scholarly journals Role of the AnomalousU(1)Afor the Solution of the Doublet–Triplet Splitting Problem via the Pseudo-Goldstone Mechanism

1997 ◽  
Vol 78 (5) ◽  
pp. 807-810 ◽  
Author(s):  
Gia Dvali ◽  
Stefan Pokorski
Keyword(s):  
Triplet Splitting ◽  
Splitting Problem

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.

REDUCED MULTIREFERENCE COUPLED-CLUSTER METHOD AND ITS APPLICATION TO THE PYRIDYNE DIRADICALS

2008 ◽  
Vol 07 (04) ◽  
pp. 805-820 ◽  
Author(s):  
XIANGZHU LI ◽  
JOSEF PALDUS
Keyword(s):  
Molecular Geometry ◽  
External Source ◽  
Cluster Method ◽  
Coupled Cluster ◽  
Triplet States ◽  
Correlation Effects ◽  
Spin Multiplicity ◽  
Triplet Splitting ◽  
Singlet And Triplet States

The reduced multireference (RMR) coupled-cluster (CC) method with singles and doubles (RMR CCSD) that employs a modest-size MR CISD wave function as an external source for the most important (primary) triples and quadruples in order to account for the nondynamic correlation effects in the presence of quasidegeneracy, and which is further perturbatively corrected for the remaining (secondary) triples, RMR CCSD(T), is employed to compute the molecular geometry and the energy of the lowest-lying singlet and triplet states, as well as the corresponding singlet–triplet splitting, for all possible isomers of the m, n-pyridyne diradicals. A comparison is made with earlier results that were obtained by other authors, and the role of the multireference effects for both the geometry and the spin multiplicity of the lowest state, as described by the RMR-type methods, is demonstrated on the example of 2,6- and 3,5-pyridynes.

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
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