Predictivity of models with spontaneously broken non-Abelian discrete flavor symmetries

In a class of supersymmetric flavor models predictions are based on residual symmetries of some subsectors of the theory such as those of the charged leptons and neutrinos. However, the vacuum expectation values of the so-called flavon fields generally modify the Kähler potential of the setting, thus changing the predictions. We derive simple analytic formulae that allow us to understand the impact of these corrections on the predictions for the masses and mixing parameters. Furthermore, we discuss the effects on the vacuum alignment and on flavor changing neutral currents. Our results can also be applied to non-supersymmetric flavor models.     

Neutralino phenomenology at LEP2 in supersymmetry with bilinear breaking of R-parity

We discuss the phenomenology of the lightest neutralino in models where an effective bilinear term in the superpotential parametrizes the explicit breaking of R-parity. We consider supergravity scenarios where the lightest supersymmetric particle (LSP) is the lightest neutralino and which can be explored at LEP2. We present a detailed study of the LSP decay properties and general features of the corresponding signals expected at LEP2. We also contrast our model with gauge mediated supersymmetry breaking.     

Dark and visible matter with broken R-parity and the axion multiplet

A small breaking of R-parity reconciles thermal leptogenesis, gravitino dark matter and primordial nucleosynthesis. We find that the same breaking relaxes cosmological bounds on the axion multiplet. Naturally expected spectra become allowed and bounds from late particle decays become so weak that they are superseded by bounds from non-thermal axion production. In this sense, the strong CP problem serves as an additional motivation for broken R-parity.     

Neutrino mass patterns, R-parity violating supersymmetry and associated phenomenology

Motivated by the recent super-Kamiokande results on atmospheric neutrinos, we incorporate massive neutrinos, with large angle oscillation between the second and third generations, in a theory with R-parity violating supersymmetry. The general features of such a theory are briefly reviewed. We emphasize its testability through the observation of comparable numbers of muons and taus, produced together with the W-boson, in decays of the lightest neutralino. A distinctly measurable decay gap is another remarkable feature of such a scenario.     

Weyl gauging and spontaneously broken Lorentz symmetry: Some alternative models

Some new effective actions are suggested for theories in which the affine connection is not completely specified by the metric. The new actions lead to models in which the metric, torsion, and Weyl vector fields all propagate. The dimensionally reduced versions do not contain third derivatives of the gauge potentials in the field equation. Some simple models which exhibit simultaneous breaking of Weyl andD-dimensional Lorentz symmetry are investigated. It is shown that it is possible for this effect to occur in any model in which the field action contains the Einstein-Hilbert term. This is due to the fact that the contortion occurs in this object as part of an indefinite quadratic form.     

Ultra-light neutrinos and R-parity in superstring models

A mechanism is suggested for generating ultra-light neutrinos in intermediate scale superstring models as a consequence of R-parity conservation. Neutrino masses are suppressed by four powers of the intermediate scale and could be appropriate to explain the reduced solar neutrino flux in terms of resonant oscillations of the electron- to the muon-neutrino.     

Photon signatures for low energy supersymmetry breaking and broken R-parity

The possible phenomenological consequences of R-parity violating interactions in the framework of low energy supersymmetry breaking are studied. It is pointed out that even very weak R-parity violation would completely overshadow one of the basic signatures of low energy supersymmetry breaking models, that is the decay of the next to lightest supersymmetric particle into a photon (lepton) and missing energy. Thus, the observation of these decays would put very strong limits on R-parity violating couplings. Vice-versa, if R-parity violation is established experimentally, before a detailed knowledge of the spectrum is obtained, it will be very difficult to distinguish gravity mediated from low energy gauge mediated supersymmetry breaking scenarios. Those conclusions are very model independent. We also comment on the possibility of mixing between charged and neutral leptons with charginos and neutralinos, respectively, and its phenomenological consequences for the photon (lepton) signatures, in scenarios where this mixing is generated by the presence of bilinear or trilinear R-parity violating terms in the superpotential.     

Explicit R-parity breaking in supersymmetric models

Supersymmetric models generally invoke R parity to ensure that baryon and lepton numbers are symmetries of the renormalizable operators of the low-energy effective theory. The phenomenology of lepton-number violation is analyzed in low-energy models in which R parity is explicitly broken by superrenormalizable operators. Constraints on lepton-number violating parameters are found to be mild. The photino is able to decay, avoiding a stringent cosmological lower bound on its mass. Alternatives to R parity are considered in the context of an SU(5) grand unified model coupled to N=1 supergravity. One possibility, θ parity, leads to new mechanisms for baryon- number violation in addition to lepton-number violation.     

A simple explanation of the PVLAS anomaly in spontaneously broken mirror models

The PVLAS anomaly can be explained if there exist millicharged particles of mass ?0.1 eV$?0.1\text{eV}$ and electric charge ?∼¹⁰⁻⁶e$\mathrm{?}\sim {10}^{\mathrm{-6}}e$. We point out that such particles occur naturally in spontaneously broken mirror models. We argue that this interpretation of the PVLAS anomaly is not in conflict with astrophysical constraints due to the self interactions of the millicharged particles which lead them to be trapped within stars. This conclusion also holds for a generic paraphoton model.     

Subquark pregeometry with spontaneously broken conformal invariance

We present a model of subquark pregeometry in which the Higgs scalar as well as the space-time metric appears as a composite of subquark-antisubquark pairs. The effective langrangian becomes the einstein one with no cosmological term when conformal invariance is broken spontaneously.     

The spontaneously broken supersymmetry in quantum field theory

It is shown that every spontaneous breaking of supersymmetry can be accomplished by means of a locally conserved supercurrent

$\text{εαβf}{}^{\mathrm{+}}{}_{\mathrm{<mtext>\gamma </mtext><mtext>?</mtext>}}\text{, α, β, γ = 1, 2,}$

$\text{εαβ =}\text{0}\text{1}\text{?1}\text{1}$

, where $\text{f}{}^{\mathrm{+}}{}_{\mathrm{<mtext>\gamma </mtext><mtext>?</mtext>}}$ is a massless field satisfying the Weyl Equation. For a given supercurrent $\text{jαβ}\text{γ}\text{?}$ the necessary condition that it will break spontaneously the supersymmetry is

$\text{jαβ}\text{γ}\text{?}\text{?jβα}\text{γ}\text{?}\text{≠0.}$

It is shown that the anticommutation relations of the broken supercharges are not related to the energy-momentum vector.Similar procedure applied in case of a vector field is inconclusive.The extension of the Maisson and Reeh statement on the helicity of Goldstone fields is given.     

Cosmological solutions in a spontaneously broken gauge theory

We consider solutions of the Yang-Mills-Higgs system coupled to gravity in asymptotically de Sitter space-time. The basic features of two classes of solutions are discussed, one of them corresponding to magnetic monopoles, the other one to sphalerons. We find that although the total mass within the cosmological horizon of these configurations is finite, their mass evaluated at timelike infinity generically diverges for most values of the cosmological constant. Also, no solutions exist in the absence of a Higgs potential.