D-term spectroscopy in realistic heterotic-string models

1999/07/13 by Athanasios Dedes, A. Dedes, Alon E. Faraggi +1
Physics and Astronomy · #Black Holes and Theoretical Physics #Heterotic string theory #Mathematical physics #Orbifold #Particle physics #Particle physics theoretical and experimental studies #Physics #Quantum Chromodynamics and Particle Interactions #Supersymmetry #Symmetry breaking #hep-ph #hep-th

paper · pdf · doi:10.1103/physrevd.62.016010

published as Phys.Rev. D62 (2000) 016010 · 27 pages, 8 figures

arxiv created 1999/07/13 · openalex publication_date 2000/06/12 · arxiv updated 2009/11/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05

Abstract

The recent emergence of free fermionic heterotic string models with solely the MSSM charged spectrum below the string scale reinforces the motivation to investigate the pheneomelogical characteristics of this class of string models, which possess an underlying Z₂\ifmmode×\else\texttimes\fiZ₂ orbifold structure. An important property of the Z₂\ifmmode×\else\texttimes\fiZ₂ orbifold is the cyclic permutation symmetry between the three twisted sectors. If preserved in the three-generation models the cyclic permutation symmetry results in a family universal anomalous U(1)_A, which is instrumental in explaining squark degeneracy, provided that the dominant component of supersymmetry breaking arises from the U(1)_A D term. Interestingly, the contribution of the family-universal D_A term to the squark masses may be intrafamily nonuniversal, and may differ from the usual (universal) boundary conditions assumed in the MSSM. We contemplate how D_A-term spectroscopy may be instrumental in studying superstring models irrespective of our ignorance of the details of supersymmetry breaking. We examine the possible effect of the intrafamily nonuniversality on the resulting SUSY spectrum and the values of the strong coupling, effective weak mixing angle, and W-gauge boson mass, up to a two-loop accuracy, in the two models (universal and nonuniversal). We find that nonuniversality relaxes the constraint of color and charge breaking minima which appears in the universal case. In addition, it predicts a 3% smaller value of \ensuremathα_s due to different threshold masses obtained in the latter scenario. Finally, we present the experimentally allowed predictions of the two models in an M₀ and M_1/2 parameter space.

Citations

• Gluino condensation in superstring models
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• Family universal anomalous U(1) in realistic superstring derived models