Showing papers on "Superpotential published in 1992"

Fractional charges in a superstring-derived standardlike model.

Abstract: We investigate the presence of fractionally charged states in the massless sector of our superstring-derived standardlike model. We show that these states are divided into three classes. The states in two of these classes will receive a Planck mass, at the trilinear level of the superpotential, by giving a vacuum expectation value to a set of neutral singlets in the string model, while the states of the third class are exotic color triplets and are therefore confined and may become superheavy at the nonrenormalizable level of the superpotential.

Duality-Invariant Gaugino Condensation and One-Loop Corrected Kahler Potentials in String Theory

Abstract: The duality-invariant gaugino condensation with or without massive matter fields is re-analysed, taking into account the dependence of the string threshold corrections on the moduli fields and recent results concerning one-loop corrected K\"ahler potentials. The scalar potential of the theory for a generic superpotential is also calculated.

Neutrino masses within the minimal supersymmetric standard model.

Abstract: We investigate the possibility of accommodating neutrino masses compatible with the Mikheyev- Smirnov-Wolfenstein study of the solar neutrino deficit within the minimal supersymmetric standard model. The «gravity-induced» seesaw mechanism based on an interplay of nonrenormalizable and renormalizable terms in the superpotential allows neutrino masses m v ∞m u 2 /M I , with m u the corresponding quark mass and M I ≃ 4 × 10 11 GeV, while at the same time ensuring the grand desert with the gauge coupling unification at M U ≃ 2 × 10 16 GeV

On the Moduli Space of the $T^6/Z_3$ Orbifold and Its Modular Group

Abstract: We describe the duality group $\Gamma=SU(3,3,Z)$ for the Narain lattice of the $T^6/Z_3$ orbifold and its action on the corresponding moduli space. A symplectic embedding of the momenta and winding numbers allows us to connect the orbifold lattice to the special geometry of the moduli space. As an application, a formal expression for an automorphic function, which is a candidate for a non--perturbative superpotential, is given.

Supersymmetric Quantum Theory

Abstract: We recall the treatment of the harmonic oscillator by means of ladder operators a and a † and pose the following question: Can one also represent other Hamiltonians as the “absolute square” of an operator and then construct their solutions algebraically?

The Marinari-Parisi model and collective field theory

Abstract: We derive the supersymmetric collective field theory for the Marinari-Parisi model. For a specific choice of the superpotential, to leading order we find a one-parameter family of ground states which can be connected via instantons. At this level of analysis the instanton size implied by the underlying matrix model does not appear.

The Marinari-Parisi Model and Collective Field Theory

Abstract: We derive the supersymmetric collective field theory for the Marinari-Parisi model. For a specific choice of the superpotential, to leading order we find a one parameter family of ground states which can be connected via instantons. At this level of analysis the instanton size implied by the underlying matrix model does not appear.

Local behavior in supersymmetric quantum mechanics

Abstract: In supersymmetric quantum mechanics, the differential equations corresponding to exactly solvable potentials may be treated by algebraic methods. By use of a system of geodesic polar coordinates on a Riemannian manifold, and subsequent transformation to a Schrodinger equation with a potential in two ways, it is demonstrated that the local behavior of the exactly solvable potentials considered in supersymmetric quantum mechanics corresponds to isotropic harmonic oscillator and Poschl–Teller potential problems.

The Breaking of the SU(3)**3 gauge group

Abstract: We discuss why the SU(3)^3 supersymmetric model with the most general superpotential can naturally break to the standard model if gauge singlets and a discrete symmetry are included. This mechanism does away with the need for fine-tuning in the form of the assumed absence of certain terms in the superpotential. It also automatically guarantees that any abelian discrete phase symmetry of the GUT will survive the symmetry breaking. Such a discrete symmetry, also known as the matter parity, is needed to suppress both proton decay and the flavor changing neutral current (FCNC), and may help solve the hierarchy problem.

Supersymmetry in Anti‐de Sitter Space

Abstract: We review the renormalization of the ground state solution of extended supergravity and super-symmetric Kaluza-Klein theories. The computation of an adiabatic expansion of the effective action to the one-loop order yields the result that a linear superfield insertion in the superpotential is needed, in order to renormalize the nonvanishing one-particle-irreducible one-point functions, whereas supersymmetry is preserved at each extremum of the effective potential. The calculation of the one-particle-irreducible two-and three-point functions shows that neither the mass nor the interaction lagrangians get renormalized to the one-loop order. We conclude that the one-loop effects proportional to the contraction parameter of the curved background space force a violation of the no-renormalization theorem.

Supersymmetric quantum mechanics, anomalies and factorization

Abstract: The explicit symmetry breaking phenomenon in supersymmetric quantum mechanics (SUSY QM) is analysed in terms of anomalies. The anomalous behaviour can be assigned to the supersymmetric charges which define the two Hamiltonians of the model. The relation between the presence of anomalies and the factorization of the Schrodinger equations is also discussed.

The Search for a realistic flipped SU(5) string model

Abstract: We present an extensive search for a general class of flipped $SU(5)$ models built within the free fermionic formulation of the heterotic string. We describe a set of algorithms which constitute the basis for a computer program capable of generating systematically the massless spectrum and the superpotential of all possible models within the class we consider. Our search through the huge parameter space to be explored is simplified considerably by the constraint of $N=1$ spacetime supersymmetry and the need for extra $Q,\bar Q$ representations beyond the standard ones in order to possibly achieve string gauge coupling unification at scales of ${\cal O}(10^{18}\GeV)$. Our results are remarkably simple and evidence the large degree of redundancy in this kind of constructions. We find one model with gauge group $SU(5)\times U(1)_\ty\times SO(10)_h\times SU(4)_h\times U(1)^5$ and fairly acceptable phenomenological properties. We study the $D$- and $F$-flatness constraints and the symmetry breaking pattern in this model and conclude that string gauge coupling unification is quite possible.

Supersymmetric quantum mechanics and two-dimensional systems

Abstract: We introduce a non usual realization of the supersyrnmetric algebra that enables us to treat two-dirnensional systems in a simple way. We study the Hartmann potential as an example. ~. Here, we intend to introduce a simple alternative realization of the superalgebra which allows us to treat quantum systems iii two dimensions. This realization is applicable to Harniltonians that can be written in two separated equations (sec. 2). We take the Hart- mann potentia17 that has been used to study the ben- zene molecule, as an example of this realization and we find its supersymmetric version (sec. 3). From Hart- mann supersymmet4c Hamiltonian we construct new potentials whose spectra and eigenfunctions are related with the original Hartmann potential (sec. 4).

Stringy Domain Walls and Other Stringy Topological Defects

Abstract: We point out that the moduli sector of the $(2,2)$ string compactification with its nonperturbatively preserved non-compact symmetries is a framework to study global topological defects Based on the target space modular invariance of the nonperturbative superpotential of the four-dimensional $N=1$ supersymmetric string vacua, topologically stable stringy domain walls are found Explicit supersymmetric solutions for the modulus field and the metric, which saturate the Bogomol'nyi bound, are presented They interpolate between {\it non-degenerate} vacua As a corollary, this defines a new notion of vacuum degeneracy of supersymmetric vacua Nonsupersymmetric stringy domain walls are discussed as well The moduli sectors with more than one modulus and the non-compact continous symmetry preserved allow for global monopole-type and texture-type configurations

Relativistic theory of superpotentials for a nonhomogeneous spatially isotropic medium

Abstract: This work deals with the relativistic, coordinate invariant theory of electromagnetic wave propagation in a nonhomogeneous medium that is spatially isotropic with respect to the generalized 4-velocity. The existence of a new superpotential for the electromagnetic field is established. The governing field equation for the superpotential is derived via a generalized Lorentz gauge condition for the electromagnetic potential and two new tensor identities involving the curvature tensor. The new field equation takes a simple form which reveals the effect of non-rigidity, rotation, acceleration, and incomplete material isotropy with respect to the Fermi frames as well as curvature and nonhomogeneous material properties.