gν⊥ decays are possible where ντ is an extra neutrino,-squarks and gluinos may decay into τ or ντ,-the photino γ̃g can decay into ν⊥ff̄ with a detectable secondary vertex,-single production of (R-odd) sparticles may occur.

A nucleus (Z, A) may capture two atomic electrons to become (Z − 2, A). For Majorana neutrinos this may occur with no neutrino emission, the process is a virtual mixing of the parent atom and the daughter atom with two electron holes. The process becomes real as the daughter atom de-excites. In some cases where the daughter nucleus is excited, the neutrinoless decay may be enhanced by its proximity to a virtual resonance. We identify the transition as a good case. The no-neutrino lifetime for mν = 30 eV ranges from 1022 to 1027 years as a function of the insufficiently well determined distance to resonance. The signatures of the two- or no-neutrino modes are very different.

In the standard theory we discuss a mechanism of interference between two different tree-level charged current amplitudes to induce CP violation. The asymmetry between conjugate Cabibbo disfavoured modes of charged bottom meson decays is considered. Estimates for two-body decays ofB u andB c are presented. We find thatB u−→D −+D 0*, for instance, can give a big CP asymmetry with values ≈1–50%, depending on the angle and phase parameters.

We argue that the observed quark and lepton masses are related at momenta larger than 1015 GeV as follows: mb = mτ, mμ = 3ms and me = md/3. We construct a model in which these factors of three arise naturally — because quarks come in three colors.

We show that charged current interactions involving the superheavy bosons in the SU(5) model contain new mixing angles and phases. The consequences for the estimations of the proton instability are briefly discussed.

Previous estimates for the stability of matter through baryon-number violating nucleon decays are refined by taking into account all possible diagrams that contribute to the process. As a result, we obtain τ(p) ∼ τ(n) ∼ 1033y, not quite one order of magnitude smaller than previous estimates. Most of the decays will produce mesons, but no direct muon. Muon-producing decays are only ∼ 10% of all decays. Although the theoretical errors are large (about one order of magnitude) we conclude that, if the effect is there, and experiments sensitive to detection of mesons (and not only muons) are devised, an increase of two to three orders of magnitude in the present experimental accuracy may reveal it.

We have studied neutral strange particle production in the bubble chamber Gargamelle filled with propane and exposed to antineutrinos from the CERN PS. Cross sections are presented for Λ, Σ0 and K0 production. Associated production reactions (ΔS = 0) have been observed in the charged and the neutral current channels. From 45 candidates for the quasi-elastic reaction , on bound and free protons, estimates of the axial transition form factor MA have been made using the total cross section and the t distribution. The weighted average from the two methods is MA = 862 ± 190 MeV. From a subsample of 15 candidates for interactions on free protons in propane, with (28±6)% background from interactions on bound protons, we obtain MA = 883 ± 243 MeV. The polarization of the Λ hyperons has been studied for the quasi-elastic reaction. We observe a significant Λ polarization in the production plane, normal to the Λ line of flight. The observed polarizations agree well with the predicted theoretical polarizations without any contribution from second-class axial coupling.

A novel and parameter free approach to mu capture is introduced. The inclusive capture rate at maximal energy transfer is connected with the off-mass shell s and p wave scattering lengths for pions. Inside PCAC a rigorous lower bound for the rate results. The vector current contributions are shown to be insignificant. In a numerical illustration it is shown that this picture qualitatively explains the high energy nucleons emitted in mu capture. Present address: Physics Department, University of Bergen, Norway.

We propose a test of the validity of SU(2) ⊗ U(1) as the gauge group of weak and electromagnetic interactions. We find that, among the seven empirical neutral current couplings, there are two restrictions which do not rely on a particular model. The relations are 2(GV + GA) + (α + β) + 3(γ + δ) = 0 and 2k − (α + β) + 3(γ + δ) = 0, where where α, β, γ, δ (GV, GA) are the couplings measured in neutrino-hadron (electron) scattering and κ is obtained from interference experiments. We also find several inequalities. Comparison with present data is given.