The Veneziano Amplitude via Mostly BRST Exact Operator

Abstract

The Veneziano amplitude is derived from fixing one degree of freedom of $PSL(2,\mathbb{R})$ symmetry by the insertion of a mostly BRST exact operator. Evaluating the five-point function which consists of four open string tachyons and this gauge fixing operator, we find it equals the Veneziano amplitude up to a sign factor. The sign factor is interpreted as a signed intersection number.The result implies that the mostly BRST exact operator, which is originally used to provide two-point string amplitudes, correctly fixes the $PSL(2,\mathbb{R})$ gauge symmetry for general amplitudes. We conjecture an expression for general $n$-point tree amplitudes with an insertion of this gauge fixing operator.

1+18 pages, 8 figures

References in corpus (2)

• Two-Point Superstring Tree Amplitudes Using the Pure Spinor Formalism
• Reduction of Open String Amplitudes by Mostly BRST Exact Operators