Revisiting higher-spin gyromagnetic couplings

We analyze Bosonic, Heterotic, and Type II string theories compactified on a generic torus having constant moduli. By computing the hamiltonian giving the interaction between massive string excitations and U(1) gauge fields arising from the graviton and Kalb-Ramond field upon compactification, we derive a general formula for such couplings that turns out to be universal in all these theories. We also confirm our result by explicitly evaluating the relevant string three-point amplitudes. From this expression, we determine the gyromagnetic ratio g of massive string states coupled to both gauge-fields. For a generic mixed symmetry state, there is one gyromagnetic coupling associated with each row of the corresponding Young Tableau diagram. For all the states having zero Kaluza Klein or Winding charges, the value of g turns out to be 1. We also explicitly consider totally symmetric and mixed symmetry states (having two rows in the Young diagram) associated with the first Regge-trajectory and obtain their corresponding g value.

Automated summary

The paper analyzes Bosonic, Heterotic, and Type II string theories compactified on a generic torus with constant moduli, deriving a general formula for the couplings between massive string excitations and U(1) gauge fields. The universal nature of these couplings in all theories is confirmed through explicit evaluation of relevant string three-point amplitudes. The gyromagnetic ratio g for massive string states coupled to gauge fields is determined, with specific considerations given for mixed symmetry states and those with zero Kaluza Klein or Winding charges resulting in a g value of 1.