A three-generation SU(4)×O(4) string model

Antoniadis, Ignatios; Leontaris, G.K.; Rizos, John

doi:10.1016/0370-2693(90)90127-r

Cited by 299 publications

(448 citation statements)

References 23 publications

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“…For such strings, there are 4 ND directions which provide 4 zero modes in the NS sector (directions 4,5,6,7) while from the NN and DD directions we have zero modes in the R sector ( directions 2,3,8,9) The invariant (complex) scalars (NS sector) must satisfy…”

Section: D-branes At Orbifold Singularitiesmentioning

confidence: 99%

D‐branes in Standard Model building, gravity and cosmology

Kiritsis

2004

Fortschritte der Physik

151

193

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D-branes are by now an integral part of our toolbox towards understanding nature. In this review we will describe recent progress in their use to realize fundamental interactions. The realization of the Standard Model and relevant physics and problems will be detailed. New ideas on realizing 4-dimensional gravity use the brane idea in an important way. Such approaches will be reviewed and compared to the standard paradigm of compactification. Branes can play a pivotal role both in early-and late-universe cosmology mainly via the brane-universe paradigm. Brane realizations of various cosmological ideas (early inflation, sources for dark matter and dark energy, massive gravity etc) will be also reviewed.

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Section: D-branes At Orbifold Singularitiesmentioning

confidence: 99%

D‐branes in Standard Model building, gravity and cosmology

Kiritsis

2004

Fortschritte der Physik

151

193

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“…[69], and of analogous results obtained for the free fermionic formulation of string theory [70] (for applications based on this formulation, see e.g., Ref. [71], [30], [31] and [72]), that grand unification occurs, through symmetries like E 6 , SO(10) or SU(5), only in some higher dimension (d > 4), and that the breaking of the unification gauge symmetry to some lower symmetry containing the standard model gauge group as well as doublet-triplet splitting occurs in the process of compactification. More specifically the latter two phenomena take place through either (a) Wilson lines [69], or (b) orbifolds [73] (for an incomplete list of recent attempts based on orbifold compactification, see e.g., Refs.…”

Section: Conventional Versus Other Approachesmentioning

confidence: 58%

“…However, no such mechanism has emerged yet, in string theory, for the GUT-like solutions [29]. 3 Non-GUT string solutions, based on symmetries like G(224) or G(2113) for example, have a distinct advantage in this regard, in that the dangerous color triplets, which would induce rapid proton decay, are often naturally projected out for such solutions [30,31]. Furthermore, the non-GUT solutions invariably possess new "flavor" gauge symmetries, which distinguish between families.…”

Section: The Need For Supersymmetry: Mssm Versus String Unificationsmentioning

confidence: 99%

“…Ref. [30] and [31]), but the new d = 5 operators, related to the Majorana masses of the RH neutrinos and the CKM mixings, should very likely be present for such a model, as much as for SO (10). These would induce proton decay 22 .…”

Section: Contribution From the New D=5 Operatorsmentioning

confidence: 99%

“…More specifically the latter two phenomena take place through either (a) Wilson lines [69], or (b) orbifolds [73] (for an incomplete list of recent attempts based on orbifold compactification, see e.g., Refs. [74,75,76,77,79,80,81]), or (c) essentially equivalently by a set of boundary conditions together with the associated GSO projections for the free fermionic formulation (see e.g., [30,31,71,72]), or (d) discrete symmetries operating in higher dimensions [82].…”

Section: Conventional Versus Other Approachesmentioning

confidence: 99%

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Probing grand unification with fermion masses, neutrino oscillations and proton decay

Pati

2003

Pramana - J Phys

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It is noted that one is now in possession of a set of facts, which may be viewed as the matching pieces of a puzzle; in that all of them can be resolved by just one idea-that is grand unification. These include (i) the observed family-structure, (ii) quantization of electric charge, (iii) the meeting of the three gauge couplings, (iv) neutrino oscillations [in particular the value ∆m 2 (ν µ − ν τ ), suggested by SuperK], (v) the intricate pattern of the masses and mixings of the fermions, including the smallness of V cb and the largeness of θ osc νµντ , and (vi) the need for B-L as a generator to implement baryogenesis (via leptogenesis). All these pieces fit beautifully together within a single puzzle board framed by supersymmetric unification, based on either SO(10) or a string-unified G(224)-symmetry. The two notable pieces of the puzzle still missing, however, are proton decay and supersymmetry.A concrete proposal is presented within a predictive SO(10)/G(224)-framework that successfully describes the masses and mixings of all fermions, including the neutrinos-with eight predictions, all in agreement with observation. Within this framework, a systematic study of proton decay is carried out, which (a) pays special attention to its dependence on the fermion masses, and (b) limits the threshold corrections so as to preserve natural coupling unification. The study updates prior work by Babu, Pati and Wilczek, in the context of both MSSM and its (interesting) variant, the so-called ESSM, by allowing for improved values of the matrix elements and of the short-and long-distance renormalization effects. It shows that a conservative upper limit on the proton lifetime is about (1/3 -2)×10 34 years, with νK + being the dominant decay mode, and quite possibly µ + K 0 and e + π 0 being prominent. This in turn strongly suggests that an improvement in the current sensitivity by a factor of five to ten (compared to SuperK) ought to reveal proton decay. Otherwise some promising and remarkably successful ideas on unification would suffer a major setback. For comparison, some alternatives to the conventional approach to unification pursued here are mentioned at the end.

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MSHSM – Minimal Standard Heterotic String Models

Faraggi¹

2010

Fortschritte der Physik

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A three-generation SU(4)×O(4) string model

Cited by 299 publications

References 23 publications

D‐branes in Standard Model building, gravity and cosmology

D‐branes in Standard Model building, gravity and cosmology

Probing grand unification with fermion masses, neutrino oscillations and proton decay

MSHSM – Minimal Standard Heterotic String Models

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