15348251
Implications of unitarity and precision measurements on CKM matrix elements
Abstract Unitarity along with precision measurements of sin 2 β , V u s and V c b allows one to find a lower bound V u b ⩾ 0.0035 which, on using the recently measured angle α of the unitarity triangle, translates to V u b = 0.0035 ± 0.0002 . This precise value, stable for a good deal of changes in α , along with CP violating phase δ found from unitarity allows the construction of a ‘precise’ CKM matrix. The above unitarity based value of V u b is in agreement with the latest exclusive value used as input by UTfit, CKMfitter, HFAG, however underlines the so-called ‘tension’ faced by the latest inclusive V u b = 0.00449 ± 0.00033 . Further, using this inclusive value of V u b along with the latest sin 2 β , one finds δ = 23 ° – 39 ° , again in conflict with δ measured in B-decays. The calculated ranges of the elements of the CKM matrix are in excellent agreement with those obtained recently by UTfit, CKMfitter and HFAG. Also, the ratio V t s V t d is in agreement with its latest measured value, whereas there is some disagreement between the ‘measured’ and the calculated V t d values.
119298119
Unitarity constraints on trimaximal mixing
When the neutrino mass eigenstate {nu}{sub 2} is trimaximally mixed, the mixing matrix is called trimaximal. The middle column of the trimaximal mixing matrix is identical to tribimaximal mixing and the other two columns are subject to unitarity constraints. This corresponds to a mixing matrix with four independent parameters in the most general case. Apart from the two Majorana phases, the mixing matrix has only one free parameter in the CP conserving limit. Trimaximality results in interesting interplay between mixing angles and CP violation. A notion of maximal CP violation naturally emerges here: CP violation is maximal for maximal 2-3 mixing. Similarly, there is a natural constraint on the deviation from maximal 2-3 mixing which takes its maximal value in the CP conserving limit.
16931053
CP-odd weak basis invariants and texture zeros
We construct the CP-odd weak basis invariants from the neutrino mass matrix in a weak basis, in which the charged lepton mass matrix is diagonal, and find the necessary and sufficient conditions for CP conservation. We study the interrelationships between different CP-odd weak basis invariants to examine their implications for the Dirac- and Majorana-type CP violating phases for the phenomenologically allowed Frampton-Glashow-Marfatia texture zero structures of the neutrino mass matrix.
16460683
MODEL INDEPENDENT CONSTRAINTS ON NON-ELECTRONIC FLAVORS IN THE SOLAR BORON NEUTRINO FLUX
We perform the most general model-independent analysis of the latest 391-Day Salt Phase SNO Data Set incorporating the super-Kamiokande ES flux measurement and obtain bounds on the antineutrino and sterile neutrino flux in the solar 8B neutrino flux reaching the detectors on the earth. The muon/tauon antineutrino flux is found to be disallowed at 1.4σ C.L. The sterile flux is found to be nonzero at about 1.26 standard deviations.
15297169
Phenomenological implications of a class of neutrino mass matrices
Phenomenological implications of a class of lepton mass matrices with parallel texture structure have been examined and phenomenologically interesting constraints on charged lepton and neutrino mass matrix parameters have been obtained.
2063566
Phenomenology of Two-Texture Zero Neutrino Mass Matrices
The generic predictions of two-texture zero neutrino mass matrices in the flavor basis have been examined especially in relation to the degeneracies between mass matrices within a class and interesting constraints on the neutrino parameters have been obtained. It is shown that the knowledge of the octant of ${\ensuremath{\theta}}_{23}$, the sign of $\mathrm{cos}﻿\ensuremath{\delta}$, and neutrino mass hierarchy can be used to lift these degeneracies.
122510459
Exact Bianchi Type-I Cosmological Models in a Scalar-Tensor Theory
Abstract
In this paper, a spatially homogeneous and anisotropic Bianchi type-I space-time filled with perfect fluid is investigated within the framework of a scalar-tensor theory proposed by Saez and Ballester. Two different physically viable models of the universe are obtained by using a special law of variation for Hubble’s parameter that yields a constant value of deceleration parameter. One of the models is found to generalize a model recently investigated by Reddy et al. (Astrophys. Space Sci. 306:171, 2006). The Einstein’s field equations are solved exactly and the solutions are found to be consistent with the recent observations of type Ia supernovae. A detailed study of physical and kinematical properties of the models is carried out.

117717582
The Bottom of the Main Sequence and Beyond: Speculations, Calculations, Observations, and Discoveries (1958-2002)
In this paper, I briefly review the theoretical and observational work done since 1958 on the gaseous objects with mass below the H-burning limit. Special attention is paid to the theory that I developed during the period 1958-1962 for the hydrogen-rich gaseous objects with mass below the minimum main sequence mass of ~ 0.08 Msun. The three main predictions of this theory (Kumar 1962a; Kumar 1962b; Kumar 1963a; Kumar 1963b) are discussed. Fragmentation processes for interstellar clouds are discussed, and it is pointed out that the minimum mass of a gaseous fragment may be as low as 0.001 Msun. Observational results obtained since 1995 on the luminous and dark objects of very low mass are briefly reviewed. Comments are made on the basic nature of the stars and planets, and it is pointed out that processes of star formation are fundamentally different from those of planet formation. Arguments are presented to show that some of the very-low-mass dark companions, discovered since 1995, were most probably formed by the star formation processes and not by the planet formation processes.
14314222
A Large area plastic scintillator detector array for fast neutron measurements
Abstract A large area plastic scintillator detector array ( ∼ 1 × 1 m 2 ) has been set up for fast neutron spectroscopy at the BARC-TIFR Pelletron laboratory, Mumbai. The energy, time and position response has been measured for electrons using radioactive sources and for monoenergetic neutrons using the 7 Li ( p , n 1 ) 7 Be * ( 0.429 MeV ) reaction at proton energies between 6.3 and 19 MeV. A Monte Carlo simulation of the energy dependent efficiency of the array for neutron detection is in agreement with the 7 Li ( p , n 1 ) measurements. The array has been used to measure the neutron spectrum, in the energy range of 4–12 MeV, in the reaction C 12 + Nb 93 at E ( C 12 ) = 40 MeV . This is in reasonable agreement with a statistical model calculation.
120879756
Neck formation and deformation effects in a preformed cluster model of exotic cluster decays
Using the nuclear proximity approach and the two center nuclear shape parametrization, the interaction potential between two deformed and pole-to-pole oriented nuclei forming a necked configuration in the overlap region is calculated and its role is studied for the cluster decay half-lives. The barrier is found to move to a larger relative separation, with its proximity minimum lying in the neighborhood of the Q value of decay and its height and width reduced considerably. For cluster decay calculations in the preformed cluster model of Malik and Gupta, due to deformations and orientations of nuclei, the (empirical) preformation factor is found to get reduced considerably and agrees nicely with other model calculations known to be successful for their predictions of cluster decay half-lives. Comparison with the earlier case of nuclei treated as spheres suggests that the effects of both deformations and neck formation get compensated by choosing the position of cluster preformation and the inner classical turning point for penetrability calculations at the touching configuration of spherical nuclei. {copyright} {ital 1997} {ital The American Physical Society}
122883207
AN EXACT BIANCHI TYPE-I COSMOLOGICAL MODEL IN LYRA'S MANIFOLD
A spatially homogeneous and anisotropic Bianchi type-I space–time has been studied within the framework of Lyra's geometry. Exact solutions of the Einstein's field equations have been obtained with a time dependent gauge function by using a special law of variation for Hubble's parameter that yields a constant value of deceleration parameter. It has been found that the solutions generalize the solutions obtained by Rahaman et al. [Astrophys. Space Sci.299, 211 (2005)] and are consistent with the recent observations of type Ia supernovae. A detailed study of physical and kinematical properties of the model has been carried out.