See-saw mechanism and four light neutrino state

A formal proof is given that in a see-saw type neutrino mass matrix with only two neutrino mass scales ($m_D \ll m_R$) and the maximal rank of $m_{R(D)}$, we can not get a fourth light sterile neutrino.Comment: 5 page

The Sliding Singlet Mechanism with Gauge Mediated Supersymmetry Breaking

The sliding singlet mechanism is one of the most interesting solutions of the triplet-doublet splitting problem. We analyze this mechanism in the gauge mediated supersymmetry breaking scenario. We show that the sliding singlet mechanism does not work in the naive gauge mediation scenario because of the singlet linear terms derived from the gravity, although $F$ term is much smaller than the one in the gravity mediation scenario. We also consider the extension in order for the sliding singlet mechanism to work.Comment: LaTeX 15 pages, no figures, mistakes in Eq.(3.27) crrected, a part of conclusion correcte

Phenomenological Consequences of sub-leading Terms in See-Saw Formulas

Several aspects of next-to-leading (NLO) order corrections to see-saw formulas are discussed and phenomenologically relevant situations are identified. We generalize the formalism to calculate the NLO terms developed for the type I see-saw to variants like the inverse, double or linear see-saw, i.e., to cases in which more than two mass scales are present. In the standard type I case with very heavy fermion singlets the sub-leading terms are negligible. However, effects in the percent regime are possible when sub-matrices of the complete neutral fermion mass matrix obey a moderate hierarchy, e.g. weak scale and TeV scale. Examples are cancellations of large terms leading to small neutrino masses, or inverse see-saw scenarios. We furthermore identify situations in which no NLO corrections to certain observables arise, namely for mu-tau symmetry and cases with a vanishing neutrino mass. Finally, we emphasize that the unavoidable unitarity violation in see-saw scenarios with extra fermions can be calculated with the formalism in a straightforward manner.Comment: 22 pages, matches published versio

Dynamical Doublet-Triplet Higgs Mass Splitting

We propose a new mechanism towards the solution to the doublet-triplet Higgs mass splitting problem in the supersymmetric grand unified theory. Our model is based on the gauge group $SU(5)_H \times SU(5)_{GUT}$, where $SU(5)_H$ and $SU(5)_{GUT}$ are a new strong gauge interaction and the ordinary grand unified gauge group, respectively. The doublet-triplet Higgs mass splitting is realized through the quantum deformation of moduli space caused by the strong $SU(5)_H$ gauge dynamics. The low energy description of our model is given by the minimal supersymmetric standard model.Comment: 9 pages, LaTeX, the version to be published in Phys. Rev. D. (some typographical errors have been corrected

Connecting bimaximal neutrino mixing to a light sterile neutrino

It is shown that if small neutrino masses owe their origin to the conventional seesaw mechanism and the MNS mixing matrix is in the exact bimaximal form, then there exist symmetries in the theory that allow one of the righthanded neutrinos to become naturally massless, making it a candidate for the sterile neutrino discussed in the literature. Departures from the exact bimaximal limit leads to tiny mass for the sterile neutrino as well as its mixing to the active neutrinos. This provides a minimal theoretical framework where a simultaneous explanation of the solar, atmospheric and LSND observations within the so-called 3+1 scenario may be possible.Comment: new references added; paper accepted for publication in Phys. Rev. D.(rapid communications); note adde

Identifying causes of Western Pacific ITCZ drift in ECMWF System 4 hindcasts

The development of systematic biases in climate models used in operational seasonal forecasting adversely affects the quality of forecasts they produce. In this study, we examine the initial evolution of systematic biases in the ECMWF System 4 forecast model, and isolate aspects of the model simulations that lead to the development of these biases. We focus on the tendency of the simulated intertropical convergence zone in the western equatorial Pacific to drift northwards by between 0.5° and 3° of latitude depending on season. Comparing observations with both fully coupled atmosphere–ocean hindcasts and atmosphere-only hindcasts (driven by observed sea-surface temperatures), we show that the northward drift is caused by a cooling of the sea-surface temperature on the Equator. The cooling is associated with anomalous easterly wind stress and excessive evaporation during the first twenty days of hindcast, both of which occur whether air-sea interactions are permitted or not. The easterly wind bias develops immediately after initialisation throughout the lower troposphere; a westerly bias develops in the upper troposphere after about ten days of hindcast. At this point, the baroclinic structure of the wind bias suggests coupling with errors in convective heating, although the initial wind bias is barotropic in structure and appears to have an alternative origin

The minimal adjoint-SU (5) x Z(4) GUT model

An extension of the adjoint SU (5) model with a flavour symmetry based on the Z(4) group is investigated. The Z(4) symmetry is introduced with the aim of leading the up-and down-quark mass matrices to the Nearest-Neighbour-Interaction form. As a consequence of the discrete symmetry embedded in the SU (5) gauge group, the charged lepton mass matrix also gets the same form. Within this model, light neutrinos get their masses through type-I, type-III and one-loop radiative seesaw mechanisms, implemented, respectively, via a singlet, a triplet and an octet from the adjoint fermionic 24 fields. It is demonstrated that the neutrino phenomenology forces the introduction of at least three 24 fermionic multiplets. The symmetry SU (5) x Z(4) allows only two viable zero textures for the effective neutrino mass matrix. It is showed that one texture is only compatible with normal hierarchy and the other with inverted hierarchy in the light neutrino mass spectrum. Finally, it is also demonstrated that Z(4) freezes out the possibility of proton decay through exchange of coloured Higgs triplets at tree-level

Electron spin resonance evidence for dimer formation in high spin iron(III)-octaethylporphyrin and iron(III)-meso-nitro-octaethylporphyrin in solution

E.s.r. signals representing a dimeric species and another form of aggregation in high-spin FeIIICl-meso-nitro-octaethylporphyrin (OEP) (1) are presented, and a spectral assignment is made for the dimer signal to a transition within the lowest triplet levels

Evidence for dimer formation of nitrosyl(meso-2,3,7,8,12,13,17,18-octaethyl-5-nitroporphyrinato)iron(II) and its implication in the interpretation of the electron spin resonance spectrum of the nitrosyl-haemoglobin-salicylate system

Dimer formation of the title complex in toluene has been demonstrated by an electron spin resonance study of this complex at a high concentration at 9 K, and the approximate dimer structure has been determined by spectral simulation. The observation enables us to interpret the hitherto unexplained four resonance absorptions which are known to appear in nitric oxide ligated haemoglobin (NO-haem) as a result of interaction with salicylate, on the basis of similar dimer formation of the NO-haem prosthetic groups. The event appears to take place intramolecularly by association of NO-haem molecules coming out of the haem pockets, and the complex is stabilized by the globin structure

Concentration- and solvent-dependent electron spin resonance signals and dimer formation of high-spin iron(III) porphyrins

High-spin iron(III) prophyrins in frozen solutions show extra e.s.r. signals, in addition to the well known parallel (g = 2) and perpendicular (g = 6) absorption, which are remarkably sensitive to the concentration, solvent composition, pH, or the temperature. For example, two signals with g values around 3 and 11, respectively, are observed in moderately concentrated solutions of chloro(meso-nitro-octaethylporphyrinato)iron(III), in neutral and alkaline solutions of hemin when methanol is added, or in acidic solutions of tetrasodium phenylporphyrin-tetrasulphonatoferrate(III). The signals to higher field with g ca. 3 are interpreted as belonging to a dimeric species, on the basis of a simulation made by assuming a structure having two porphyrin planes arranged parallel. Another characteristic signal, which was observed in alkaline solutions of hemin or the tetrasodium ferrate, appears as a pair of shoulders with the g = 6 monomer peak in the middle. This type of signal is assigned to a dimer having a large Fe-Fe distance as well as skew angle. The effect of adding methanol, ethanol, or sucrose to the alkaline solutions of hemin, inducing further additional signals, and that of NaCl addition, which suppresses the overall intensity, are described and discussed in relation to previous studies by spectrophotometric and magnetic susceptibility measurements