Francesco Bigazzi

Non-critical holography and four-dimensional CFT's with fundamentals

We find non-critical string backgrounds in five and eight dimensions, holographically related to four-dimensional conformal field theories with = 0 and = 1 supersymmetries. In the five-dimensional case we find an AdS5 background metric for a string model related to non-supersymmetric, conformal QCD with large number of colors and flavors and discuss the conjectured existence of a conformal window from the point of view of our solution. In the eight-dimensional string theory, we build a family of solutions of the form AdS5 ? 3 with 3 a squashed three-sphere. For a special value of the ratio Nf/Nc, the background can be interpreted as the supersymmetric near-horizon limit of a system of color and flavor branes on 1,3 times a known four-dimensional generalization of the cigar. The = 1 dual theory with fundamental matter should have an IR fixed point only for a fixed ratio Nf/Nc. General features of the string/gauge theory correspondence for theories with fundamental flavors are also addressed.

New checks and subtleties for AdS/CFT and a-maximization

We provide a cross-check of AdS/CFT and a-charge maximization for a four dimensional = 1 SCFT with irrational R-charges. The gauge theory is the low energy effective theory of N D3-branes at the tip of the complex cone over the first del Pezzo surface. By carefully taking into account the subtle issue of flavor symmetry breaking at the fixed point, we show, using a-maximization, that this theory has in fact irrational central charge and R-charges. Our results perfectly match with those inherited from the recently discovered supergravity dual background. Along analogous lines, we make novel predictions for the still unknown AdS dual of the quiver theory for the second del Pezzo surface. This should flow to a SCFT with irrational charges, too. All of our results differ from previous findings in the literature and outline interesting subtleties in a-maximization and AdS/CFT techniques overlooked in the past.

Supersymmetry breaking at the end of a cascade of Seiberg dualities

We study the IR dynamics of the cascading nonconformal quiver theory on

Klebanov-Witten theory with massive dynamical flavors

N

The Klebanov-Strassler model with massive dynamical flavors

regular and

Heavy-quark potential with dynamical flavors: A first-order transition

M

Non chiral dynamical flavors and screening on the conifold

fractional D3 branes at the tip of the complex cone over the first del Pezzo surface. The horizon of this cone is the irregular Sasaki-Einstein manifold

Screening effects on meson masses from holography

{Y}^{2,1}

Hydrodynamics of fundamental matter

. Our analysis shows that at the end of the cascade supersymmetry is dynamically broken.

New predictions on meson decays from string splitting

We consider the addition of a large number of massive dynamical flavors to the Klebanov-Witten theory, the quiver gauge theory describing the low energy dynamics of Nc D3-branes at the conifold singularity. Massive flavors are introduced by means of Nf D7-branes which are holomorphically embedded and smeared along the transverse directions. After some general comments on the validity of the smearing procedure, we find the full backreacted supergravity solution corresponding to a particular class of massive embeddings. The solution depends on a running effective number of flavors, whose functional form follows from the smeared embedding. The running reflects the integrating in/out of massive degrees of freedom in the dual field theory as the energy scale is changed. We study how the dynamics of the theory depends on the flavor parameters, mainly focusing on the static quark-antiquark potential. As expected, we find that the dynamical flavors tend to screen the static color charges.