New effects in gauge theory from pp-wave superstrings

It has recently been observed that IIB string theory in the pp-wave background can be used to calculate certain quantities, such as the dimensions of BMN operators, as exact functions of the effective coupling λ′=λ/J2. These functions interpolate smoothly between the weak and strong effective coupling regimes of N=4 SYM theory at large R charge J. In this Letter we use the pp-wave superstring field theory of to study more complicated observables. The expansion of the three-string interaction vertex suggests more complicated interpolating functions which in general give rise to fractional powers of λ′ in physical observables at weak effective coupling.