Microstate Dependence of Scattering from the D1-D5 System

Understand

We investigate the question of distinguishing between different microstates of the D1-D5 system (with charges Q_1 and Q_5), by scattering with an incoherent beam, composed of a supergravity probe, with central energy E_0 and width (\Delta E).

• The scattering is studied in the dual CFT description in the orbifold limit for finite R, where R is the radius of the circle on which the D1 branes are wrapped.
• When R(\Delta E) >> 1, the absorption cross-section is found to be independent of the microstate and identical to the leading semiclassical answer computed from the naive geometry.
• For smaller (\Delta E), the answer depends on the particular microstate, which we examine for both typical and atypical microstates.