On the spectrum of open strings in the Hard-Wall model of AdS/QCD: the role of S5

We revisit the problem of a classical open string representing a meson in the hard-wall geometry and consider the S 5 compact space. The existence of a confining region leads to a discrete set of string configurations parameterized by the number n of complete turnarounds S 5 great circles. Unlike the conformal case, the string in the bulk can explore S 5 even in the case of equal boundary conditions on its endpoints. The string solutions are parameterized by an internal dimensionless conserved charge l n . The q q ¯ potential is linear for large separations, and the string tension is sensitive to l n .