Two-point tree-level amplitudes in bosonic closed string theory are described by a correlation function within the BRST formalism, which respects manifest Lorentz and conformal invariance. In the derivation of the two-point amplitudes, we use the mostly BRST exact operator, which has been introduced for two-point open string amplitudes, and a closed string vertex with ghost number three, which has been explored in our recent work, in addition to the conventional one.

中文翻译：

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BRST 形式中的两点闭弦振幅


玻色子闭弦理论中的两点树级振幅由 BRST 形式主义中的相关函数描述，该形式主义尊重明显的洛伦兹和共形不变性。在两点振幅的推导中，我们主要使用 BRST 精确算子（该算子已针对两点开弦振幅引入），以及具有幽灵编号 3 的闭弦顶点（在我们最近的工作中已对此进行了探索）除了常规的。