K. Enqvist

Observables in Low-Energy Superstring Models

We compile phenomenological constraints on the minimal low-energy effective theory which can be obtained from the superstring by Calabi-Yau compactification. Mixing with the single additional neutral gauge boson in this model reduces the mass of the conventional Z0, Field vacuum expectation values are constrained by the experimental upper bound on this shift. Then, requiring the sneutrino mass squared to be positive constrains the scale of supersymmetry breaking more than do lower bounds on the masses of new charged particles and of sparticles. More model-dependent constraints follow from the “naturalness” requirement that observables do not depend sensitively on input parameters. We find a preference for the second neutral gauge boson to weigh ≲320 GeV,

Aspects of the super-unification of strong, electroweak and gravitational interactions

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Gaugino masses and grand unification

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Experimental Predictions from the Superstring

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A Very Light Gravitino in a No Scale Model

GeV and

Problems for (2, 0) compactifications

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Non-compact supergravity solves problems

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Primordial nucleosynthesis, additional neutrinos and neutral currents from the superstring

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Scales in superstring models

GeV. Dynamical generation of the gauge hi...

Cosmological difficulties for intermediate scales in superstring models

Abstract We develop a strategy for extracting low-energy phenomenological four-dimensional physics from the superstring. We discuss supersymmetry and gauge symmetry breaking, emphasizing key ingredients in the construction of a realistic model based on Calabi-Yau compactification. The incorporation of a no-scale mechanism for the dynamical generation of the electroweak gauge hierarchy imposes a unique choice of the gauge group SU(3) × SU(2) × U(1)2, an almost unique set of matter fields and of Yukawa couplings. Our phenomenological analysis of this model includes the derivation of bounds on the mass of the new neutral gauge boson from the Z0 boson mass, low-energy neutral currents, and cosmology. We calculate the ratios of sparticle masses and give estimates of their magnitudes. These are based on detailed dynamical calculations demonstrating the feasibility of weak gauge symmetry breaking, made possible by radiative corrections to supersymmetry breaking initiated by a gaugino mass.