| 1. |
- Apruzzi, Fabio, et al.
(author)
-
On AdS(7) stability
- 2020
-
In: Journal of High Energy Physics (JHEP). - 1126-6708 .- 1029-8479. ; :07
-
Journal article (peer-reviewed)abstract
- AdS7 supersymmetric solutions in type IIA have been classified, and they are infinitely many. Moreover, every such solution has a non-supersymmetric sister. In this pa- per, we study the perturbative and non-perturbative stability of these non-supersymmetric solutions, focusing on cases without orientifolds. Perturbatively, we first look at the KK spectrum of spin-2 excitations. This does not exhibit instabilities, but it does show that there is no separation of scales for either the BPS and the non-BPS case, thus proving for supersymmetric AdS7 a well-known recent conjecture. We then use 7d gauged supergravity and a brane polarization computation to access part of the spectrum of KK scalars. The result signals an instability for all non-supersymmetric solutions except those that have a single D8 on each side. We finally look at non-perturbative instabilities, and find that NS5 bubbles make these remaining solutions decay.
|
|
| 2. |
- Bah, Ibrahima, et al.
(author)
-
AdS(5) compactifications with punctures in massive IIA supergravity
- 2017
-
In: Journal of High Energy Physics (JHEP). - 1126-6708 .- 1029-8479. ; :11
-
Journal article (peer-reviewed)abstract
- We find AdS(5) solutions holographically dual to compactifications of six-dimensional N=(1,0) supersymmetric field theories on Riemann surfaces with punctures. We simplify a previous analysis of supersymmetric AdS(5) IIA solutions, and with a suitable Ansatz we find explicit solutions organized in three classes, where an O8-D8 stack, D6- and D4-branes are simultaneously present, localized and partially localized. The D4-branes are smeared over the Riemann surface and this is interpreted as the presence of a uniform distribution of punctures. For the first class we identify the corresponding six-dimensional theory as an E-string theory coupled to a quiver gauge theory. The second class of solutions lacks D6-branes and its central charge scales as n(5/2), suggesting a five-dimensional origin for the dual field theory. The last class has elements of the previous two.
|
|
| 3. |
- Del Zotto, Michele, et al.
(author)
-
6d Conformal Matter
- 2015
-
In: Journal of High Energy Physics (JHEP). - : Springer Nature. - 1126-6708 .- 1029-8479. ; :2
-
Journal article (peer-reviewed)abstract
- A single M5-brane probing G, an ADE-type singularity, leads to a system which has G × G global symmetry and can be viewed as “bifundamental” (G, G) matter. For the A N series, this leads to the usual notion of bifundamental matter. For the other cases it corresponds to a strongly interacting (1, 0) superconformal system in six dimensions. Similarly, an ADE singularity intersecting the Hořava-Witten wall leads to a superconformal matter system with E 8 × G global symmetry. Using the F-theory realization of these theories, we elucidate the Coulomb/tensor branch of (G, G′) conformal matter. This leads to the notion of fractionalization of an M5-brane on an ADE singularity as well as fractionalization of the intersection point of the ADE singularity with the Hořava-Witten wall. Partial Higgsing of these theories leads to new 6d SCFTs in the infrared, which we also characterize. This generalizes the class of (1, 0) theories which can be perturbatively realized by suspended branes in IIA string theory. By reducing on a circle, we arrive at novel duals for 5d affine quiver theories. Introducing many M5-branes leads to large N gravity duals.
|
|
| 4. |
- Dibitetto, Giuseppe, et al.
(author)
-
AdS3 solutions with exceptional supersymmetry
- 2018
-
In: Fortschritte der Physik. - : Wiley. - 0015-8208 .- 1521-3978. ; 66:10
-
Journal article (peer-reviewed)abstract
- Among the possible superalgebras that contain the AdS3 isometries, two interesting possibilities are the exceptional F (4) and G(3). Their R-symmetry is respectively SO(7) and G(2), and the amount of supersymmetry N = 8 and N = 7. We find that there exist two (locally) unique solutions in type IIA supergravity that realize these superalgebras, and we provide their analytic expressions. In both cases, the internal space is obtained by a round six-sphere fibred over an interval, with an O8-plane at one end. The R-symmetry is the symmetry group of the sphere; in the G(3) case, it is broken to G(2) by fluxes. We also find several numerical N = 1 solutions with G(2) flavor symmetry, with various localized sources, including O2-planes and O8-planes.
|
|
| 5. |
- Lindström, Ulf, et al.
(author)
-
Generalized complex manifolds and supersymmetry
- 2005
-
In: Communications in Mathematical Physics. - : Springer Science and Business Media LLC. - 0010-3616 .- 1432-0916. ; 257, s. 235-256
-
Journal article (peer-reviewed)abstract
- We find a worldsheet realization of generalized complex geometry, a notion introduced recently by Hitchin which interpolates between complex and symplectic manifolds. The two-dimensional model we construct is a supersymmetric relative of the Poisson sigma model used in context of deformation quantization.
|
|
| 6. |
- Panizo Pérez, Daniel
(author)
-
Blowing Bubbles from String Theory
- 2024
-
Doctoral thesis (other academic/artistic)abstract
- Since the discovery of the accelerated expansion of the universe at the end of the nineties, physicists have tried to describe this cosmological behaviour from theories that are complete in the ultraviolet regime, i.e. theories that are well defined at arbitrarily high energies. The most fundamental property that any proposed model must reproduce is that of a de Sitter space in the lower-dimensional description. In other words, an accelerated expanding four-dimensional cosmology driven by an unknown energy dubbed as dark energy.String theory seems to be the most promising candidate for a theory of quantum gravity, as it naturally accommodates the graviton, the quantum propagator of gravity and fulfills all the requirements to be an ultraviolet-complete theory. However, despite all the efforts of recent decades, no lower-dimensional effective field theory description with the desired positive cosmological constant has yet been obtained. This suspicious conspiracy has motivated the physics community to take a different approach; to investigate what criteria lower-dimensional effective field theories of gauge fields coupled to gravity should satisfy to be derived from string theory rather than aiming to derive four-dimensional effective field theories directly from string theory. One of the most striking conclusions that can be drawn from these criteria is that four-dimensional de Sitter cosmology may belong to the swampland, the set of effective field theories that cannot be obtained from string theory.In the first part of this monograph we will review both classical and quantum approaches to four-dimensional cosmology and then introduce the main aspects and issues faced by the aforementioned string cosmology constructions. The second part of this thesis presents an alternative and novel realisation of a four-dimensional expanding cosmology from string theory. This low-dimensional universe rides a three-dimensional brane that mediates the decay between two different five-dimensional and non-supersymmetric anti-de Sitter vacua. This proposal, known as the Dark Bubble model, turns into advantages some of the liabilities found within the swampland programme, granting an innovative way of realising dark energy from string theory. In this work, we will discuss the top-down construction of the Dark Bubble model from ten-dimensional supergravity, the higher-dimensional origin of four-dimensional dark energy and the new intrinsic hierarchy of energy scales that emerges from this stringy construction. Furthermore, we will also show how four-dimensional matter, radiation and both gravitational and electromagnetic waves will arise naturally from features of the higher-dimensional spacetime.
|
|
| 7. |
- Passias, Achilleas, et al.
(author)
-
A massive class of N=2 AdS(4) IIA solutions
- 2018
-
In: Journal of High Energy Physics (JHEP). - : SPRINGER. - 1126-6708 .- 1029-8479. ; :10
-
Journal article (peer-reviewed)abstract
- We initiate a classification of N = 2 supersymmetric AdS4 solutions of (massive) type IIA supergravity. The internal space is locally equipped with either an SU(2) or an identity structure. We focus on the SU(2) structure and determine the conditions it satisfies, dictated by supersymmetry. Imposing as an Ansatz that the internal space is complex, we reduce the problem of finding solutions to a Riccati ODE, which we solve analytically. We obtain in this fashion a large number of new families of solutions, both regular as well as with localized O8-planes and conical Calabi-Yau singularities. We also recover many solutions already discussed in the literature.
|
|
| 8. |
- Passias, Achilleas, et al.
(author)
-
N=2 supersymmetric AdS(4) solutions of type IIB supergravity
- 2018
-
In: Journal of High Energy Physics (JHEP). - : SPRINGER. - 1126-6708 .- 1029-8479. ; :4
-
Journal article (peer-reviewed)abstract
- We analyze general N = 2 supersymmetric AdS(4) solutions of type IIB super gravity. Utilizing a set of pure spinor equations directly adapted to N = 2, the necessary and sufficient conditions for supersymmetry are reduced to a concise system of partial differential equations for two functions which determine the solutions. We show that using this system analytic solutions can be generated, thus potentially expanding the rather limited set of known AdS(4) solutions in type IIB supergravity.
|
|
| 9. |
- Vargas, Sergio C., 1989-
(author)
-
Vacua in String Theory : de Sitter Space and Stability in Flux Compactifications
- 2018
-
Doctoral thesis (other academic/artistic)abstract
- Our understanding of cosmology has evolved radically in the last decades. Current models demand the presence of dark energy in our universe and the most favored candidate behind this component is a small positive cosmological constant that characterizes a de Sitter (dS) spacetime. Simultaneously, theoretical physicists have stood up to the challenge of building a consistent theory of quantum gravity and string theory has raised as a strong contender.In this thesis we present some explorations within supergravity, a low energy limit of string theory, studying non-supersymmetric vacua, its stability, and the possibility of finding dS.We study the landscape of flux compactifications to produce dS with non-geometric fluxes. We find precise analytic procedures to find perturbatively stable dS near supersymmetric and no-scale Minkowski in a potential derived from type IIB compactifications. We also provide analytical evidence of naked singularities being produced in supergravity backgrounds after the introduction of anti-Dp-branes, at both vanishing and finite temperature.In order to study the problem of semi-classical stability, we explore compactifications with anti-de Sitter as external space. We argue that truncations to closed-string-sector excitations of non-supersymmetric theories may be non-perturbatively protected by the existence of globally defined fake-superpotentials if they are perturbatively stable, a reasoning that goes in line with the standard positive energy theorems.We find that non-supersymmetric solutions tend to manifest modes with masses under the Breitenlohner-Freedman bound once the open-string-sector is explored while supersymmetric solutions remain stable. We see this as a hint in the nature of the instabilities predicted by the weak gravity conjecture.
|
|
