Browsing by Author "Ricco, Antonio"

Now showing 1 - 4 of 4
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    Conifold geometries, matrix models and quantum solutions
    (2005) Bonelli, Giulio; Bonora, Loriano; Ricco, Antonio; Physics; Elementary Particle Theory
    This paper is a continuation of hepth/0507224 where open topological B-models describing D-branes on 2-cycles of local Calabi--Yau geometries with conical singularities were studied. After a short review, the paper expands in particular on two aspects: the gauge fixing problem in the reduction to two dimensions and the quantum matrix model solutions.
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    Conifold geometries, topological strings and multi-matrix models
    (2005) Bonelli, Giulio; Bonora, Loriano; Ricco, Antonio; Physics; Elementary Particle Theory
    We study open B-model representing D-branes on 2-cycles of local Calabi-Yau geometries. To this end we work out a reduction technique linking D-branes partition functions and multimatrix models in the case of conifold geometries so that the matrix potential is related to the complex moduli of the conifold. We study the geometric engineering of the multi-matrix models and focus on two-matrix models with bilinear couplings. We show how to solve this models in an exact way, without resorting to the customary saddle point/large N approximation. The method consists of solving the quantum equations of motion and using the flow equations of the underlying integrable hierarchy to derive explicit expressions for correlators. Finally we show how to incorporate in this formalism the description of several group of D-branes wrapped around different cycles.
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    Flavour from partially resolved singularities
    (2006-04-18T12:58:24Z) Bonelli, Giulio; Bonora, Loriano; Ricco, Antonio; Physics; Elementary Particle Theory
    In this letter we study topological open string field theory on D--branes in a IIB background given by non compact CY geometries ${\cal O}(n)\oplus{\cal O}(-2-n)$ on $\P1$ with a singular point at which an extra fiber sits. We wrap $N$ D5-branes on $\P1$ and $M$ effective D3-branes at singular points, which are actually D5--branes wrapped on a shrinking cycle. We calculate the holomorphic Chern-Simons partition function for the above models in a deformed complex structure and find that it reduces to multi--matrix models with flavour. These are the matrix models whose resolvents have been shown to satisfy the generalized Konishi anomaly equations with flavour. In the $n=0$ case, corresponding to a partial resolution of the $A_2$ singularity, the quantum superpotential in the ${\cal N}=1$ unitary SYM with one adjoint and $M$ fundamentals is obtained. The $n=1$ case is also studied and shown to give rise to two--matrix models which for a particular set of couplings can be exactly solved. We explicitly show how to solve such a class of models by a quantum equation of motion technique.
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    Normal bundles to Laufer rational curves in local Calabi-Yau threefolds
    (2005) Bruzzo, Ugo; Ricco, Antonio; Mathematics; Mathematical Physics
    We prove a conjecture by F. Ferrari. Let X be the total space of a nonlinear deformation of a rank 2 holomorphic vector bundle on a smooth rational curve, such that X has trivial canonical bundle and has sections. Then the normal bundle to such sections is computed in terms of the rank of the Hessian of a suitably defined superpotential at its critical points.