The Effects of Majorana Phases in Estimating the Masses of Neutrinos

Majorana CP violating phases coming from heavy right-handed Majorana mass matrices ($M_{RR}$) are considered to estimate the masses of neutrinos.The effects of phases on quasi-degenerate neutrinos mass matrix obeying $\mu$-$\tau$ symmetry predicts the results consistent with observations for (i) solar mixing angle($\theta_{12}$) below TBM, (ii) absolute neutrino mass parameters[$m_{ee}$] in neutrinoless double beta ($0\nu\beta\beta$) decay, and (iii) cosmological upper bound $\sum_{i}m_{i}$. Analysis is carried out through parameterization of light left-handed Majorana neutrino matrices $(m_{LL})$ using only two unknown parameters $(\epsilon,\eta)$ within $\mu$-$\tau$ symmetry. We consider the charge lepton and up quark matrices as diagonal form of Dirac neutrino mass matrix $(m_{LR})$, and $m_{RR}$ are genrated using $m_{LL}$ through inversion of Type-I seesaw formula. The analysis shows that the masses of neutrinos are in agreement with the upper bound from cosmology and neutrinoless double beta decay. The results presented in this article will have important implications in discriminating the neutrinos mass models.Comment: arXiv admin note: substantial text overlap with arXiv:1206.343

Quasi-Degenerate Neutrino Masses with Normal and Inverted Hierarchy

The effects of CP-phases on the three absolute quasi-degenerate Majorana neutrino (QDN) masses are stud-ied with neutrino mass matrices obeying {\mu} - {\tau} symmetry for normal as well as inverted hierarchical mass patterns. We have made further investigations on 1) the prediction of solar mixing angle which lies below tri-bimaximal mixing value in consistent with neutrino oscillation observational data, 2) the prediction on absolute neutrino mass parameter (mee) in 0{\nu}{\beta}{\beta} decay, and 3) cosmological bound on the sum of the three absolute neutrino masses. The numerical analysis is carried out through the parameterization of neu- trino mass matrices using only two unknown parameters ({\epsilon}, {\eta}) within {\mu} - {\tau} symmetry. The results show the validity of QDN mass models in both normal and inverted hierarchical patterns. These models are far from discrimination and hence not yet ruled out. The results presented in this article are new and have subtle ef- fects in the discrimination of neutrino mass models.Comment: 8 pages, gave a contributory Talk at Ist IAS-CERN Singpore, Jan 2012; Journal of Modern Physics (JMP), Vol 2. No.11, November 2011 US

BARYON ASYMMETRY IN NEUTRINO MASS MODELS WITH AND WITHOUT �

We investigate the comparative studies of cosmological baryon asymmetry in different neutrino mass models with and without 13 by considering the three diagonal form of Dirac neutrino mass matrices: down quark (4,2), up-quark (8,4) and charged lepton (6,2). The predictions of any models with 13 are consistent in all the three stages of leptogenesis calculations and the results are better than the predictions of any models without 13 which are consistent in a piecemeal manner with the observational data. For the best model NH-IA (6,2) without 13, the predicted inflaton mass required to produce the observed baryon asymmetry is found to be ~3.6 × 1010 GeV corresponding to reheating temperature ~4.5 × 106 GeV, while for the same model with 13: ~2.24 × 1011 GeV, ~4.865 × 106 GeV and weak scale gravitino mass 2/3~100 GeV without causing the gravitino problem. These values apply to the recent discovery of Higgs boson of mass ~ 125 GeV. The relic abundance of gravitino is proportional to the reheating temperature of the thermal bath. One can have the right order of relic dark matter abundance only if the reheating temperature is bounded to below 107GeV. PACS numbers: 12.60.-I, 14.60.Pq, 95.35. +d, 98.80.C

BARYON ASYMMETRY IN NEUTRINO MASS MODELS WITH AND WITHOUT �

We investigate the comparative studies of cosmological baryon asymmetry in different neutrino mass models with and without 13 by considering the three diagonal form of Dirac neutrino mass matrices: down quark (4,2), up-quark (8,4) and charged lepton (6,2). The predictions of any models with 13 are consistent in all the three stages of leptogenesis calculations and the results are better than the predictions of any models without 13 which are consistent in a piecemeal manner with the observational data. For the best model NH-IA (6,2) without 13, the predicted inflaton mass required to produce the observed baryon asymmetry is found to be ~3.6 × 1010 GeV corresponding to reheating temperature ~4.5 × 106 GeV, while for the same model with 13: ~2.24 × 1011 GeV, ~4.865 × 106 GeV and weak scale gravitino mass 2/3~100 GeV without causing the gravitino problem. These values apply to the recent discovery of Higgs boson of mass ~ 125 GeV. The relic abundance of gravitino is proportional to the reheating temperature of the thermal bath. One can have the right order of relic dark matter abundance only if the reheating temperature is bounded to below 107GeV. PACS numbers: 12.60.-I, 14.60.Pq, 95.35. +d, 98.80.C

Neutrino Mixing Phenomenology: A4A_4 Discrete Flavor Symmetry with Type-I Seesaw Mechanism

We study a neutrino mass model with $A_4$ flavor symmetry using a type-I seesaw mechanism. The inclusion of extra flavons in our model leads to the deviations from exact tribimaximal mixing pattern resulting in a nonzero $\theta_{13}$ consistent with the recent experimental results and a sum rule for light neutrino masses is also obtained. In this framework, a connection is established among the mixing angles ($\theta_{13}$, $\theta_{12}$, $\theta_{13}$) and the Dirac CP-violation phase $\delta_{CP}$. This model also allows us a prediction of Jarlskog parameter $J_{CP}$ and the octant of the mixing angle $\theta_{23}$. We use the parameter space of our model of neutrino masses to study the neutrinoless double beta decay parameter $m_{ee}$.Comment: 15 pages, 3 Figures, 2 Table

Non-zero θ13\theta_{13}, CP-violation and Neutrinoless Double Beta Decay for Neutrino Mixing in the A4×Z2×Z2′A_4\times Z_2\times Z_2^\prime Flavor Symmetry Model

We study the modification of the Altarelli-Feruglio $A_4$ flavor symmetry model by adding three singlet flavons $\xi'$, $\xi''$ and $\rho$ and the model is augmented with extra $Z_2\times Z_2^ \prime$ symmetry to prevent the unwanted terms in our study. The addition of these three flavons lead to two higher order corrections in the form of two perturbation parameters $\epsilon$ and $\epsilon^\prime$. These corrections yield the deviation from exact tri-bimaximal (TBM) neutrino mixing pattern by producing a non-zero $\theta_{13}$ and other neutrino oscillation parameters which are consistent with the latest experimental data. In both the corrections, the neutrino masses are generated via Weinberg operator. The analysis of the perturbation parameters $\epsilon$ and $\epsilon^\prime$, shows that normal hierarchy (NH) and inverted hierarchy (IH) for $\epsilon$ does not change much. However, as the values of $\epsilon^\prime$ increases, $\theta_{23}$ occupies the lower octant for NH case. We further investigate the neutrinoless double beta decay parmeter $m_{\beta\beta}$ using the parameter space of the model for both normal and inverted hierarchies of neutrino masses.Comment: 19 pages, 6 figures, 3 table

Neutrino Mass Model in the Context of Δ(54)⊗Z2⊗Z3⊗Z4\boldsymbol{\Delta(54) \otimes Z_2\otimes Z_3 \otimes Z_4} Flavor Symmetries with Inverse Seesaw Mechanism

Our analysis involves enhancing the $\Delta(54)$ flavor symmetry model with Inverse Seesaw mechanism along with two SM Higgs through the incorporation of distinct flavons. Additionally, we introduce supplementary $Z_2\otimes Z_3 \otimes Z_4$ symmetries to eliminate any undesirable components within our investigation. The exact tri-bimaximal neutrino mixing pattern undergoes a deviation as a result of the incorporation of extra flavons, leading to the emergence of a non-zero reactor angle $\theta_{13}$ that aligns with the latest experimental findings. It was found that for our model the atmospheric oscillation parameter occupies the lower octant for normal hierarchy case. We also examine the parameter space of the model for normal hierarchy to explore the Dirac CP ($\delta_{CP}$), Jarlskog invariant parameter ($J$) and the Neutrinoless double-beta decay parameter ($m_{\beta\beta}$) and found it in agreement with the neutrino latest data. Hence our model may be testable in the future neutrino experiments.Comment: 18 pages, 6 figures, 3 table

Lower gut abundance of Eubacterium rectale is linked to COVID-19 mortality

IntroductionEmerging preclinical and clinical studies suggest that altered gut microbiome composition and functions are associated with coronavirus 2019 (COVID- 19) severity and its long-term complications. We hypothesize that COVID-19 outcome is associated with gut microbiome status in population-based settings.MethodsGut metagenomic data of the adult population consisting of 2871 subjects from 16 countries were obtained from ExperimentHub through R, while the dynamic death data of COVID-19 patients between January 22, 2020 and December 8, 2020 in each country was acquired from Johns Hopkins Coronavirus Resource Center. An adjusted stable mortality rate (SMR) was used to represent these countries’ mortality and correlated with the mean relative abundance (mRA) of healthy adult gut microbiome species.ResultsAfter excluding bacterial species with low prevalence (prevalence <0.2 in the included countries), the β-diversity was significantly higher in the countries with high SMR when compared with those with median or low SMR (p <0.001). We then identified the mRA of two butyrate producers, Eubacterium rectale and Roseburia intestinalis, that were negatively correlated with SMR during the study period. And the reduction of these species was associated with severer COVID-19 manifestation.ConclusionPopulation-based microbiome signatures with the stable mortality rate of COVID-19 in different countries suggest that altered gut microbiome composition and functions are associated with mortality of COVID-19