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Closed Superstring Emission from Rolling Tachyon Backgrounds

Jessie Shelton
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Abstract

We compute the lowest components of the Type II Ramond-Ramond boundary state for the tachyon profile $T (X) = λe ^{X ^ 0/\sqrt{2}}$ by direct path integral evaluation. The calculation is made possible by noting that the integrals involved in the requisite disk one-point functions reduce to integrals over the product group manifold $U (n)\times U (m)$. We further note that one-point functions of more general closed string operators in this background can also be related to $U (n)\times U (m)$ group integrals. Using this boundary state, we compute the closed string emission from a decaying unstable D$p$-brane of Type II string theory. We also discuss closed string emission from the tachyon profile $T (X) =λ\cosh (X ^ 0/\sqrt{2})$. We find in both cases that the total number of particles produced diverges for $p = 0$, while the energy radiated into closed string modes diverges for $p\leq 2$, in precise analogy to the bosonic case.

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Jessie Shelton. 2004-11-03. Closed Superstring Emission from Rolling Tachyon Backgrounds. https://doi.org/10.1088/1126-6708%2F2005%2F01%2F037

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