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Active and sterile neutrino phenomenology with A 4 based minimal extended seesaw
http://repo.scoap3.org/record/31558
We study a model of neutrino within the framework of minimal extended seesaw (MES), which plays an important role in active and sterile neutrino phenomenology in (3+1) scheme. The A4 flavor symmetry is augmented by additional Z4×Z3 symmetry to constraint the Yukawa Lagrangian of the model. We use non-trivial Dirac mass matrix, with broken μ−τ symmetry, as the origin of leptonic mixing. Interestingly, such structure of mixing naturally leads to the non-zero reactor mixing angle θ13 . Non-degenerate mass structure for right-handed neutrino MR is considered so that we can further extend our study to Leptogenesis. We have also considered three different cases for sterile neutrino mass, MS to check the viability of this model, within the allowed 3 σ bound in this MES framework.Das, PritamWed, 13 Mar 2019 14:38:12 GMThttp://repo.scoap3.org/record/31558urn:ISSN:0550-3213Elsevier2019-04Common origin of nonzero <math><msub><mi>θ</mi><mn>13</mn></msub></math> and baryon asymmetry of the Universe in a TeV scale seesaw model with <math><msub><mi>A</mi><mn>4</mn></msub></math> flavor symmetry
http://repo.scoap3.org/record/26075
We study the possibility of generating nonzero reactor mixing angle θ13 and baryon asymmetry of the Universe within the framework of an A4 flavor symmetric model. Using the conventional type I seesaw mechanism we construct the Dirac and Majorana mass matrices that give rise to the correct light neutrino mass matrix. Keeping the right-handed neutrino mass matrix structure trivial so that it gives rise to a (quasi) degenerate spectrum of heavy neutrinos suitable for resonant leptogenesis at TeV scale, we generate the nontrivial structure of Dirac neutrino mass matrix that can lead to the light neutrino mixing through the type I seesaw formula. Interestingly, such a setup naturally leads to nonzero θ13 due to the existence of antisymmetric contraction of the product of two triplet representations of A4. Such an antisymmetric part of the triplet products usually vanishes for right-handed neutrino Majorana mass terms, leading to μ−τ symmetric scenarios in the most economical setups. We constrain the model parameters from the requirement of producing the correct neutrino data as well as baryon asymmetry of the Universe for right-handed neutrino mass scale around TeV. The A4 symmetry is augmented by additional Z3×Z2 symmetry to make sure that the splitting between right-handed neutrinos required for resonant leptogenesis is generated only by next to leading order terms, making it naturally small. We find that the inverted hierarchical light neutrino masses give more allowed parameter space consistent with neutrino and baryon asymmetry data.Borah, DebasishFri, 08 Jun 2018 20:19:24 GMThttp://repo.scoap3.org/record/26075urn:ISSN:2470-0029APS2018-06-08Neutrino phenomenology and scalar Dark Matter with A 4 flavor symmetry in Inverse and type II seesaw
http://repo.scoap3.org/record/17507
We present a TeV scale seesaw mechanism for exploring the dark matter and neutrino phenomenology in the light of recent neutrino and cosmology data. A different realization of the Inverse seesaw (ISS) mechanism with A4 flavor symmetry is being implemented as a leading contribution to the light neutrino mass matrix which usually gives rise to vanishing reactor mixing angle θ13 . Using a non-diagonal form of Dirac neutrino mass matrix and 3 σ values of mass square differences we parameterize the neutrino mass matrix in terms of Dirac Yukawa coupling “ y ”. We then use type II seesaw as a perturbation which turns out to be active to have a non-vanishing reactor mixing angle without much disturbing the other neutrino oscillation parameters. Then we constrain a common parameter space satisfying the non-zero θ13 , Yukawa coupling and the relic abundance of dark matter. Contributions of neutrinoless double beta decay are also included for standard as well as non-standard interaction. This study may have relevance in future neutrino and Dark Matter experiments.Mukherjee, AnanyaTue, 18 Oct 2016 14:35:50 GMThttp://repo.scoap3.org/record/17507urn:ISSN:0550-3213Elsevier2017-09-09Corrections to scaling neutrino mixing: Non-zero θ13,δCP and baryon asymmetry
http://repo.scoap3.org/record/9548
We study a very specific type of neutrino mass and mixing structure based on the idea of Strong Scaling Ansatz (SSA) where the ratios of neutrino mass matrix elements belonging to two different columns are equal. There are three such possibilities, all of which are disfavored by the latest neutrino oscillation data. We focus on the specific scenario which predicts vanishing reactor mixing angle θ13 and inverted hierarchy with vanishing lightest neutrino mass. Motivated by several recent attempts to explain non-zero θ13 by incorporating corrections to a leading order neutrino mass or mixing matrix giving θ13=0 , here we study the origin of non-zero θ13 as well as leptonic Dirac CP phase δCP by incorporating two different corrections to scaling neutrino mass and mixing: one, where type II seesaw acts as a correction to scaling neutrino mass matrix and the other, with charged lepton correction to scaling neutrino mixing. Although scaling neutrino mass matrix originating from type I seesaw predicts inverted hierarchy, the total neutrino mass matrix after type II seesaw correction can give rise to either normal or inverted hierarchy. However, charged lepton corrections do not disturb the inverted hierarchy prediction of scaling neutrino mass matrix. We further discriminate between neutrino hierarchies, different choices of lightest neutrino mass and Dirac CP phase by calculating baryon asymmetry and comparing with the observations made by the Planck experiment.Kalita, RupamThu, 12 Mar 2015 13:57:12 GMThttp://repo.scoap3.org/record/9548urn:ISSN:0550-3213Elsevier2015-05Radiative generation of non-zero <math altimg="si1.gif" xmlns="http://www.w3.org/1998/Math/MathML"><msub><mrow><mi>θ</mi></mrow><mrow><mn>13</mn></mrow></msub></math> in MSSM with broken <math altimg="si2.gif" xmlns="http://www.w3.org/1998/Math/MathML"><msub><mrow><mi>A</mi></mrow><mrow><mn>4</mn></mrow></msub></math> flavor symmetry
http://repo.scoap3.org/record/2970
We study the renormalization group effects on neutrino masses and mixing in Minimal Supersymmetric Standard Model (MSSM) by considering a μ–τ symmetric mass matrix at high energy scale giving rise to Tri-Bi-Maximal (TBM) type mixing. We outline a flavor symmetry model based on A4 symmetry giving rise to the desired neutrino mass matrix at high energy scale. We take the three neutrino mass eigenvalues at high energy scale as input parameters and compute the neutrino parameters at low energy by taking into account of renormalization group effects. We observe that the correct output values of neutrino parameters at low energy are obtained only when the input mass eigenvalues are large |m1,2,3|=0.08–0.12 eV with a very mild hierarchy of either inverted or normal type. A large inverted or normal hierarchical pattern of neutrino masses is disfavored within our framework. We also find a preference towards higher values of tan β , the ratio of vacuum expectation values (vev) of two Higgs doublets in MSSM in order to arrive at the correct low energy output. Such a model predicting large neutrino mass eigenvalues with very mild hierarchy and large tan β could have tantalizing signatures at oscillation, neutrino-less double beta decay as well as collider experiments.Borah, ManikantaFri, 27 Jun 2014 13:59:27 GMThttp://repo.scoap3.org/record/2970urn:ISSN:0550-3213Elsevier2014-08