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1.
Generalized Couch-Torrence symmetry for rotating extremal black holes in maximal supergravity
Mirjam Cvetič, Christopher N. Pope, Aritra Saha, 2020, izvirni znanstveni članek

Opis: 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.
Ključne besede: black holes, supergravity, supersymmetry, conformal symmetry
Objavljeno v DKUM: 23.10.2023; Ogledov: 406; Prenosov: 4
.pdf Celotno besedilo (287,15 KB)
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2.
String Universality and Non-Simply-Connected Gauge Groups in 8D
Mirjam Cvetič, Markus Dierigl, Ling Lin, Hao Y. Zhang, 2020, izvirni znanstveni članek

Opis: 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.
Ključne besede: supergravity theories, string theory, 8D string models
Objavljeno v DKUM: 16.10.2023; Ogledov: 453; Prenosov: 15
.pdf Celotno besedilo (207,17 KB)
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3.
Conformal symmetries for extremal black holes with general asymptotic scalars in STU supergravity
Mirjam Cvetič, Christopher N. Pope, Aritra Saha, 2021, izvirni znanstveni članek

Opis: We present a construction of the most general BPS black holes of STU supergravity (N = 2 supersymmetric D = 4 supergravity coupled to three vector supermultiplets) with arbitrary asymptotic values of the scalar fields. These solutions are obtained by acting with a subset of the global symmetry generators on STU BPS black holes with zero values of the asymptotic scalars, both in the U-duality and the heterotic frame. The solutions are parameterized by fourteen parameters: four electric and four magnetic charges, and the asymptotic values of the six scalar fields. We also present BPS black hole solutions of a consistently truncated STU supergravity, which are parameterized by two electric and two magnetic charges and two scalar fields. These latter solutions are significantly simplified, and are very suitable for further explicit studies. We also explore a conformal inversion symmetry of the Couch-Torrence type, which maps any member of the fourteen-parameter family of BPS black holes to another member of the family. Furthermore, these solutions are expected to be valuable in the studies of various swampland conjectures in the moduli space of string compactifications.
Ključne besede: black holes, extended supersymmetry, supergravity models, string theory
Objavljeno v DKUM: 16.10.2023; Ogledov: 237; Prenosov: 12
.pdf Celotno besedilo (636,89 KB)
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4.
Flavor symmetries and automatic enhancement in the 6D supergravity swampland
Mirjam Cvetič, Ling Lin, Andrew P. Turner, 2022, izvirni znanstveni članek

Opis: We argue for the quantum-gravitational inconsistency of certain 6D N ¼ ð1; 0Þ supergravity theories, whose anomaly-free gauge algebra g and hypermultiplet spectrum M were observed by Raghuram et al. [J. High Energy Phys. 07 (2021) 048] to be realizable only as part of a larger gauge sector ðg0 ⊃ g; M0 ⊃ MÞ in F-theory. To detach any reference to a string theoretic method of construction, we utilize flavor symmetries to provide compelling reasons why the vast majority of such ðg; MÞ theories are not compatible with quantum gravity constraints, and how the “automatic enhancement” to ðg0 ; M0 Þ remedies this. In the first class of models, with g0 ¼ g ⊕ h, we show that there exists an unbroken flavor symmetry h acting on the matter M, which, if ungauged, would violate the no-global-symmetries hypothesis. This argument also applies to 1-form center symmetries, which govern the gauge group topology and massive states in representations different from those of massless states. In a second class, we find that g is incompatible with the flavor symmetry of certain supersymmetric strings that must exist by the completeness hypothesis.
Ključne besede: supergravity theories, supersymmetric strings, quantum gravity constraints, Gauge theories, Higher-dimensional field theories, strings & branes, supergravity, symmetries
Objavljeno v DKUM: 25.09.2023; Ogledov: 180; Prenosov: 7
.pdf Celotno besedilo (317,88 KB)
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5.
All eight- and nine-dimensional string vacua from junctions
Mirjam Cvetič, Markus Dierigl, Ling Lin, Hao Y. Zhang, 2022, izvirni znanstveni članek

Opis: String and 5-brane junctions are shown to succinctly classify all known 8D N ¼ 1 string vacua. This requires an extension of the description for ordinary ½p; q-7-branes to consistently include O7þ planes, which then naturally encodes the dynamics of spn gauge algebras, including their p-form center symmetries. Central to this analysis are loop junctions, i.e., strings/5-branes which encircle stacks of 7-branes and O7þs. Loop junctions further signal the appearance of affine symmetries of emergent 9D descriptions at the 8D moduli space’s boundaries. Such limits reproduce all 9D string vacua, including the two disconnected rank (1,1) moduli components.
Ključne besede: 9D string vacua, 8D string vacua, anomalies, M-theory, Non-Abelian gauge theories, quantum gravity, string dualities, strings & branes, supergravity, Gauge symmetries
Objavljeno v DKUM: 22.09.2023; Ogledov: 211; Prenosov: 16
.pdf Celotno besedilo (1,09 MB)
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6.
Vacuum polarization of STU black holes and their subtracted geometry limit
Mirjam Cvetič, G. W. Gibbons, Zain H. Saleem, Alejandro Satz, 2015, izvirni znanstveni članek

Opis: We study the vacuum polarization of a massless minimally coupled scalar field at the horizon of four-charge STU black holes. We compare the results for the standard asymptotically flat black holes and for the black holes obtained in the "subtracted limit", both in the general static case and at the horizon pole for the general rotating case. The original and the subtracted results are identical only in the BPS limit, and have opposite sign in the extremal Kerr limit. We also compute the vacuum polarization on the static solutions that interpolate between both the original and the subtracted case through a solution-generating transformation and show that the vacuum polarization stays positive throughout the interpolating solution. In the appendix we provide a closed-form solution for the Green's function on general (static or rotating) subtracted black hole geometries.
Ključne besede: black holes, supergravity, string theory, conformal field models, string duality
Objavljeno v DKUM: 27.06.2017; Ogledov: 1543; Prenosov: 358
.pdf Celotno besedilo (372,93 KB)
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7.
Three-family particle physics models from global F-theory compactifications
Mirjam Cvetič, Denis Klevers, Damian Kaloni Mayorga Pena, Paul Oehlmann, Jonas Reuter, 2015, izvirni znanstveni članek

Opis: We construct four-dimensional, globally consistent F-theory models with three chiral generations, whose gauge group and matter representations coincide with those of the Minimal Supersymmetric Standard Model, the Pati-Salam Model and the Trinification Model. These models result from compactification on toric hypersurface fibrations X with the choice of base P-3. We observe that the F-theory conditions on the G(4)-flux restrict the number of families to be at least three. We comment on the phenomenology of the models, and for Pati-Salam and Trinification models discuss the Higgsing to the Standard Model. A central point of this work is the construction of globally consistent G(4)-flux. For this purpose we compute the vertical cohomology H-V((2,2)) (X) in each case and solve the conditions imposed by matching the M- and F-theoretical 3D Chern-Simons terms. We explicitly check that the expressions found for the G(4)-flux allow for a cancellation of D3-brane tadpoles. We also use the integrality of 3D Chern-Simons terms to ensure that our G(4)-flux solutions are adequately quantized.
Ključne besede: black holes, supergravity, string theory, conformal field models, string duality
Objavljeno v DKUM: 27.06.2017; Ogledov: 2027; Prenosov: 364
.pdf Celotno besedilo (890,06 KB)
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8.
On finiteness of type IIB compactifications : magnetized branes on elliptic Calabi-Yau threefolds
Mirjam Cvetič, James Halverson, Denis Klevers, Peng Song, 2014, izvirni znanstveni članek

Opis: The string landscape satisfies interesting finiteness properties imposed by supersymmetry and string-theoretical consistency conditions. We study N = 1 supersymmetric compactifications of Type IIB string theory on smooth elliptically fibered Calabi-Yau threefolds at large volume with magnetized D9-branes and D5-branes. We prove that supersymmetry and tadpole cancellation conditions imply that there is a finite number of such configurations. In particular, we derive an explicitly computable bound on the number of magnetic flux quanta, as well as the number of D5-branes, which is independent of the continuous moduli of the setup. The proof applies if a number of easy to check geometric conditions of the twofold base are met. We show that these geometric conditions are satisfied for the almost Fano twofold bases given by each toric variety associated to a reflexive two-dimensional polytope as well as by the generic del Pezzo surfaces dP(n) with n = 0, ..., 8. Physically, this finiteness proof shows that there exist a finite collection of four-dimensional gauge groups and chiral matter spectra in the 4D supergravity theories realized by these compactifications. As a by-product we explicitly construct all generators of the Kaahler cones of dP(n) and work out their relation to representation theory.
Ključne besede: black holes, supergravity, string theory, conformal field models, string duality
Objavljeno v DKUM: 27.06.2017; Ogledov: 1904; Prenosov: 152
.pdf Celotno besedilo (1,01 MB)
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9.
Electrodynamics of black holes in STU supergravity
Mirjam Cvetič, G. W. Gibbons, Christopher N. Pope, Zain H. Saleem, 2014, izvirni znanstveni članek

Opis: External magnetic fields can probe the composite structure of black holes in string theory. With this motivation we study magnetised four-charge black holes in the STU model, a consistent truncation of maximally supersymmetric supergravity with four types of electromagnetic fields. We employ solution generating techniques to obtain Melvin backgrounds, and black holes in these backgrounds. For an initially electrically charged static black hole immersed in magnetic fields, we calculate the resultant angular momenta and analyse their global structure. Examples are given for which the ergoregion does not extend to infinity. We calculate magnetic moments and gyromagnetic ratios via Larmor's formula. Our results are consistent with earlier special cases. A scaling limit and associated subtracted geometry in a single surviving magnetic field is shown to lift to AdS(3) x S-2. Magnetizing magnetically charged black holes give static solutions with conical singularities representing strings or struts holding the black holes against magnetic forces. In some cases it is possible to balance these magnetic forces.
Ključne besede: black holes, supergravity, string theory, conformal field models, string duality
Objavljeno v DKUM: 27.06.2017; Ogledov: 1348; Prenosov: 409
.pdf Celotno besedilo (563,26 KB)
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10.
Super-geometrodynamics
Mirjam Cvetič, G. W. Gibbons, Christopher N. Pope, 2015, izvirni znanstveni članek

Opis: We present explicit solutions of the time-symmetric initial value constraints, expressed in terms of freely specifiable harmonic functions for examples of supergravity theories, which emerge as effective theories of compactified string theory. These results are a prerequisite for the study of the time-evolution of topologically non-trivial initial data for supergravity theories, thus generalising the "Geometrodynamics" program of Einstein-Maxwell theory to that of supergravity theories. Specifically, we focus on examples of multiple electric Maxwell and scalar fields, and analyse the initial data problem for the general Einstein-Maxwell-Dilaton theory both with one and two Maxwell fields, and the STU model. The solutions are given in terms of up to eight arbitrary harmonic functions in the STU model. As a by-product, in order compare our results with known static solutions, the metric in isotropic coordinates and all the sources of the non-extremal black holes are expressed entirely in terms of harmonic functions. We also comment on generalizations to time-nonsymmetric initial data and their relation to cosmological solutions of gauged so-called fake supergravities with positive cosmological constant.
Ključne besede: black holes, supergravity, string theory, conformal field models, string duality
Objavljeno v DKUM: 14.06.2017; Ogledov: 1594; Prenosov: 173
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