Paolo Merlatti

N=1 and N=2 super-Yang–Mills theories from wrapped branes☆

We consider supergravity solutions of D5-branes wrapped on supersymmetric 2-cycles and use them to discuss relevant features of four-dimensional N=1 and N=2 super-Yang–Mills theories with gauge group SU(N). In particular in the N=1 case, using a gravitational dual of the gaugino condensate, we obtain the complete NSVZ β-function. We also find non-perturbative corrections associated to fractional instantons with charge 2/N. These non-perturbative effects modify the running of the coupling constant which remains finite even at small scales in a way that resembles to the soft confinement scenario of QCD.

Shadow multiplets in AdS4/CFT3 and the super-Higgs mechanism☆

Abstract We discuss a general pairing that occurs in compactifications of M-theory on AdS 4 ×X 7 backgrounds between massless ultra short multiplets and their massive shadows, namely certain universal long multiplets with fixed protected dimensions. In particular, we consider the shadow of the short graviton multiplet in N =3 compactifications. It turns out to be a massive spin- 3/2 multiplet with scale dimension E 0 =3 and with the quantum numbers of a super-Higgs multiplet. Hence each N =3 AdS 4 ×X 7 vacuum is actually to be interpreted as a spontaneously broken phase of an N =4 theory. Comparison with standard gauged N =4 supergravity in 4 dimensions reveals the unexpected bound E 0 on the dimension of the broken gravitino multiplet. This hints to the existence of new versions of extended supergravities, in particular N =4 where such upper bounds are evaded and where all possible vacua have a reduced supersymmetry N 0 N . We name them shadow supergravities. In particular, using arguments based on the solvable Lie algebra parametrization of the scalar manifold, we discuss the possible structure of shadow N =4 supergravity. Using our previous results on the SCFT dual of the AdS 4 ×N 0,1,0 vacuum we discuss the SCFT realization of the universal N =3 shadow multiplet. RG flows from an N =4 to an N =3 phase are ruled out by the fact that the N =4 vacuum is at infinite distance in moduli space, denoting the presence of a topology change.We discuss a general pairing that occurs in compactifications of M-theory on AdS_4 x X^7 backgrounds between massless ultra short multiplets and their massive shadows, namely certain universal long multiplets with fixed protected dimensions. In particular we consider the shadow of the short graviton multiplet in N=3 compactifications. It turns out to be a massive spin 3/2 multiplet with scale dimension E_0=3 and with the quantum numbers of a super-Higgs multiplet. Hence each N=3 AdS_4 x X^7 vacuum is actually to be interpreted as a spontaneously broken phase of an N=4 theory. Comparison with standard gauged N=4 supergravity in 4 dimensions reveals the unexpected bound E_0<3 on the dimension of the broken gravitino multiplet. This hints to the existence of new versions of extended supergravities, in particular N=4 where such upper bounds are evaded and where all possible vacua have a reduced supersymmetry N_0<N. We name them shadow supergravities. In particular, using arguments based on the solvable Lie algebra parametrization of the scalar manifold, we discuss the possible structure of shadow N=4 supergravity. Using our previous results on the SCFT dual of the AdS_4 x N^{0,1,0} vacuum we discuss the SCFT realization of the universal N=3 shadow multiplet. RG flows from an N=4 to an N=3 phase are ruled out by the fact that the N=4 vacuum is at infinite distance in moduli space, denoting the presence of a topology change.

World-volume action for fractional branes☆

Abstract We study the world-volume action of fractional D p -branes of type IIA string theory compactified on the orbifold T 4 / Z 2 . The geometric relation between these branes and wrapped branes is investigated using conformal techniques. In particular we examine in detail various scattering amplitudes and find that the leading low-energy interactions are consistent with the boundary action derived geometrically.

M-theory on AdS4×Q111: the complete Osp (2|4)×SU(2)×SU(2)×SU(2) spectrum from harmonic analysis

In this paper we derive, by means of harmonic analysis, the complete spectrum of Osp(2|4) × SU( 2) × SU( 2) × SU( 2) multiplets from which one obtains compactifying D = 11 supergravity on the homogeneous space Q 111 .I n particular, we analyse the structure of the short multiplets and compare them to the corresponding composite operators of the N = 2 conformal field theory dual to such a compactification, found in a previous publication. We find complete agreement between the quantum numbers of the supergravity multiplets on one hand and those of the conformal operators on the other hand, confirming the structure of the conjectured SCFT. However, the determination of the actual spectrum by harmonic analysis teaches us a lot more: indeed we find out which multiplets are present for each representation of the isometry group, how many there are, the exact values of the hypercharge and of the ‘energy’ for each multiplet.In this paper by means of harmonic analysis we derive the complete spectrum of Osp(2|4) x SU(2) x SU(2) x SU(2) multiplets that one obtains compactifying D=11 supergravity on the homogeneous space Q^{111}. In particular we analyze the structure of the short multiplets and compare them with the corresponding composite operators of the N=2 conformal field theory dual to such a compactification, found in a previous publication. We get complete agreement between the quantum numbers of the supergravity multiplets on one side and those of the conformal operators on the other side, confirming the structure of the conjectured SCFT. However the determination of the actual spectrum by harmonic analysis teaches us a lot more: indeed we find out which multiplets are present for each representation of the isometry group, how many they are, the exact values of the hypercharge and of the energy for each multiplet.

The enhançon mechanism for fractional branes

Abstract We study the enhancon mechanism for fractional D-branes in conifold and orbifold backgrounds and show how it can resolve the repulson singularity of these geometries. In particular, we show that the consistency of the excision process requires that the interior space be not empty. In the orbifold case, we exploit the boundary state formalism to obtain an explicit conformal description and emphasize the non-trivial role of the volume of the internal manifold.

Non-perturbative physics of Script N = 1 super Yang-Mills theories

We discuss some of the recent developments of super Yang–Mills theories in the context of the gauge–string correspondence.

Non-perturbative physics of = 1 super Yang-Mills theories

We discuss some of the recent developments of super Yang–Mills theories in the context of the gauge–string correspondence.

Non-perturbative physics of N = 1 super Yang-Mills theories

We discuss some of the recent developments of super Yang–Mills theories in the context of the gauge–string correspondence.

About the enhançon mechanism

I study the enhancon mechanism for fractional D-branes in conifold and orbifold backgrounds and show how it can resolve the “repulson” singularity of these geometries. In particular I show that the consistency of the excision process requires that the interior space be not empty.