String predictions for near future colliders from one-loop scattering amplitudes around D-brane worlds

TL;DR

This work derives compact one-loop scattering amplitudes for four open-string vector bosons in supersymmetric vacua with intersecting or magnetized D-branes on toroidal orbifolds, using the NSR formalism. The authors organize CP-even and CP-odd contributions across ${\cal N}=4,1,2$ sectors, expressing results via a small set of modular objects ${\cal E}_{\cal N}$ and ${\cal J}_{\cal N}$ and sector-dependent zero-mode factors, and validate them against singularity structures and modular transformations. Focusing on forward scattering, they apply the optical theorem to extract the total cross section for decays into bulk closed strings, revealing a characteristic threshold structure tied to internal geometry and brane configurations, while noting the absence of tachyonic poles and the potential for phenomenological interpretation with soft observables. Although not immediately applicable to LHC-like signatures, the results provide a tractable framework for connecting open-string loop dynamics to near-term collider phenomenology in models with low string scales and large extra dimensions. The study highlights modular-covariant simplifications, the role of internal CFT data, and avenues for extension to genuinely interacting internal SCFTs and RR backgrounds.

Abstract

We derive compact expressions for one-loop scattering amplitudes of four open-string vector bosons around supersymmetric configurations with intersecting or magnetized D-branes on toroidal orbifolds. We check the validity of our formulae against the structure of their singularities and their behaviour under modular transformations to the transverse channel, exposing closed string exchange. We then specialize to the case of forward scattering and compute the total cross section for two massless open string vector bosons on the brane to decay into closed strings in the bulk, relying on the optical theorem. Although not directly related to collider signatures our predictions represent a step forward towards unveiling phenomenological implications of open and unoriented superstrings