D-brane recoil and infrared divergences in string theory

Abstract

It is shown that there are logarithmic operators in D-brane backgrounds that lead to infrared divergences in open-string loop amplitudes. These divergences can be canceled by changing the closed-string background by operators that correspond to the D-brane moving with constant velocity after some instant in time, since it is precisely such operators that give rise to the appropriate ultraviolet divergences in the closed-string channel.