Sphere tachyon position integral
= Sphere tachyon position integral
The tree-level <Polyakov path integral> for closed-string <tachyons> reduces in <conformal gauge> to their vertex-position integral on the <Riemann sphere>. Three positions are fixed by the residual <Möbius group>; the other $N-3$ complex positions are integrated. The embedding-field Gaussian integral produces <momentum conservation> and the <Koba-Nielsen factor>.