Antisymmetric tensor matter fields: an abelian model

We present a simple renormalizable abelian gauge model which includes antisymmetric second-rank tensor fields as matter fields rather than gauge fields known for a long time. The free action is conformally rather than gauge invariant. The quantization of the free fields is analyzed and the one-loop renormalization-group functions are evaluated. Transverse free waves are found to convey no energy. The coupling constant of the axial-vector abelian gauge interaction exhibits asymptotically free ultraviolet behavior, while the self-couplings of the tensor fields do not asymptotically diminish.Comment: 9 pages, Pisa preprint IFUP-TH 47/9

Origin and Phenomenology of Weak-Doublet Spin-1 Bosons

We study phenomenological consequences of the Standard Model extension by the new spin-1 fields with the internal quantum numbers of the electroweak Higgs doublets. We show, that there are at least three different classes of theories, all motivated by the hierarchy problem, which predict appearance of such vector weak-doublets not far from the weak scale. The common feature for all the models is the existence of an SU(3) gauge extension of the weak SU(2) group, which is broken down to the latter at some energy scale around TeV. The Higgs doublet then emerges as either a pseudo-Nambu-Goldstone boson of a global remnant of SU(3), or as a symmetry partner of the true eaten-up Goldstone boson. In the third class, the Higgs is a scalar component of a high-dimensional SU(3) gauge field. The common phenomenological feature of these theories is the existence of the electroweak doublet vectors (Z*,W*), which in contrast to well-known Z' and W' bosons posses only anomalous (magnetic moment type) couplings with ordinary light fermions. This fact leads to some unique signatures for their detection at the hadron colliders.Comment: 7 pages, 5 figure

On V_ud determination from kaon decays

The pion beta decay pi^+ -> pi^0 e^+ nu proceeds through pure weak vector hadronic currents and, therefore, the theoretical prediction for it is more reliable than for the processes with axial-vector current contribution. For example, recently the pion beta decay has been used for V_ud determination. The main aim of this letter is to point that kaon beta decay K^0 -> K^+(pi^+ pi^0) e^- nu-bar analogously can be used for this purpose.Comment: 3 pages, no figures, one reference adde

A frequentist analysis of solar neutrino data

We calculate with Monte Carlo the goodness of fit and the confidence level of the standard allowed regions for the neutrino oscillation parameters obtained from the fit of solar neutrino data. We show that the values of the goodness of fit and of the confidence level of the allowed regions are significantly smaller than the standard ones. Using Neyman's method, we also calculate exact allowed regions with correct frequentist coverage. We show that the standard allowed region around the global minimum of the least-squares function is a reasonable approximation of the exact one, whereas the size of the other regions is dramatically underestimated in the standard method.Comment: 19 page

Morphologic and optical characterization of ZnO:Co thin films grown by PLD

The morphological properties of the surface and optical characteristics of nanocomposite ZnO:Co structures grown on substrates of monocrystalline silicon and sapphire by pulsed laser deposition (PLD) method have been studied. The influence of thermal annealing on formation of characteristically developed surface of films has been analyzed. The experimental transmission and reflectance spectra in the visible region have been measured. In the framework of the dielectric function, the optical constants n and k and dispersion parameters of oscillators that provide the best fit with experimental data have been obtained. From the infrared reflectance spectra of ZnO:Co structures, the frequency positions of Е₁(LO) and Е₁(ТО) optical phonons have been determined. It gives a possibility to suppose that the obtained films possess the wurtzite structure

Search for Tensor Interactions in Kaon Decays at DAΦ\PhiNE

The semileptonic kaon decays $K_{l2\gamma}$ and $K_{l3}$ are considered. We use the most general forms of the matrix elements for these decays. Additional terms could arise as a result of new tensor interactions between quarks and leptons. Such terms have been detected in a recent experiments. The high precision experiments at DA$\Phi$NE may be ideal to confirm these results.Comment: 8 LaTeX pages, no figure

Model Independent Information On Solar Neutrino Oscillations

We present the results of a Bayesian analysis of solar neutrino data in terms of nu_e->nu_{mu,tau} oscillations, independent from the Standard Solar Model predictions for the solar neutrino fluxes. We show that such a model independent analysis allows to constraint the values of the neutrino mixing parameters in limited regions around the usual SMA, LMA, LOW and VO regions. Furthermore, there is a strong indication in favor of large neutrino mixing and large values of Delta m^2 (LMA region). We calculate also the allowed ranges of the neutrino fluxes and we show that they are in good agreement with the Standard Solar Model prediction. In particular, the ratio of the 8B flux with its Standard Solar Model prediction is constrained in the interval [0.45,1.42] with 99.73% probability. Finally, we show that the hypothesis of no neutrino oscillations is strongly disfavored in a model independent way with respect to the hypothesis of neutrino oscillations.Comment: 40 pages, 20 figures. Added references and improved figure

Form Factors in the radiative pion decay

We perform an analysis of the form factors that rule the structure-dependent amplitude in the radiative pion decay. The resonance contributions to pion -> e nu_e gamma decays are computed through the proper construction of the vector and axial-vector form factors by setting the QCD driven asymptotic properties of the three-point Green functions VVP and VAP, and by demanding the smoothing of the form factors at high transfer of momentum. A comparison between theoretical and experimental determinations of the form factors is also carried out. We also consider and evaluate the role played by a non-standard tensor form factor. We conclude that, at present and due to the hadronic incertitudes, the search for New Physics in this process is not feasible.Comment: 14 pages, no figures. Typos corrected. Accepted for publication in The European Physical Journal

Nonequilibrium Neutrino Oscillations and Primordial Production of He-4

We studied nonequilibrium oscillations between left-handed electron neutrinos and nonthermalized sterile neutrinos in medium for resonant and nonresonant cases. The exact kinetic equations for neutrinos, written in terms of neutrino density matrix in {\it momentum space} were analyzed. The evolution of neutrino density matrix was numerically calculated. This allowed to study precisely the evolution of the neutrino number densities, energy spectrum distortion and the asymmetry between neutrinos and antineutrinos for each momentum mode. The influence of nonequilibrium oscillations on the primordial production of He-4 was calculated. Cosmological constraints on the oscillation parameters were obtained.Comment: LaTeX, 7 pages, 6 Postscript figures, figures are included in the revised text (epsf.sty

Supernova neutrino oscillations: A simple analytical approach

Analyses of observable supernova neutrino oscillation effects require the calculation of the electron (anti)neutrino survival probability P_ee along a given supernova matter density profile. We propose a simple analytical prescription for P_ee, based on a double-exponential form for the crossing probability and on the concept of maximum violation of adiabaticity. In the case of two-flavor transitions, the prescription is shown to reproduce accurately, in the whole neutrino oscillation parameter space, the results of exact numerical calculations for generic (realistic or power-law) profiles. The analytical approach is then generalized to cover three-flavor transitions with (direct or inverse) mass spectrum hierarchy, and to incorporate Earth matter effects. Compact analytical expressions, explicitly showing the symmetry properties of P_ee, are provided for practical calculations.Comment: 22 pages (RevTeX) + 5 figures (PostScript