Boundary State for Magnetized D9 Branes and One-Loop Calculation
  We construct the boundary state describing magnetized D9 branes in R^{3,1} x T^6 and we use it to compute the annulus and Moebius amplitudes. We derive from them, by using open/closed string duality, the number of Landau levels on the torus T^d. 
Paolo Di Vecchia, Antonella Liccardo, Raffaele Marotta, Franco   Pezzella and Igor Pesando