arXiv subjects

Abhijit Borah

Publications and source records attributed to Abhijit Borah.

4 recordsLinked to original sources

arXiv2009

Degenerate neutrino mass models revisited

A parametrisation of the degenerate neutrino mass matrix obeying $μ-τ$ symmetry, is introduced for detailed numerical analysis. As a continuation of our earlier work on normal and inverted hierarchical models, the present parametrisation for degenerate models has the ability to lower the solar mixing angle below the tri-bimaximal value $\tan^{2}θ_{12}=0.5$, while maintaining the condition of maximal atmospheric mixing angle and zero reactor angle. The combined data on the mass-squared differences derived from various oscillation experiments, and also from the bounds on absolute neutrino masses in $0νββ$ decay and cosmology, gives certain constraints on the validity of the degenerate models.

hep-ph↗

arXiv2006

Lowering solar mixing angle in inverted hierarchy without charged lepton corrections

In the present work, the inverted hierarchical neutrino mass model which is characterised by opposite CP parity in the first two mass eigenvalues $(m_1,-m_2,m_3)$, is studied in order to lower the predicted value of solar mixing angle $\tan^2θ_{12}$, from the tri-bimaximal mixing (TBM), without sacrificing the conditions of maximal atmospheric mixing angle and zero reactor angle. The present attempt is different from the earlier approach where the correction from the charged lepton mass matrix is included in the leptonic mixing matrix to lower the prediction on solar mixing angle. The lowering of the solar mixing angle without charged lepton correction, can be obtained through the variation of the input value of a flavour twister term present in the texture of neutrino mass matrix having a 2-3 symmetry. The present analysis agrees with the latest experimental bounds on neutrino mass parameters and also represents an important result on the survival of the inverted hierarchical neutrino mass models having opposite CP parity in the first two eigenvalues.

hep-ph↗

arXiv2006

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 ($θ_{12}$) from tri-bimaximal mixings, without sacrificing the predictions of maximal atmospheric mixing angle ($θ_{23}=π/4$) and zero reactor angle ($θ_{13}=0$). 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 $\bigtriangleup m^2_{21}$ and $\bigtriangleup m^2_{23]$, we calculate the predictions on $\tan^2θ_{12}=0.5, 0.45, 0.35$ 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.

hep-ph↗

arXiv2002

Interaction of Coupled Higher Order Nonlinear SCHRÖdinger Equation Solitons

The novel inelastic collision properties of two-soliton interaction for an $n$-component coupled higher order nonlinear Schrödinger equation are studied. Some interesting features of three soliton interactions, related to the integrability of the $n$-component coupled higher order nonlinear Schrödinger equation are also discussed.

nlin.SI↗