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Papers by Daniel Pacifici

Research paper thumbnail of Exact results in N=2 gauge theories

We derive exact formulae for the partition function and the expectation values of Wilson/'t H... more We derive exact formulae for the partition function and the expectation values of Wilson/'t Hooft loops, thus directly checking their S-duality transformations. We focus on a special class of N=2 gauge theories on S^4 with fundamental matter. In particular we show that, for a specific choice of the masses, the matrix model integral defining the gauge theory partition function localizes around a finite set of critical points where it can be explicitly evaluated and written in terms of generalized hypergeometric functions. From the AGT perspective the gauge theory partition function, evaluated with this choice of masses, is viewed as a four point correlator involving the insertion of a degenerated field. The well known simplicity of the degenerated correlator reflects the fact that for these choices of masses only a very restrictive type of instanton configurations contributes to the gauge theory partition function.

Research paper thumbnail of Mass-deformed brane tilings

Journal of High Energy Physics, 2014

We study renormalization group flows among N = 1 SCFTs realized on the worldvolume of D3-branes p... more We study renormalization group flows among N = 1 SCFTs realized on the worldvolume of D3-branes probing toric Calabi-Yau singularities, thus admitting a brane tiling description. The flows are triggered by masses for adjoint or vector-like pairs of bifundamentals and are generalizations of the Klebanov-Witten construction of the N = 1 theory for the conifold starting from the N = 2 theory for the C 2 /Z 2 orbifold. In order to preserve the toric condition pairs of masses with opposite signs have to be switched on. We offer a geometric interpretation of the flows as complex deformations of the Calabi-Yau singularity preserving the toric condition. For orbifolds, we support this interpretation by an explicit string amplitude computation of the gauge invariant mass terms generated by imaginary self-dual 3-form fluxes in the twisted sector. In agreement with the holographic a-theorem, the volume of the Sasaki-Einstein 5-base of the Calabi-Yau cone always increases along the flow.

Research paper thumbnail of Unoriented quivers with flavour

Journal of High Energy Physics, 2014

ABSTRACT We discuss unoriented quivers with flavour that arise from D3-branes at local orbifold s... more ABSTRACT We discuss unoriented quivers with flavour that arise from D3-branes at local orbifold singularities, in the presence of Omega-planes and non-compact D7-branes. We produce a wide class of unoriented quiver gauge theories, including new instances of N=1 superconformal theories. We then consider unoriented D-brane instanton corrections of both `gauge' and `exotic' kinds. In particular, we show that conformal symmetry can be dynamically broken via the generation of exotic superpotentials. Finally we discuss aspects of the recently proposed N=1 remnant of N=4 S-duality. We identify new candidate dual pairs for the C^3/Z_n series of unoriented quiver gauge theories with n odd.

Research paper thumbnail of Branes, U-folds and hyperelliptic fibrations

Journal of High Energy Physics, 2013

We construct a class of supersymmetric vacua of type IIB string theory describing systems of thre... more We construct a class of supersymmetric vacua of type IIB string theory describing systems of three-and seven-branes non-perturbatively completed by brane instantons. The vacua are specified by a set of holomorphic functions defined over a complex plane up to non-trivial U-duality monodromies around the brane locations. In the simplest setting, the solutions can be seen as a generalization of F-theory elliptic fibrations, where the torus fiber is replaced by a genus two Riemann surface with periods encoding the information on the axio-dilaton, the warp factor and the NS-NS and R-R fluxes.

Research paper thumbnail of Deformed Seiberg-Witten curves for ADE quivers

Journal of High Energy Physics, 2013

ABSTRACT We derive Seiberg-Witten like equations encoding the dynamics of N=2 ADE quiver gauge th... more ABSTRACT We derive Seiberg-Witten like equations encoding the dynamics of N=2 ADE quiver gauge theories in presence of a non-trivial Omega-background along a two dimensional plane. The epsilon-deformed prepotential and the chiral correlators of the gauge theory are extracted from difference equations that can be thought as a non-commutative (or quantum) version of the Seiberg-Witten curves for the quiver.

Research paper thumbnail of Multi instanton tests of holography

Journal of High Energy Physics, 2011

Gauge theories living on stacks of D7-branes are holographically related to IIB gravitational bac... more Gauge theories living on stacks of D7-branes are holographically related to IIB gravitational backgrounds with a varying axion-dilaton field (F-theory). The axion-dilaton field is generated by D7, O7 and Dinstanton sources and can be written in terms of the chiral correlators of the eight dimensional gauge theory living on the D7-branes. Using localization techniques, we prove that the same correlators determine the gauge coupling of the four-dimensional N = 2 supersymmetric SU (2) gauge theories living on the elementary D3-brane which probes the F-theory geometries.

Research paper thumbnail of Phenomenological study on the wino radiative decay in anomalous U(1)^{′} models

Physical Review D, 2010

An extension of the Standard Model by at least one extra U(1) gauge symmetry has been investigate... more An extension of the Standard Model by at least one extra U(1) gauge symmetry has been investigated by many authors. In this paper we explore the possibility that this extra U(1) is anomalous. One of the possible signatures of this model could be given by the photons produced in the decays of the NLSP into the LSP.

Research paper thumbnail of Gauge theories on Ω-backgrounds from non commutative Seiberg-Witten curves

Journal of High Energy Physics, 2011

We study the dynamics of a N = 2 supersymmetric SU (N ) gauge theory with fundamental or adjoint ... more We study the dynamics of a N = 2 supersymmetric SU (N ) gauge theory with fundamental or adjoint matter in presence of a non trivial Ω-background along a two dimensional plane. The prepotential and chiral correlators of the gauge theory can be obtained, via a saddle point analysis, from an equation which can be viewed as a non commutative version of the "standard" Seiberg and Witten curve.

Research paper thumbnail of Exact results in N=2 gauge theories

We derive exact formulae for the partition function and the expectation values of Wilson/'t H... more We derive exact formulae for the partition function and the expectation values of Wilson/'t Hooft loops, thus directly checking their S-duality transformations. We focus on a special class of N=2 gauge theories on S^4 with fundamental matter. In particular we show that, for a specific choice of the masses, the matrix model integral defining the gauge theory partition function localizes around a finite set of critical points where it can be explicitly evaluated and written in terms of generalized hypergeometric functions. From the AGT perspective the gauge theory partition function, evaluated with this choice of masses, is viewed as a four point correlator involving the insertion of a degenerated field. The well known simplicity of the degenerated correlator reflects the fact that for these choices of masses only a very restrictive type of instanton configurations contributes to the gauge theory partition function.

Research paper thumbnail of Mass-deformed brane tilings

Journal of High Energy Physics, 2014

We study renormalization group flows among N = 1 SCFTs realized on the worldvolume of D3-branes p... more We study renormalization group flows among N = 1 SCFTs realized on the worldvolume of D3-branes probing toric Calabi-Yau singularities, thus admitting a brane tiling description. The flows are triggered by masses for adjoint or vector-like pairs of bifundamentals and are generalizations of the Klebanov-Witten construction of the N = 1 theory for the conifold starting from the N = 2 theory for the C 2 /Z 2 orbifold. In order to preserve the toric condition pairs of masses with opposite signs have to be switched on. We offer a geometric interpretation of the flows as complex deformations of the Calabi-Yau singularity preserving the toric condition. For orbifolds, we support this interpretation by an explicit string amplitude computation of the gauge invariant mass terms generated by imaginary self-dual 3-form fluxes in the twisted sector. In agreement with the holographic a-theorem, the volume of the Sasaki-Einstein 5-base of the Calabi-Yau cone always increases along the flow.

Research paper thumbnail of Unoriented quivers with flavour

Journal of High Energy Physics, 2014

ABSTRACT We discuss unoriented quivers with flavour that arise from D3-branes at local orbifold s... more ABSTRACT We discuss unoriented quivers with flavour that arise from D3-branes at local orbifold singularities, in the presence of Omega-planes and non-compact D7-branes. We produce a wide class of unoriented quiver gauge theories, including new instances of N=1 superconformal theories. We then consider unoriented D-brane instanton corrections of both `gauge' and `exotic' kinds. In particular, we show that conformal symmetry can be dynamically broken via the generation of exotic superpotentials. Finally we discuss aspects of the recently proposed N=1 remnant of N=4 S-duality. We identify new candidate dual pairs for the C^3/Z_n series of unoriented quiver gauge theories with n odd.

Research paper thumbnail of Branes, U-folds and hyperelliptic fibrations

Journal of High Energy Physics, 2013

We construct a class of supersymmetric vacua of type IIB string theory describing systems of thre... more We construct a class of supersymmetric vacua of type IIB string theory describing systems of three-and seven-branes non-perturbatively completed by brane instantons. The vacua are specified by a set of holomorphic functions defined over a complex plane up to non-trivial U-duality monodromies around the brane locations. In the simplest setting, the solutions can be seen as a generalization of F-theory elliptic fibrations, where the torus fiber is replaced by a genus two Riemann surface with periods encoding the information on the axio-dilaton, the warp factor and the NS-NS and R-R fluxes.

Research paper thumbnail of Deformed Seiberg-Witten curves for ADE quivers

Journal of High Energy Physics, 2013

ABSTRACT We derive Seiberg-Witten like equations encoding the dynamics of N=2 ADE quiver gauge th... more ABSTRACT We derive Seiberg-Witten like equations encoding the dynamics of N=2 ADE quiver gauge theories in presence of a non-trivial Omega-background along a two dimensional plane. The epsilon-deformed prepotential and the chiral correlators of the gauge theory are extracted from difference equations that can be thought as a non-commutative (or quantum) version of the Seiberg-Witten curves for the quiver.

Research paper thumbnail of Multi instanton tests of holography

Journal of High Energy Physics, 2011

Gauge theories living on stacks of D7-branes are holographically related to IIB gravitational bac... more Gauge theories living on stacks of D7-branes are holographically related to IIB gravitational backgrounds with a varying axion-dilaton field (F-theory). The axion-dilaton field is generated by D7, O7 and Dinstanton sources and can be written in terms of the chiral correlators of the eight dimensional gauge theory living on the D7-branes. Using localization techniques, we prove that the same correlators determine the gauge coupling of the four-dimensional N = 2 supersymmetric SU (2) gauge theories living on the elementary D3-brane which probes the F-theory geometries.

Research paper thumbnail of Phenomenological study on the wino radiative decay in anomalous U(1)^{′} models

Physical Review D, 2010

An extension of the Standard Model by at least one extra U(1) gauge symmetry has been investigate... more An extension of the Standard Model by at least one extra U(1) gauge symmetry has been investigated by many authors. In this paper we explore the possibility that this extra U(1) is anomalous. One of the possible signatures of this model could be given by the photons produced in the decays of the NLSP into the LSP.

Research paper thumbnail of Gauge theories on Ω-backgrounds from non commutative Seiberg-Witten curves

Journal of High Energy Physics, 2011

We study the dynamics of a N = 2 supersymmetric SU (N ) gauge theory with fundamental or adjoint ... more We study the dynamics of a N = 2 supersymmetric SU (N ) gauge theory with fundamental or adjoint matter in presence of a non trivial Ω-background along a two dimensional plane. The prepotential and chiral correlators of the gauge theory can be obtained, via a saddle point analysis, from an equation which can be viewed as a non commutative version of the "standard" Seiberg and Witten curve.