Prof. Dr. Olaf Hohm
Profil
Forschungsthemen4
Duality Symmetries, Higher Derivatives, and their Applications in Cosmology (Symmetries-Cosmology)
Quelle ↗Förderer: Horizon 2020: ERC Consolidator Grant Zeitraum: 09/2018 - 08/2023 Projektleitung: Prof. Dr. Olaf Hohm
GRK 2575/1: Überdenken der Quantenfeldtheorie
Quelle ↗Förderer: DFG Graduiertenkolleg Zeitraum: 04/2020 - 09/2024 Projektleitung: Prof. Dr. Jan Plefka
GRK 2575/2: Überdenken der Quantenfeldtheorie
Quelle ↗Förderer: DFG Graduiertenkolleg Zeitraum: 10/2024 - 03/2029 Projektleitung: Prof. Dr. Jan Plefka
GRK 2575: Überdenken der Quantenfeldtheorie
Quelle ↗Förderer: DFG Graduiertenkolleg Zeitraum: 04/2020 - 03/2029 Projektleitung: Prof. Dr. Jan Plefka
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Publikationen25
Top 25 nach Zitationen — Quelle: OpenAlex (BAAI/bge-m3 embedded für Matching).
Physical Review Letters · 865 Zitationen · DOI
A particular higher-derivative extension of the Einstein-Hilbert action in three spacetime dimensions is shown to be equivalent at the linearized level to the (unitary) Pauli-Fierz action for a massive spin-2 field. A more general model, which also includes "topologically-massive" gravity as a special case, propagates the two spin-2 helicity states with different masses. We discuss the extension to massive N-extended supergravity, and we present a "cosmological" extension that admits an anti-de Sitter vacuum.
Journal of High Energy Physics · 654 Zitationen · DOI
Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D, Particles, fields, gravitation, and cosmology · 345 Zitationen · DOI
We explore the space of static solutions of the recently discovered three-dimensional ``new massive gravity'' (NMG), allowing for either sign of the Einstein-Hilbert term and a cosmological term parametrized by a dimensionless constant $\ensuremath{\lambda}$. For $\ensuremath{\lambda}=\ensuremath{-}1$ we find black hole solutions asymptotic (but not isometric) to the unique (anti) de Sitter [(A)dS] vacuum, including extremal black holes that interpolate between this vacuum and $(\mathrm{A}){\mathrm{dS}}_{2}\ifmmode\times\else\texttimes\fi{}{S}^{1}$. We also investigate unitarity of linearized NMG in (A)dS vacua. We find unitary theories for some dS vacua, but (bulk) unitarity in AdS implies negative central charge of the dual conformal field theories (CFT), except for $\ensuremath{\lambda}=3$ where the central charge vanishes and the bulk gravitons are replaced by ``massive photons.'' A similar phenomenon is found in the massless limit of NMG, for which the linearized equations become equivalent to Maxwell's equations.
314 Zitationen
Double field theory describes a massless subsector of closed string theory with both momentum and winding excitations. The gauge algebra is governed by the Courant bracket in certain subsectors of this double field theory. We construct the associated nonlinear background-independent action that is T-duality invariant and realizes the Courant gauge algebra. The action is the sum of a standard action for gravity, antisymmetric tensor, and dilaton fields written with ordinary derivatives, a similar action for dual fields with dual derivatives, and a mixed term that is needed for gauge invariance.
Fortschritte der Physik · 302 Zitationen · DOI
Abstract We review double field theory (DFT) with emphasis on the doubled spacetime and its generalized coordinate transformations, which unify diffeomorphisms and b‐field gauge transformations. We illustrate how the composition of generalized coordinate transformations fails to associate. Moreover, in dimensional reduction, the O(d,d) T‐duality transformations of fields can be obtained as generalized diffeomorphisms. Restricted to a half‐dimensional subspace, DFT includes ‘generalized geometry’, but is more general in that local patches of the doubled space may be glued together with generalized coordinate transformations. Indeed, we show that for certain T‐fold backgrounds with non‐geometric fluxes, there are generalized coordinate transformations that induce, as gauge symmetries of DFT, the requisite O(d,d;ℤ) monodromy transformations. Finally we review recent results on the α ′ extension of DFT which, reduced to the half‐dimensional subspace, yields intriguing modifications of the basic structures of generalized geometry.
Physical Review Letters · 271 Zitationen · DOI
Eleven-dimensional supergravity reveals large exceptional symmetries upon reduction, in accordance with the U-duality groups of M theory, but their higher-dimensional geometric origin has remained a mystery. In this Letter, we show that D=11 supergravity can be extended to be fully covariant under the exceptional groups E(n(n)), n=6, 7, 8. Motivated by a similar formulation of double field theory we introduce an extended "exceptional spacetime." We illustrate the construction by giving the explicit E(6(6)) covariant form: the full D=11 supergravity, in a 5+6 splitting of coordinates but without truncation, embeds into an E(6(6)) covariant 5+27 dimensional theory. We argue that this covariant form likewise comprises type IIB supergravity.
Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D, Particles, fields, gravitation, and cosmology · 239 Zitationen · DOI
We present the details of the recently constructed ${\mathrm{E}}_{6(6)}$-covariant extension of 11-dimensional supergravity. This theory requires a $5+27$-dimensional spacetime in which the ``internal'' coordinates transform in the $\overline{\mathbf{27}}$ of ${\mathrm{E}}_{6(6)}$. All fields are ${\mathrm{E}}_{6(6)}$ tensors and transform under (gauged) internal generalized diffeomorphisms. The ``Kaluza-Klein'' vector field acts as a gauge field for the ${\mathrm{E}}_{6(6)}$-covariant ``E-bracket'' rather than a Lie bracket, requiring the presence of 2-forms akin to the tensor hierarchy of gauged supergravity. We construct the complete and unique action that is gauge invariant under generalized diffeomorphisms in the internal and external coordinates. The theory is subject to covariant section constraints on the derivatives, implying that only a subset of the extra 27 coordinates is physical. We give two solutions of the section constraints: the first preserves GL(6) and embeds the action of the complete (i.e. untruncated) 11-dimensional supergravity; the second preserves $\text{GL}(5)\ifmmode\times\else\texttimes\fi{}\text{SL}(2)$ and embeds complete type IIB supergravity. As a byproduct, we thus obtain an off-shell action for type IIB supergravity.
Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D, Particles, fields, gravitation, and cosmology · 217 Zitationen · DOI
We develop exceptional field theory for ${\mathrm{E}}_{8(8)}$, defined on a ($3+248$)-dimensional generalized spacetime with extended coordinates in the adjoint representation of ${\mathrm{E}}_{8(8)}$. The fields transform under ${\mathrm{E}}_{8(8)}$ generalized diffeomorphisms and are subject to covariant section constraints. The bosonic fields include an ``internal'' dreibein and an ${\mathrm{E}}_{8(8)}$-valued ``zweihundertachtundvierzigbein'' (248-bein). Crucially, the theory also features gauge vectors for the ${\mathrm{E}}_{8(8)}$ E bracket governing the generalized diffeomorphism algebra and covariantly constrained gauge vectors for a separate but constrained ${\mathrm{E}}_{8(8)}$ gauge symmetry. The complete bosonic theory, with a novel Chern-Simons term for the gauge vectors, is uniquely determined by gauge invariance under internal and external generalized diffeomorphisms. The theory consistently comprises components of the dual graviton encoded in the 248-bein. Upon picking particular solutions of the constraints the theory reduces to $D=11$ or type IIB supergravity, for which the dual graviton becomes pure gauge. This resolves the dual graviton problem, as we discuss in detail.
Journal of High Energy Physics · 209 Zitationen · DOI
Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D, Particles, fields, gravitation, and cosmology · 196 Zitationen · DOI
We introduce the exceptional field theory for the group ${\mathrm{E}}_{7(7)}$, based on a $(4+56)$-dimensional spacetime subject to a covariant section condition. The ``internal'' generalized diffeomorphisms of the coordinates in the fundamental representation of ${\mathrm{E}}_{7(7)}$ are governed by a covariant ``E-bracket,'' which is gauged by 56 vector fields. We construct the complete and unique set of field equations that is gauge invariant under generalized diffeomorphisms in the internal and external coordinates. Among them are featured the non-Abelian twisted self-duality equations for the 56 gauge vectors. We discuss the explicit solutions of the section condition describing the embedding of the full, untruncated 11-dimensional and type IIB supergravity, respectively. As a new feature compared to the previously constructed ${E}_{6(6)}$ formulation, some components among the 56 gauge vectors descend from the 11-dimensional dual graviton but nevertheless allow for a consistent coupling by virtue of a covariantly constrained compensating 2-form gauge field.
Journal of High Energy Physics · 190 Zitationen · DOI
We develop doubled-coordinate field theory to determine the α ′ corrections to the massless sector of oriented bosonic closed string theory. Our key tool is a string current algebra of free left-handed bosons that makes O(D,D) T-duality manifest. While T-dualities are unchanged, diffeomorphisms and b-field gauge transformations receive corrections, with a gauge algebra given by an α ′-deformation of the duality-covariantized Courant bracket. The action is cubic in a double metric field, an unconstrained extension of the generalized metric that encodes the gravitational fields. Our approach provides a consistent truncation of string theory to massless fields with corrections that close at finite order in α ′.
Journal of High Energy Physics · 178 Zitationen · DOI
We present the generalized Scherk-Schwarz reduction ansatz for the full supersymmetric exceptional field theory in terms of group valued twist matrices subject to consistency equations. With this ansatz the field equations precisely reduce to those of lower-dimensional gauged supergravity parametrized by an embedding tensor. We explicitly construct a family of twist matrices as solutions of the consistency equations. They induce gauged supergravities with gauge groups SO(p, q) and CSO(p, q, r). Geometrically, they describe compactifications on internal spaces given by spheres and (warped) hyperboloides H p,q , thus extending the applicability of generalized Scherk-Schwarz reductions beyond homogeneous spaces. Together with the dictionary that relates exceptional field theory to D = 11 and IIB supergravity, respectively, the construction defines an entire new family of consistent truncations of the original theories. These include not only compactifications on spheres of different dimensions (such as AdS5 × S 5), but also various hyperboloid compactifications giving rise to a higher-dimensional embedding of supergravities with non-compact and non-semisimple gauge groups.
Physical Review Letters · 159 Zitationen · DOI
We present a unified description of the low-energy limits of type-II string theories. This is achieved by a formulation that doubles the space-time coordinates in order to realize the T-duality group O(10,10) geometrically. The Ramond-Ramond fields are described by a spinor of O(10,10), which couples to the gravitational fields via the Spin(10,10) representative of the so-called generalized metric. This theory, which is supplemented by a T-duality covariant self-duality constraint, unifies the type-II theories in that each of them is obtained for a particular subspace of the doubled space.
Fortschritte der Physik · 156 Zitationen · DOI
We review and develop the general properties of algebras focusing on the gauge structure of the associated field theories. Motivated by the homotopy Lie algebra of closed string field theory and the work of Roytenberg and Weinstein describing the Courant bracket in this language we investigate the structure of general gauge invariant perturbative field theories. We sketch such formulations for non‐abelian gauge theories, Einstein gravity, and for double field theory. We find that there is an algebra for the gauge structure and a larger one for the full interacting field theory. Theories where the gauge structure is a strict Lie algebra often require the full algebra for the interacting theory. The analysis suggests that algebras provide a classification of perturbative gauge invariant classical field theories.
Physical Review Letters · 146 Zitationen · DOI
We give a geometrical interpretation of the nongeometric $Q$ and $R$ fluxes. To this end, we consider double field theory in a formulation that is related to the conventional one by a field redefinition taking the form of a $T$ duality inversion. The $R$ flux is a tensor under diffeomorphisms and satisfies a nontrivial Bianchi identity. The $Q$ flux can be viewed as part of a connection that covariantizes the winding derivatives with respect to diffeomorphisms. We give a higher-dimensional action with a kinetic term for the $R$ flux and a ``dual'' Einstein-Hilbert term containing the connection $Q$.
Journal of High Energy Physics · 135 Zitationen · DOI
127 Zitationen
We extend the recently constructed double field theory formulation of the low-energy theory of the closed bosonic string to the heterotic string. The action can be written in terms of a generalized metric that is a covariant tensor under O(D,D+n), where n denotes the number of gauge vectors, and n additional coordinates are introduced together with a covariant constraint that locally removes these new coordinates. For the abelian subsector, the action takes the same structural form as for the bosonic string, but based on the enlarged generalized metric, thereby featuring a global O(D,D+n) symmetry. After turning on non-abelian gauge couplings, this global symmetry is broken, but the action can still be written in a fully O(D,D+n) covariant fashion, in analogy to similar constructions in gauged supergravities.
123 Zitationen
Abstract In this paper we propose ten‐dimensional realizations of the non‐geometric fluxes Q and R . In particular, they appear in the NSNS Lagrangian after performing a field redefinition that takes the form of a T‐duality transformation. Double field theory simplifies the computation of the field redefinition significantly, and also completes the higher‐dimensional picture by providing a geometrical role for the non‐geometric fluxes once the winding derivatives are taken into account. The relation to four‐dimensional gauged supergravities, together with the global obstructions of non‐geometry, are discussed.
Journal of High Energy Physics · 120 Zitationen · DOI
We investigate α′ corrections of bosonic strings in the framework of double field theory. The previously introduced “doubled α′-geometry” gives α′-deformed gauge transformations arising in the Green-Schwarz anomaly cancellation mechanism but does not apply to bosonic strings. These require a different deformation of the duality-covariantized Courant bracket which governs the gauge structure. This is revealed by examining the α′ corrections in the gauge algebra of closed string field theory. We construct a four-derivative cubic double field theory action invariant under the deformed gauge transformations, giving a first glimpse of the gauge principle underlying bosonic string α′ corrections. The usual metric and b-field are related to the duality covariant fields by non-covariant field redefinitions.
Journal of High Energy Physics · 111 Zitationen · DOI
We give the supersymmetric extension of exceptional field theory for E7(7), which is based on a (4 + 56)-dimensional generalized spacetime subject to a covariant constraint. The fermions are tensors under the local Lorentz group SO(1, 3) × SU(8) and transform as scalar densities under the E7(7) (internal) generalized diffeomorphisms. The supersymmetry transformations are manifestly covariant under these symmetries and close, in particular, into the generalized diffeomorphisms of the 56-dimensional space. We give the fermionic field equations and prove supersymmetric invariance. We establish the consistency of these results with the recently constructed generalized geometric formulation of D = 11 supergravity.
109 Zitationen
Double field theory provides T-duality covariant generalized tensors that are natural extensions of the scalar and Ricci curvatures of Riemannian geometry. We search for a similar extension of the Riemann curvature tensor by developing a geometry based on the generalized metric and the dilaton. We find a duality covariant Riemann tensor whose contractions give the Ricci and scalar curvatures, but that is not fully determined in terms of the physical fields. This suggests that α′ corrections to the effective action require α′ corrections to T-duality transformations and/or generalized diffeomorphisms. Further evidence to this effect is found by an additional computation that shows that there is no T-duality invariant four-derivative object built from the generalized metric and the dilaton that reduces to the square of the Riemann tensor.
Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D, Particles, fields, gravitation, and cosmology · 108 Zitationen · DOI
We use exceptional field theory as a tool to work out the full nonlinear reduction ansatz for the ${\mathrm{AdS}}_{5}\ifmmode\times\else\texttimes\fi{}{S}^{5}$ compactification of IIB supergravity and its noncompact counterparts in which the sphere ${S}^{5}$ is replaced by the inhomogeneous hyperboloidal space ${H}^{p,q}$. The resulting theories are the maximal 5D supergravities with gauge groups $\mathrm{SO}(p,q)$. They are consistent truncations in the sense that every solution of 5D supergravity lifts to a solution of IIB supergravity. In particular, every stationary point and every holographic renormalization group flow of the scalar potentials for the compact and noncompact 5D gaugings directly lift to solutions of IIB supergravity.
Physical review. D/Physical review. D. · 105 Zitationen · DOI
In the context of string theory, the authors consider purely time-dependent cosmological backgrounds and compute corrections to the action to all orders in $\ensuremath{\alpha}$' (string length). The resulting equations of motion can be integrated perturbatively to any order in $\ensuremath{\alpha}$', which allows the authors to find non-perturbative de Sitter vacua. Even though the models considered are not phenomenologically viable, this is a remarkable result.
Fortschritte der Physik · 100 Zitationen · DOI
Abstract We show how superconformal gaugings in three dimensions can be systematically constructed using the embedding tensor technique. These gaugings have been argued to describe the worldvolume theory of multiple M2‐branes. Applying our technique we construct the most general superconformal gaugings with 𝒩 = 5, 6 and 8 supersymmetry. In the case of 𝒩 = 5 supersymmetry we find three exceptional gaugings. We briefly discuss new developments concerning the massive deformations of the superconformal gauge theories.
97 Zitationen
We construct the N = 1 three-dimensional supergravity theory with cosmological, Einstein-Hilbert, Lorentz Chern-Simons, and general curvature squared terms. We determine the general supersymmetric configuration, and find a family of supersymmetric adS vacua with the supersymmetric Minkowski vacuum as a limiting case. Linearizing about the Minkowski vacuum, we find three classes of unitary theories; one is the supersymmetric extension of the recently discovered ‘massive 3D gravity’. Another is a ‘new topologically massive supergravity ’ (with no Einstein-Hilbert term) that propagates a single (2, 3 2) helicity supermultiplet. Contents 1
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GRK 2575/2: Überdenken der Quantenfeldtheorie
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Stammdaten
Identität, Organisation und Kontakt aus HU-FIS.
- Name
- Prof. Dr. Olaf Hohm
- Titel
- Prof. Dr.
- Fakultät
- Mathematisch-Naturwissenschaftliche Fakultät
- Institut
- Institut für Physik
- Arbeitsgruppe
- Kosmologie und Stringtheorie
- Telefon
- +49 30 2093-66455
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