Light unstable sterile neutrino

Rajasekaran, G.

doi:10.1103/physrevd.64.117303

Cited by 335 publications

(589 citation statements)

References 24 publications

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“…The relevant coefficients (V L ) 13 and (V L ) 23 for the µ → eγ process are proportional to λ 2 · O(ǫ)(≤ λ 3 ) and λ · O(ǫ)(≤ λ 2 ) respectively. Though, the exact values depend on combinations of ǫ, we expect the product (V L ) 13 (V L ) 23 to be close to V ub V cb ≤ λ 5 .…”

Section: Lepton Number Violating Effectsmentioning

confidence: 99%

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Neutrino masses and mixing: singular mass matrices and quark–lepton symmetry

Doršner

Smirnov

2004

Nuclear Physics B

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We suggest an approach to explain the observed pattern of the neutrino masses and mixing which employs the weakly violated quark-lepton equality and does not require introduction of an ad hoc symmetry of the neutrino sector. The mass matrices are nearly equal for all quarks and leptons. They have very small determinant and hierarchical form with expansion parameter λ ∼ sin θ c ∼ m µ /m τ . The latter can be realized, e.g., in the model with U (1) family symmetry.The equality is violated at the ∼ λ 2 level. Large lepton mixing appears as a result of summation of the neutrino and charged lepton rotations which diagonalize corresponding mass matrices in contrast with the quark sector where the up quark and down quark rotations cancel each other.We show that the flip of the sign of rotation in the neutrino sector is a result of the seesaw mechanism which also enhances the neutrino mixing. In this approach one expects, in general, deviation of the 2-3 mixing from maximal, s 13 ∼ (1 -3)λ 2 , hierarchical neutrino mass spectrum, and m ee < 10 −2 eV. The scenario is consistent with the thermal leptogenesis and (in SUSY context) bounds on lepton number violating processes, like µ → eγ.

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Section: Lepton Number Violating Effectsmentioning

confidence: 99%

“…There is a number of studies which explore various "neutrino symmetries" like Z 2 , A 4 [13] or SO(3) [14,15,16] (see [17] for review). Apparently these symmetries being exact or approximate cannot be extended to the charged lepton sector where the hierarchy of masses, and in particular, inequality m µ ≪ m τ , exists.…”

Section: Introductionmentioning

confidence: 99%

Neutrino masses and mixing: singular mass matrices and quark–lepton symmetry

Doršner

Smirnov

2004

Nuclear Physics B

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“…There are various aspects of the flavour puzzle, such as the hierarchy among the quark masses, the origin of CP violation, and the largeness of the leptonic mixing angles, which have turned out to be close to "tri-bimaximal" [1]. In particular this latter observation has led to increasing interest in non-Abelian discrete family symmetries for flavour model building [2].…”

Section: Introductionmentioning

confidence: 99%

Right unitarity triangles and tri-bimaximal mixing from discrete symmetries and unification

et al. 2011

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We propose new classes of models which predict both tri-bimaximal lepton mixing and a right-angled Cabibbo-Kobayashi-Maskawa (CKM) unitarity triangle, α ≈ 90 • . The ingredients of the models include a supersymmetric (SUSY) unified gauge group such as SU(5), a discrete family symmetry such as A 4 or S 4 , a shaping symmetry including products of Z 2 and Z 4 groups as well as spontaneous CP violation. We show how the vacuum alignment in such models allows a simple explanation of α ≈ 90 • by a combination of purely real or purely imaginary vacuum expectation values (vevs) of the flavons responsible for family symmetry breaking. This leads to quark mass matrices with 1-3 texture zeros that satisfy the "phase sum rule" and lepton mass matrices that satisfy the "lepton mixing sum rule" together with a new prediction that the leptonic CP violating oscillation phase is close to either 0 • , 90 • , 180 • , or 270 • depending on the model, with neutrino masses being purely real (no complex Majorana phases). This leads to the possibility of having right-angled unitarity triangles in both the quark and lepton sectors.

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“…There are two shortcomings of the discussed symmetry: 1 An interesting class of models is based on the A 4 symmetry group of even permutations of four elements [45,67,68]. It is the symmetry of the tetrahedron and has the irreducible representations 3, 1, 1 ′ and 1 ′′ .…”

Section: Neutrinos and New Symmetries Of Naturementioning

confidence: 99%

Neutrino mass and New physics

Smirnov

2006

J. Phys.: Conf. Ser.

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We review the present state and future outlook of our understanding of neutrino masses and mixings. We discuss what we think are the most important perspectives on the plausible and natural scenarios for neutrinos and attempt to throw light onto the flavor problem of quarks and leptons. This review focuses on the seesaw mechanism, which fits into a big picture of particle physics such as supersymmetry and grand unification providing a unified approach to the flavor problem of quarks and leptons. We argue that in combination with family symmetries, this may be at the heart of a unified understanding of the flavor puzzle. We also discuss other new physics ideas such as neutrinos in models with extra dimensions and possible theoretical implications of sterile neutrinos. We outline some tests for the various schemes.

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Light unstable sterile neutrino

Cited by 335 publications

References 24 publications

Neutrino masses and mixing: singular mass matrices and quark–lepton symmetry

Neutrino masses and mixing: singular mass matrices and quark–lepton symmetry

Right unitarity triangles and tri-bimaximal mixing from discrete symmetries and unification

Neutrino mass and New physics

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