Superstring Scattering from O-planes

TL;DR

This paper derives scattering amplitudes involving superstring states and O-planes, demonstrating gauge invariance and providing insights into the low-energy effective action and coupling differences between O-planes and D-branes.

Contribution

It introduces vertex operators for superstring states in the presence of O-planes and computes gauge-invariant scattering amplitudes, linking them to the effective action.

Findings

Amplitudes can be expressed in Veneziano-type formulas.

Amplitudes are gauge invariant unlike previous results.

Identifies a coupling factor difference between O-planes and D-branes.

Abstract

We write the vertex operators of massless NS-NS and RR states of Type II superstring theory in the presence of Orientifold p-planes. They include the usual vertex operators of Type II theory and their images. We then calculate the two-point functions of these vertex operators at the projective plane PR_2 level. We show that the result can be written in the Veneziano-type formulae, with the same kinematic factor that appears in the D_p-branes amplitudes. While the scattering amplitudes with the usual vertex operators are not gauge invariant, the above amplitudes are invariant. From the amplitude describing scattering of two NS-NS states off the O-plane, we find the low energy effective action of O-planes. The result shows a relative factor 2^{p-6} between couplings to O-planes and to D-branes at (\alpha')^2 order.