20 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
Axially symmetric, asymptotically flat vacuum metric with a naked singularity and closed timelike curves
We present an axially symmetric, asymptotically flat empty space solution of
the Einstein field equations containing a naked singularity. The spacetime is
regular everywhere except on the symmetry axis where it possess a true
curvature singularity. The spacetime is of type D in the Petrov classification
scheme and is locally isometric to the metrics of case IV in the Kinnersley
classification of type D vacuum metrics. Additionally, the spacetime also shows
the evolution of closed timelike curves (CTCs) from an initial hypersurface
free from CTCs.Comment: 8 pages, no figure
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
Inverted Hierarchical Model of Neutrino Masses Revisited
In this letter we highlight the inherent problems associted with the inverted
hierarchical model of neutrinos with only three generations and suggest
possible solutions within the MSSM. we discuss the new parametrisation of the
solar mixing angle which can identify the light side and dark side of the data.
We then argue whether the inverted hierarchical neutrino mass matrix can
explain the large mixing angle(LMA) MSW solution of the solar neutrino anomaly
in the presence of an appropriate texture of charged lepton mass matrix. In
model independent way we explore such specific form of the charged lepton mass
matrix having special structure in 1-2 block. The contribution to the solar
mass splitting arising out of radiative corrections in MSSM, is calculated,
thus making the model stable under radiative corrections.Comment: 4pages (To appear in Physics Letters
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
modifie