1. Separability of the Dirac equation in the STU black hole spacetime : Pairwise-equal charge case studyMirjam Cvetič, M. M. Stetsko, 2023, original scientific article Abstract: We study the separability of the Dirac equation in the background of four dimensional charged rotating asymptotically flat black hole solution of supergravity and the low energy string theory known as STU black hole. In particular, we analyze in detail the separability conditions in the pairwise equal charge STU black hole space-time [M. Cvetič and D. Youm, Phys. Rev. D 54, 2612 (1996).]. While in the latter case the minimally coupled Dirac equation is not separable, the introduction of a specific torsion term ensures the separability. The source of the torsion is the Kalb-Ramond field, which is an integral part of string theory, but further aspects of its properties and coupling to fermionic fields remain to be studied. To derive the torsion, two different approaches are used in conformally related frames, showing that the torsion is not unique. The correspondingly modified Dirac equations in the Einstein and string frames are shown to be separable. Furthermore, the massless radial and angular wave equations are examined; they show close similarity with corresponding equations for the standard Kerr background. A generalization of the Teukolsky equation for the pairwise equal case is conjectured. We also briefly analyze a technically sophisticated radial equation in the massive case.
Keywords: quantum fields of spacetime, supergravity, curved spacetime, Dirac equation
Published in DKUM: 19.07.2024; Views: 165; Downloads: 10
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2. 0-form, 1-form, and 2-group symmetries via cutting and gluing of orbifoldsMirjam Cvetič, Jonathan J. Heckman, Max Hübner, Ethan Torres, 2022, original scientific article Abstract: Orbifold singularities of M-theory constitute the building blocks of a broad class of supersymmetric quantum field theories (SQFTs). In this paper we show how the local data of these geometries determine global data on the resulting higher symmetries of these systems. In particular, via a process of cutting and gluing, we show how local orbifold singularities encode the 0-form, 1-form, and 2-group symmetries of the resulting SQFTs. Geometrically, this is obtained from the possible singularities that extend to the boundary of the noncompact geometry. The resulting category of boundary conditions then captures these symmetries and is equivalently specified by the orbifold homology of the boundary geometry. We illustrate these general points in the context of a number of examples, including five-dimensional (5D) superconformal field theories engineered via orbifold singularities, 5D gauge theories engineered via singular elliptically fibered Calabi-Yau threefolds, as well as four-dimensional supersymmetric quantum chromodynamics-like theories engineered via M-theory on noncompact G2 spaces.
Keywords: F-theory, compactifications, classification, singularities, instantons, geometry
Published in DKUM: 06.06.2024; Views: 159; Downloads: 10
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3. Long-range forces between nonidentical black holes with non-BPS extremal limitsSera Cremonini, Mirjam Cvetič, Christopher N. Pope, Aritra Saha, 2022, original scientific article Abstract: Motivated by recent studies of long-range forces between identical black holes, we extend these considerations by investigating the forces between two nonidentical black holes. We focus on classes of theories where charged black holes can have extremal limits that are not BPS. These theories, which live in arbitrary spacetime dimension, comprise gravity coupled to N 2-form field strengths and (N − 1) scalar fields. In the solutions we consider, each field strength carries an electric charge. The black hole solutions are governed by the SLðN þ 1; RÞ Toda equations. In four dimensions, the black hole solutions in the SLð3; RÞ example are equivalent to the “Kaluza-Klein dyons.” We find that any pair of such extremal black holes that are not identical (up to overall scaling) will repel one another. We also show that there can exist pairs of non-extremal, nonidentical black holes which obey a zero-force condition. Finally, we find indications of similar results in the higher examples, such as SLð4; RÞ.
Keywords: astronomy, astrophysics, black holes, spacetime dimensions
Published in DKUM: 06.06.2024; Views: 115; Downloads: 12
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4. Quadrillion F-theory compactifications with the exact chiral spectrum of the standard modelMirjam Cvetič, James Halverson, Ling Lin, Mingqiang Liu, Jianjun Paul Tian, 2019, original scientific article Abstract: We present O(10(15)) string compactifications with the exact chiral spectrum of the standard model of particle physics. This ensemble of globally consistent F-theory compactifications automatically realizes gauge coupling unification. Utilizing the power of algebraic geometry, all global consistency conditions can be reduced to a single criterion on the base of the underlying elliptically fibered Calabi-Yau fourfolds. For toric bases, this criterion only depends on an associated polytope and is satisfied for at least O(10(15)) bases, each of which defines a distinct compactification.
Keywords: FLUX, F-theory, string compactifications, chiral spectrum
Published in DKUM: 23.10.2023; Views: 489; Downloads: 19
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5. Constraints on standard model constructions in F-theoryMirjam Cvetič, James Halverson, Ling Lin, Cody Long, 2020, original scientific article Abstract: We argue that the following three statements cannot all be true: (i) our vacuum is a type IIB/F-theory vacuum at moderate to large h(1,1); (ii) the alpha' expansion is controlled via the supergravity approximation, a la the Kachru-Kallosh-Linde-Trivedi and Large Volume scenarios; and (iii) there are no additional gauged sectors from 7-branes. Since nearly all known globally consistent F-theory models with the exact chiral spectrum of the Standard Model and gauge coupling unification occur at moderate h(1,1), this finding calls for new moduli stabilization scenarios or/and a rich 7-brane dark sector.
Keywords: brane worlds, compactification, string theory
Published in DKUM: 23.10.2023; Views: 497; Downloads: 26
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6. Generalized Couch-Torrence symmetry for rotating extremal black holes in maximal supergravityMirjam Cvetič, Christopher N. Pope, Aritra Saha, 2020, original scientific article Abstract: he extremal Reissner-Nordstrom black hole admits a conformal inversion symmetry, in which the metric is mapped into itself under an inversion of the radial coordinate combined with a conformal rescaling. In the rotating generalization, Couch and Torrence showed that the Kerr- Newman metric no longer exhibits a conformal inversion symmetry, but the radial equation arising in the separation of the massless Klein-Gordon equation admits a mode-dependent inversion symmetry, where the radius of inversion depends upon the energy and azimuthal angular momentum of the mode. It was more recently shown that the static four-charge extremal black holes of STU supergravity (i.e., N = 2 supergravity in four dimension coupled to three vector multiplets) admit a generalization of the conformal inversion symmetry, in which the conformally inverted metric is a member of the same four-charge black hole family but with transformed charges. In this paper we study further generalizations of these inversion symmetries, within the general class of extremal STU supergravity black holes. For the rotating black holes, where again the massless Klein-Gordon equation is separable, we show that examples with four electric charges exhibit a generalization of the Couch-Torrence symmetry of the radial equation. Now, as in the conformal inversion of the static specializations, the inversion of the radial equation maps it to the radial equation for a rotating black hole with transformed electric charges. We also study the inversion transformations for the general case of extremal Bogomol'nyi-Prasad-Sommerfield STU black holes carrying eight charges (four electric plus four magnetic), and argue that analogous generalizations of the inversion symmetries exist for both the static and the rotating cases.
Keywords: black holes, supergravity, supersymmetry, conformal symmetry
Published in DKUM: 23.10.2023; Views: 562; Downloads: 18
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7. Geometric unification of Higgs bundle vacuaMirjam Cvetič, Jonathan J. Heckman, Thomas B. Rochais, Ethan Torres, Gianluca Zoccarato, 2020, original scientific article Abstract: Higgs bundles are a central tool used to study a range of intersecting brane systems in string compactifications. Solutions to the internal gauge theory equations of motion for the corresponding worldvolume theories of brans give rise to different low energy effective field theories. This has been heavily used in the study of M-theory on local G(2) spaces and F-theory on local elliptically fibered CalabiYau fourfolds. In this paper we show that the 3D N = 1 effective field theory defined by M-theory on a local spin(7) space unifies the Higgs bundle data associated with 4D N = 1 M- and F-theory vacua. This 3D system appears as an interface with finite thickness between different 4D vacua. We develop the general formalism of M-theory on such local spin(7) spaces and build explicit interpolating solutions. This provides a complementary local gauge theory analysis of a recently proposed approach to constructing spin(7) spaces from generalized connected sums.
Keywords: F-theory, Higgs, M-theory, field theories, spin spices
Published in DKUM: 23.10.2023; Views: 504; Downloads: 20
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8. String Universality and Non-Simply-Connected Gauge Groups in 8DMirjam Cvetič, Markus Dierigl, Ling Lin, Hao Y. Zhang, 2020, original scientific article Abstract: We present a consistency condition for 8D N 1 supergravity theories with nontrivial global structure G=Z for the non-Abelian gauge group, based on an anomaly involving the Z 1-form center symmetry. The interplay with other swampland criteria identifies the majority of 8D theories with gauge group G=Z, which have no string theory realization, as inconsistent quantum theories when coupled to gravity. While this condition is equivalent to geometric properties of elliptic K3 surfaces in F-theory compactifications, it constrains the unexplored landscape of gauge groups in other 8D string models.
Keywords: supergravity theories, string theory, 8D string models
Published in DKUM: 16.10.2023; Views: 557; Downloads: 27
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9. Gaussian null coordinates for rotating charged black holes and conserved chargesMirjam Cvetič, Christopher N. Pope, Aritra Saha, Alejandro Satz, 2020, original scientific article Abstract: Motivated by the study of conserved Aretakis charges for a scalar field on the horizon of an extremal black hole, we construct the metrics for certain classes of four-dimensional and five-dimensional extremal rotating black holes in Gaussian null coordinates. We obtain these as expansions in powers of the radial coordinate, up to sufficient order to be able to compute the Aretakis charges. The metrics we consider are for 4-charge black holes in four-dimensional STU supergravity (N = 2 supergravity coupled to three vector multiplets) (including the Kerr-Newman black hole in the equal-charge case) and the general 3-charge black holes in five-dimensional STU supergravity. We also investigate the circumstances under which the Aretakis charges of an extremal black hole can be mapped by conformal inversion of the metric into Newman-Penrose charges at null infinity. We show that while this works for four-dimensional static black holes, a simple radial inversion fails in rotating cases because a necessary conformal symmetry of the massless scalar equation breaks down. We also discuss that a massless scalar field in dimensions higher than four does not have any conserved Newman-Penrose charge, even in a static asymptotically flat spacetime.
Keywords: supergravitiy, flat spacetime, black hole, four-dimensional rotating, metrics
Published in DKUM: 16.10.2023; Views: 342; Downloads: 29
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10. T-branes and G(2) backgroundsRodrigo Barbosa, Mirjam Cvetič, Jonathan J. Heckman, Craig Lawrie, Ethan Torres, Gianluca Zoccarato, 2020, original scientific article Abstract: Compactification of M-string theory on manifolds with G(2) structure yields a wide variety of 4D and 3D physical theories. We analyze the local geometry of such compactifications as captured by a gauge theory obtained from a three-manifold of ADE singularities. Generic gauge theory solutions include a nontrivial gauge field flux as well as normal deformations to the three-manifold captured by noncommuting matrix coordinates, a signal of T-brane phenomena. Solutions of the 3D gauge theory on a three-manifold are given by a deformation of the Hitchin system on a marked Riemann surface which is fibered over an interval. We present explicit examples of such backgrounds as well as the profile of the corresponding zero modes for localized chiral matter. We also provide a purely algebraic prescription for characterizing localized matter for such T-brane configurations. The geometric interpretation of this gauge theory description provides a generalization of twisted connected sums with codimension seven singularities at localized regions of the geometry. It also indicates that geometric codimension six singularities can sometimes support 4D chiral matter due to physical structure "hidden" in T-branes.
Keywords: Yang-Mills connections, spin(7), holonomy, bundles, metrics
Published in DKUM: 16.10.2023; Views: 240; Downloads: 27
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