63 research outputs found
Yang-Baxter Deformations Beyond Coset Spaces (a slick way to do TsT)
Yang-Baxter string sigma-models provide a systematic way to deform coset
geometries, such as , while retaining the -model
integrability. It has been shown that the Yang-Baxter deformation in target
space is simply an open-closed string map that can be defined for any geometry,
not just coset spaces. Given a geometry with an isometry group and a bivector
that is assumed to be a linear combination of antisymmetric products of Killing
vectors, we show the equations of motion of (generalized) supergravity reduce
to the Classical Yang-Baxter Equation associated with the isometry group,
proving the statement made in [1]. These results bring us closer to the proof
of the "YB solution generating technique" for (generalized) supergravity
advertised in [1] and in particular provide an economical way to perform TsT
transformations.Comment: 33 pages; v2 typos fixed and reference added; v3 further improvements
in text, matches published version; v4 typo in expression for B (4.9)
correcte
Calibrated Entanglement Entropy
The Ryu-Takayanagi prescription reduces the problem of calculating
entanglement entropy in CFTs to the determination of minimal surfaces in a dual
anti-de Sitter geometry. For 3D gravity theories and BTZ black holes, we
identify the minimal surfaces as special Lagrangian cycles calibrated by the
real part of the holomorphic one-form of a spacelike hypersurface. We show that
(generalised) calibrations provide a unified way to determine holographic
entanglement entropy from minimal surfaces, which is applicable to warped
AdS geometries. We briefly discuss generalisations to higher dimensions.Comment: v1 22 pages, 1 figure; v2 appendix improved and moved into the body
to show the application of calibrations to find minimal surfaces in warped
AdS, matches published versio
in generalized supergravity
We showed in previous work that for homogeneous Yang-Baxter (YB) deformations
of AdSS, the open string metric and coupling, and as a result the
closed string density , remain undeformed. In this work,
in addition to extending these results to the deformation associated with the
modified CYBE, or -deformation, we identify the Page forms as the open
string counterpart for RR fields and demonstrate case by case that the non-zero
Page forms remain invariant under YB deformations. We give a physical meaning
to the Killing vector of generalized supergravity and show for all YB
deformations: 1) appears as a current for center of mass motion on the
worldvolume of a D-branes probing the background, 2) is equal to the
divergence of the noncommutativity parameter, 3) exhibits "holographic"
behavior, where the radial component of vanishes at the AdS boundary, and
4) in pure spinor formalism is related to a certain state in the BRST
cohomology.Comment: 11 pages, 2 column; v2 references updated; v3 to appear in EPJ
Non-relativistic M-Theory solutions based on Kähler-Einstein spaces
We present new families of non-supersymmetric solutions of D=11 supergravity with non-relativistic symmetry, based on six-dimensional Kaehler-Einstein manifolds. In constructing these solutions, we make use of a consistent reduction to a five-dimensional gravity theory coupled to a massive scalar and vector field. This theory admits a non-relativistic CFT dual with dynamical exponent z=4, which may be uplifted to D=11 supergravity. Finally, we generalise this solution and find new solutions with various z, including z=2
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.Comment: 1+30 pages, footnote adde
Classical Yang-Baxter equation from supergravity
© 2018 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the »https://creativecommons.org/licenses/by/4.0/» Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP 3 . We promote the open-closed string map, originally formulated by Seiberg & Witten, to a solution generating prescription in generalized supergravity. The approach hinges on a knowledge of an antisymmetric bivector Θ, built from antisymmetric products of Killing vectors, which is specified by the equations of motion. In the cases we study, the equations of motion reproduce the classical Yang-Baxter equation (CYBE) and Θ is the most general r-matrix solution. Our work generalizes Yang-Baxter deformations to non-coset spaces and unlocks gravity as a means to classify r-matrix solutions to the CYBE
Calibrated entanglement entropy
© 2017, The Author(s). The Ryu-Takayanagi prescription reduces the problem of calculating entanglement entropy in CFTs to the determination of minimal surfaces in a dual anti-de Sitter geometry. For 3D gravity theories and BTZ black holes, we identify the minimal surfaces as special Lagrangian cycles calibrated by the real part of the holomorphic one-form of a spacelike hypersurface. We show that (generalised) calibrations provide a unified way to determine holographic entanglement entropy from minimal surfaces, which is applicable to warped AdS 3 geometries. We briefly discuss generalisations to higher dimensions
Yang-Baxter σ -models, conformal twists, and noncommutative Yang-Mills theory
© 2017 American Physical Society.The Yang-Baxter σ-model is a systematic way to generate integrable deformations of AdS5×S5. We recast the deformations as seen by open strings, where the metric is undeformed AdS5×S5 with constant string coupling, and all information about the deformation is encoded in the noncommutative (NC) parameter Θ. We identify the deformations of AdS5 as twists of the conformal algebra, thus explaining the noncommutativity. We show that the unimodularity condition on r-matrices for supergravity solutions translates into Θ being divergence-free. Integrability of the σ-model for unimodular r-matrices implies the existence and planar integrability of the dual NC gauge theory
Non-abelian T-duality, Ramond Fields and Coset Geometries
We extend previous work on non-abelian T-duality in the presence of Ramond
fluxes to cases in which the duality group acts with isotropy such as in
backgrounds containing coset spaces. In the process we generate new
supergravity solutions related to D-brane configurations and to standard
supergravity compactifications.Comment: 35 pages, Late
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