- #1

Maurice7510

- 55

- 1

and DD BCs along ##X^a, a = n, \ldots, 25## then you get, from ##\alpha^{i,a}_{-1}|0,p\rangle ##, ##n## massless vectors and ##24-n## massless scalars. I understand that for the first excited level, ##M^2=0## and so we have no mass, but what suggests that these are scalars or vectors? In the case where we have two branes separated by a distance ##\delta##, with find ##M^2\propto\delta^2## which, in addition to the vector/scalar nature of the excitations, I don't understand.