439 research outputs found

    Sufficient second-order optimality conditions for semilinear control problems with pointwise state constraints

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    Second-order sufficient optimality conditions are established for the optimal control of semilinear elliptic and parabolic equations with pointwise constraints on the control and the state. In contrast to former publications on this subject, the cone of critical directions is the smallest possible in the sense that the second-order sufficient conditions are the closest to the associated necessary ones. The theory is developed for elliptic distributed controls in domains up to dimension three. Moreover, problems of elliptic boundary control and parabolic distributed control are discussed in spatial domains of dimension two and one, respectively

    On non-perturbative corrections to the Kahler potential

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    We present the results of a detailed investigation into the consequences of adding specific string motivated non-perturbative corrections to the usual tree level Kahler potential in dilaton dominated scenarios. The success of the model is judged through our ability to obtain a realistic VEV for the dilaton < Re S > ~ 2, corresponding to the true minima of the scalar potential and being associated with a reasonable value for the SUSY breaking scale via the gravitino mass. The status of the so-called moduli problem is also reviewed in each of the ansatze studied. Those include previous proposals made in the context of both the chiral and the linear multiplet formalisms to describe gaugino condensation, and a new ansatz which shows explicitly the equivalence between the two.Comment: 11 pages, LaTex, uses psfig.sty with 4 figure

    The μ\mu problem, and B and L Conservation with a Discrete Gauge R Symmetry

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    We examine in a generic context how the μ\mu problem can be resolved by means of a spontaneously broken gauge symmetry. We then focus on the new scheme based on a discrete gauge R symmetry which is spontaneously broken by nonperturbative hidden sector dynamics triggering supersymmetry breaking also. The possibility to suppress the dangerous baryon and/or lepton number violating interactions by means of this discrete R symmetry is examined also together with some phenomenological consequences.Comment: 13 pages, RevTex, no figure

    Model Independent Properties and Cosmological Implications of the Dilaton and Moduli Sectors of 4-d Strings

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    We show that if there is a realistic 4-d string, the dilaton and moduli supermultiplets will generically acquire a small mass O(m_{3/2}), providing the only vacuum-independent evidence of low-energy physics in string theory beyond the supersymmetric standard model. The only assumptions behind this result are (i) softly broken supersymmetry at low energies with zero cosmological constant, (ii) these particles interact with gravitational strength and the scalar components have a flat potential in perturbation theory, which are well-known properties of string theories. (iii) They acquire a vevvev of the order of the Planck scale (as required for the correct value of the gauge coupling constants and the expected compactification scale) after supersymmetry gets broken. We explore the cosmological implications of these particles. Similar to the gravitino, the fermionic states may overclose the Universe if they are stable or destroy nucleosynthesis if they decay unless their masses belong to a certain range or inflation dilutes them. For the scalar states it is known that the problem cannot be entirely solved by inflation, since oscillations around the minimum of the potential can lead to a huge entropy generation at late times. We discus some possible ways to alleviate this entropy problem, that favour low-temperature baryogenesis, and also comment on the possible role of these particles as dark matter candidates or as sources of the baryon asymmetry through their decay.Comment: 15 pages,CERN-TH.6958/93,NEIP-93-006, IEM-FT-75/93, Late

    Non-Universal Gaugino Masses and the Fate of mu -> e gamma

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    We study charged lepton flavor violating processes in the context of supersymmetric models with non-universal gaugino masses. We consider the generic case of free gaugino masses, as well as specific models based on gaugino mediation and SU(5) GUTs. Under the assumption that the main source of lepton flavor violation resides in the off-diagonal elements of the left handed slepton mass matrix, we show that BR(mu->e gamma) strongly depends on gaugino non-universality. When M_1 and M_2 have opposite signs, cancellations occurring between the neutralino and the chargino contributions can suppress, even completely, the branching ratio of charged lepton flavor violating decays. Moreover, we find that for M_3> M_2,M_1, BR(mu->e gamma) is an increasing function of M_3.Comment: 14 pages, 10 figures; Accepted for publication in Nuclear Physics

    Flavor changing neutral current constraints on standard-like orbifold models

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    We examine for standard-like orbifold compactification models the constraints due to quarks and leptons generation non-universality of soft supersymmetry breaking interactions. We follow the approach initiated by Ibanez and Lust and developed by Brignole, Ibanez and Munoz. The breaking of supersymmetry is represented in terms of dilaton and moduli auxiliary field components and, consistently with a vanishing cosmological constant, is parametrized in terms of the dilaton-moduli mixing angle θ\theta and the gravitino mass scale mgm_g. The soft breaking interactions (gaugino masses, squarks and sleptons mass matrices, scalars interactions A and B coupling constants) are calculable as a function of these parameters and of the discrete set of modular weight parameters specifying the modular transformation properties of the low-energy fields. We solve the renormalization group one-loop equations for the full set of gauge, Yukawa and supersymmetry breaking coupling constants.Comment: 32 page

    Stabilizing dilaton and baryogenesis

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    Entropy production by the dilaton decay is studied in the model where the dilaton acquires potential via gaugino condensation in the hidden gauge group. Its effect on the Affleck-Dine baryogenesis is investigated with and without non-renormalizable terms in the potential. It is shown that the baryon asymmetry produced by this mechanism with the higher-dimensional terms is diluted by the dilaton decay and can be regulated to the observed value.Comment: 20 pages, 3 figures, baryon asymmetry revised, errors corrected, references and comments adde

    El aeropuerto, una interfaz conectiva en el territorio

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    El presente trabajo tiene por objeto señalar algunos aspectos de conflictividad de las instalaciones aeroportuarias de nuestro medio en relación con su presencia en el territorio y con su vinculación con las estructuras urbanas. Uno de los temas principales de esta conflictividad es la escasa conectividad que presentan los aeropuertos provocados por falta de planificación integral, inversiones y actualización de criterios infraestructurales. Por otro lado, las relaciones físicas entre el aeropuerto y su predio y la estructura urbana vecina, denotan otras áreas de conflicto que reclaman una visión sistémica en el campo de la planificación territorial.Grupo de Transporte Aéreo - Grupo de Ingeniería Aplicada a la Industri
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