We investigate a neutrino mass model in which the neutrino data is accounted for by bilinear R-parity violating supersymmetry with anomaly mediated supersymmetry breaking. We focus on the CERN Large Hadron Collider (LHC) phenomenology, studying the reach of generic supersymmetry search channels with leptons, missing energy and jets. A special feature of this model is the existence of long lived neutralinos and charginos which decay inside the detector leading to detached vertices. We demonstrate that the largest reach is obtained in the displaced vertices channel and that practically all of the reasonable parameter space will be covered with an integrated luminosity of 10 fb-1. We also compare the displaced vertex reaches of the LHC and Tevatron.
Some aspects of bilinear R-Parity violation, the simplest extension of the MSSM which does not conserve R-Parity, are reviewed in comparison with the MSSM. We put special emphasis on the effect of quantum corrections.
We analyse an extension of the minimal supersymmetric standard model including the dominant trilinear and bilinear R-parity violating contributions. We take the trilinear terms from the superpotential and the bilinear terms from the superpotential as well as the scalar potential. We compute the neutrino masses induced by those couplings and determine the allowed ranges of the R-parity violating parameters that are consistent with the latest SNO results, atmospheric data and the Chooz constraint. We also estimate the effective mass for neutrinoless double beta decay in such scenarios.
We reexamine the idea that bilinear R-parity violating couplings can be responsible for leptogenesis. We prove that, to have lepton number violation before the electroweak phase transition, misalignment between the lepton-Higgsino and slepton-Higgs sectors must be involved. The processes that generate a lepton asymmetry are bino or wino decays into a lepton-Higgs and slepton-Higgsino final states. Since these decays occur mainly while the gauginos are still in thermal equilibrium, they quantitatively fail to produce the observed baryon asymmetry of the universe.
We consider neutrino masses generated at tree level and at one loop, through fermion--sfermion loop diagrams, in the MSSM with R-parity violation. Using the $(3\times 3)$ mass and mixing matrices for three generations of neutrinos and the present experimental results on neutrinos from laboratories and astrophysics simultaneously, we put bounds on both trilinear ($λ_{ijk}, λ'_{ijk}$) and bilinear ($μ_{e},μ_μ,μ_τ$) R-parity-violating couplings.
Bilinear R-parity violation is a simple extension of the MSSM allowing for Majorana neutrino masses. One of the three neutrinos picks up mass by mixing with the neutralinos of the MSSM, while the other two neutrinos gain mass from 1-loop corrections. Once 1-loop corrections are carefully taken into account the model is able to explain solar and atmospheric neutrino data for specific though simple choices of the R-parity violating parameters.
Neutrinoless double beta ($\znbb$) decay is considered within bilinear R-parity breaking supersymmetry, including the full one-loop corrections to the neutrino-neutralino mass matrix. Expected rates for $\znbb$ decay in this model are discussed in light of recent atmospheric and solar neutrino data. We conclude that (a) tree-level calculations for $\znbb$ decay within the bilinear model are not reliable in the range of parameters preferred by current solar and atmospheric neutrino problems. And (b) if the solar and atmospheric neutrino problems are to be solved within bilinear R-parity violati…
We study the collider phenomenology of bilinear R-parity violating supergravity, the simplest effective model for supersymmetric neutrino masses accounting for the current neutrino oscillation data. At the CERN Large Hadron Collider the center-of-mass energy will be high enough to probe directly these models through the search for the superpartners of the Standard Model (SM) particles. We analyze the impact of R-parity violation on the canonical supersymmetry searches - that is, we examine how the decay of the lightest supersymmetric particle (LSP) via bilinear R-parity violating interactions …
Bilinear R-parity violating supersymmetric model is a viable model which can explain the smallness of neutrino masses and the mixing pattern in the lepton sector. In this model, there is a common set of parameters which determine the neutralino and chargino masses, also determine the neutrino masses and the anomalous magnetic moment of muon, $(g-2)_μ$. From the experimental data on neutrino masses and mixing angles, and also from the fact that the experimentally measured value of $(g-2)_μ$ differs from the corresponding standard model value by 3$σ$, we have analyzed some constraints on these m…
Supersymmetric models with broken R-parity induced by lepton number violating terms provide a calculable framework for neutrino masses and mixings. Within models with bilinear R-parity breaking six new physical phases appear which are potential sources of novel CP-violating phenomena compared to the minimal supersymmetric extension of the standard model. We consider CP-violating observables in the decays of the lightest supersymmetric particle in this class of models. We show that: (i) Neutrino physics requires a strong correlation between three different pairs of phases, thus reducing the eff…
The Large Hadron Collider has recently discovered a Higgs-like particle having a mass around 125 GeV and also indicated that there is an enhancement in the Higgs to diphoton decay rate as compared to that in the standard model. We have studied implications of these discoveries in the bilinear R-parity violating supersymmetric model, whose main motivation is to explain the non-zero masses for neutrinos. The R-parity violating parameters in this model are $ε$ and $b_ε$, and these parameters determine the scale of neutrino masses. If the enhancement in the Higgs to diphoton decay rate is true, th…
R-parity can be violated through either bilinear and/or trilinear terms in the superpotential. The decay properties of sneutrinos can be used to obtain information about the relative importance of these couplings provided sneutrinos are the lightest supersymmetric particles. We show that in some specific scenarios it is even possible to decide whether bilinear or trilinear terms give the dominant contribution to the neutrino mass matrix.
The experimental measurement of $B(b \to sγ)$ imposes important constraints on the charged Higgs boson mass in the MSSM. If squarks are in the few TeV range, the charged Higgs boson mass in the MSSM must satisfy $m_{H^{\pm}} \gsim 440$ GeV. For lighter squarks, then light charged Higgs bosons can be reconciled with $B(b \to sγ)$ only if there is also a light chargino. In the MSSM if we impose $m_{χ^{\pm}_1}>90$ GeV then we need $m_{H^{\pm}} \gsim 110$ GeV. We show that by adding bilinear R--Parity violation (BRpV) in the tau sector, these bounds are relaxed. The bound on $m_{H^{\pm}}$ in the M…
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…
We confront the R-parity violating MSSM model with the neutrino oscillation data. Investigating the 1-loop particle-sparticle diagrams with additional bilinear insertions on the external neutrino lines we construct the relevant contributions to the neutrino mass matrix. A comparison of the so-obtained matrices with the experimental ones assuming normal or inverted hierarchy and taking into account possible CP violating phases, allows to set constraints on the values of the bilinear coupling constants. A similar calculation is presented with the input from the Heidelberg-Moscow neutrinoless dou…
We consider the most general supersymmetric model with minimal particle content and an additional discrete Z_3 symmetry (instead of R-parity), which allows lepton number violating terms and results in non-zero Majorana neutrino masses. We investigate whether the currently measured values for lepton masses and mixing can be reproduced. We set up a framework in which Lagrangian parameters can be initialised without recourse to assumptions concerning trilinear or bilinear superpotential terms, CP-conservation or intergenerational mixing and analyse in detail the one loop corrections to the neutri…
Neutrinoless double beta ($\znbb$) decay violates lepton number; its absence stringently constrains the parameters of theories beyond the standard model in which the neutrino has a Majorana mass. R-parity violating weak-scale supersymmetry is a prominent example of such models. Double beta decay in supersymmetry with explicit bilinear R-parity breaking is discussed and current limits on the $\znbb$ decay half life of $^{76}$Ge are used to extract upper bounds on the R-parity breaking parameters of the first generation. Moreover, it is shown that the effective Majorana neutrino mass, measured i…
We consider all possible scalar bilinears, which couple to two fermions of the standard model. The various baryon and lepton number violating couplings allowed by these exotic scalars are studied. We then discuss which ones are constrained by limits on proton decay (to a lepton and a meson as well as to three leptons), neutron-antineutron oscillations, and neutrinoless double beta decay.
We calculate the neutrino mass matrix up to one loop order in the MSSM without R-parity, including the bilinears in the mass insertion approximation. This introduces additional diagrams usually neglected in the literature. We systematically consider the possible new diagrams, and find a few missing from our previous work. We provide analytic expressions for the mass matrix elements in the neutrino flavour basis, which are independent of the $H_d - L_i$ basis choice in the Lagrangian. We compare the contributions from different diagrams, and make ``Lagrangian-basis-independent'' estimates of wh…
We present a study of charged lepton mass matrix diagonalization in R-parity violating SUSY. The case in which the bilinear couplings $μ_i$ have large values is given special attention.
We consider the neutrino oscillations within the minimal supersymmetric standard model with R-parity violation. The Super-Kamiokande atmospheric neutrino data are used to set limits on the bilinear R-parity violating terms. These very stringent limits are out of reach of the other experiments at present and in the near future.
We present analytic expressions corresponding to a set of one loop Feynman diagrams, built within R-parity violating (RpV) minimal supersymmetric standard model (MSSM). Diagrams involve both bilinear and trilinear RpV couplings and represent Majorana neutrino masses and magnetic moments.
Neutrino masses and mixing are generated in a supersymmetric standard model when R-parity is violated in bilinear mass terms. The mixing matrix among the neutrinos takes a restrictive form if the lepton flavor universality holds in the R-parity violating soft masses. It turns out that only the small angle MSW solution to the solar neutrino problem is consistent with the result of the CHOOZ experiment and the atmospheric neutrino data.
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 of approximately $(θ^2)^δ$ eV where $θ\approx 0.22$ 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) the tree level neutrino mass falls in the range suggested by the atmospheric neutrino pr…
We consider the charged scalar boson phenomenology in the bilinear R-parity breaking model which induces a mixing between staus and the charged Higgs boson. The charged Higgs boson mass can be lower than expected in the MSSM, even before including radiative corrections. The R-parity violating decay rates can be comparable or even bigger than the R-parity conserving ones. These features could have implications for charged supersymmetric scalar boson searches at future accelerators.
We analyse a simple RPV extension of the MSSM, with bilinear R-parity violation in the soft terms and vevs, but not between the terms in the superpotential. The model gives two massive neutrinos, and can fit all constraints from neutrino data. We show analytically how to compute the lepton number violating Lagrangian parameters from neutrino masses and mixing angles. Conversely, we numerically vary the bilinear couplings as input parameters to determine the allowed ranges that are consistent with neutrino data. We briefly comment on the implications of our bounds for low energy LFV processes.
R-parity violating bilinear (soft) terms in the supersymmetric standard model would be the leading source for nonzero neutrino masses and mixing. We point out that the mixing between neutralinos (charginos) and neutrinos (charged leptons) driven by the bilinear terms take factorized forms, which may enable us to probe the neutrino mixing parameters in a collider. It is then shown that the Super-Kamiokande data on atmospheric neutrinos require all the baryon number violating couplings to be substantially suppressed: $λ''_{\rm any} <10^{-9}$.
The minimum supersymmetric standard model with bilinear R-parity violation is studied systematically. Considering low-energy supersymmetry, we examine the structure of the bilinear R-parity violating model carefully. We analyze the mixing such as Higgs bosons with sleptons, neutralinos with neutrinos and charginos with charged leptons in the model. Possible and some important physics results such as the lightest Higgs may heavy than the weak Z-boson at tree level etc are obtained. The Feynman rules for the model are derived in $'$t Hooft- Feynman gauge, which is convenient if perturbative calc…
The straightforward supersymmetrization of the Standard Model (SM) results in a phenomenologically inconsistent theory in which Baryon number ($B$) and Lepton number ($L$) are violated by dimension 4 operators, inducing fast proton decay. Proton stability allows only for separate $L$ or $B$ violation and, if neutrinos are massive Majorana particles, $L$ violating terms must be present. In this thesis I will study a Supersymmetric Standard Model (SSM) realization with $B$ conservation and minimal $L$ violation. In this framework $L$ is mildly violated only by super-renormalizable terms, allowin…
We examine the possible resolution of the recently observed polarization anomaly in B0(bar{B}0) -> phi K*0(bar{K}*0) decay within R-parity violating (RPV) SUSY. We show that a combination of the superpotential trilinear (RPV)-interactions, with the couplings lambda', and the soft SUSY breaking bilinear RPV, sneutrino-Higgs mixing, proportional to tilde{mu}**2, can potentially generate the effective operators with the chirality structure necessary to account for this anomaly. However, we demonstrate that the existing experimental data on Bs -> mu+ mu- decay lead to stringent upper limits on the…
We compute one loop neutrino masses in the R-parity violating Minimal Supersymmetric Model, including the bilinear R-parity violating masses in the mass insertion approximation. To the order we calculate, our results are independent of the Higgs-lepton basis choice. We have a variety of perturbative parameters-gauge, yukawa and trilinear couplings, and R_p violating masses. Their relative magnitudes determine which diagrams are relevant for neutrino mass calculations. We find new loop diagrams which can be relevant and have frequently been neglected in the past. For the Grossman-Haber neutral …
Bilinear R-parity violation provides an attractive origin for neutrino masses and mixings. In such schemes the gravitino is a viable decaying dark matter particle whose R-parity violating decays lead to monochromatic photons with rates accessible to astrophysical observations. We determine the parameter region allowed by gamma-ray line searches, dark matter relic abundance and neutrino oscillation data, obtaining a limit on the gravitino mass $m_{\tilde G} \lsim$ 1-10 GeV corresponding to a relatively low reheat temperature $T_R \lsim$ few $\times 10^7-10^8$ GeV. Neutrino mass and mixing param…
The constraints on an R-parity violating supersymmetric theory arising from the recent SuperKamiokande results on atmospheric neutrinos are studied, with special reference to a scenario with bilinear R-parity violating terms. Considering both the fermionic and scalar sectors, we find that a large area of the parameter space is allowed, in terms of both the lepton-number violating entries in the superpotential and the soft R-violating terms in the scalar potential, and that no fine-tuning is required. However, the need to avoid flavour changing neutral currents puts additional restrictions on t…
Bilinear R-parity violation (BRPV) provides the simplest intrinsically supersymmetric neutrino mass generation scheme. While neutrino mixing parameters can be probed in high energy accelerators, they are unfortunately not predicted by the theory. Here we propose a model based on the discrete flavor symmetry $A_4$ with a single R-parity violating parameter, leading to (i) correct Cabbibo mixing given by the Gatto-Sartori-Tonin formula, and a successful unification-like b-tau mass relation, and (ii) a correlation between the lepton mixing angles $θ_{13}$ and $θ_{23}$ in agreement with recent neu…
We give an analytical calculation of solar neutrino masses and mixing at one-loop order within bilinear R-parity breaking supersymmetry, and compare our results to the exact numerical calculation. Our method is based on a systematic perturbative expansion of R-parity violating vertices to leading order. We find in general quite good agreement between approximate and full numerical calculation, but the approximate expressions are much simpler to implement. Our formalism works especially well for the case of the large mixing angle MSW solution (LMA-MSW), now strongly favoured by the recent KamLA…
A minimal particle content supersymmetric model with a discrete Z_3 symmetry, allowing lepton number violating terms, is studied. Within this model, the neutrino masses and mixing can be generated by lepton number violating couplings. Choosing parameters which correctly describe both the masses and mixing in the neutrino sector, we consider their repercussions in flavour violating radiative lepton decays, l --> l' gamma. Such decays have not been observed and, accordingly, soon to be improved, upper bounds on their branching ratios exist. We do not assume dominance of either the bilinear or tr…
We reanalyze the contributions to neutrinoless double beta ($\znbb$) decay from supersymmetry with explicit breaking of R-parity. Although we keep both bilinear and trilinear terms, our emphasis is put on bilinear R-parity breaking terms, because these mimic more closely the models where the breaking of R-parity is spontaneous. Comparing the relevant Feynman diagrams we conclude that the usual mass mechanism of double beta decay is the dominant one. From the non-observation of $\znbb$ decay we set limits on the bilinear R-parity breaking parameters of typically a (few) 100 $keV$. Despite such …
The contribution of the R-parity violating trilinear couplings in the supersymmetric model to the fermion electric dipole moment is analyzed at the two-loop level. We show that in general, the Barr-Zee type contribution to the fermion electric dipole moment with the exchange of W and Z bosons is not small compared to the currently known photon exchange one with R-parity violating interactions. We will then give new upper bounds on the imaginary parts of R-parity violating couplings from the experimental data of the electric dipole moments of the electron and of the neutron. The effect due to b…
We derive stringent upper bounds on all the $(λ''_{ijk} μ_l)$-type combinations from the consideration of proton stability, where $λ''_{ijk}$ are baryon-number-violating trilinear couplings and $μ_l$ are lepton-number-violating bilinear mass parameters in a R-parity-violating supersymmetric theory.
We present a systematic analysis at the leading log order of the influence of combination of bilinear and trilinear R-parity violating couplings on the decay b-->s gamma. Such contributions have never been explored in the context of this decay. We show that influence of charged-slepton-Higgs mixing mediated loops can dominate the SM and MSSM contributions and hence can provide strong bounds on the combination of bilinear-trilinear R-parity violating couplings. Such contributions are also enhanced by large tan beta. With substantially extended basis of operators (28 operators), we provide illus…
In supersymmetric theories, sneutrino--anti-sneutrino mixing can occur with the oscillation time $\sim 0.01$ ps corresponding the atmospheric neutrino mass scale $\sim 0.05$ eV. We explore the possibility of observing sneutrino oscillation phenomena and CP violation when R-parity violation explains the observed neutrino masses and mixing. It is shown for some parameter region in the bilinear model of R-parity violation that the tiny sneutrino mass splitting and time-dependent CP violating asymmetries could be measured in the future experiments if the tau sneutrino is the lightest supersymmetri…
A scheme is described in which the light gravitino in low energy SUSY breaking models mixes with neutrinos. The mixing between gravitino and neutrinos arises through the standard model symmetry breaking and an R-parity and lepton number violating bilinear term in the superpotential. It is shown that mixings compatible with the neutrino experiments can be obtained within the cosmological bound on the bilinear term set by the baryon asymmetry of the universe.
The minimal supersymmetric Standard Model with explicit R-parity nonconservation contains bilinear terms involving the left-handed lepton superfields and the Higgs chiral multiplet with hypercharge Y=+1, which cannot in general be rotated away in the presence of soft-supersymmetry- breaking interactions. These bilinear lepton-number-violating terms are found to give rise to non-zero vacuum expectation values of the scalar neutrinos. This leads to nonuniversal and flavour-violating tree-level couplings of the W and Z bosons to charged leptons and neutrinos. The parameter space of this novel sce…
We consider the Next to Minimal Supersymmetric Standard Model (NMSSM) which provides a natural solution to the so-called mu problem by introducing a new gauge-singlet superfield S. We realize that a new mechanism of neutrino mass suppression, based on the R-parity violating bilinear terms mu_i L_i H_u mixing neutrinos and higgsinos, arises within the NMSSM, offering thus an original solution to the neutrino mass problem (connected to the solution for the mu problem). We generate realistic (Majorana) neutrino mass values without requiring any strong hierarchy amongst the fundamental parameters,…
In the so-called ``yukawaon" model, the (effective) Yukawa coupling constants $Y_f^{eff}$ are given by vacuum expectation values (VEVs) of scalars $Y_f$ (yukawaons) with $3\times 3$ components. In the present model, all of the VEV matrices $\langle Y_f \rangle$ are given by a bilinear form of VEVs of flavons $Φ_f$, $\langle Y_f \rangle_i^{\ j} = k_f \langle Φ_f\rangle_{ik} \langle \barΦ_f\rangle^{kj}$, where $Φ_f$ is assigned to ${\bf 6}$ of U(3) family symmetry. As input parameters with family-number dependent values, we use only charged lepton mass values. Under this formulation, we can give…
R-parity and L violation in the MSSM would be the origin of the neutrino oscillation observed in Super-Kamiokande. A distinctive feature of this framework is that it can be tested in colliders by observing decay products of the destabilized LSP. We examine all the possible decay processes of the neutralino LSP assuming the bilinear contribution to neutrino masses dominates over the trilinear one which gives rise to the solar neutrino mass. We find that it is possible to probe neutrino oscillations through colliders in most of the R-parity conserving MSSM parameter space.
The flavor violating $μ^--e^-$ conversion in nuclei is studied within the minimal supersymmetric standard model. We focus on the R-parity violating contributions at tree level including the trilinear and the bilinear terms in the superpotential as well as in the soft supersymmetry breaking sector. The nucleon and nuclear structure have consistently been taken into account in the expression of the $μ^--e^-$ conversion branching ratio constructed in this framework. We have found that the contribution of the strange quark sea of the nucleon is comparable with that of the valence quarks. From the …
In a R-parity violating (RPV) model of neutrino mass with three bilinear couplings $μ_i$ and three trilinear couplings $λ'_{i33}$, where $i$ is the lepton index, we find six generic scenarios each with a distinctive pattern of the trilinear couplings consistent with the oscillation data. These patterns may be reflected in direct RPV decays of the lighter top squark or in the RPV decays of the lightest superparticle, assumed to be the lightest neutralino. Typical signal sizes at the Tevatron RUN II and the LHC have been estimated and the results turn out to be encouraging.
We present the full result for the down squark mass-squared matrix in the complete theory of supersymmetry without R-parity where all kind of R-parity violating terms are admitted without bias. An optimal parametrization, the single-VEV parametrization, is used. The major result is a new contribution to $LR$ squark mixing, involving both bilinear and trilinear R-parity violating couplings. Among other things, the latter leads to neutron electric dipole moment at one-loop level. Similiar mechanism leading to electron electric dipole moment at the same level. We present here a short report on ma…
In an R-parity violating supersymmetric scenario, the lightest neutralino $\tilde χ^0_1$ is no longer a stable particle. We calculate the branching ratio for the decay mode $\tilde χ^0_1 \longrightarrow νγ$ which occurs at the one-loop level. Taking into account bilinear as well as trilinear lepton number violating interactions as the sources of R-parity violation, we make a detailed scan of the parameter space, both with and without gaugino mass unification and including the constraints on the neutrino sector from the recent Superkamiokande results. This study enables one to suggest interesti…
In supersymmetric models neutrino data can be explained by R-parity violating operators which violate lepton number by one unit. The so called bilinear model can account for the observed neutrino data and predicts at the same time several decay properties of the lightest supersymmetric particle. In this paper we discuss the expected precision to determine these parameters by combining neutrino and LHC data and discuss the most important observables. We show that one can expect a rather accurate determination of the underlying R-parity parameters assuming mSUGRA relations between the R-parity c…
We present an on-shell renormalization scheme for the neutralino and chargino mass matrices for two R-parity violating models, namely bilinear R-parity violation and the munuSSM with one right-handed neutrino superfield. We discuss in both models how to obtain neutrino masses and mixing angles correctly as well as differences to the existing DRbar calculations. Both models predict correlations between neutrino mixing angles and ratios of R-parity violating decays such as neutralino_1 -> l W which can be tested for example at the LHC. We point out that there are cases where one has to include t…
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,mu,tau} in the charged sector can lead to measurable rates for BR(mu->e gamma)and $BR(tau-> mu gamma). We find that some of the R-parity violating terms that are compatible with the observed atmospheric neutrino oscillations could lead to rates for mu->e gamma measurable in projected experiments. Howeve…
We analyze the production of multileptons in the simplest supergravity model with bilinear violation of R parity at the Fermilab Tevatron. Despite the small R-parity violating couplings needed to generate the neutrino masses indicated by current atmospheric neutrino data, the lightest supersymmetric particle is unstable and can decay inside the detector. This leads to a phenomenology quite distinct from that of the R-parity conserving scenario. We quantify by how much the supersymmetric multilepton signals differ from the R-parity conserving expectations, displaying our results in the $m_0 \ot…
$R$-parity violating supersymmetric models (RPV SUSY) are becoming increasingly more appealing than its $R$-parity conserving counterpart in view of the hitherto non-observation of SUSY signals at the LHC. In this paper, we discuss RPV scenarios where neutrino masses are naturally generated, namely RPV through bilinear terms (bRPV) and the $μ$-from-$ν$ supersymmetric standard model ($μν$SSM). The latter is characterised by a rich Higgs sector that easily accommodates a 125-GeV Higgs boson. The phenomenology of such models at the LHC is reviewed, giving emphasis on final states with displaced o…
After discussion of mechanisms of lepton number violation, we consider meson decays $K^+ \toπ^ - \ell ^ + \ell '^ +$ and $D^ + \to K^ - \ell ^ + \ell '^ +$ ($\ell,\ell ' = e,μ$) with $ΔL= 2$ in the Standard Model extended by massive Majorana neutrinos and in a supersymmetric extension of the Standard Model with explicit breaking of R-parity by trilinear or bilinear Yukawa couplings in the superpotential. We give estimates of the branching ratios for these decays and compare the effectiveness of various decay mechanisms taking into account present experimental bounds on lepton mixing, masses of…
The lack of experimental evidence for supersymmetry motivates R-parity violating realizations of the MSSM. Dropping R-parity, alternative symmetries have to be imposed in order to stabilize the proton. We determine the possible discrete R and non-R symmetries, which allow for renormalizable R-parity violating terms in the superpotential and which, at the effective level, are consistent with the constraints from nucleon decay. Assuming a gauge origin, we require the symmetry to be discrete gauge anomaly-free, allowing also for cancellation via the Green Schwarz mechanism. Furthermore, we demand…
The patterns of $R$ violation resulting from imposition of a gauged U(1) horizontal symmetry on the minimal supersymmetric standard model are systematically analyzed. We concentrate on class of models with integer U(1) charges chosen to reproduce the quark masses and mixings as well as charged lepton masses exactly or approximately. The U(1) charges are further restricted by the requirement that very large bilinear lepton number violating terms should not be allowed in the superpotential. It is shown that this leads to severely constrained patterns of trilinear interactions. Specifically, only…
We show how R-parity can be dynamically broken by non-perturbative quantum gravity effects. In particular, in D-brane models, Exotic instantons provide a simple and calculable mechanism for the generation of R-parity violating bilinear, trilinear and higher order superpotential terms. We show examples of MSSM-like D-brane models, in which one Exotic Instanton induces only one term among the possible R-parity violating superpotentials. Naturally, the idea can be generalized for other gauge groups. As a consequence, a dynamical violation of R-parity does not necessarily destabilize the proton, i…
We discuss lepton flavour violating signals at the LHC in the framework of supersymmetric theories. We consider R-parity conserving as well as R-parity violating scenarios. In the case of R-parity conservation we show that in decays of supersymmetric particles large regions in parameter exist where lepton flavour violating decay modes have large branching ratios despite the stringent constraints from the non-observation of rare lepton decays. We discuss briefly some consequences for discovery potential and the measurements of edge-variables at LHC within the SPS1a scenario. In the case of R-pa…
