Constraining an R-parity violating supersymmetric theory from the SuperKamiokande data on atmospheric neutrinos (original) (raw)
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Super-Kamiokande constraints on R-parity violating supersymmetry
Physics Letters B, 1998
We consider the neutrino oscillations within the minimal supersymmetric standard model with R-parity violation (R p / MSSM). The Super-Kamiokande atmospheric neutrino data are used to set limits on the bilinear R-parity violating terms of the R p / MSSM. These very stringent limits are out of reach of the other experiments at present and in the near future.
Bilinear R-parity violation and small neutrino masses: a self-consistent framework
Physics Letters B, 2000
We study extensions of supersymmetric models without R-parity which include an anomalous U (1) H horizontal symmetry. Bilinear R-parity violating terms induce a neutrino mass at tree level m tree ν ≈ (θ 2 ) δ eV where θ ≃ 0.22 is the U (1) H breaking parameter and δ is an integer number that depends on the horizontal charges of the leptons. For δ = 1 a unique self-consistent model arises in which i) all the superpotential trilinear R-parity violating couplings are forbidden by holomorphy; ii) m tree ν falls in the range suggested by the atmospheric neutrino problem; iii) radiative contributions to neutrino masses are strongly suppressed resulting in ∆m 2 solar ≈ few 10 −8 eV 2 which only allows for the LOW (or quasi-vacuum) solution to the solar neutrino problem; iv) the neutrino mixing angles are not suppressed by powers of θ and can naturally be large.
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The simplest unified extension of the Minimal Supersymmetric Standard Model with bi-linear R-parity violation naturally predicts a hierarchical neutrino mass spectrum, suitable to explain atmospheric and solar neutrino fluxes. We study whether the individual violation of the lepton numbers L e,µ,τ in the charged sector can lead to measurable rates for BR(µ → eγ) and BR(τ → µγ). We find that some of the R-parity violating terms that are compatible with the observed atmospheric neutrino oscillations could lead to rates for µ → eγ measurable in projected experiments. However, the ∆m 2 12 obtained for those parameters is too high to be compatible with the solar neutrino data, excluding therefore the possibility of having measurable rates for µ → eγ in the model.
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We study neutrino masses and mixing in R-parity violating supersymmetric models with generic soft supersymmetry breaking terms. Neutrinos acquire masses from various sources: Tree level neutrino–neutralino mixing and loop effects proportional to bilinear and/or trilinear R-parity violating parameters. Each of these contributions is controlled by different parameters and have different suppression or enhancement factors which we identified. Within an Abelian horizontal symmetry framework these factors are related and specific predictions can be made. We found that the main contributions to the neutrino masses are from the tree level and the bilinear loops and that the observed neutrino data can be accommodated once mild fine-tuning is allowed.
The European Physical Journal C, 2002
A new three flavor oscillation solution of the solar neutrino deficit in R-parity violating supersymmetry Abstract We present a solution of the solar neutrino deficit using three flavors of neutrinos within the R-parity non-conserving supersymmetric model. In vacuum, mass and mixing is restricted to the ν µ -ν τ sector only, which we choose in consistency with the requirements of the atmospheric neutrino anomaly. The ν e is massless and unmixed. The flavor changing and flavor diagonal neutral currents present in the model and an energy-dependent resonance-induced ν e -ν µ mixing in the sun result in the new solution to the solar neutrino problem. The best fit to the solar neutrino rates and spectrum (1258-day SK data) requires a mass square difference ∼ 10 −5 eV 2 in vacuum between the two lightest neutrinos. This solution cannot accommodate a significant day-night effect for solar neutrinos.
Lepton-flavor violation in supersymmetric models with trilinear R-parity violation
Physical Review D, 2001
U (1) family symmetries have led to successful predictions of the fermion mass spectrum and the mixing angles of the hadronic sector. In the context of the supersymmetric unified theories, they further imply a non-trivial mass structure for the scalar partners, giving rise to new sources of flavour violation. While τ → µγ decays are mostly expected to arise at rates significantly smaller than the current experimental limits, the µ → eγ rare decays impose important bounds on the model parameters. Even if universal soft-terms are assumed at the GUT scale, when massive neutrinos are included in these theories, new mixings appear in the soft-terms. The predicted branching ratios for rare decays are in this case below the experimental bounds.
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Physical Review D, 2005
We show that a supersymmetric standard model exhibiting anomaly mediated supersymmetry breaking can generate naturally the observed neutrino mass spectrum as well mixings when we include bilinear R-parity violation interactions. In this model, one of the neutrinos gets its mass due to the tree-level mixing with the neutralinos induced by the R-parity violating interactions while the other two neutrinos acquire their masses due to radiative corrections. One interesting feature of this scenario is that the lightest supersymmetric particle is unstable and its decay can be observed at high energy colliders, providing a falsifiable test of the model.
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Physics Letters B, 2000
We propose a simple extension of the MSSM based on extra compact dimensions which includes an SU (2) ⊗ U (1) singlet superfield. The fermion present in this superfield is the sterile neutrino, which combines with one linear combination of ν e − ν µ − ν τ to form a Dirac pair whose mass accounts for the LSND anomaly. Its small mass can be ascribed to a volume suppression factor associated with extra compact dimensions. On the other hand the sterile neutrino scalar partner can trigger the spontaneous violation of R-parity, thereby inducing the necessary mass splittings to fit also the solar and atmospheric neutrino data. Thus the model can explain all neutrino oscillation data. It leads to four predictions for the neutrino oscillation parameters and implies that the atmospheric neutrino problem must include at least some ν µ → ν s oscillations, which will be testable in the near future. Moreover it also predicts that the lightest supersymmetric particle (LSP) decays visibly via lepton number violating modes, which could be searched for at present and future accelerators.
Two-loop neutrino masses with large R-parity violating interactions in supersymmetry
Journal of High Energy Physics, 2008
We attempt to reconcile large trilinear R-parity violating interactions in a supersymmetric (SUSY) theory with the observed pattern of neutrino masses and mixing. We show that, with a restricted number of such interaction terms with the λ ′-type couplings in the range (0.1-1.0), it is possible to forbid one-loop contributions to the neutrino mass matrix. This is illustrated with the help of a 'working example' where an econnomic choice of SUSY parameters is made, with three nonvanishing and 'large' R-parity violating terms in the superpotential. The two-loop contributions in such a case can not only generate the masses in the requisite order but can also lead us to specific allowed regions of the parameter space.
Supersymmetry without R-parity and without lepton number
Arxiv preprint hep-ph/9505248, 1995
We investigate Supersymmetric models where neither R parity nor lepton number is imposed. Neutrino masses can be kept highly suppressed compared to the electroweak scale if the µ-terms in the superpotential are aligned with the SUSY-breaking bilinear B-terms. This situation arises naturally in the framework of horizontal symmetries. The same symmetries suppress the trilinear R parity violating terms in the superpotential to an acceptable level.