Higher Spin Scattering in Superstring Theory

TL;DR

This paper calculates scattering amplitudes involving high-spin states in open superstring theory, providing explicit formulas for cubic and four-point interactions, which could inform both experimental searches and theoretical understanding of higher spin dynamics.

Contribution

It presents explicit vertex operators and scattering amplitude calculations for high-spin states on the leading Regge trajectory in superstring theory, including general n-level couplings and symmetry properties.

Findings

Explicit formulas for cubic couplings of high-spin states.

Four-point amplitudes with one high-spin and three massless states.

Results applicable in lower-dimensional compactifications, relevant for LHC scenarios.

Abstract

We compute scattering amplitudes of leading Regge trajectory states in open superstring theories. Highest spin states at mass level n with spin s=n+1 for bosons and s=n+1/2 for fermions are generated by particularly simple vertex operators. Hence, the cubic couplings of bosons and fermions on the leading Regge trajectory are given for arbitrary n. The same can be achieved for higher point amplitudes, and this article focuses on four point level with one heavy maximum spin state and three massless states in any bose-fermi combination, putting particular emphasis on manifest cyclic symmetry. Except for the four fermion coupling, all our results remain valid in any D<10 dimensional compactification scenario, so they might become relevant at LHC in case of an experimentally accessible low string scale. But even if not directly observable, superstring amplitudes provide important clues on higher spin dynamics and their consistent interactions in field theory.