We compute the lowest components of the type-II Ramond-Ramond boundary state for the tachyon profile T(X) = λeX0/√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(X0/√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.
- Superstrings and Heterotic Strings
- Tachyon Condensation
ASJC Scopus subject areas
- Nuclear and High Energy Physics