No Arabic abstract
The supersymmetric Nambu-Jona-Lasinio model proposed by Cheng, Dai, Faisel and Kong is re-analyzed by using an auxiliary superfield method in which a hidden local U(1) symmetry emerges. It is shown that, in the healthy field-space region where no negative metric particles appear, only SUSY preserving vacua can be realized in the weak coupling regime and a composite massive spin-1 supermultiplets appear as a result of spontaneous breaking of the hidden local U(1) symmetry. In the strong coupling regime, on the other hand, SUSY is dynamically broken, but it is always accompanied by negative metric particles.
We study the vacuum condensate characterizing many physical phenomena. We show that such a condensate may leads to non-trivial components of the dark energy and of the dark matter and may induces the spontaneous supersymmetry breaking, in a supersymmetric context. In particular, we consider the condensate induced by thermal states, fields in curved space-time and mixed particles.
Motivated by supersymmetry breaking in matrix model formulations of superstrings, we present some concrete models, in which the supersymmetry is preserved for any finite $N$, but gets broken at infinite $N$, where $N$ is the rank of matrix variables. The models are defined as supersymmetric field theories coupled to some matrix models, and in the induced action obtained after integrating out the matrices, supersymmetry is spontaneously broken only when $N$ is infinity. In our models, the large value of $N$ gives a natural explanation for the origin of small parameters appearing in the field theories which trigger the supersymmetry breaking. In particular, in the case of the ORaifeartaigh model coupled to a certain supersymmetric matrix model, a nonsupersymmetric metastable vacuum appears near the origin of the field space, which is far from the position of the supersymmetric vacuum. We estimate its lifetime as a function of $N$.
We study nonlinear vacuum electrodynamics in a first-order formulation proposed by Plebanski. By applying a Dirac constraint analysis, we derive an effective Hamiltonian, together with the equations of motion. We show that there exists a large class of potentials for which the effective Hamiltonian is bounded from below, while at the same time possessing stationary points in which the field strength acquires a nonzero vacuum expectation value. The associated spontaneous breaking of Lorentz symmetry can in principle be detected by coupling the model to a suitable external current, or to gravity. We show that the possible vacua can be classified in four classes. We study some of their properties, using explicit examples for illustration.
We discuss the possibility of finding scenarios, within type IIB string theory compactified on Calabi-Yau orientifolds with fluxes, for realizing gauge mediated supersymmetry breaking. We find that while in principle such scenarios are not ruled out, in practice it is hard to get acceptable constructions, since typically, supersymmetry breaking cannot be separated from the stabilization of the light modulus.
The dynamics of a vortex string, which describes the Nambu-Goldtone modes of the spontaneous breakdown of the target space D=4, N=1 supersymmetry and internal $U(1)_R$ symmetry to the world sheet ISO(1,1) symmetry, is constructed by using the approach of nonlinear realization. The resulting action describing the low energy oscillations of the string into the covolume (super)space is found to have an invariant synthesis form of the Akulov-Volkov and Nambu-Goto actions. Its dual scalar field action is obtained by means of introducing two vectorial Lagrangian multipliers into the action of the string