Broken R Parity, Neutrino Anomalies and Collider Tests (original) (raw)
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Neutrino masses in supersymmetry with spontaneously broken R-parity
1992
The neutrino mass spectrum that arises in supersymmetry models with spontaneously broken R-parity is studied in detail. We analyse the attainable values for rn,, rn, and rn,, once all observational constraints have been incorporated, including both those that arise from collider experiments such as LEP, as well as weak interaction constraints, such as the non-observation of neutrinoless double-/3 decay, the limits from neutrino oscillation searches. etc. For natural choices of the parameters neutrino masses arise in a very striking pattern: while v~and have masses lying in the adequate range for the explanation of the observed deficit in the solar neutrino flux via the MSW effect, the v~mass is large enough to lead to novel signatures associated with the r-lepton that could be seen both at LEP as well as at a tau factory. These provide an additional tool to probe the parameters characterizing the solar neutrino conversions in conventional accelerator experiments. The related processes include the single-chargino Z-decay branching ratio BR(Z ,~i-) as large as 6x iO-~and single-majoron emission r-decay branching ratios T -~~z+J as large as iO~corresponding to solar neutrino oscillation parameters in the non-adiabatic branch favoured by present solar neutrino data. The r-neutrino is naturally much heavier than and decays to it via majoron emission, with a lifetime short enough to obey cosmological limits.
Neutrinos in anomaly mediated supersymmetry breaking with R-parity violation
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.
Collider signatures of neutrino masses and mixing from R-parity violation
Physical Review D - PHYS REV D, 2002
R-parity violation in the supersymmetric standard model can be the source of neutrino masses and mixing. We analyze the neutrino mass matrix coming from either bilinear or trilinear R-parity violation and its collider signatures, assuming that the atmospheric and solar neutrino data are explained by three active neutrino oscillations. Taking the gauge mediated supersymmetry breaking mechanism, we show that the lightest neutralino decays well inside the detector and the model could be tested by observing its branching ratios in the future colliders. In the bilinear model where only the small solar neutrino mixing angle can be accommodated, the relation, 10310^3103 BR($\nu e^\pm \tau^\mp$) sim\simsim BR($\nu \mu^\pm \tau^\mp$) approx\approxapprox BR($\nu \tau^\pm \tau^\mp$), serves as a robust test of the model. The large mixing angle solution can be realized in the trilinear model which predicts BR($\nu e^\pm \tau^\mp$) sim\simsim BR($\nu \mu^\pm \tau^\mp$) sim\simsim BR($\nu \tau^\pm \tau^\mp$). In either ca...
Physical Review D, 2000
The simplest unified extension of the Minimal Supersymmetric Standard Model with bi-linear R-Parity violation naturally predicts a hierarchical neutrino mass spectrum, in which one neutrino acquires mass by mixing with neutralinos, while the other two get mass radiatively. We have performed a full one-loop calculation of the neutralino-neutrino mass matrix in the bi-linear R p / MSSM, taking special care to achieve a manifestly gauge invariant calculation. Moreover we have performed the renormalization of the heaviest neutrino, needed in order to get meaningful results. The atmospheric mass scale and maximal mixing angle arise from tree-level physics, while solar neutrino scale and oscillations follow from calculable one-loop corrections. If universal supergravity assumptions are made on the soft-supersymmetry breaking terms then the atmospheric scale is calculable as a function of a single R p / violating parameter by the renormalization group evolution due to the non-zero bottom quark Yukawa coupling. The solar neutrino problem must be accounted for by the small mixing angle (SMA) MSW solution. If these assumptions are relaxed then one can implement large mixing angle solutions, either MSW or just-so. The theory predicts the lightest supersymmetic particle (LSP) decay to be observable at high-energy colliders, despite the smallness of neutrino masses indicated by experiment. This provides an independent way to test this solution of the atmospheric and solar neutrino anomalies.
Neutrino masses and sneutrino mixing in R-parity violating supersymmetry
1999
R-parity-violating supersymmetry with a conserved baryon number B provides a framework for particle physics with lepton number (L) violating interactions. Two important probes of the L-violating physics are neutrino masses and sneutrino-antisneutrino mass-splittings. We evaluate these quantities in the context of the most general CP-conserving, R-parity-violating B-conserving extension of the minimal supersymmetric standard model. In generic three-generation models, three sneutrino-antisneutrino mass splittings are generated at tree-level. In contrast, only one neutrino mass is generated at tree-level; the other two neutrinos acquire masses at one-loop. In many models, the dominant contribution to the radiative neutrino masses is induced by the non-zero sneutrino-antisneutrino mass splitting. * Invited talk presented by Yuval Grossman at the American Physical Society (APS) meeting of the Division of Particles and Fields (DPF99).
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.
Neutrino masses in R-parity violating supersymmetric models
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.
(S)neutrino properties in R-parity-violating supersymmetry: CP-conserving phenomena
Physical Review D, 1999
R-parity-violating supersymmetry (with a conserved baryon number B) provides a framework for particle physics with lepton number (L) violating interactions. We examine in detail the structure of the most general R-parityviolating (B-conserving) model of low-energy supersymmetry. We analyze the mixing of Higgs bosons with sleptons and the mixing of charginos and neutralinos with charged leptons and neutrinos, respectively. Implications for neutrino and sneutrino masses and mixing and CP-conserving sneutrino phenomena are considered. L-violating low-energy supersymmetry can be probed at future colliders by studying the phenomenology of sneutrinos. Sneutrinoantisneutrino mass splittings and lifetime differences can provide new opportunities to probe lepton number violation at colliders.
Solar and atmospheric neutrino oscillations from bilinear R-parity violation
Journal of High Energy Physics, 2000
We discuss general predictions for neutrino masses and mixing angles from R parity violation in the Minimal Supersymmetric Standard Model. If the soft supersymmetry breaking terms are flavor blind at short distance, then the leptonic analogue of the CKM matrix depends on only two real parameters, which are completely determined by fits to solar and atmospheric neutrino oscillations. Either the small angle MSW, large angle MSW, or "just-so" solutions to the solar neutrino problem are allowed, although the large angle MSW solution requires substantial fine-tuning. The latter two cases require significant ν µ → ν e oscillations of atmospheric neutrinos. We present a model which could explain bilinear R parity violation as a consequence of spontaneous symmetry violation by a dynamical supersymmetry breaking sector. The decay length and branching ratios of the LSP are estimated.
Reconciling neutrino anomalies in a simple four-neutrino scheme with R-parity violation
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.