World-sheet supersymmetry.
TL;DR: The progressive imposition of world-sheet supersymmetry from (1,0) to (2,2) is systematically analyzed and generalized; at each step, implications both for M and for the background gauge connection are stated.
Abstract: For the classical nonlinear $\ensuremath{\sigma}$ model on a general target manifold $M$, the progressive imposition of world-sheet supersymmetry (with torsion) from (1,0) to (2,2) is systematically analyzed and generalized; at each step, implications both for $M$ and for the background gauge connection are stated. Quantum conformal invariance is then imposed. Our analysis applies to superstrings without known space-time supersymmetry.
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TL;DR: In this paper, the anomalous U(1) symmetry in realistic free fermionic models has been studied in detail and several phenomenological issues related to this symmetry have been discussed.
Abstract: The realistic free fermionic models have had an intriguing success in explaining different properties of the observed particle spectrum. In this paper we discuss in some detail the anomalous U(1) symmetry which exists in these models. We study the properties of the anomalous U(1) in both the more realistic NAHE-based free fermionic models and those in a general NAHE class. Appearance of an anomalous U(1) in the more realistic NAHE models is shown to be an effect of reduction of world sheet supersymmetry from (2,2) to (2,0). We show, however, that in more general (2,1) and (2,0) models, all U(1) can remain anomaly-free under certain conditions. Several phenomenological issues related to the anomalous U(1) are discussed. In particular, we note that in some examples the anomalous U(1) arises from the breaking E6 → SO(10)×U(1)A, resulting in U(1)A being family universal.
66 citations
01 Jan 1987
TL;DR: The supersymmetric sigma-model in O+1 dimensions has been shown to be renor-malizable in this paper, which has been used to give elegant new proofs of index theorems and Morse inequalities.
Abstract: A non-linear sigma-model is a scalar field theory in which the scalar field takes values in some non-trivial manifold M, the target space. The most studied case is that in which M is a symmetric space such as a sphere or complex projective space, but here we shall consider general target manifolds. In four space-time dimensions, the sigma-model is non- renormalizable, but has been useful as an effective theory describing the low energy behaviour of scalar mesons and occurs naturally in supergravity theories. In two space-time dimensions, however, the sigma-model is renor- malizable [1] and has historically been of interest as a non-trivial “toy” field theory in which calculations are easier than in higher dimensional models such as gauge theories.The supersymmetric sigma-model [2] has a rich geometrical structure [3,4] and has led to interesting mathematical results,such as the construction of new complex geometies [4–7]. Some of these supersymmetric models have been shown to be completely free of ultra-violet divergences [8]. The supersymmetric sigma-model in O+1 dimensions, i. e. the quantum mechanics of a (super-) particle confined to M, has been used to give elegant new proofs of index theorems [9] and Morse inequalities [10].
49 citations
TL;DR: In this paper, a generalization of the compactification on the Calabi-Yau spaces is presented, where the gauge connection is not an embedding of the spin connection but rather a connection on a more general holomorphic vector bundle over a complex manifold.
8 citations
TL;DR: In this paper, the constraints arising from the progressive imposition of (p,q) world sheet supersymmetry are analyzed, allowing a wider class of models with additional symmetries.
6 citations
TL;DR: In this paper, the anomalous U(1) symmetry in realistic free fermionic models was studied in a general NAHE class and several phenomenological issues related to this symmetry were discussed.
Abstract: The realistic free fermionic models have had an intriguing success in explaining different properties of the observed particle spectrum. In this paper we discuss in some detail the anomalous U(1) symmetry which exists in these models. We study the properties of the anomalous U(1) in both the more realistic NAHE--based free fermionic models and those in a general NAHE class. Appearance of an anomalous U(1) in the more realistic NAHE models is shown to be an effect of reduction of world-sheet supersymmetry from (2,2) to (2,0). We show, however, that in more general (2,1) and (2,0) models, all U(1) can remain anomaly-free under certain conditions. Several phenomenological issues related to the anomalous U(1) are discussed. In particular, we note that in some examples the anomalous U(1) arises from the breaking $E_6 -> SO(10) X U(1)_A$, resulting in $U(1)_A$ being family universal.
1 citations