Boron abundance and solar neutrino spectrum distortion

The presence of neutrinos from Boron decay in the flux observed on Earth is attested by the observation of their energy spectrum. Possible distortions of the spectrum investigated in current detectors are often interpreted in terms of evidence in favour or against various schemes of neutrino oscillations. We stress here that a distortion of the spectrum at high energies could also result from an increase in the ratio of neutrinos originating from ($^3$He+p) and $^8$B reactions. While a $^8$B neutrino depletion would contribute to this effect, an increase in the Hep contribution seems also needed to reproduce the preliminary data.Comment: 8 pages, 2 figures; abstract and introduction rewritten to match the conclusions bette

See-saw neutrino masses and large mixing angles in the vortex background on a sphere

In the vortex background on a sphere, a single 6-dimensional fermion family gives rise to 3 zero-modes in the 4-dimensional point of view, which may explain the replication of families in the Standard Model. Previously, it had been shown that realistic hierarchical mass and mixing patterns can be reproduced for the quarks and the charged leptons. Here, we show that the addition of a single heavy 6-dimensional field that is gauge singlet, unbound to the vortex, and embedded with a bulk Majorana mass enables to generate 4D Majorana masses for the light neutrinos through the see-saw mechanism. The scheme is very predictive. The hierarchical structure of the fermion zero-modes leads automatically to an inverted pseudo-Dirac mass pattern, and always predicts one maximal angle in the neutrino see-saw matrix. It is possible to obtain a second large mixing angle from either the charged lepton or the neutrino sector, and we demonstrate that this model can fit all observed data in neutrino oscillations experiments. Also, U_{e3} is found to be of the order ~0.1.Comment: 23 pages, 1 figur

Molecular Engineering of the Internal Charge Transfer in Thiophene−Triphenylamine Hybrid π-Conjugated Systems

Introduction of electroaccepting groups at the periphery of triphenylamine-based derivatives leads to an internal charge-transfer band. Syntheses and spectroscopic, electrochemical, and theoretical studies of various derivatives which differ by the strength and the number of electroacceptor groups are presented. These various results show that the ICT band and the acceptor/donor abilities of derivatives can be finely tuned

Leptogenesis, Z' bosons, and the reheating temperature of the Universe

We study the impact for leptogenesis of new U(1) gauge bosons coupled to the heavy Majorana neutrinos. They can significantly enhance the efficiency of thermal scenarios in the weak washout regime as long as the Z' masses are not much larger than the reheating temperature ($M_{Z'}<10 T_{rh}$), with the highest efficiencies obtained for Z' bosons considerably heavier than the heavy neutrinos ($M_{Z'} > 100 M_1$). We show how the allowed region of the parameter space is modified in the presence of a Z' and we also obtain the minimum reheating temperature that is required for these models to be successful.Comment: 14 pages, 6 figures; One figure added, discussion on the reheating temperature extende

CP violation in 5D Split Fermions Scenario

We give a new configuration of split fermion positions in one extra dimension with two different Yukawa coupling strengths for up-type, $h_u$, and down-type, $h_d$, quarks at $\frac{h_u}{h_d}=36.0$. The new configurations can give enough CP violating (CPV) phase for accommodating all currently observed CPV processes. Therefore, a 5D standard model with split fermions is viable. In addition to the standard CKM phase, new CPV sources involving Kaluza-Klein(KK) gauge bosons coupling which arise from the fact that unitary rotation which transforms weak eigenstates into their mass eigenstates only holds for the zero modes which are the SM fields and not for the KK excitations. We have examined the physics of kaon, neutron, and $B/D$ mesons and found the most stringent bound on the size $R$ of the extra dimension comes from $|\epsilon_K|$. Moreover, it depends sensitively on the width, $\sigma$, of the Gaussian wavefunction in the extra dimension used to describe of the fermions. When $\sigma/R \ll 1$, the constraint will be lifted due to GIM suppression on the flavor changing neutral current(FCNC) and CPV couplings.Comment: 24 pages, 8 figure

Synthesis, spectroscopic and electrochemical properties of new covalent assemblies between TTF and various acceptors

Five new acceptor-π–TTF-π-acceptor (A–D–A) triads that contain pyridine, quinoline, nitrophenyl or nitrofuryl groups as acceptor unit have been synthesized by two-fold Wittig olefination reactions and their electrochemical behavior has been studied by cyclic voltammetry (CV). The intramolecular charge transfer (ICT) band in these molecules was characterized by UV–visible electronic absorption spectroscopy and these studies were completed by DFT calculations in the gas phase. These materials appear to be good candidates for the preparation of electroactive discrete metal complexes or coordination polymers as well as for the preparation of radical cations salts

Localisation of Fermions to brane: Codimension d≥2d \geq 2

We investigate $4+d$ dimensional fermionic models in which the system in codimension-$d$ supports a topologically stable solution, and in which the fermion may be localised to the brane, with power law in 'instanton' backgrounds and exponentially in 'soliton' backgrounds. When the fermions are isoscalars, the mechanism fails, while for isospinor fermions it is successful. As backgrounds we consider instantons of Yang--Mills and sigma models in even codimensions, solitons of sigma models in odd codimensions, as well as solitons of Higgs and Goldstone models in all codimensions.Comment: 20 pages latex; expande

Custodial SU(2) Violation and the Origin of Fermion Masses

Custodial $SU(2)$ breaking due to dynamical fermion masses is studied in a rather general context and it is shown how some well known limiting cases are correctly described. The type of ``gap equation'' which can systematically lead to extra negative contributions to the so--called $\rho$--parameter is emphasized. Furthermore general model independent features are discussed and it is shown how electro--weak precision measurements can be sensitive to the fermion content and/or dynamical features of a given theory.Comment: HD-THEP-92-55, 18 pages and 2 pages of figures appended as Postscript fil

Searching for family-number conserving neutral gauge bosons from extra dimensions

Previous studies have shown how the three generations of the Standard Model fermions can arise from a single generation in more than four dimensions, and how off-diagonal neutral couplings arise for gauge-boson Kaluza-Klein recurrences. These couplings conserve family number in the leading approximation. While an existing example, built on a spherical geometry, suggests a high compactification scale, we conjecture that the overall structure is generic, and work out possible signatures at colliders, compatible with rare decays data.Comment: 4 pages, 2 figures, jetpl.cls style, references adde

Bound on the Dark Matter Density in the Solar System from Planetary Motions

High precision planet orbital data extracted from direct observation, spacecraft explorations and laser ranging techniques enable to put a strong constraint on the maximal dark matter density of a spherical halo centered around the Sun. The maximal density at Earth's location is of the order $10^5$ ${\rm GeV/cm^3}$ and shows only a mild dependence on the slope of the halo profile, taken between 0 and -2. This bound is somewhat better than that obtained from the perihelion precession limits.Comment: 7 pages, 1 figur