scholarly journals Light colour-triplet Higgs is compatible with proton stability: An alternative approach to the doublet-triplet splitting problem

1996 ◽  
Vol 372 (1-2) ◽  
pp. 113-120 ◽  
Author(s):  
Gia Dvali
Keyword(s):  
Triplet Splitting ◽  
Alternative Approach ◽  
Splitting Problem ◽  
Proton Stability

scholarly journals SUPERSYMMETRIC UNIFICATION AND R SYMMETRIES

2012 ◽  
Vol 27 (40) ◽  
pp. 1230044 ◽  
Author(s):  
MU-CHUN CHEN ◽  
MAXIMILIAN FALLBACHER ◽  
MICHAEL RATZ
Keyword(s):  
Higgs Mass ◽  
Mass Term ◽  
Four Dimensions ◽  
Grand Unified Theories ◽  
Triplet Splitting ◽  
Fermion Masses ◽  
Higher Dimensional ◽  
Splitting Problem ◽  
Order Four

We review the role of R symmetries in models of supersymmetric unification in four and more dimensions, and in string theory. We show that, if one demands anomaly freedom and fermion masses, only R symmetries can forbid the supersymmetric Higgs mass term μ. We then review the proof that R symmetries are not available in conventional grand unified theories (GUTs) and argue that this prevents natural solutions to the doublet–triplet splitting problem in four dimensions. On the other hand, higher-dimensional GUTs do not suffer from this problem. We briefly comment on an explicit string-derived model in which the μ and dimension-5 proton decay problems are solved simultaneously by an order four discrete R symmetry. We also comment on the higher-dimensional origin of this symmetry.

Back to the doublet-triplet splitting problem

1993 ◽  
Vol 312 (1-2) ◽  
pp. 137-142 ◽  
Author(s):  
R. Barbieri ◽  
G. Dvali ◽  
M. Moretti
Keyword(s):  
Triplet Splitting ◽  
Splitting Problem

scholarly journals A REVIEW OF THREE-FAMILY GRAND UNIFIED STRING MODELS

1998 ◽  
Vol 13 (15) ◽  
pp. 2551-2598 ◽  
Author(s):  
ZURAB KAKUSHADZE ◽  
GARY SHIU ◽  
S.-H. HENRY TYE ◽  
YAN VTOROV-KAREVSKY
Keyword(s):  
Supersymmetry Breaking ◽  
Fine Tuning ◽  
Tree Level ◽  
Hierarchy Problem ◽  
Triplet Splitting ◽  
Mass Matrices ◽  
String Models ◽  
Proton Stability ◽  
Breaking Scale

We review the construction and classification of three-family grand unified models within the framework of asymmetric orbifolds in perturbative heterotic superstring. We give a detailed survey of all such models which is organized to aid analysis of their phenomenological properties. We compute tree level superpotentials for these models. These superpotentials are used to analyze the issues of proton stability (doublet–triplet splitting and R-parity-violating terms) and Yukawa mass matrices. To have agreement with phenomenological data all these models seem to require a certain degree of fine-tuning. We also analyze the possible patterns of supersymmetry breaking in these models. We find that the supersymmetry breaking scale comes out either too high to explain the electroweak hierarchy problem, or below the electroweak scale unless some degree of fine-tuning is involved. Thus, none of the models at hand seem to be phenomenologically flawless.

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