Symmetry breaking in string theories via orbifolds

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1986

OSTI ID:6696688

Dixon, L J

The author studies vacuum states for string theories which can be obtained from the trivial background of flat space-time by identifying points under a discrete group of rotations and translations. In the case of the heterotic string these space-time transformations will be accompanied by gauge transformations. This general procedure describes a variety of vacuum states, including superstrings propagating on the singular limits of certain Calabi-Yau manifolds (orbifolds), but also including modular-invariant ten-dimensional models without space-time supersymmetry. The most interesting of these latter possibilities is a tachyon-free theory with gauge group O(16) circle x O(16), chiral fermions, and a positive one-loop contribution to the cosmological constant. In the case of the heterotic string on a six-dimensional orbifold one can construct a large number of models with (2,2) or (0,2) world-sheet supersymmetry. The author classifies the (2,2) models with four or fewer generations of chiral fermions in four dimensions, and gives examples of three-generation (0,2) models. He describes the construction of scattering amplitudes for strings on orbifolds, and indicate how these amplitudes may be used to determine whether or not nearby Calabi-Yau manifolds are superstring or heterotic string vacua at the classical level.

• Research Organization: Princeton Univ., NJ (USA)
• OSTI ID: 6696688
• Country of Publication: United States
• Language: English

Related Subjects

645400* -- High Energy Physics-- Field Theory
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
AMPLITUDES
COMPOSITE MODELS
EXTENDED PARTICLE MODEL
FERMIONS
FUNDAMENTAL CONSTANTS
MANY-DIMENSIONAL CALCULATIONS
MATHEMATICAL MANIFOLDS
MATHEMATICAL MODELS
PARTICLE MODELS
QUARK MODEL
SCATTERING AMPLITUDES
SPACE-TIME
STRING MODELS
SUPERSYMMETRY
SYMMETRY
TRANSFORMATIONS
VACUUM STATES