Quark mass hierarchy in 3-3-1 models

We study the mass spectrum of the quark sector in an special type I-like model with gauge symmetry $SU(3)_c \otimes SU(3)_L \otimes U(1)_X$. By considering couplings with scalar triplets at large ($\sim TeV$) and small ($\sim GeV$) scales, we obtain specific zero-texture mass matrices for the quarks which predict three massless quarks ($u,d,s$) and three massive quarks ($c,b,t$) at the electroweak scale ($\sim$ GeV). Taking into account mixing couplings with three heavy quarks at large scales predicted by the model, the three massless quarks obtain masses at small order that depends on the inverse of the large scale. Thus, masses of the form $m_u \lesssim m_d < m_s \sim MeV$ and $m_{c,b,t} \sim GeV$ can be obtained naturally from the gauge structure of the model

Structural aspects of Hamilton-Jacobi theory

In our previous papers [11,13] we showed that the Hamilton-Jacobi problem can be regarded as a way to describe a given dynamics on a phase space manifold in terms of a family of dynamics on a lower-dimensional manifold. We also showed how constants of the motion help to solve the Hamilton-Jacobi equation. Here we want to delve into this interpretation by considering the most general case: a dynamical system on a manifold that is described in terms of a family of dynamics (`slicing vector fields') on lower-dimensional manifolds. We identify the relevant geometric structures that lead from this decomposition of the dynamics to the classical Hamilton-Jacobi theory, by considering special cases like fibred manifolds and Hamiltonian dynamics, in the symplectic framework and the Poisson one. We also show how a set of functions on a tangent bundle can determine a second-order dynamics for which they are constants of the motion.Comment: 26 pages. Minor changes (some minor mistakes are corrected

Spin-orbit induced mixed-spin ground state in RRNiO3_3 perovskites probed by XAS: new insight into the metal to insulator transition

We report on a Ni L$_{2,3}$ edges x-ray absorption spectroscopy (XAS) study in $R$NiO$_3$ perovskites. These compounds exhibit a metal to insulator ($MI$) transition as temperature decreases. The L$_{3}$ edge presents a clear splitting in the insulating state, associated to a less hybridized ground state. Using charge transfer multiplet calculations, we establish the importance of the crystal field and 3d spin-orbit coupling to create a mixed-spin ground state. We explain the $MI$ transition in $R$NiO$_3$ perovskites in terms of modifications in the Ni$^{3+}$ crystal field splitting that induces a spin transition from an essentially low-spin (LS) to a mixed-spin state.Comment: 4 pages, 4 figures, accepted as PRB - Rapid Comm. Dez. 200

Procedencia de los alimentos utilizados en las explotaciones de vacuno lechero del Principado de Asturias

publishedTomo I . Sección: Sistemas Ganaderos-Economía y Gestión. Sesión: Producción de leche. Ponencia nº 2

Análisis de los suelos del piedemoente de la vertiente norte de la Sierra de Alhama (Granada, España)

[Resumen] El piedemonte que enlaza la sierra de Alhama y el poljé de Zafarraya puede considerarse como un glacis incipiente sobre el que desarrollan suelos cuya morfología es heredada del material parental. Los suelos son mayoritariamente Gleysoles y Regosoles, con o sin carbonatos, arcillosos y de fuerte consistencia, motivo que asociado al relieve justifica el alto índice de erosionabilidad y el que exijan un serio acondicionamiento para ser usado agricolamente. Dada la posición fisiográfica y la propia naturaleza edáfica, también se utiliza el terreno para almacenar agua de lluvia destinada a riego. En cuanto a la génesis, son suelos poco Desarrolla dos y el hecho evolutivo más significativo es la transformación de la arcilla heredada (ilita-interestratificados-esmectita).[Abstract] The footslope in between Alhama mountain rouge and Zafarraya polje could be considered as an incipient glacis which shows soil with an inherited morphology from the parent material developing over it. Soils are mainly Gleysols and Regosols, with or without carbonates, clayed and with a strong consistence; these characteristics asociated to relief are the justification of the high erodibility index and the excigence of a serious arranging to be farmerly used. With the fisiographic position and own edaphic nature given, even the land use could be in order to store rainfall water for irrigation. For genetical studies, these are low developed soils and the most significant thing in their evolution is the inherated clay transformation (illite-interstratified-smectite)

The lightest Higgs boson production at photon colliders in the 2HDM-III

The branching ratios of the lightest CP-even Higgs boson $h^0$, in the framework of the General Two Higgs Doublet Model are calculated. Different scenarios are presented taking into account constraints obtained in previous works on the flavor changing neutral currents factors. Plausible scenarios with flavour changing processes at tree level like $b \bar s$ and $t \bar c$ are analyzed for relevant region of parameters. The loop-induced Higgs couplings to photon pairs can be tested with a photon collider. The number of events of $h^0$ as a resonance in photon colliders are calculated taking into account its corresponding background signal in TESLA, CLIC and NLC.Comment: 1. Universidad Nacional de Colombia, Bogota, Colombia. (2) Universidad de Valencia, Valencia, Spain. 21 pages, 5 figures, RevTe