Light stringy states

TL;DR

This paper investigates the spectrum of open strings at D6-brane intersections, identifying light massive states whose masses depend on intersection angles, and confirms their presence through scattering amplitude analysis.

Contribution

It provides a detailed analysis of twisted open string states at D-brane intersections, including vertex operators and mass scaling, extending previous work with explicit amplitude calculations.

Findings

Light states have masses scaling as M^2 ~ θ M_s^2.

Confirmed the existence of light massive states via scattering amplitudes.

Identified the signs of intersection angles affecting the spectrum.

Abstract

We carefully study the spectrum of open strings localized at the intersections of D6-branes and identify the lowest massive 'twisted' states and their vertex operators, paying particular attention to the signs of the intersection angles. We argue that the masses of the lightest states scale as M^2 ~ \theta M^2_s and can thus be parametrically smaller than the string scale. Relying on previous analyses, we compute scattering amplitudes of massless 'twisted' open strings and study their factorization, confirming the presence of the light massive states as sub-dominant poles in one of the channels.