Probing Wilson Loops in AdS/QCD

We use AdS/QCD to analyze the quark and gluon scalar and pseudo-scalar condensates around static color sources described by a circular Wilson loop. We also derive the static dipole-dipole interactions between rectangular Wilson loops in AdS/QCD and discuss their relevance for static string interactions in QCD at strong coupling.Comment: 6 pages, 2 figure

Heavy Holographic Exotics: Tetraquarks as Efimov States

We provide a holographic description of non-strange multiquark exotics as compact topological molecules by binding heavy-light mesons to a tunneling configuration in D8-D$\bar 8$ that is homotopic to the vacuum state with fixed Chern-Simons number. In the tunneling process, the heavy-light mesons transmute to fermions. Their binding is generic and arises from a trade-off between the dipole attraction induced by the Chern-Simons term and the U(1) fermionic repulsion. In the heavy quark limit, the open-flavor tetraquark exotics $QQ\bar q\bar q$ and $\bar Q\bar Q qq$, emerge as bound Efimov states in a degenerate multiplet $IJ^\pi=(00^+ , 01^+)$ with opposite intrinsic Chern-Simons numbers $\pm \frac 12$. The hidden-flavor tetraquark exotics such as $Q\bar Q q\bar q$, $QQ\bar Q\bar q$ and $QQ\bar Q\bar Q$ as compact topological molecules are unbound. Other exotics are also discussed.Comment: 16 pages, 13 figure