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S. Dev

Publications and source records attributed to S. Dev.

36 records · Page 2Linked to original sources
arXiv2010

CP-odd Weak Basis Invariants for Neutrino Mass Matrices with a Texture Zero and a Vanishing Minor

We construct the $CP$-odd weak basis invariants in the flavor basis for all the phenomenologically viable neutrino mass matrices with a texture zero and a vanishing minor and, also, find the necessary and sufficient conditions for $CP$ invariance . We examine the interrelationships between different $CP$-odd weak basis invariants for these texture structures and investigate their implications for Dirac- and Majorana-type $CP$ violation.

hep-ph↗
arXiv2010

Parallel hybrid textures of lepton mass matrices

We analyse the parallel hybrid texture structures in the charged lepton and the neutrino sector. These parallel hybrid texture structures have physical implications as they cannot be obtained from arbitrary lepton mass matrices through weak basis transformations. The total sixty parallel hybrid texture structures can be grouped into twelve classes, and all the hybrid textures in the same class have identical physical implications. We examine all the twelve classes under the assumption of non-factorizable phases in the neutrino mass matrix. Five out of the total twelve classes are found to be phenomenologically disallowed. We study the phenomenological implications of the allowed classes for 1-3 mixing angle, Majorana and Dirac-type $CP$ violating phases. Interesting constraints on effective Majorana mass are obtained for all the allowed classes.

hep-ph↗
arXiv2010

Leptogenesis in a Hybrid Texture Neutrino Mass Model

We investigate the CP asymmetry for a hybrid texture of the neutrino mass matrix predicted by $Q_8$ family symmetry in the context of the type-I seesaw mechanism and examine its consequences for leptogenesis. We, also, calculate the resulting Baryon Asymmetry of the Universe (BAU) for this texture.

hep-ph↗
arXiv2010

Neutrino Mass Matrices with a Texture Zero and a Vanishing Minor

We study the implications of the simultaneous existence of a texture zero and a vanishing minor in the neutrino mass matrix. There are thirty six possible texture structures of this type, twenty one of which reduce to two texture zero cases which have, already, been extensively studied. Of the remaining fifteen textures only six are allowed by the current data. We examine the phenomenological implications of the allowed texture structures for Majorana type CP-violating phases, 1-3 mixing angle and Dirac type CP-violating phase. All these possible textures can be generated through the seesaw mechanism and realized in the framework of discrete abelian flavor symmetry. We present the symmetry realization of these texture structures.

hep-ph↗
arXiv2010

Phenomenological Analysis of Hybrid Textures of Neutrinos

We present a comprehensive phenomenological analysis of the allowed hybrid textures of neutrinos. Out of a total of sixty hybrid textures with one equality between the elements of neutrino mass matrix and one texture zero only twenty three are found to be viable at 99% C.L. whereas the earlier analysis found fifty four to be viable. We examine the phenomenological implications of the allowed hybrid textures including Majorana type CP-violating phases, 1-3 mixing angle and Dirac type CP-violating phase, $δ$. We, also, obtain lower bound on effective Majorana mass for all the allowed hybrid textures.

hep-ph↗
arXiv2009

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.

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arXiv2008

Texture 4 zero Fritzsch-like lepton mass matrices

For Majorana or Dirac neutrinos, using Fritzsch-like texture 4 zero mass matrices with parallel texture structures for the charged leptons and the Dirac neutrino mass matrix (M_{νD}), detailed predictions for cases pertaining to normal/inverted hierarchy as well as degenerate scenarios of neutrino masses have been carried out. The inverted hierarchy as well as degenerate scenarios seem to be ruled out at 3 σC.L. for both Majorana and Dirac neutrinos. For normal hierarchy, Jarlskog's rephasing invariant parameter J, the CP violating Dirac-like phase δand the effective neutrino mass m_{ee} have been calculated. For this case, lower limits of m_{ν_1} and θ_{13} would have implications for the nature of neutrinos.

hep-ph↗
arXiv2008

Two-Zero Symmetric Neutrino Mass Matrices in Minimal Supersymmetric SO(10)

The phenomenological neutrino mass matrix for two-zero symmetric texture has been obtained and used to rule out all possible two-zero symmetric neutrino mass matrices obtained from Yukawa couplings to $\mathbf{10}$ and $\mathbf{126}$ Higgs representations within the framework of minimal supersymmetric SO(10).

hep-ph↗
arXiv2007

CP Violation in Two Zero Texture Neutrino Mass Matrices

It has been shown that the neutrino mass matrices with two texture zeros in the charged lepton basis predict non-zero 1-3 mixing and are necessarily CP violating with one possible exception in class C for maximal mixing.

hep-ph↗
arXiv2007

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 $θ_{23}$, the sign of $\cosδ$ and neutrino mass hierarchy can be used to lift these degeneracies.

hep-ph↗
arXiv2007

Phenomenological Implications of a Class of Neutrino Mass Matrices

The generic predictions of two-texture zero neutrino mass matrices of class A in the flavor basis have been reexamined especially in relation to the degeneracy between mass matrices of types A_1 and A_2 and interesting constraints on the neutrino parameters have been obtained. It is shown that the octant of $θ_{23}$ and the quadrant of the Dirac-type CP-violating phase $δ$ can be used to lift this degeneracy.

hep-ph↗
arXiv2007

Neutrino Parameter Space for a Vanishing $ee$ Element in the Neutrino Mass Matrix

The consequences of a texture zero at the $ee$ entry of neutrino mass matrix in the flavor basis, which also implies a vanishing effective Majorana mass for neutrinoless double beta decay, have been studied for Majorana neutrinos. The neutrino parameter space under this condition has been constrained in the light of all available neutrino data including the CHOOZ bound on $s_{13}^{2}$.

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arXiv2006

Spectral Distortions at Super-Kamiokande

We examine the effect of the rise in the survival probability of the electron neutrinos with the decrease in the neutrino energy on the recoil electron spectrum at Super-Kamiokande.

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arXiv2005

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 $^{8}$B neutrino flux reaching the detectors on the earth. The muon/ tauon antineutrino flux is found to be disallowed at 1.4$σ$ C.L. The sterile flux is found to be non-zero at about 1.26 standard deviations.

hep-ph↗
arXiv2005

Constraints on Weakly Mixed Sterile Neutrinos in the Light of SNO Salt Phase and 766.3 Ty KamLAND Data

The possibility of flavor transitions into sterile neutrinos (accompanying the dominant LMA transitions) in the solar boron neutrino flux has been examined in a scenario proposed by Hollanda and Smirnov to overcome some generic problems of the pure LMA scenario. It is found that the most recent SNO salt phase solar neutrino data and the KamLAND 766.3 Ty spectral data, allow for a significant sterile presence in the solar boron neutrino flux reaching the earth.

hep-ph↗
arXiv2004

Constraints on the Neutrino Parameters from the `Rise-up' in the Boron Neutrino Spectrum at Low Energies

The rise-up in boron neutrino spectrum at low energies has been studied within the framework of `pure LMA' scenario. Indirect bounds on the spectral `upturn' have been obtained from the available solar neutrino data. These bounds have been used to demonstrate the efficacy of the precision measurements of the `upturn' for further constraining the neutrino parameter space allowed by SNO salt phase data. The sterile neutrino flux has been constrained in the light of the recent 766.3 Ty KamLAND spectral data.

hep-ph↗
arXiv2003

Neutrino Oscillations, Solar Antineutrinos and the Solar Magnetic Fields

Even after the confirmation of the large mixing angle (LMA) solution of the solar neutrino problem, the scope for resonant spin- flavor precession (RSFP) transitions as a subdominant effect still exists. In this work,we have considered suitably suppressed RSFP transitions in addition to the dominant LMA flavor transitions and translated the bounds on the antineutrino flux into the bounds on the product of neutrino magnetic moment and solar magnetic field. The low and intermediate energy neutrinos have been included in the analysis by obtaining indirect bounds on the corresponding antineutrino fluxes for these components. It is assumed that the missing beryllium neutrinos are being converted into muon antineutrinos via RSFP transitions in the Sun.

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