The Tachyon in a Linear Expanding Universe

Abstract

We investigate the tachyon coupling in a static Robertson--Walker like metric background. For a tachyon and dilaton field which are only time dependent one can rewrite this model as a SU(2) Wess--Zumino--Witten model and a scalar Feigin--Fuchs theory. In this case the restriction to a real exponential tachyon field fixes the level $k$ of the Wess--Zumino--Witten model. For a spatially dependent tachyon the world radius and the dilaton are quantized in terms of $k$ and the tachyon by two integers, i.e. one has a discrete set of fields. The spatial part of the tachyon is given by Chebyshev polynomials of the second kind. An investigation of the tachyon mass shows that the tachyon is massless for $k=1$.

10 pages, Latex, DESY 92-179

References in corpus (3)

• Elements of String Cosmology
• A Closed, Expanding Universe in String Theory
• Cosmological String Backgrounds from Gauged WZW Models

Cited by in corpus (5)

• Exact Supersymmetric String Solutions in Curved Gravitational Backgrounds
• Four Dimensional Gravitational Backgrounds Based on N=4 c=4 Superconformal Systems
• Cosmological Evolution of a Brane Universe in a Type 0 String Background
• Cosmological String Solutions in 4 Dimensions from 5d Black Holes
• A Monopole Solution in open String Theory