Discriminating Majorana neutrino phases in the light of lepton flavor violation and leptogenesis in type I+II seesaw models

Kalita, Rupam; Borah, Debasish

doi:10.1142/s0217751x15501304

Cited by 3 publications

(2 citation statements)

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“…Such a combination of type I and type II seesaw together can also explain non-zero reactor mixing angle θ 13 as well as CP phases, as discussed in the works [48][49][50][51][52][53]. Making use of the presence of two equally dominating seesaw terms in the neutrino mass formula, we consider the possibility where either type I or type II or both type I and type II mass matrices can be arbitrary while structural cancellation [54] between them can give rise to the correct light neutrino mass matrix.…”

Section: Introductionmentioning

confidence: 99%

“…Making use of the presence of two equally dominating seesaw terms in the neutrino mass formula, we consider the possibility where either type I or type II or both type I and type II mass matrices can be arbitrary while structural cancellation [54] between them can give rise to the correct light neutrino mass matrix. Instead of considering completely arbitrary type I and type II mass matrices, we consider a specific type I seesaw mass matrix: tribimaximal (TBM) type which gives θ 13 = 0 [48][49][50][51][52][53]. The type II seesaw mass matrix is then…”

Section: Introductionmentioning

confidence: 99%

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Neutrinoless double beta decay in type I+II seesaw models

Borah

Dasgupta

2015

J. High Energ. Phys.

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We study neutrinoless double beta decay in left-right symmetric extension of the standard model with type I and type II seesaw origin of neutrino masses. Due to the enhanced gauge symmetry as well as extended scalar sector, there are several new physics sources of neutrinoless double beta decay in this model. Ignoring the left-right gauge boson mixing and heavy-light neutrino mixing, we first compute the contributions to neutrinoless double beta decay for type I and type II dominant seesaw separately and compare with the standard light neutrino contributions. We then repeat the exercise by considering the presence of both type I and type II seesaw, having non-negligible contributions to light neutrino masses and show the difference in results from individual seesaw cases. Assuming the new gauge bosons and scalars to be around a TeV, we constrain different parameters of the model including both heavy and light neutrino masses from the requirement of keeping the new physics contribution to neutrinoless double beta decay amplitude below the upper limit set by the GERDA experiment and also satisfying bounds from lepton flavor violation, cosmology and colliders.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Neutrinoless double beta decay in type I+II seesaw models

Borah

Dasgupta

2015

J. High Energ. Phys.

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Octant Degeneracy and Quadrant of Leptonic CPV Phase at Long BaselineνExperiments and Baryogenesis

Bora

Ghosh

Dutta

2016

Advances in High Energy Physics

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In a recent work by us, we have studied, how CP violation discovery potential can be improved at long baseline neutrino experiments (LBNE/DUNE), by combining with its ND (near detector) and reactor experiments. In this work, we discuss how this study can be further analysed to resolve entanglement of the quadrant of leptonic CPV phase and Octant of atmospheric mixing angle θ23, at LBNEs. The study is done for both NH (Normal hierarchy) and IH (Inverted hierarchy), HO (Higher Octant) and LO (Lower Octant). We show how baryogenesis can enhance the effect of resolving this entanglement, and how possible values of the leptonic CP-violating phase δCP can be predicted in this context. With respect to the latest global fit data of neutrino mixing angles, we predict the values of δCP for different cases. In this context we present favoured values of δCP (δCP range at ≥ 2σ ) constrained by the latest updated BAU range and also confront our predictions of δCP with an up-to-date global analysis of neutrino oscillation data. We find that some region of the favoured δCP parameter space lies within the best fit values around δCP ≃ 1.3π − 1.4π. A detailed analytic and numerical study of baryogenesis through leptogenesis is performed in this framework in a model independent way. I. INTRODUCTIONToday, physics is going through precision era-this is more so for Neutrino physics. With the measurement of reactor mixing angle θ 13 [1-3] precisely by reactor experiments, the unknown quantities left to be measured in neutrino sector are − leptonic CP violating phase [4][5][6][7][8][9], octant of atmospheric angle θ 23 [10-14], mass hierarchy, nature of neutrino etc. Long baseline neutrino experiments (LBNE [15, 16], NOνA [17] , T2K [18], MINOS [19], LBNO [20] etc) may be very promising, in measuring many of these sensitive parameters. Measuring leptonic CP violation (CPV) is one of the most demanding tasks in future neutrino experiments [21]. The relatively large value of the reactor mixing angle θ 13 measured with a high precision in neutrino experiments [1]has opened up a wide range of possibilities to examine CP violation in the lepton sector. The leptonic CPV phase can be induced by the PMNS neutrino mixing matrix [22] which holds, in addition to the three mixing angles, a Dirac type CP violating phase in general as it exists in the quark sector, and two extra phases if neutrinos are Majorana particles. Even if we do not yet have significant evidence for leptonic CPV, the current global fit to available neutrino data manifests nontrivial values of the Dirac-type CP phase [23,24]. In this context, possible size of leptonic CP violation detectable through neutrino oscillations can be predicted. Recently, [4], we have explored possibiities of improving CP violation discovery potential of newly planned Long-Baseline Neutrino Experiments (earlier LBNE, now called DUNE) in USA. In neutrino oscillation probability expression P(ν µ → ν e ) relevant for LBNEs, the term due to significant matter effect, changes sign when oscillation is cha...

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