  We attempt to obtain realistic glueball Regge trajectories from the
gauge/string correspondence. To this end we study closed spinning string
configurations in two supergravity backgrounds: Klebanov-Strassler (KS) and
Maldacena-Nunez (MN) which are dual to confining gauge theories. These
backgrounds represent two embeddings of N=1 SYM, in the large rank limit, in
string theory. The classical configuration we consider is that of a folded
closed string spinning in a supergravity region with vanishing transverse
radius (\tau = 0) which is dual to the IR of the gauge theory. Classically, a
spinning string yields a linear Regge trajectory with zero intercept. By
performing a semi-classical analysis we find that quantum effects alter both
the linearity of the trajectory and the vanishing classical intercept:
J:=\alpha(t)= \alpha_0 + \alpha' t +\beta\sqrt{t}. Two features of our Regge
trajectories are compatible with the experimental Pomeron trajectory: positive
intercept and positive curvature. The fact that both KS and MN string
backgrounds give the same functional expression of the Regge trajectories
suggests that in fact we are observing string states dual to N=1 SYM.

High Energy Physics - Theory;High Energy Physics - Phenomenology