Time-delay at higher genus in high-energy open string scattering

We explore some aspects of causal time-delay in open string scattering stud ied recently by Seiberg, Susskind and Toumbas. By examining high-energy sca ttering amplitudes at higher order in perturbation theory, we argue that ca usal time-delay at Gth order is 1/(G + 1) times smaller than the time-delay at tree level. We propose a space-time interpretation of the result by uti lizing the picture of the high-energy open string scattering put forward by Gross and Mafies. We argue that the phenomenon of reduced time-delay is at tributed to the universal feature of the space-time string trajectory in hi gh-energy scattering that string shape at higher order remains the same as that at tree level but overall scale is reduced. We also discuss implicatio ns to the space-time uncertainty principle and make brief comments on causa l time-delay behavior in space/time noncommutative field theory. (C) 2001 P ublished by Elsevier Science B.V.