arXiv subjects

Eoin Ó Colgáin

Publications and source records attributed to Eoin Ó Colgáin.

At least 73 records · Page 4Linked to original sources

arXiv2015

Warped AdS$_3$, dS$_3$ and flows from $\mathcal{N} = (0,2)$ SCFTs

We present the general form of all timelike supersymmetric solutions to 3D U(1)^3 gauged supergravity, a known consistent truncation of string theory. We uncover a rich vacuum structure, including an infinite class of new timelike-warped AdS_3 (Goedel) and timelike-warped dS_3 critical points. We outline the construction of supersymmetric flows, driven by irrelevant scalar operators in the SCFT, which interpolate between critical points. For flows from AdS_3 to Goedel, the natural candidate for the central charge decreases along the flow. Flows to timelike-warped dS_3 exhibit topology change.

hep-th↗

arXiv2015

Supergravity dual of c-extremization

Recently a general principle, called c-extremization, which determines the exact R-symmetry of two-dimensional SCFTs with N = (0,2) supersymmetry was identified. In this note we show that the supergravity dual corresponds to the extremization of the T-tensor of N = 2 gauged supergravity in three-dimensions. To support this claim, we demonstrate that the expected central charge of SCFTs arising from twisted compactifications of four-dimensional N = 4 SYM on Riemann surfaces, whose gravity dual is a reduction of five-dimensional U(1)^3 gauged supergravity, is recovered in the three-dimensional framework.

hep-th↗

arXiv2014

Warped Ricci-flat reductions

We present a simple class of warped-product vacuum (Ricci-flat) solutions to ten and eleven-dimensional supergravity, where the internal space is flat and the warp factor supports de Sitter (dS) and anti-de Sitter (AdS) vacua in addition to trivial Minkowski vacua. We outline the construction of consistent Kaluza-Klein (KK) reductions and show that, although our vacuum solutions are non-supersymmetric, these are closely related to the bosonic part of well-known maximally supersymmetric reductions on spheres. We comment on the stability of our solutions, noting that (A)dS$_3$ vacua pass routine stability tests.

hep-th↗

arXiv2014

SUSY properties of warped AdS$_3$

We examine supersymmetric properties of null-warped AdS$_3$, or alternatively Schrodinger geometries, dual to putative warped CFTs in two dimensions. We classify super Schrodinger subalgebras of the superalgebra psu(1, 1$|$2) $\oplus$ psu(1, 1$|$2), corresponding to the superconformal algebra of the AdS$_3 \times$ S$^3$ geometry. We comment on geometric realisations and provide a string theory description with enhanced supersymmetry in terms of intersecting D3-branes. For type IIB supergravity solutions based on T$^{1,1}$, we consider the relationship between five-dimensional Schrodinger solutions and their three-dimensional null-warped counterparts, corresponding to R symmetry twists. Finally, we study a family of null-warped AdS$_3$ solutions in a setting where there is an ambiguity over the R symmetry and confirm that, for examples admitting a Kaluza-Klein (KK) reduction to three dimensions, the minimisation of a real superpotential of the three-dimensional gauged supergravity captures the central charge and R symmetry.

hep-th↗

arXiv2013

An alternative IIB embedding of F(4) gauged supergravity

Through the construction of a complete non-linear Kaluza-Klein reduction ansatz from type IIB supergravity to Romans' F(4) gauged supergravity, we identify a recently discovered supersymmetric AdS_6 solution as the IIB uplift of the supersymmetric vacuum of Romans' theory. We present new IIB uplifts of a number of known solutions of Romans' theory and comment on supersymmetry in higher-dimensions where it is expected.

hep-th↗

arXiv2013

Beyond LLM in M-theory

The Lin, Lunin, Maldacena (LLM) ansatz in D = 11 supports two independent Killing directions when a general Killing spinor ansatz is considered. Here we show that these directions always commute, identify when the Killing spinors are charged, and show that both their inner product and resulting geometry are governed by two fundamental constants. In particular, setting one constant to zero leads to AdS7 x S4, setting the other to zero gives AdS4 x S7, while flat spacetime is recovered when both these constants are zero. Furthermore, when the constants are equal, the spacetime is either LLM, or it corresponds to the Kowalski-Glikman solution where the constants are simply the mass parameter.

hep-th↗

arXiv2013

Fermionic T-duality: A snapshot review

Through a self-dual mapping of the geometry AdS5 x S5, fermionic T-duality provides a beautiful geometric interpretation of hidden symmetries for scattering amplitudes in N=4 super-Yang-Mills. Starting with Green-Schwarz sigma-models, we consolidate developments in this area into this small review. In particular, we discuss the translation of fermionic T-duality into the supergravity fields via pure spinor formalism and show that a general class of fermionic transformations can be identified directly in the supergravity. In addition to discussing fermionic T-duality for the geometry AdS4 x CP3, dual to N=6 ABJM theory, we review work on other self-dual geometries. Finally, we present a short round-up of studies with a formal interest in fermionic T-duality.

hep-th↗

arXiv2013

Charged Black Branes with Hyperscaling Violating Factor

We present an analytic solution of a charged black hole with hyperscaling violating factor in an Einstein-Maxwell-Dilaton model where the scalar potential is key to the existence of a solution. This solution provides a candidate gravitational description of theories with hyperscaling violation at both finite temperature and finite charge density. Using this background we explore certain features of these theories via AdS/CFT correspondence. Finally, we discuss embeddings based on the well-known sphere reductions of ten and eleven-dimensional supergravity.

hep-th↗

arXiv2012

Non-Abelian T-duality and consistent truncations in type-II supergravity

For a general class of SO(4) symmetric backgrounds in type II-supergravity, we show that the action of non-Abelian T-duality can be described via consistent truncation to seven dimensional theories with seemingly massive modes. As such, any solution to these theories uplifts to both massive type IIA and IIB supergravities presenting an invertible map between the two. For supersymmetric backgrounds, we show that for spinors transforming under SO(4) the non-Abelian T-duality transformation breaks the original supersymmetry by half. We use these mappings to generate the non-Abelian T-duals of the maximally supersymmetric pp-wave, the Lin, Lunin, Maldacena geometries and spacetimes with Lifshitz symmetry.

hep-th↗

arXiv2012

Self-duality of the D1-D5 near-horizon

We explore fermionic T-duality and self-duality in the geometry AdS3 x S3 x T4 in type IIB supergravity. We explicitly construct the Killing spinors and the fermionic T-duality isometries and show that the geometry is self-dual under a combination of two bosonic AdS3 T-dualities, four fermionic T-dualities and either two additional T-dualities along T4 or two T-dualities along S3. In addition, we show that the presence of a B-field acts as an obstacle to self-duality, a property attributable to S- duality and fermionic T-duality not commuting. Finally, we argue that fermionic T-duality may be extended to CY2 = K3, a setting where we cannot explicitly construct the Killing spinors.

hep-th↗

arXiv2011

Fermionic T-duality in the pp-wave limit

AdS5 X S5 and its pp-wave limit are self-dual under transformations involving eight fermionic T-dualities, a property which accounts for symmetries seen in scattering amplitudes in N=4 super-Yang-Mills. Despite strong evidence for similar symmetries in the amplitudes of three-dimensional N=6 ABJM theory, a corresponding self-duality in the dual geometry AdS4 X CP3 currently eludes us. Here, working with the type IIA pp-wave limit of AdS4 X CP3 preserving twenty four supercharges, we show that the pp-wave is self-dual with respect to eight commuting fermionic T-dualities and not the six expected. In addition, we show the same symmetry can be found in a superposition pp-wave and a generic pp-wave with twenty and sixteen unbroken supersymmetries respectively, strongly suggesting that self-duality under fermionic T-duality may be a symmetry of all pp-waves.

hep-th↗

arXiv2011

A search for AdS5 X S2 IIB supergravity solutions dual to N = 2 SCFTs

We present a systematic search for Type IIB supergravity solutions whose spacetimes include AdS5 and S2 factors, which would be candidate duals to N = 2 four-dimensional Superconformal field theories. The candidate solutions encode the SU(2) R-symmetry geometrically on the S2 and an additional Killing vector generates the U(1) R-symmetry. By analysing the Killing spinor equations we show that no such solutions exist. This suggests that, if Type IIB backgrounds dual to N = 2 SCFTs exist, the SU(2) R-symmetry is realised non-geometrically. Finally, we also show that, in the context of both N = 1 and N = 2 Type IIB backgrounds with an AdS5 factor, the only candidate U(1) R-symmetry Killing vector directions are the ones that appear for generic values of the Killing spinors; no further Killing vectors exist for special values of the Killing spinors.

hep-th↗

arXiv2011

On the generality of the LLM geometries in M-theory

In this note we revisit the Lin, Lunin, Maldacena (LLM) class of d=11 supergravity solutions with symmetry SO(6) X SO(3) X R, but generalise to allow for all fluxes consistent with the isometries. Using the Killing spinor equation, we prove there are no supersymmetric geometries with additional fluxes beyond the LLM ansatz. In addition, the LLM relationship between Killing spinors, ε_- = - γ_5 ε_+, may be seen as a consequence of identifying two Killing directions identified through the Killing spinor equation corresponding to candidate R-symmetry directions.

hep-th↗

arXiv2011

3D gauged supergravity from wrapped M5-branes with AdS/CMT applications

By identifying a bosonic consistent truncation from the 1/4-BPS wrapped M5-brane geometry of Maldacena, Strominger and Witten in D = 11 supergravity and finding a supersymmetric extension, we recover an N = 2 D = 3 supergravity theory. Reductions of a large class of supersymmetric solutions corresponding to wrapped M2 and M5-branes lead to black strings and warped AdS3 solutions preserving supersymmetry. With a view to AdS/CMT applications, we also construct a numerical hairy BTZ black hole and, as a preliminary step in this direction, determine the conductivity of the dual CFT.

hep-th↗

arXiv2010

Supersymmetric AdS3 X S2 M-theory geometries with fluxes

Motivated by a recent observation that the LLM geometries admit 1/4-BPS M5-brane probes with worldvolume AdS3 X Σ_2 X S1 preserving the R-symmetry, we initiate a classification of the most general AdS3 X S2 geometries in M-theory. We retain all field strengths consistent with symmetry and derive the torsion conditions for M_6 in terms of two linearly independent spinors. Surprisingly, we identify three Killing directions for M_6, but only two of these generate isometries of the overall ansatz. We show that the existence of this third direction depends on the norm of the spinors. Then, specialising to the case where the spinors define an SU(2)-structure and the class of solutions is 1/4-BPS, we note that supersymmetry dictates that all magnetic fluxes necessarily thread the S2. Finally, by assuming that the two remaining Killing directions are parallel and aligned with one of the two vectors defining the SU(2)-structure, we derive a general relationship for the two spinors before extracting a known class of solutions from the torsion conditions.

hep-th↗

arXiv2010

Compactification driven Hilltop Inflation in Einstein-Yang-Mills

Starting from Einstein-Yang-Mills in higher dimensions with an instanton on a compact sphere, we dimensionally reduce to find an effective four-dimensional action describing "hilltop" inflation. Using recent CMB data, we analyse the parameter space of this model to search for viable set-ups. One unique feature of this class of inflationary models is that the value of the inflaton field, or alternatively, the size of the compact sphere, is stabilised dynamically during the inflationary process.

astro-ph.CO↗

arXiv2009

Positronium-like states from supergravity

We study semi-classical rotating open strings ending on a probe Dp-brane close to a stack of extremal, non-extremal Dp-branes and Dp-branes with $B$-fields. These states may be interpreted as positronium-like bound states of spinning W-bosons in an $SU(N+1) \to SU(N) \times U(1)$ theory. In each case, we describe the behaviour of the strings and examine the relation between the energy and the angular momentum of the bound state.

hep-th↗

arXiv2009

NR $CFT_3$ duals in M-theory

We extend the search for supergravity solution duals of non-relativistic $d=3$ CFTs to $d=11$ supergravity. We consider the internal space to be an $S^2$ bundle over a product base: $S^2 \times S^2$ and $S^2 \times T^2$. For purely M-theoretic $S^2 \times S^2$, we find only magnetic fluxes preserving two supersymmetries. $S^2 \times T^2$ is far richer admitting in addition to magnetic fluxes, various non-trivial electric fluxes which break all supersymmetry.

hep-th↗