arXiv subjects

Raghavendra Srikanth Hundi

Publications and source records attributed to Raghavendra Srikanth Hundi.

10 recordsLinked to original sources

arXiv2025

Lepton flavor violation in the Majorana and Dirac scotogenic models

In this work we have considered two minimal versions of scotogenic models, where neutrinos acquire masses through a radiative mechanism. We call these two models as Majorana and Dirac scotogenic models. In the former model, neutrinos have Majorana nature, and in the later one, neutrinos are Dirac particles. These two models are related to each other in terms of additional fields and symmetries of the model. Hence, to compare these two models in future experiments, we have analyzed lepton flavor violating (LFV) processes in both of them, in the charged lepton sector. We have found that the 3-body LFV decays in both these models can get different contributions. Among all the LFV decays and after satisfying relevant constraints, we have found that $τ\to3μ$ can have a branching ratio as high as $10^{-10}(10^{-11})$ in the Majorana(Dirac) scotogenic model.

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arXiv2023

Study on the global minimum and $H\toγγ$ in the Dirac scotogenic model

We have analyzed the vacuum structure of the Dirac scotogenic model, whose scalar sector consists of two complex Higgs doublets and a real singlet field. In this model, the standard model like Higgs doublet acquires non-zero vacuum expectation value (VEV), whereas, the other two fields acquire zero VEVs. This pattern of VEVs constitute a minimum, which is the desired vacuum of the model. After analyzing the scalar potential of this model, we have found that other vacua are also possible in this model. We have shown that plenty of parameter space exist where the desired vacuum of this model is the global minimum. We have studied the implications of scalar sector of this model on the observable quantity of signal strength of Higgs to diphoton decay. After evaluating this quantity, we have found that the current experimental values of this quantity can be fitted in this model. Lastly, we have studied on the possibility of making any of the additional scalar fields of this model as a candidate for dark matter.

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arXiv2022

Lepton and quark mixing patterns with generalized CP transformations

In this work, we have modified a scenario, originally proposed by Grimus and Lavoura, in order to obtain maximal values for atmospheric mixing angle and CP violating Dirac phase of the lepton sector. To achieve this, we have employed CP and some discrete symmetries in a type II seesaw model. In order to make predictions about neutrino mass ordering and the smallness of the reactor angle, we have obtained some conditions on the elements of the neutrino mass matrix of our model. Finally, within the framework of our model, we have studied quark masses and mixing pattern.

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arXiv2022

Lepton flavor violating $Z$ and Higgs decays in the scotogenic model

In this work, we have studied lepton flavor violating (LFV) decays of $Z$ gauge boson and Higgs boson ($H$) in the scotogenic model. We have computed branching ratios for the decays $Z\to\ell_α\ell_β$ and $H\to\ell_α\ell_β$ in this model. Here, $\ell_α$ and $\ell_β$ are different charged lepton fields. After fitting to the neutrino oscillation observables in the scotogenic model, we have found that the branching ratios for the LFV decays of $Z$ and $H$ can be as large as $\sim10^{-8}$ and $\sim10^{-3}$ respectively. However, after satisfying the constraints due to non-observation of $\ell_α\to\ell_βγ$ decays, the above mentioned branching ratio results are found to be suppressed by a factor of $\sim10^{-7}$.

hep-ph↗

arXiv2022

Analyses of scalar potential and lepton flavor violating decays in a model with $A_4$ symmetry

We have considered a model, originally proposed by Ma and Wegman, where the mixing pattern in neutrino sector is explained with three Higgs doublets, six Higgs triplets and $A_4$ symmetry. The mixing pattern is explained with the help of vacuum expectation values (VEVs) of the above mentioned doublets and triplets. In order to study about the VEVs of the scalar fields, we construct the full invariant scalar potential of this model. After minimizing this scalar potential, we have found that two Higgs triplets can acquire zero VEVs. In order to generate non-zero VEVs to all the six Higgs triplets, we have added two more Higgs doublets to the model. Thereafter we have demonstrated that the current neutrino oscillation data can be consistently explained in our model. To study some phenomenological implications of this model, we have worked out on the branching ratios for lepton flavor violating decays.

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arXiv2021

Neutrino Mixing by modifying the Yukawa coupling structure of constrained sequential dominance

In the constrained sequential dominance (CSD), tri-bimaximal mixing (TBM) pattern in the neutrino sector has been explained, by proposing a certain Yukawa coupling structure for the right-handed neutrinos of the model. However, from the current experimental data it is known that the values of neutrino mixing angles are deviated from the TBM values. In order to explain this neutrino mixing, we first propose a phenomenological model where we consider Yukawa couplings which are modified from that of CSD. Essentially, we add small complex parameters to the Yukawa couplings of CSD. Using these modified Yukawa couplings, we demonstrate that neutrino mixing angles can deviate from their TBM values. We also construct a model, based on a flavor symmetry, in order to justify the modified form of Yukawa couplings of our work.

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arXiv2020

Neutrino masses and mixing angles in a model with six Higgs triplets and $A_4$ symmetry

We have considered a model \cite{ma-weg}, where masses and a mixing pattern for neutrinos are governed by six Higgs triplets and $A_4$ symmetry. In this model we have applied a certain diagonalisation procedure through which we have shown that neutrino masses can have both normal or inverted hierarchy. We have also shown that current neutrino oscillation data can be explained in this model.

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arXiv2015

$μ\to eγ$ in a supersymmetric radiative neutrino mass model

We have considered a supersymmetric version of the inert Higgs doublet model, whose motivation is to explain smallness of neutrino masses and existence of dark matter. In this supersymmetric model, due to the presence of discrete symmetries, neutrinos acquire masses at loop level. After computing these neutrino masses, in order to fit the neutrino oscillation data, we have shown that by tuning some supersymmetry breaking soft parameters of the model, neutrino Yukawa couplings can be unsuppressed. In the above mentioned parameter space, we have computed branching ratio of the decay $μ\to eγ$. To be consistent with the current experimental upper bound on $Br(μ\to eγ)$, we have obtained constraints on the right-handed neutrino mass of this model.

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arXiv2007

Invisibly decaying Higgs boson in the Littlest Higgs model with T-parity

We show that there are regions in the parameter space of the Littlest Higgs model with T-parity, allowed by electroweak precision data, where the Higgs boson can decay invisibly into a pair of heavy photons A_H with a substantial branching ratio. For a symmetry breaking scale f in the range 450-600 GeV, the BR(H -> A_H A_H) can be up to 95% for an intermediate mass Higgs, and from 20% down to a few percents for a Higgs boson of mass 200 GeV or above. The total decay width of the Higgs boson can thereby be enhanced by an order of magnitude compared to the Standard Model for Higgs masses around 130 GeV.

hep-ph↗

arXiv2007

Invisible Higgs boson decay in the littlest Higgs model with T-parity

We study the invisible decay of the Higgs boson into a pair of stable, heavy photons, H -> A_H A_H, in the littlest Higgs model with T-parity. For a symmetry breaking scale of f = 450 GeV, the branching ratio H -> A_H A_H can be as high as 93% for Higgs masses below 150 GeV. For f = 500 GeV, the invisible branching ratio is about 75% in the Higgs mass range 135 - 150 GeV and 10 (5.5)% for m_H = 200 (600) GeV. It drops to a few percent for f larger than 600 GeV. We have found regions in parameter space, allowed by the electroweak precision data, with such low values of f for 115 GeV < m_H < 650 GeV.

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