Δπ decay of baryons in a flux-tube-breaking mechanism

Based on the flux-tube-breaking mechanism, we have previously studied the strong decay of nonstrange baryons into the elastic and several inelastic channels. Here, we extend these studies toΔ π decay. We compare our results with those of Koniuk and Isgur and with recently improved experimental data. We also present results of a new and improved calculation ofN π decay and discuss the problem of resonance identification.     

Event excess in the MiniBooNE search for ¯νμ→¯νe oscillations

The MiniBooNE experiment at Fermilab reports results from a search for ˉν_{μ}→ˉν_{e} oscillations, using a data sample corresponding to 5.66×102? protons on target. An excess of 20.9±14.0 events is observed in the energy range 475相似文献   

L/E-flatness of the electron-like event ratio, in Super-Kamiokande and a degeneracy, in neutrino masses

We show that the L/E-flatness of the electron-like event ratio in the Super-Kamiokande atmospheric neutrino data implies the equality of the expectation values for the muon and tau neutrino masses. We establish this result by obtaining a set of three constraints on the neutrino-oscillation mixing matrix as contained in the indicated flatness. The resulting 3×3 neutrino-oscillation matrix depends only on one angle. A remarkable result that follows directly from this matrix is the consistency between the mixing angles observed by LSND and Super-Kamiokande.     

PKP simulation of size effect on interaction field distribution in highly ordered ferromagnetic nanowire arrays

Perpendicular structured nanowire arrays interaction field distributions (IFDs), as revealed from first-order reversal curves (FORC) diagrams, are related to the presence of the demagnetizing field in the system. Despite the similarity between the geometric properties of bit patterned media and mentioned nanowire arrays, FORC diagrams of these two types of systems are not similar essentially due to the different number of magnetic entities influencing the switch of an individual element. We show that one Preisach–Krasnosel'skii–Pokrovskii (PKP) symmetrical hysteron can be representative of an ideal infinite nanowire array when the field is applied along the wires. Starting from this observation, we present a very simple model based on PKP symmetrical hysterons that can be applied to real finite ferromagnetic nanowire arrays, and is able to describe a wide class of experimentally observed FORC distributions, revealing features due to size effects. We also present IFDs modeled for different geometric characteristics such as array size, interwire distance, and nanowire dimensions, and an identification procedure for the proposed model.     

Positive parity nonstrange baryons beyond 2 GeV

Previous studies of nonstrange baryons are extended to resonances of mass beyond 2 GeV, belonging to the N = 4 band. The framework is a semi-relativistic constituent quark model. The quark-quark interaction contains a Coulomb plus linear confinement term and a short-range spin-spin term. It turns out that the string tension value of 1 GeV fm^?1 fixed previously in the N ≤ 3 bands is compatible with the N = 4 band. It is shown that the three-body confinement potential plays an important role in describing the inner structure of the band. The decay widths are calculated in a flux-tube breaking mechanism and compared to data and other models.     

A general model for power dissipation by domain wall movement in thin ferromagnetic films

In this work we present a model for magnetic domain wall (DW) dynamics in metallic ferromagnets with uniaxial anisotropy. The model allows us to consider both viscous and eddy current dampings. While the latter mechanism involves only one degree of freedom — the coordinate of the DW, the former involves all degrees of freedom of the spins in magnetic domains and in DW’s. The structure of the DW itself must then be considered, the conjecture used allowing one to describe the spin precessions which may appear in low quality factor Q materials. The model built is nonlinear, allowing one to deal with the set of complex susceptibilities characterizing the response to an ac drive field in strongly nonlinear circumstances, and has a general character, due to the normalized quantities used. In this work we analyze the susceptibility and the dissipated power spectra as functions of a dc transversal field, which can be treated only by this kind of models. We show that the viscous damping can become comparable to eddy current damping when precessions are excited.     

Measurement of the transition dipole moment of the first hot band of the nu2 mode of the methyl radical by diode laser spectroscopy

The line strengths of five Q-branch lines of the first hot band of the out-of-plane bending vibration (2(1)(2)) of the methyl radical, CH 3, have been measured using infrared laser absorption spectroscopy. The spectra of the radical were measured in situ in a microwave discharge using ditertiary butyl peroxide, diluted in argon as the precursor. The line strengths were used to determine the transition dipole moment of the hot band. Absolute concentrations of the radical were required for this purpose, and these were determined kinetically from the measured decays of the spectral lines after the discharge was extinguished. The translational, rotational, and vibrational temperatures were also determined spectroscopically from measured integrated line intensities and line widths. The transition dipole moment of the first hot band was determined to be 0.31(6) D. This value is in satisfactory agreement with the value of 0.27(3) D from a high-precision ab initio calculation using the self-consistent electron pairs (SCEP) method reported by Botschwina, Flesch, and Meyer [Botschwina, P.; Flesch, J.; Meyer, W. Chem. Phys. 1983, 74, 321].     

Ising-like model study of size dependence relaxation in spin crossover complexes

In this paper we present a theoretical study of size effects during relaxation in spin transition solids. The systems are described using an Ising-like model consisting of molecules having two energy levels and fictitious spin values of +1, (HS) and −1 (LS). We compare relaxation in various 2D or 3D systems (rectangular, hexagonal or cubic) and we realise an exhaustive analysis of the parameters that influence the relaxation in small size samples. The differences between homogenous and inhomogeneous systems reflected on the shapes of relaxation curves are discussed and analysed.     

The tensor part of Skyrme's interaction

A tensor part is added to central and spin-orbit parts of Skyrme's effective interaction and its contribution to the Hartree-Fock spin-orbit coupling of spherical spin-unsaturated nuclei is analysed. Minor improvements to spin-orbit splittings can be achieved if the strengths of the tensor interaction are treated as free parameters, but the fit to experiment deteriorates if the tensor interaction contribution is estimated for a realistic interaction.