Recombination of intersecting D-branes in tachyon field theory

The mechanism of recombination of intersecting D-branes is investigated within the framework of effective tachyon field theory. We regard the branes as the kink-type tachyon condensed states and use the effective two-tachyon Lagrangian to study the off-diagonal fluctuations therein. It is seen that there is a tachyonic mode in the off-diagonal fluctuations, which signs the instability of the intersecting D-branes. We diagonalize the two-by-two tachyonic matrix field and see that the corresponding eigenfunctions could be used to describe the new recombined branes. Our prescription can be extended to discuss the general behavior of the recombination of intersection D-branes with arbitrary shapes. We present in detail the physical reasons behind the mathematical process of diagonalizing the tachyonic matrix field.