arXiv subjects

P. Merlatti

Publications and source records attributed to P. Merlatti.

13 recordsLinked to original sources

arXiv2007

Getting N=1 super Yang-Mills from strings

In the context of the gauge-string correspondence, we discuss the spontaneous partial breaking of supersymmetry. Starting from the orbifold of S^5, supersymmetry breaking leads us to consider the (resolved) conifold background and some of the gauge dynamics encoded in that geometry. Using this gravity dual, we compute the low energy effective superpotential for such N=1 theories. We are naturally led to extend the Veneziano-Yankielowicz one: glueball fields appear.

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arXiv2005

N=1 Super Yang-Mills Domain Walls via The Extended Veneziano Yankielowicz Theory

We investigate the vacuum structure of pure SU(N) N=1 super Yang-Mills. The theory is expected to possess N vacua with associated domain walls. We show that the newly extended version of the low energy effective Lagrangian for super Yang-Mills supports the BPS domain wall solutions associated with any two vacua aligned with the origin of the moduli space. For the two color theory the domain wall analysis is complete. We also find new non BPS domain wall solutions connecting any two vacua of the underling SU(N) super Yang-Mills theory not necessarely aligned. When two vacua are aligned with the origin of the moduli space these solutions are the BPS ones. We also discuss the generic BPS domain wall solutions connecting any two vacua within the extended Veneziano-Yankielowicz theory.

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arXiv2004

Information on the Super Yang-Mills Spectrum

We investigate the spectrum of the lightest states of N=1 Super Yang-Mills. We first study the spectrum using the recently extended Veneziano Yankielowicz theory containing also the glueball states besides the gluinoball ones. Using a simple Kahler term we show that within the effective Lagrangian approach one can accommodate either the possibility in which the glueballs are heavier or lighter than the gluinoball fields. We then provide an effective Lagrangian independent argument which allows, using information about ordinary QCD, to deduce that the lightest states in super Yang-Mills are the gluinoballs. This helps constraining the Kahler term of the effective Lagrangian. Using this information and the effective Lagrangian we note that there is a small mixing among the gluinoball and glueball states.

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arXiv2004

Extending the Veneziano-Yankielowicz Effective Theory

We extend the Veneziano Yankielowicz (VY) effective theory in order to account for ordinary glueball states. We propose a new form of the superpotential including a chiral superfield for the glueball degrees of freedom. When integrating it ``out'' we obtain the VY superpotential while the N vacua of the theory naturally emerge. This fact has a counterpart in the Dijkgraaf and Vafa geometric approach. We suggest a link of the new field with the underlying degrees of freedom which allows us to integrate it ``in'' the VY theory. We finally break supersymmetry by adding a gluino mass and show that the Kahler independent part of the ``potential'' has the same form of the ordinary Yang-Mills glueball effective potential.

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arXiv2003

A note on the dual of N=1 super Yang-Mills theory

We refine the dictionary of the gauge/gravity correspondence realizing N=1 super Yang-Mills by means of D5-branes wrapped on a resolved Calabi-Yau space. This is done by fixing an ambiguity on the correct interpretation of the holographic dual of the running gauge coupling and amounts to identify a specific 2-cycle in the dual ten-dimensional supergravity background. In doing so, we also discuss the role played in this context by gauge transformations in the relevant seven-dimensional gauged supergravity. While all nice properties of the duality are maintained, this modification of the dictionary has some interesting physical consequences and solves a puzzle recently raised in the literature. In this refined framework, it is also straightforward to see how the correspondence naturally realizes a geometric transition.

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arXiv2003

N=1 super Yang-Mills theories and wrapped branes

I consider supergravity solutions of D5 branes wrapped on supersymmetric 2-cycles and use them to discuss relevant features of four-dimensional N=1 super Yang-Mills theories with gauge group SU(N). In particular, using a gravitational dual of the gaugino condensate, it is shown that is possible to obtain the complete NSVZ $β$-function. It is also described how different aspects of the gauge theory are nicely encoded in this supergravity solution.

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arXiv2002

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 beta-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.

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arXiv2001

About The Enhancon 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.

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arXiv2001

The enhancon mechanism for fractional branes

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.

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arXiv2001

World Volume Action for Fractional Branes

We study the world volume action of fractional Dp-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.

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arXiv2000

M -theory on AdS_4 x Q^{111}: The complete Osp(2|4) x SU(2) x SU(2) x SU(2) spectrum from harmonic analysis

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.

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arXiv2000

Shadow multiplets in AdS_4/CFT_3 and the super-Higgs mechanism: hints of new shadow supergravities

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.

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arXiv2000

Rings of short N=3 superfields in three dimensions and M-theory on AdS_4 x N^{0,1,0}

In this paper we investigate three-dimensional superconformal gauge theories with N=3 supersymmetry. Independently from specific models, we derive the shortening conditions for unitary representations of the Osp(3|4) superalgebra and we express them in terms of differential constraints on three dimensional N=3 superfields. We find a ring structure underlying these short representations, which is just the direct generalization of the chiral ring structure of N=2 theories. When the superconformal field theory is realized on the world-volume of an M2-brane such superfield ring is the counterpart of the ring defined by the algebraic geometry of the 8-dimensional cone transverse to the brane. This and other arguments identify the N=3 superconformal field theory dual to M-theory compactified on AdS_4 x N^{0,1,0}. It is an N=3 gauge theory with SU(N) x SU(N) gauge group coupled to a suitable set of hypermultiplets, with an additional Chern Simons interaction. The AdS/CFT correspondence can be directly verified using the recently worked out Kaluza Klein spectrum of N^{0,1,0} and we find a perfect match. We also note that besides the usual set of BPS conformal operators dual to the lightest KK states, we find that the composite operators corresponding to certain massive KK modes are organized into a massive spin 3/2 N=3 multiplet that might be identified with the super-Higgs multiplet of a spontaneously broken N=4 theory. We investigate this intriguing and inspiring feature in a separate paper.

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