Three generations in the fermionic construction

Chaudhuri, Siddhartha; Hockney, G.; Lykken, J.

doi:10.1016/0550-3213(96)00142-3

Cited by 91 publications

(159 citation statements)

References 66 publications

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“…In Figure II we show our results for values of Λ 3 which step by a factor of four; we assume Λ SUSY = 1 TeV for these (solid) curves. For comparison we also show the MSSM unification predictions (dashed) with Λ SUSY stepping by factors of four; in the MSSM case we take k Y = 5/3 and assume threshold corrections 64) where each of the quantities on the right-hand side are assumed as above. We also show with error bars the experimental values (5.25).…”

Section: Gauge Coupling Unificationmentioning

confidence: 99%

Spectra in Standard-like Z3 Orbifold Models

Giedt

2002

Annals of Physics

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General features of the spectra of matter states in all 175 models found in a previous work by the author are discussed. Only twenty patterns of representations are found to occur. Accomodation of the Minimal Supersymmetric Standard Model (MSSM) spectrum is addressed. States beyond those contained in the MSSM and nonstandard hypercharge normalization are shown to be generic, though some models do allow for the usual hypercharge normalization found in SU (5) embeddings of the Standard Model gauge group. The minimum value of the hypercharge normalization consistent with accomodation of the MSSM is determined for each model. In some cases, the normalization can be smaller than that corresponding to an SU (5) embedding of the Standard Model gauge group, similar to what has been found in free fermionic models. Bizzare hypercharges typically occur for exotic states, allowing for matter which does not occur in the decomposition of SU (5) representations-a result which has been noted many times before in four-dimensional string models. Only one of the twenty patterns of representations, comprising seven of the 175 models, is found to be without an anomalous U (1). The sizes of nonvanishing vacuum expectation values induced by the anomalous U (1) are studied. It is found that large radius moduli stabilization may lead to the breakdown of σ-model perturbativity. Various quantities of interest in effective supergravity model building are tabulated for the set of 175 models. In particular, it is found that string moduli masses appear to be generically quite near the gravitino mass. String scale gauge coupling unification is shown to be possible, albeit contrived, in an example model. The intermediate scales of exotic particles are estimated and the degree of fine-tuning is studied.

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Section: Gauge Coupling Unificationmentioning

confidence: 99%

Spectra in Standard-like Z3 Orbifold Models

Giedt

2002

Annals of Physics

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“…reproduce the massless root vectors in the lattice of SO (12). Here e i = {e I i } are six linearly-independent vielbeins normalized so that (e i ) 2 = 2.…”

Section: General Structure Of Free Fermionic Modelsmentioning

confidence: 99%

“…The same model is obtained in the geometric (bosonic) language by tuning the background fields to the values corresponding to the SO(12) lattice. The metric of the six-dimensional compactified manifold is then the Cartan matrix of SO (12), while the antisymmetric tensor is given by…”

Section: General Structure Of Free Fermionic Modelsmentioning

confidence: 99%

“…A particular class of string compactifications that exhibit promising phenomenological properties are the so-called free fermionic heterotic-string models [4,5,6,7,8,9,10,11,12,13]. These models are related to Z 2 × Z 2 orbifold compactifications [14], and many of their appealing phenomenological properties are rooted in the underlying Z 2 × Z 2 orbifold structure [14].…”

Section: Introductionmentioning

confidence: 99%

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Moduli fixing in realistic string vacua

Faraggi¹

2005

Nuclear Physics B

115

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I demonstrate the existence of quasi-realistic heterotic-string models in which all the untwisted Kähler and complex structure moduli, as well as all of the twisted sectors moduli, are projected out by the generalized GSO projections. I discuss the conditions and characteristics of the models that produce this result. The existence of such models offers a novel perspective on the realization of extra dimensions in string theory. In this view, while the geometrical picture provides a useful mean to classify string vacua, in the phenomenologically viable cases there is no physical realization of extra dimensions. The models under consideration correspond to Z 2 × Z 2 orbifolds of six dimensional tori, plus additional identifications by internal shifts and twists. The special property of the Z 2 × Z 2 orbifold is that it may act on the compactified dimensions as real, rather than complex, dimensions. This property enables an asymmetric projection on all six internal coordinates, which enables the projection of all the untwisted Kähler and complex structure moduli. * faraggi@thphys.ox.ac.uk

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“…Thus, R-parity violation is allowed while proton decay is forbidden. It will be of further interest to examine whether similar mechanism can operate in other string models [20,21]. For example, the SO(6) × SO(4) type models are of particular interest as they also can in principle differentiate between the lepton-number and baryon-number violating operators.…”

Section: Qldnmentioning

confidence: 99%

R-parity violation in superstring derived models

Faraggi

1997

Physics Letters B

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The ALEPH collaboration has recently reported a significant excess of fourjet events at the LEP 1.5 and LEP 2 experiments. While not yet confirmed by the other collaborations, it was recently proposed that this excess may be explained by certain R-parity violating operators in supersymmetric models. R-parity violating operators introduce the danger of inducing rapid proton decay. I discuss how the operators required to explain the ALEPH four jet events may arise from superstring derived models without inducing rapid proton de-

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Three generations in the fermionic construction

Cited by 91 publications

References 66 publications

Spectra in Standard-like Z3 Orbifold Models

Spectra in Standard-like Z3 Orbifold Models

Moduli fixing in realistic string vacua

R-parity violation in superstring derived models

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