scholarly journals Moduli forces in string models with large internal dimensions

1999 ◽  
Vol 561 (1-2) ◽  
pp. 17-29 ◽  
Author(s):  
Edi Halyo
Keyword(s):  
2021 ◽  
Vol 2021 (8) ◽  
Author(s):  
Anamaría Font ◽  
Bernardo Fraiman ◽  
Mariana Graña ◽  
Carmen A. Núñez ◽  
Héctor Parra De Freitas

Abstract Compactifications of the heterotic string on special Td/ℤ2 orbifolds realize a landscape of string models with 16 supercharges and a gauge group on the left-moving sector of reduced rank d + 8. The momenta of untwisted and twisted states span a lattice known as the Mikhailov lattice II(d), which is not self-dual for d > 1. By using computer algorithms which exploit the properties of lattice embeddings, we perform a systematic exploration of the moduli space for d ≤ 2, and give a list of maximally enhanced points where the U(1)d+8 enhances to a rank d + 8 non-Abelian gauge group. For d = 1, these groups are simply-laced and simply-connected, and in fact can be obtained from the Dynkin diagram of E10. For d = 2 there are also symplectic and doubly-connected groups. For the latter we find the precise form of their fundamental groups from embeddings of lattices into the dual of II(2). Our results easily generalize to d > 2.


2020 ◽  
Vol 2020 (10) ◽  
Author(s):  
Ivano Basile ◽  
Stefano Lanza

Abstract We study de Sitter configurations in ten-dimensional string models where supersymmetry is either absent or broken at the string scale. To this end, we derive expressions for the cosmological constant in general warped flux compactifications with localized sources, which yield no-go theorems that extend previous works on supersymmetric cases. We frame our results within a dimensional reduction and connect them to a number of Swampland conjectures, corroborating them further in the absence of supersymmetry. Furthermore, we construct a top-down string embedding of de Sitter brane-world cosmologies within unstable anti-de Sitter landscapes, providing a concrete realization of a recently revisited proposal.


2005 ◽  
Vol 20 (29) ◽  
pp. 7032-7034 ◽  
Author(s):  
T. S. YULDASHBAEV ◽  
KH. NURITDINOV

According to Pamir X-ray Emulsion Chamber (XEC) experimental data at the energies E est > 2 × 1016 eV the fraction of events with four "aligned" most energetic particles increases sharply for families without leading secondary particles. That energy dependence is not described by Quark Gluon String Models.


2011 ◽  
Vol 2011 ◽  
pp. 1-15 ◽  
Author(s):  
Ralph Blumenhagen ◽  
Benjamin Jurke ◽  
Thorsten Rahn

Novel nonstandard techniques for the computation of cohomology classes on toric varieties are summarized. After an introduction of the basic definitions and properties of toric geometry, we discuss a specific computational algorithm for the determination of the dimension of line-bundle-valued cohomology groups on toric varieties. Applications to the computation of chiral massless matter spectra in string compactifications are discussed, and using the software packagecohomCalg, its utility is highlighted on a new target space dual pair of(0,2)heterotic string models.


2015 ◽  
Vol 91 (6) ◽  
Author(s):  
Alon E. Faraggi ◽  
Hasan Sonmez

2010 ◽  
Vol 58 (7-9) ◽  
pp. 883-887 ◽  
Author(s):  
I. Florakis
Keyword(s):  

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