A new look at one-loop integrals in string theory

Understand

We revisit the evaluation of one-loop modular integrals in string theory, employing new methods that, unlike the traditional 'orbit method', keep T-duality manifest throughout.

• In particular, we apply the Rankin-Selberg-Zagier approach to cases where the integrand function grows at most polynomially in the IR.
• Furthermore, we introduce new techniques in the case where `unphysical tachyons' contribute to the one-loop couplings.
• These methods can be viewed as a modular invariant version of dimensional regularisation.