66 research outputs found
Right-handed Majorana Neutrino Mass Matrices for Generating Bimaximal Mixings in Degenerate and Inverted Models of Neutrinos
An attempt is made to generate the bimaximal mixings of the three species of
neutrinos from the textures of the right-handed Majorana neutrino mass
matrices. We extend our earlier work in this paper for the generation of the
nearly degenerate as well as the inverted hierarchical models of the
left-handed Majorana neutrino mass matrices using the non-diagonal textures of
the right-handed Majorana neutrino mass matrices and the diagonal form of the
Dirac neutrino mass matrices, within the frame work of the seesaw mechanism in
a model independent way. Such Majorana neutrino mass models are important to
explain the recently reported result on the neutrinoless double beat decay
(0/nu/beta/beta) experiment,together with the earlier established data on LMA
MSW solar and atmospheric neutrino oscillations.Comment: 14 pages, To appear in IJMPA (2003
Bimaximal Mixings from the Texture of the Right-handed Majorana Neutrino Mass Matrix
We study the origin of neutrino masses and mixing angles which can accomodate
the LMA MSW solutions of the solar neutrino anomaly as well as the solution of
the atmospheric neutrino problem, within the framework of the see-saw
mechanism. We employ the diagonal form of the Dirac neutrino mass matrices with
the physical masses as diagonal elements in the hierarchical order. Such choice
has been motivated from the fact that the known CKM angles for the quark
sector, are relatively small. We consider both possibilities where the Dirac
neutrino mass matrix is either the charged lepton or the up-quark mass matrix
within the framework of SO(10) GUT with or without supersymmetry. The non-zero
texture of the right-handed Majorana neutrino mass matrix is used for
the generation of the desired bimaximal mixings in a model independent way.
Both hierarchical and inverted hierarchical models of the left-handed Majorana
neutrino mass matrices are generated and then discussed with examples
Numerical consistency check between two approaches to radiative corrections for neutrino masses and mixings
We briefly outline the two popular approaches on radiative corrections to
neutrino masses and mixing angles, and then carry out a detailed numerical
analysis for a consistency check between them in MSSM. We find that the two
approaches are nearly consistent with a small discrepancy of a factor of 13
percent in mass eigenvalues at low energy scale, but the predictions on mixing
angles are almost consistent. We check the stability of the three types of
neutrino models, i.e., hierarchical, inverted hierarchical and degenerate
models, under radiative corrections, using both approaches, and find consistent
conclusions. The neutrino mass models which are found to be stable under
radiative corrections in MSSM are the normal hierarchical model and the
inverted hierarchical model with opposite CP parity. We also carry out
numerical analysis on some important conjectures related to radiative
corrections in MSSM, viz., radiative magnification of solar and atmospheric
mixings in case of nearly degenerate model having same CP parity (MPR
conjecture) and radiative generation of solar mass scale in exactly two-fold
degenerate model with opposite CP parity and non-zero reactor angle (JM
conjecture). We observe certain exceptions to these conjectures. Finally the
effect of scale-dependent vacuum expectation value in neutrino mass
renormalisation is discussed.Comment: 26 pages, 5 figures,references added, typos corrected and text
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Deviation from tri-bimaximal mixings in two types of inverted hierarchical neutrino mass models
An attempt is made to explore the possibility for deviations of solar mixing
angle () from tri-bimaximal mixings, without sacrificing the
predictions of maximal atmospheric mixing angle () and zero
reactor angle (). We find that the above conjecture can be
automatically realised in the inverted hierarchical neutrino mass model having
2-3 symmetry, in the basis where charged lepton mass matrix is diagonal. For
the observed ranges of and \bigtriangleup m^2_{23],
we calculate the predictions on for
different input values of the parameters in the neutrino mass matrix. We also
observe a possible crossing over from one type of inverted hierarchical model
having same CP parity (Type-IHA) to other type having opposite CP parity
(Type-IHB). Such neutrino mass matrices can be obtained from the canonical
seesaw formula using diagonal form of Dirac neutrino mass matrix and
non-diagonal texture of right-handed Majorana mass matrix, and may have
important implications in model building using discrete as well as non-abelian
symmetry groups.Comment: 13 pages, 7 figure
Discriminating neutrino mass models using Type II seesaw formula
In this paper we propose a kind of natural selection which can discriminate
the three possible neutrino mass models, namely the degenerate, inverted
hierarchical and normal hierarchical models, using the framework of Type II
seesaw formula. We arrive at a conclusion that the inverted hierarchical model
appears to be most favourable whereas the normal hierarchical model follows
next to it. The degenerate model is found to be most unfavourable. We use the
hypothesis that those neutrino mass models in which Type I seesaw term
dominates over the Type II left-handed Higgs triplet term are favoured to
survive in nature.Comment: No change in the results, a few references added, some changes in
Type[IIB] calculation
Deciphering the Arginine-Binding Preferences at the Substrate-Binding Groove of Ser/Thr Kinases by Computational Surface Mapping
Protein kinases are key signaling enzymes that catalyze the transfer of γ-phosphate from an ATP molecule to a phospho-accepting residue in the substrate. Unraveling the molecular features that govern the preference of kinases for particular residues flanking the phosphoacceptor is important for understanding kinase specificities toward their substrates and for designing substrate-like peptidic inhibitors. We applied ANCHORSmap, a new fragment-based computational approach for mapping amino acid side chains on protein surfaces, to predict and characterize the preference of kinases toward Arginine binding. We focus on positions P−2 and P−5, commonly occupied by Arginine (Arg) in substrates of basophilic Ser/Thr kinases. The method accurately identified all the P−2/P−5 Arg binding sites previously determined by X-ray crystallography and produced Arg preferences that corresponded to those experimentally found by peptide arrays. The predicted Arg-binding positions and their associated pockets were analyzed in terms of shape, physicochemical properties, amino acid composition, and in-silico mutagenesis, providing structural rationalization for previously unexplained trends in kinase preferences toward Arg moieties. This methodology sheds light on several kinases that were described in the literature as having non-trivial preferences for Arg, and provides some surprising departures from the prevailing views regarding residues that determine kinase specificity toward Arg. In particular, we found that the preference for a P−5 Arg is not necessarily governed by the 170/230 acidic pair, as was previously assumed, but by several different pairs of acidic residues, selected from positions 133, 169, and 230 (PKA numbering). The acidic residue at position 230 serves as a pivotal element in recognizing Arg from both the P−2 and P−5 positions
A class of neuro-computational methods for assamese fricative classification
In this work, a class of neuro-computational classifiers are used for classification of fricative
phonemes of Assamese language. Initially, a Recurrent Neural Network (RNN) based
classifier is used for classification. Later, another neuro fuzzy classifier is used for classification.
We have used two different feature sets for the work, one using the specific
acoustic-phonetic characteristics and another temporal attributes using linear prediction
cepstral coefficients (LPCC) and a Self Organizing Map (SOM). Here, we present the
experimental details and performance difference obtained by replacing the RNN based
classifier with an adaptive neuro fuzzy inference system (ANFIS) based block for both
the feature sets to recognize Assamese fricative sounds
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