Anomalous and Linear Holographic Hard Wall Models for Glueballs and the Pomeron

Abstract: In this work we propose improved holographic hard wall (HW) models by the inclusion of anomalous dimensions in the dual operators that describe glueballs inspired by the AdS/CFT correspondence. The anomalous dimensions come from well known semi-classical gauge/string duality analysis showing a dependence with the logarithm of spin $S$ of the boundary states. We show that these logarithm anomalous dimensions of the high spin operators combined with the usual HW model allow us to match the pomeron trajectory and give glueball masses which are better than that of the original HW and soft wall (SW) models in comparison with lattice data. We also build up other anomalous HW (AHW) models considering that the logarithm anomalous dimensions can be approximated by a truncated series of odd powers of the difference $\sqrt{S}-1/\sqrt{S}$. These models also fit the pomeron trajectory and produce good glueball masses. Then, we consider an anomalous dimension which is proportional to $\sqrt{S}$, providing reasonable results. Finally, we propose an asymptotic linear AHW model which effective dimensions for high spins operators are of the form $\Delta=a\sqrt{S}+b$, where $a$ and $b$ are constants to be fixed by comparison with the soft pomeron trajectory. In this last model, the Regge trajectory is asymptotically linear even for very high spins ($J\sim 100$) matching the soft pomeron trajectory accurately and generates glueball masses with deviations with respect to the lattice data better than the original HW and SW models.