Type IIB E4H4g−4 conjectures Original Research Article

We propose SL(2, Z) (and SL(3, Z))-invariant conjectures for all R4H4g−4 couplings of Type IIB strings on R10 (and R8 × T2), generalizing conjectures of Green and Gutperle (and Kiritsis and Pioline) for the R4 coupling. A strong check for our conjectures is that on T2 at weak coupling, they reproduce the multiloop scattering amplitudes which had been previously computed using N = 2 strings in the N = 4 topological formalism. Applications to (p, q) string production in a background H field, generalizing Schwingerʹs computation for pair production in a constant F field, are suggested.