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## Cosmological constraints on string scale and coupling arising from tachyonic instability

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Article number 84 25/08/2005 Journal of High Energy Physics 8 2005 Published English

### Abstract

We demonstrate that string motivated inflation ending via tachyonic instability leaves a detectable imprint on the cosmic microwave background (CMB) radiation by virtue of the excitation of non-Gaussian gravitational fluctuations. The present WMAP bound on non-Gaussianity is shown to constrain the string scale by $M_S/M_P\leq 10^{-4}$ for string coupling \$g_{s} M_{P}

### Bibliographic note

12 pages, 2 figures, typo corrected, discussion and references added