The Holographic Models of the scalar sector of QCD

We investigate the AdS/QCD duality for the two-point correlation functions of the lowest dimension scalar meson and scalar glueball operators, in the case of the Soft Wall holographic model of QCD. Masses and decay constants as well as gluon condensates are compared to their QCD estimates. In particular, the role of the boundary conditions for the bulk-to-boundary propagators is emphasized.Comment: Invited talk at the 5th International Conference on Quarks and Nuclear Physics QNP'09, Beijing, China, 21-26 September 2009. To be published in Chinese Physics

Quark-antiquark bound state equation in the Wilson loop approach with minimal surfaces

The quark-antiquark gauge invariant Green function is studied through its dependence on Wilson loops. The latter are saturated, in the large Nc limit and for large contours, by minimal surfaces. A covariant bound state equation is derived which in the center-of-mass frame and at equal-times takes the form of a Breit-Salpeter type equation. The large-distance interaction potentials reduce in the static case to a confining linear vector potential. In general, the interaction potentials involve contributions having the structure of flux tube like terms.Comment: 9 pages, 4 figures. Talk given by H.S. at the Workshop QCD at Work 2005, Conversano, Italy, 16-20 June 2005. To appear in the Proceedings (AIP

From accelerating and Poincar\'e coordinates to black holes in spacelike warped AdS3_3, and back

We first review spacelike stretched warped AdS$_3$ and we describe its black hole quotients by using accelerating and Poincar\'e coordinates. We then describe the maximal analytic extension of the black holes and present their causal diagrams. Finally, we calculate spacetime limits of the black hole phase space $(T_R,T_L)$. This is done by requiring that the identification vector $\partial_\theta$ has a finite non-zero limit. The limits we obtain are the self-dual solution in accelerating or Poincar\'e coordinates, depending respectively on whether the limiting spacetimes are non-extremal or extremal, and warped AdS with a periodic proper time identification.Comment: 43 pages, 11 figures. v4: version to appear in CQG, presentation changes (parts to appendices