### Abstract

We compute the lowest components of the type-II Ramond-Ramond boundary state for the tachyon profile T(X) = λe^{X0/√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) × 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) × U(m) group integrals. Using this boundary state, we compute the closed string emission from a decaying unstable Dp-brane of type-II string theory. We also discuss closed string emission from the tachyon profile T(X) = λcosh(X^{0}/√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 ≤ 2, in precise analogy to the bosonic case.

Original language | English (US) |
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Pages (from-to) | 841-863 |

Number of pages | 23 |

Journal | Journal of High Energy Physics |

Issue number | 1 |

DOIs | |

State | Published - Jan 2005 |

### Keywords

- Superstrings and Heterotic Strings
- Tachyon Condensation

### ASJC Scopus subject areas

- Nuclear and High Energy Physics