scholarly journals PROGRESS IN WEAKLY COUPLED STRING PHENOMENOLOGY

2002 ◽  
Vol 17 (supp01) ◽  
pp. 70-83
Author(s):  
MARY K. GAILLARD
Keyword(s):  
String Theory ◽  
Supersymmetry Breaking ◽  
Particle Physics ◽  
Specific Model ◽  
Heterotic String ◽  
Particle Spectrum ◽  
Heterotic String Theory ◽  
Hidden Sector ◽  
String Phenomenology ◽  
Weakly Coupled

The weakly coupled vacuum of E8 ⊗ E8 heterotic string theory remains an attractive scenario for particle physics. The particle spectrum and the issue of dilaton stabilization are reviewed. A specific model for hidden sector condensation and supersymmetry breaking, that respects known constraints from string theory, is described, and its phenomenological and cosmological implications are discussed.

Perspective on the weakly coupled heterotic string

2015 ◽  
Vol 30 (08) ◽  
pp. 1530005 ◽  
Author(s):  
Mary K. Gaillard
Keyword(s):  
String Theory ◽  
Standard Model ◽  
Supersymmetry Breaking ◽  
Heterotic String ◽  
Particle Spectrum ◽  
Promising Candidate ◽  
Heterotic String Theory ◽  
Hidden Sector ◽  
Weakly Coupled ◽  
The Standard Model

Since the first "string revolution" of 1984, the weakly coupled E8⊗E8 heterotic string theory has been a promising candidate for the underlying theory of the Standard Model. The particle spectrum and the issue of dilaton stabilization are reviewed. Specific models for hidden sector condensation and supersymmetry breaking are described and their phenomenological and cosmological implications are discussed. The importance of T-duality is emphasized. Theoretical challenges to finding a satisfactory vacuum, as well as constraints from LHC data are addressed.

STRINGY RESTRICTIONS ON THE BACKGROUNDS IN THE HETEROTIC SIGMA MODEL

1992 ◽  
Vol 07 (09) ◽  
pp. 749-756 ◽  
Author(s):  
SOUMITRA SENGUPTA ◽  
PARTHASARATHI MAJUMDAR
Keyword(s):  
String Theory ◽  
Cosmological Constant ◽  
Supersymmetry Breaking ◽  
Conformal Invariance ◽  
Sigma Model ◽  
Heterotic String ◽  
Antisymmetric Tensor ◽  
Tensor Fields ◽  
Heterotic String Theory

We show that for the heterotic string theory in the presence of arbitrary background gauge, gravitational and antisymmetric tensor fields, truncated by a general coordinate dependent compactification a la Scherk-Schwarz, the requirement of 2D conformal invariance is as restrictive as to inhibit supersymmetry breaking with vanishing cosmological constant.

scholarly journals Hierarchical structure of physical Yukawa couplings from matter field Kähler metric

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Keiya Ishiguro ◽  
Tatsuo Kobayashi ◽  
Hajime Otsuka
Keyword(s):  
String Theory ◽  
Hierarchical Structure ◽  
Matter Field ◽  
Heterotic String ◽  
Heterotic String Theory ◽  
Kähler Metric ◽  
Yukawa Couplings ◽  
String Compactifications ◽  
Kahler Metric ◽  
Matter Fields

Abstract We study the impacts of matter field Kähler metric on physical Yukawa couplings in string compactifications. Since the Kähler metric is non-trivial in general, the kinetic mixing of matter fields opens a new avenue for realizing a hierarchical structure of physical Yukawa couplings, even when holomorphic Yukawa couplings have the trivial structure. The hierarchical Yukawa couplings are demonstrated by couplings of pure untwisted modes on toroidal orbifolds and their resolutions in the context of heterotic string theory with standard embedding. Also, we study the hierarchical couplings among untwisted and twisted modes on resolved orbifolds.

scholarly journals Cascade of special holonomy manifolds and heterotic string theory

2002 ◽  
Vol 622 (1-2) ◽  
pp. 3-45 ◽  
Author(s):  
Katsuyuki Sugiyama ◽  
Satoshi Yamaguchi
Keyword(s):  
String Theory ◽  
Heterotic String ◽  
Heterotic String Theory ◽  
Special Holonomy

scholarly journals Symplectic modular symmetry in heterotic string vacua: flavor, CP, and R-symmetries

2022 ◽  
Vol 2022 (1) ◽  
Author(s):  
Keiya Ishiguro ◽  
Tatsuo Kobayashi ◽  
Hajime Otsuka
Keyword(s):  
String Theory ◽  
Common Origin ◽  
Heterotic String ◽  
Discrete Groups ◽  
Heterotic String Theory ◽  
Flavor Symmetries ◽  
Cp Symmetry

Abstract We examine a common origin of four-dimensional flavor, CP, and U(1)R symmetries in the context of heterotic string theory with standard embedding. We find that flavor and U(1)R symmetries are unified into the Sp(2h + 2, ℂ) modular symmetries of Calabi-Yau threefolds with h being the number of moduli fields. Together with the $$ {\mathbb{Z}}_2^{\mathrm{CP}} $$ ℤ 2 CP CP symmetry, they are enhanced to GSp(2h + 2, ℂ) ≃ Sp(2h + 2, ℂ) ⋊ $$ {\mathbb{Z}}_2^{\mathrm{CP}} $$ ℤ 2 CP generalized symplectic modular symmetry. We exemplify the S3, S4, T′, S9 non-Abelian flavor symmetries on explicit toroidal orbifolds with and without resolutions and ℤ2, S4 flavor symmetries on three-parameter examples of Calabi-Yau threefolds. Thus, non-trivial flavor symmetries appear in not only the exact orbifold limit but also a certain class of Calabi-Yau three-folds. These flavor symmetries are further enlarged to non-Abelian discrete groups by the CP symmetry.

scholarly journals KÄHLER STABILIZED, MODULAR INVARIANT HETEROTIC STRING MODELS

2007 ◽  
Vol 22 (08n09) ◽  
pp. 1451-1588 ◽  
Author(s):  
MARY K. GAILLARD ◽  
BRENT D. NELSON
Keyword(s):  
Heterotic String ◽  
Target Space ◽  
Modular Invariant ◽  
Heterotic String Theory ◽  
Effective Lagrangian ◽  
Parity Conservation ◽  
Weakly Coupled ◽  
String Models ◽  
Early Universe Cosmology

We review the theory and phenomenology of effective supergravity theories based on orbifold compactifications of the weakly-coupled heterotic string. In particular, we consider theories in which the four-dimensional theory displays target space modular invariance and where the dilatonic mode undergoes Kähler stabilization. A self-contained exposition of effective Lagrangian approaches to gaugino condensation and heterotic string theory is presented, leading to the development of the models of Binétruy, Gaillard and Wu. Various aspects of the phenomenology of this class of models are considered. These include issues of supersymmetry breaking and superpartner spectra, the role of anomalous U(1) factors, issues of flavor and R-parity conservation, collider signatures, axion physics, and early universe cosmology. For the vast majority of phenomenological considerations the theories reviewed here compare quite favorably to other string-derived models in the literature. Theoretical objections to the framework and directions for further research are identified and discussed.

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