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153 - Luis G.C. Rego , A. Gusso , 2005
It is predicted that for sufficiently strong electron-phonon coupling an anomalous quantum chaotic behavior develops in certain types of suspended electro-mechanical nanostructures, here comprised by a thin cylindrical quantum dot (billiard) on a sus pended rectangular dielectric plate. The deformation potential and piezoelectric interactions are considered. As a result of the electron-phonon coupling between the two systems the spectral statistics of the electro-mechanic eigenenergies exhibit an anomalous behavior. If the center of the quantum dot is located at one of the symmetry axes of the rectangular plate, the energy level distributions correspond to the Gaussian Orthogonal Ensemble (GOE), otherwise they belong to the Gaussian Unitary Ensemble (GUE), even though the system is time-reversal invariant.
We perform a theoretical analysis of a setup intended to measure the repulsive (outward) Casimir forces predicted to exist inside of perfectly conducting rectangular cavities. We consider the roles of the conductivity of the real metals, of the tempe rature and surface roughness. The use of this repulsive force to reduce friction and wear in micro and nanoelectromechanical systems (MEMS and NEMS) is also considered.
65 - A. Gusso , C. A. de S. Pires , 2003
In the minimal 3-3-1 model charged leptons come in a non-diagonal basis. Moreover the Yukawa interactions of the model lead to a non-hermitian charged lepton mass matrix. In other words, the minimal 3-3-1 model presents a very complex lepton mixing. In view of this we check rigorously if the possible textures of the lepton mass matrices allowed by the minimal 3-3-1 model can lead or not to the neutrino mixing required by the recent experiments in neutrino oscillation.
Measurements of CP--violating observables in neutrino oscillation experiments have been studied in the literature as a way to determine the CP--violating phase in the mixing matrix for leptons. Here we show that such observables also probe new neutri no interactions in the production or detection processes. Genuine CP violation and fake CP violation due to matter effects are sensitive to the imaginary and real parts of new couplings. The dependence of the CP asymmetry on source--detector distance is different from the standard one and, in particular, enhanced at short distances. We estimate that future neutrino factories will be able to probe in this way new interactions that are up to four orders of magnitude weaker than the weak interactions. We discuss the possible implications for models of new physics.
64 - E. M. Gregores 2001
We show that the accumulated LEP-II data taken at $sqrt{s} =$ 130 to 206 GeV can establish more restrictive bounds on doubly charged bileptons couplings and masses than any other experiment so far. We also analyze the discovery potential of a prospec tive linear collider operating in both $e^+ e^-$ and $e gamma$ modes.
We establish constraints on a general four-fermion contact interaction from precise measurements of electroweak parameters. We compute the one-loop contribution for the leptonic $Z$ width, anomalous magnetic, weak-magnetic, electric and weak dipole m oments of leptons in order to extract bounds on the energy scale of these effective interactions.
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