A standard-like model in the four-dimensional free fermionic string formulation

Faraggi, Alon E.; Nanopoulos, Dimitri V.; Yuan, Ke

doi:10.1016/0550-3213(90)90498-3

Cited by 275 publications

(572 citation statements)

References 33 publications

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“…The fact that three families can be obtained from heterotic strings has been demonstrated in various constructions; some early references are for example [30,31,32,33,34]. In the context of Gepner models examples were found in [5], [1] and [35].…”

Section: Introductionmentioning

confidence: 99%

Asymmetric Gepner models (revisited)

Gato-Rivera

Schellekens

2010

Nuclear Physics B

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We reconsider a class of heterotic string theories studied in 1989, based on tensor products of N = 2 minimal models with asymmetric simple current invariants. We extend this analysis from (2, 2) and (1, 2) spectra to (0, 2) spectra with SO(10) broken to the Standard Model. In the latter case the spectrum must contain fractionally charged particles. We find that in nearly all cases at least some of them are massless. However, we identify a large subclass where the fractional charges are at worst half-integer, and often vector-like. The number of families is very often reduced in comparison to the 1989 results, but there are no new tensor combinations yielding three families. All tensor combinations turn out to fall into two classes: those where the number of families is always divisible by three, and those where it is never divisible by three. We find an empirical rule to determine the class, which appears to extend beyond minimal N = 2 tensor products. We observe that distributions of physical quantities such as the number of families, singlets and mirrors have an interesting tendency towards smaller values as the gauge groups approaches the Standard Model. We compare our results with an analogous class of free fermionic models. This displays similar features, but with less resolution. Finally we present a complete scan of the three family models based on the triply-exceptional combination (1, 16 * , 16 * , 16 * ) identified originally by Gepner. We find 1220 distinct three family spectra in this case, forming 610 mirror pairs. About half of them have the gauge group SU (3) × SU (2) L × SU (2) R × U (1) 5 , the theoretical minimum, and many others are trinification models.

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Section: Introductionmentioning

confidence: 99%

Asymmetric Gepner models (revisited)

Gato-Rivera

Schellekens

2010

Nuclear Physics B

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“…The choice of generalized GSO projection coefficients of the model of table [4.26], as well as the complete mass spectrum and its charges under the four dimensional gauge group are given in ref. [6]. One of the important constraints in the construction of the free fermionic models is the requirement that the supercurrent, eq.…”

Section: Moduli In Free Fermionic Modelsmentioning

confidence: 99%

“…The ξ 2 -sector produces the spinorial 128 of SO (16) and completes the hidden gauge group to E 8 . The NAHE set divides the internal world-sheet fermions in the following way: φ 1,···,8 generate the hidden E 8 gauge group,ψ 1,···,5 generate the SO(10) gauge group, and {ȳ 3,···,6 ,η 1 }, {ȳ 1 ,ȳ 2 ,ω 5 ,ω 6 ,η 2 }, {ω 1,···,4 ,η 3 } generate the three horizontal SO (6) symmetries. The left-moving {y, ω} states are divided into {y 3,···,6 }, {y 1 , y 2 , ω 5 , ω 6 }, {ω 1,···,4 } and χ 12 , χ 34 , χ 56 generate the left-moving N = 2 world-sheet supersymmetry.…”

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

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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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“…[7]. The Minimal Superstring Standard Model has only the matter content of the Minimal Supersymmetric Model 1 (MSSM) at scales significantly below the string scale Λ H ∼ 10 17 GeV.…”

Section: Introductionmentioning

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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A standard-like model in the four-dimensional free fermionic string formulation

Cited by 275 publications

References 33 publications

Asymmetric Gepner models (revisited)

Asymmetric Gepner models (revisited)

Moduli fixing in realistic string vacua

Spectra in Standard-like Z3 Orbifold Models

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