The LHC String Hunter's Companion (II): Five-Particle Amplitudes and Universal Properties

TL;DR

This paper extends the analysis of string scattering amplitudes to five-point processes relevant for LHC signals, revealing universal features and providing tools for experimental data analysis of potential low-mass string signatures.

Contribution

It computes full five-point string disk amplitudes, identifies universal properties, and constructs a simple basis for these amplitudes, aiding LHC phenomenology.

Findings

Universal features of multi-parton string amplitudes identified.

A simple basis for five-point amplitudes constructed.

Model-dependent amplitudes involving fermions and gauge bosons discussed.

Abstract

We extend the study of scattering amplitudes presented in ``The LHC String Hunter's Companion'' to the case of five-point processes that may reveal the signals of low mass strings at the LHC and are potentially useful for detailed investigations of fundamental Regge excitations. In particular, we compute the full-fledged string disk amplitudes describing all 2->3 parton scattering subprocesses leading to the production of three hadronic jets. We cast our results in a form suitable for the implementation of stringy partonic cross sections in the LHC data analysis. We discuss the universal, model-independent features of multi-parton processes and point out the existence of even stronger universality relating N-gluon amplitudes to the amplitudes involving N-2 gluons and one quark-antiquark pair. We construct a particularly simple basis of two functions describing all universal five-point amplitudes. We also discuss model-dependent amplitudes involving four fermions and one gauge boson that may be relevant for studying jets associated to Drell-Yan pairs and other processes depending on the spectrum of Kaluza-Klein particles, thus on the geometry of compact dimensions.