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arXiv · hep-th/9508178

Threshold Corrections and Gauge Symmetry in Twisted Superstring Models

David M. Pierce
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Abstract

Threshold corrections to the running of gauge couplings are calculated for superstring models with free complex world sheet fermions. For two N=1 $SU(2)\times U(1)^5$ models, the threshold corrections lead to a small increase in the unification scale. Examples are given to illustrate how a given particle spectrum can be described by models with different boundary conditions on the internal fermions. We also discuss how complex twisted fermions can enhance the symmetry group of an N=4 $SU(3)\times U(1)\times U(1)$ model to the gauge group $SU(3)\times SU(2)\times U(1)$. It is then shown how a mixing angle analogous to the Weinberg angle depends on the boundary conditions of the internal fermions.

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David M. Pierce. 1995-09-05. Threshold Corrections and Gauge Symmetry in Twisted Superstring Models. https://doi.org/10.1103/physrevd.50.6469

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