AR_final file_2018-19
Bhag Chand Chauhan Bounds on sterile neutrino component in the solar neutrino flux Solar neutrinos studies have played a crucial role in the development of neutrino physics. It took decades to understand the mysterious nature of neutrinos and to identify a leading solution to the Solar Neutrino Problem (SNP). The mystery of the missing neutrinos deepened as subsequent ex- periments were performed. The energy spectrum of solar neutrinos, as predicted by standard solar models, is seen by different experiments as they are sensitive to different neutrino energy ranges. More than 98% of the calculated standard model solar neutrino flux lies below 1MeV. The rare 8 B neutrino flux is the high energy tail of solar neu- trinos, for which statistically significant measure- ments have been made so far, but this is just tip of an iceberg. As such, the study of low energy neutri- nos can give us better understanding and showcase the possibility of species other than three active neutrino flavours, mainly the sterile neutrinos ( ν s ) in solar neutrino flux. In the light of latest data available from various solar neutrino experiments including Borexino and KamLAND Solar phase we derive, in a model independent way, the bounds on sterile neutrino component present in the solar neu- trino flux. We update the limits on the sterile com- ponent and compare them with the previous results obtained using data from SNO solar salt phase and Super Kamiokande experiments. We retrieve the upper bounds existing in the literature and present the more stringent bounds on the sterile neutrino component. This work has been done in collabora- tion with Govind Singh, Ashish Sharma, Shankita Bhardwaj, and Surender Verma. Quark-lepton complementarity model based predic- tions for θ pmns 23 with neutrino mass hierarchy After the successful investigation and confirmation of non-zero θ pmns 13 by various experiments, we are standing at a square, where we still encounter a number of issues, which are to be settled. In this work, we have just extended our recent work to- wards a precise prediction of the θ pmns 23 mixing an- gle, taking into account the neutrino mass hierar- chy, In the QLC model, a non-trivial correlation between CKM and PMNS mixing matrices is ob- tained by taking into account the phase mismatch between quark and lepton sectors as a diagonal ma- trix Ψ = diag( e ιψ i ). After doing Monte Carlo simu- lations, we estimated the texture of the correlation matrix ( V c ) and compared the results with the stan- dard Tri-Bi-Maximal (TBM) and Bi-Maximal(BM) structures. We obtained predictions for θ pmns 23 for the two cases of neutrino mass hierarchies, i.e., nor- mal hierarchy (NH) and inverted hierarchy (IH). The precise values of θ pmns 23 , thus obtained for the two cases are about 3 σ away from each other, which can give a strong hint for the hierarchy of neutrino masses. This study has been done in collaboration with Gazal Sharma, Shankita Bhardwaj, and Su- dender Verma. Himadri Sekhar Das Dependence of light scattering properties on poros- ity, size and composition of dust aggregates In this work, we study the light scattering prop- erties of dust aggregates (0 . 7 µm . R c . 2 . 0 µm ) with a wide range of porosity ( P = 0.59 to 0.98). The simulations are executed using the Superposi- tion T-matrix code with BCCA, BA, BAM1 and BAM2 clusters of varying porosity. We investi- gate the nature and dependencies of the different scattering parameters on porosity, size and compo- sition of the aggregated particles for wavelengths 0.45 µ m and 0.65 µ m. We find that the scattering parameters are strongly correlated with the poros- ity of the aggregated structures. Our results in- dicate that, when the porosity of the aggregates decreases, keeping characteristic radius of the ag- gregates ( R c ) same for all structures, there is an enhancement in the negative polarization branch (NPB), which is accompanied by a substantial in- crease in the anisotropies present in the mate- rial. Also at the exact backscattering region, the anisotropies are found to be linearly correlated with the porosity of the aggregated structure. The com- putational study reveals that, for low absorbing materials ( k ≤ 0 . 1), the negative polarization min- imum ( P min ) is strongly correlated with the as- sociated anisotropies. Finally, we put forward a qualitative comparison between our computation- ally obtained results and some selected data from the Amsterdam Light Scattering Database for both low and high absorbing materials. The experimen- tal results also suggest that an increase in the NPB is always accompanied by an enhancement in the anisotropy at the backscattering region. This work has been done in collaboration with Prithish Halder ( 183 )
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