To investigate the critical thickness of ferroelectric BaTiO3 (BTO) films, we fabricated fully strained SrRuO3∕BTO∕SrRuO3 heterostructures on SrTiO3 substrates by pulsed laser deposition with in situ reflection high-energy electron diffraction. We varied the BTO layer thickness from 3to30nm. By fabricating 10×10μm2 capacitors, we could observe polarization versus electric-field hysteresis loops, which demonstrate the existence of ferroelectricity in BTO layers thicker than 5nm. This observation provides an experimental upper bound of 5nm for the critical thickness. The BTO thickness-dependent scaling of the remanent polarization agrees with the predictions of recent first-principle simulations [J. Junquera and P. Ghosez, Nature 422, 506 (2003)].

We study muonium-antimuonium conversion and µ + e − → µ − e + scattering within two different lepton-flavor-violating models with heavy neutrinos: model I is a typical seesaw that violates lepton number as well as flavor; model II has a neutrino mass texture where lepton number is conserved. We look for the largest possible amplitudes of these processes that are consistent with current bounds. We find that model I has very limited chance of providing an observable signal, except if a finely tuned condition in parameter space occurs. Model II, on the other hand, requires no fine tuning and could cause larger effects. However, the maximum amplitude provided by this model is still two orders of magnitude below the sensitivity of current experiments: one predicts an effective coupling G MM up to 10 −4 GF for heavy neutrino masses near 10 TeV. We have also clarified some discrepancies in previous literature on this subject.

Motivated by the indication that both the atmospheric and the solar neutrino puzzles may simultaneously be solved by (vacuum as well as matter-induced resonant) oscillations of two generations of neutrinos with large mixing, we have analyzed the data on the atmospheric and solar neutrinos assuming that all three neutrinos are maximally mixed. It is shown that the values of ∆m 2 obtained from the two-generation analyses are still valid even in the three-generation scheme, i.e. the two puzzles can be solved simultaneously if ∆m 2 31 ≃ 10 −2 eV 2 for the atmospheric neutrinos and ∆m 2 21 ≃ 10 −10 eV 2 for solar neutrinos in the maximally mixed three-generation scheme.

We study the lepton-flavor-violating reaction µ + e − → e + e − within two extensions of the standard model that include heavy neutrinos. The reaction is studied in the low energy limit in the form of muonium decay M → e + e − and in the high energy regime of a muon collider. The two theoretical models we consider are: model I, a typical see-saw model that violates lepton flavor and number by inclusion of extra right handed neutrinos, and model II, a variant where lepton number is conserved and which includes extra right handed as well as left handed neutrinos, singlets under the gauge group. We find for muonium decay into e + e − the extremely small result Br(M → e + e − ) < 10

Han, In K., Lee, J.H., K m , J.H., &m, Y.G., Kim, J.D. and Paik, I.K. 2000. Application of phase feeding in swine production. J. Appl. Anim. Res., 17: 27-56. Phase feeding is