Travelling Front of a Decaying Brane in String Field Theory

Understand

We consider the inhomogeneous decay of an unstable D-brane of bosonic string theory in a linear dilaton background in a light-cone frame.

• At the lowest level, the dynamical equation that describes this process is a generalisation (that includes nonlocality and time delay) of a reaction-diffusion equation studied by Fisher (and others).
• We argue that the equation of motion of the cubic open string field theory is satisfied at least to the second order when we start with this `Fisher deformation', a marginal operator which has a simple pole term in its OPE.
• We also compute the one-point functions of closed string operators on the disc in the presence of this deformation.