The Lorentz force between D0 and D6 branes in string and M(atrix) theory

We use different techniques to analyze the system formed by a D0-brane and a D6- brane (with background gauge fields) in relative motion. In particular, using the closed string formalism of boosted boundary states, we show the presence of a term linear in the velocity, corresponding to the Lorentz force experienced by the D0-brane moving in the magnetic background produced by the D6-brane. This term, that was missed in previous analyses of this system, comes entirely from the R–R odd spin structure and is also reproduced by a M(atrix) theory calculation.